Water Journal May - June 1995

AUSTRALIAN WATER & WASTEWATER ASSOCIATION

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• 16TH CONVENTION REPORT • FRESHWATER ECOLOGY • HEALTH RELATED MICROBIOLOGY

AUSTRALIAN WATER & WASTEWATER ASSOCIATION

Volume 22, No 2 May/June 1995 Editor E A (Bob) Swinron

CONTENTS

Editorial Correspondence

ASSOCIATION NEWS From the Federal President From the Executive Director Association Meetings

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Advertising Sales & Administration

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Margaret Bat.e.s Tel (02) 413 1288 Fax (02) 413 1047 AWWA Federal Office Level 2, 44 Hampden Road Artarmon NSW 2064

MY POINT OF VIEW Ecology: A Partnership of Knowledge Peter Cullen

Editorial Board

FEATURES Cooperative Research Centre for Freshwater Ecology • Eutrophication - Are Australian Waters Different From Those Overseas?

G Harris • Managing Non-Point Sources of Phosphorus From Rural Areas PW Cullen • Dissolved Phosphorus Concentration in the Darling River BT Hart, M Grace, R Beckett, J Van Verkel, R Oliver, C Rees • Billabongs, Floodplains and the Health of Rivers T Hillman • Urban Runoff - A Resource to be Managed A I Lawrence • Carp: The Prospects for Control?

J H Harris • Invertebrate Communities in Victorian Running Waters R Marchant, S Talman, R Norris ,.

Some Current Research Projects: • Lifestyle of the Toxic Blue Green Alga Anabaena Circinalis WvanDok • Benthic Community Metabolism in an Upland River System S Treadwell • Water Quality in the Thredbo River: Impacts of Nutrients on Periphyton Growth and Macroinvertebrates G Brown • The Role of Yabbies as Consumers in Billabong Ecology J Jordan, PS Lake Health-Related Water Microbiology: Australia Leads: But Where Next?

NJ Ashbolt Particle Counting in Water Treatment BA Murray Water Treatment Sludge - A Resource, Not A Waste T M Skene, J M Oades

8 9 12 15 16 19 25 28

F R Bishop, Chairman B N Anderson, G Cawston, MR Chapman P Draayers, W J Dulfer, GA Holder M Muntiaov, P Nadebaum, JD Parker A J Priestley, J Rissman

Branch Correspondents ACT-Alan Wade Tel (06) 207 2350 Fax (06) 248 3364 New South Wales - Mit.chell Laginestra Tel (02) 412 9974 Fax (02) 412 9876 Northern Terrirory - Ian Smith Tel (089) 82 7244 Fax (089) 41 0703 Queenaland.-1.qndsay Chapple Tel (07) 3835 0222 Fax (07) 3832 6335 South Au.etralia - Phil Thomas Tel (08) 259 0244 Fax (08) 259 0228 Tasmania - Dao Norath Tel (002) 332 596 Fax (002) 34 7 559 Victoria - Mike Muntisov Tel (03) 9600 1100 Fax (03) 9600 1300 West.em Au.etralia -Alan Maus Tel (09) 420 2465 Fax (09) 420 3178

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Eutrophication - Are Australian Waters Different From Those Overseas?

GHarris

Introduction Eutrophication is the term used to describe enrichment of water bodies, rivers and coastal waters by the addition of nutrients - particularly nitrogen and phosphorus. Symptoms of excessive nutrient enrichment are the development of algal blooms which may be toxic, anoxia in bottom waters, high concentrations of metal ions in bottom waters, fish kills and other undesirable aspects of water quality. From the manager's point of view it is desirable to control nutrient additions to water bodies so that they may be used for recreation or drinking water supplies. But how much control do we need to apply or can we apply?

Equally it is desirable to know if the ecology and biogeochemistry of Australian waters are significantly different from many of the much better understood waters overseas. We may then fully understand whether we may use internationally accepted management prescriptions here.

The Vollenweider Models More than twenty years ago Richard Vollenweider developed a set of semiempirical models which related nutrient inputs to freshwaters to phosphorus loadings (Vollenweider and Kerekes 1980). These models have become the industry standard in just about every country where managers wish to control nutrient enrichment and the growth of algal blooms. While much work on eutrophication and aquatic ecology has been done in the intervening years particularly in Europe and North America, for a variety of reasons little work has been done on eutrophication in Australian waters since the late 1970s.

What can we learn from this work and can it be applied here? I assert that the general level of knowledge in this country about the international literature of the last twenty years is not as good as it should be and that Vollenweider's models have been applied here very uncritically.

Vollenweider developed his models in two parts - a physical/chemical part and a biological part (Vollenweider and Kerekes 1980). His models are an elegant example of modelling complex ecological systems in a parsimonious way using a mixture of analytical and empirical relationships. Inflow and outflow of water and nutrients, water residence time and sedimentation were modelled by physically and mathematically rigorous equations. The residence time of water in water bodies is a key parameter which controls the balance of sedimentaWATER MAY/JUNE 1995

tion and outflow of nutrients. Biological interactions within the food chain such as the accumulation of algal biomass and grazing are less amenable to rigorous mathematical description and are usually treated by statistical and empirical models. Vollenweider's models may therefore be treated as two essentially separate subsets; loading models which have a sound basis in physical and chemical theory, and empirical statistical models which relate the yield of algal biomass (usually expressed as chlorophyll) to nutrient concentrations in the water (Ahlgren et al 1988).

Applicability of the Models Vollenweider's models were validated by reference to a large set of "snapshots" of data from many hundreds of lakes throughout the world. The phosphorus loading models work reasonably well for a "population" of lakes but can be quite imprecise when applied to individual water bodies (Ahlgren et al 1988).

In a detailed validation exercise Janus and Vollenweider (1981, 1984) compared the standard OECD relationships to data from 130 Canadian lakes and identified a number of situations where the usual relationships between flow, load and biomass did not hold. The statistical comparison identified the following problem areas: euphotic zone depth/mixing depth ratios > 1; high or irregular hydraulic load - rap t:l flushing; high mineral turbidity; N/P ratios < 5 and or total phosphorus > 100 mg.m¡3; P relatively inert or high internal load; dynamic equilibrium between load and in water concentration not attained. These models work well for the usually cool, oligotrophic, clear, deep and mono- to dimictic Northern Temperate lakes but many of these limiting assumptions are violated

by Australian lakes, storages and rivers.

This does not mean that Vollenweider's models are wrong, merely that they were built for a different set of hydrodynamic, geochemical, geomorphological and biogeographic conditions. Too many people forget this . The CRC expects to publish a detailed comparison of Australian and overseas data in the corning year.

The basic assumptions of the limiting case Vollenweider models are therefore annually averaged loads and in-water concentrations of phosphorus, a zero internal load and a sedimentation velocity: mean depth relationship of approximately unity. In other words the model assumes that the water body is a net sink for phosphorus and achieves a steady state at a scale of one year

(Harris 1986). This also effectively assumes that water residence times are of an equivalent magnitude. Phosphorus is assumed to be the limiting nutrient; which is true for most freshwaters but is not true for most coastal marine systems (Harris 1994a, b). These models should not be applied to estuaries and coastal embayments wber-e the residence time is difficult to estimate due to tidal exchange through the ocean boundary and where nitrogen is usually the limiting element. Nevertheless I have seen it done. Vollenweider's models also assume that allochthonous carbon loads are not a significant feature of the systems of interest. If sewage inputs are high enough to impact on the oxygen debt of the system (and therefore affect the cycling of N and P in the system independently of the autochthonous production and cycling of elements) then the models do not apply (and should not be applied by managers and consultants).

Effluent and urban runoff retention ponds have high organic loads and short retention times. Yet people studying such systems tell me the models are wrong! The CRC is developing new models for these syste-:ris.

Storm Events In Au~ralia, nutrient loadings are dominated by storm events so this requires a good knowledge of flow and load relationships for catchments as well as the receiving waters. In Gosser (1989) and Cullen and O'Loughlin's (1982) studies the proportion of stormflow was the major determinant of nutrient export and, in one case, 75-89% of the P loads to the river were carried in 2.8% of the time. Significantly, even in P deficient soils, storm erosion and runoff can be sufficient to produce P concentrations of up to 2.5 mg/L in the runoff.

Concentrations as high as this are sufficient to produce significant phytoplankton blooms in receiving waters as long as the runoff is a significant fraction of the water in the system after storms and as long as the particulate P is available for phytoplankton uptake and growth. This¡ is certainly true in parts of this country.

Storm loads are also modified by fire in catchments and by interannual climat.e variability (Simpson et al 1993).

Nutrient export regimes from Australian catchmen,ts are therefore quite different from overseas conditions at scales from ho.urs to decades.

Conceptually it is possible to develop loading models for storages and rivers with reduced residence times and storm flows but we do need to develop an new 9

suite of models to suit Australian conditions. I suspect that the Vollenweider approach of using a parsimonious combination of analytical and empirical models will work wonder s. We need to do more work in this area. The CRC is deve loping catchment models and load/re sponse models suitable for Australian conditions.

External P Load

Phosphorus Availability It has been argued that Australian waters differ from those overseas not only by virtue of their load/flow relationships and short residence times during flood but also in terms of the availability of phosphorus for algal growth (A modification of the phosphorus: chlorophyll relationship will alter the empirical part of Vollenweider's models and the ecological expression of the nutrient load). I cannot yet find data to unequivocally determine if Australian waters really are different in terms of total P availability from other parts of the world. Certainly Australian waters are more turbid than many in oth er parts of the world.

Particles in Australian waters are coated with organic material which ca n exchange P with the soluble and colloidal forms in the water. Oliver et al (1993) have r ecently published details of an Fe stripping method which effectively acts as an infinite sink for P and measures the P which can be stripped from particulate and other organic sources over a period of up to two hour s. They have reported an ex cell e n t compari so n between this method and measures of available P using algal culture experiments . They s howe d that differ e nt waters displayed quite different proportions of P in the various fractions . There was great variability in the proportions of P in the dissolved and colloidal fractions as well as variability in the fraction of total P that was desorbable by the Fe strip method. "Available" total P was at least 80% of total P in all cases. There is, as yet, insufficient data from a range of natural waters to show whether or not Australian waters really do have a significantly different di stribution s of P between available and non availab le pools. The CRC is actively working to solve this problem.

Turbidity or Sediment?

Storm remobilisation of sedimentary materials during flood s is characteristic of Australian waters. Wa s hout and down stream transport of suspe nd ed materials and algal populations is occasionally extensive. Furthermore because of the high dispersal properties of the clays in Australian catchments, a rigorous definition of what is sediment and what is turbidity dispersed in the water column is difficult to obtain. Today's sediments may be tomorrow's downstream turbidity and vice versa. It is therefore 10

DOP

Part P

Macrophytes

Sediment P Figure 1 P fluxes In ollgotrophlc aquatic ecosystems

External P Load

Fish

Macrophytes

Sediment P Figure 2 P fluxes in eutrophic aquatic ecosystems

difficult to estimate the residence times of phosphorus in Australian storages and river systems. As a result of flood s the exc hange of particulate materials between sediments and the water column is frequent. This problem is compounded by the fact that storm runoff may be sufficient to produce almost naturally eutrophic conditions in which sedim en t exc ha n ge of elements is more extensive and more imp ortant than in many overseas systems. We simply do not know enough abo ut the processe s which determine the rates of exchange of elements between sediments and the water column in Australian waters. The CRC has begun a series of workshops on sediment phosphorus dynamics and the microbial processes which determine

many of these exchanges.

Another reason why Australian storages differ from Northern European and N. American lakes lies in the turbidity levels. Turbid, subtropical storages frequently do not achieve the levels of algal biomass predicted by the Vollenweider models (Thornton and Rast 1993). Light attenuation by organic material and particles is just as important a modifier of the usual Vollenweider - type loa ding relationships as is the availability of P in the system. Indeed it 1s probably the major reason why t urbid Australian waters do not always achieve the biomass levels predicted. There are some intriguing relationships between r esidence time, evaporation, ionic strength, clay flocculation, turbidity, light penetraWA TER MAY/J UNE 1995

tion and algal bloom s in Au s tralian waters. Investigations by the CRC are expected to throw some light on this dimly understood problem.

¡ Algal Blooms Even in turbid Australian waters it can be predicted that reductions in the external load of nutrients will cause a reversion of system state to oligotrophic conditions and a reduction in the severity of nuisance blooms. Phosphorus loading reductions are the key control factor although nitrogen availability (which may be reduc ed by denit rification in eutrophic systems) is a further factor influencing the species composition of blooms. The cycling of nitro ge n and phosphorus within aquatic ecosystems is a function of trophic state . Phys ical processes (mixing and flow) are critical determinants of both biological and chemical processe s in wate r b odi es (Harris 1986).

The growth of algal blooms in the lower reaches of regulated river s is easily explained . Regulation of river flow and extraction of water increases the residence times of water in these systems so that they come to equal those in small lakes. Phytoplankton production dominates the system dynamics in the lower reache s of regulated river s .

Knowledge of phytoplankton growth in lakes and storages therefore has a direct application to growth in weir pools and regulated rivers. Management actions may be planned accordingly. Nutrient control strategie s and main te nance of flow are both important ways to control algal biomass. Participants in the CRC are working on environment,a,l flows and the relationships between algal biomass, species composition and the physical processes which dominat.e weir pools on the Murrumbidgee.

After twenty year s of furth er work on Australian and other water bodies we can now go further than Vo.ll enweid er and begin to understand why his models work (Harris 1994a,b). In particular we can now understand why the empirical phosphorus: chlorophyll ratio is the way it is . Increase d nutri ent loadin gs to water bodies drive a sequence of events within the ecological structure of the system. Blooms arise when external nutrient loadings exceed the capacity of the grazing food chain to ass imilate and recycl e nutri ents (Fig 1). Onc e t hi s capacity is exceeded, nutrient concentrations in the water begin to rise, larger celled species (or colonial forms) begin to predominate, phytoplank t on bioma ss increases, grazing efficiency decr eases and the nutrient r egeneration mechanisms become predominantly benthic (Fig 2). A large number of other changes in food chain and ecosystem structure accompany these changes in food chain dynamics. We now know that control of WATER MAY/JUNE 1995

nutrient loadings (in particular, phosphorus) to water bodies can control ecosystem structure and function . Many features of ecosystem structure can therefore be predicted from a knowledge of nutrient loadings, water residence times and morphometry.

Grazing Species Equally it is known that certain "keystone" species such as large Daphnia can control the development of algal blooms through grazing . Work in the northern hemi sph er e (Mazumder 1994a,b) has shown that lar ge Cladoceran grazers can significantly reduce algal biomass in storages and that, und e r certain circumstances, manipulation of food chains can be used to control algal blooms. The CRC is pursuing similar work in Australian storages (Matveev 1995) and seeks to understand more about the distribution, biomass and population dynamics of zooplankton that might act in this way. It must be remember ed that the biogeography of the Australian continent is quite different from the rest of the world and that we have a multiplicity of endemic species. As someone said to me recently "the first thing we should do is throw away our copies of Ward and Whippl e and do some home grown taxonomy".

The CR C is ac tively involved in work which aims to understand more about the identity, distribiition, abundance and roles of the Australian aquatic fauna.

Which Species of Alga?

Nuisance algal blooms are known to arise from the alterations in ecosystem structure and function which r esult from increased nutrient loadings. As Jone s (pers comm) has pointed out, even small amounts of al gal biomass can cause severe public health problems if the biomass is in just one toxic cyanobacterial species. We do get fr equent toxic outbreak s ca u se d by spec ies such as Anabaena and Micr ocystis. Th er e is, however , nothin g peculiar about th e algal species composition of Australian rivers and storages. Unlike the zooplankton many of the phytoplankton are quite cosmopolitan. Detailed comparisons of t he specie s compo sition of Au stralian storages (Harris and Baxter 1995) with that in subtropical impoundm ents in Africa and S. America (Tailin g 1986, Tundisi et al 1993) shows that we have many of the same species of Melosira, Synedra, Microcystis, Cylindro-spermopsis, and Oscillatori a as t hey do . Th e riverine species of Africa are also largely the same as her e.

Is it possible to predict which species might occur and in particular if they are going to be toxic ones? Predic tions of the species composition of algal blooms are much less secure than predictions of biomass and are based on a number of

contingent factot.s: the vagaries of immigration, biogeography, climate variability and ecological interaction to name but a few. Because of the complex non-linear interactions between components of the aquatic ecosystems, predictions of the occurrence of part icul ar spe ci es are fraught with uncertainty and probably always will be. Nevertheless Reynold s and others have shown that it is possible to predict the species composition of natural waters to some extent (Reynold s 1984, Harris 1986) - so more work needs to be done on this in Australian systems.

Th e contingen_t variability of aquatic ecosystems at the level of species is driven by a variety of processes which fluctuate at a range of temporal and spatial scales. Manipulation of species composition may be possible by means of alterations in the frequency components of environmental fluctua tions using techniques such as artificial destratification (Steinberg and Zimmerman 1988). The CRC has .fust embarked on a major prJt gram of artificial des tratification at Chaffey Dam in order to study the geochemical and ecological consequences of this management tool in an Australian storage.

Summary The r ece nt extensive outb r eaks of cyanobacterial blooms in Darling River show that eutrophication is still a problem in Australian waters. We ne ed to learn as much as possible from international "best practice" and to apply what we can he e. We also need to know in what ways Au stralian ecosyste ms are unique so we will know when we need local prescrip tions. Th e_application of Voll e nweid er 's mod els to Australi a n water s is but one example of a situation wh er e uncritical importing of overseas r esearch knowl edge and ma nagement techniques is no t necessarily the best option. The CRC mission is to show that a so phi sticate d und er sta nding of Australian aquatic ecology is an essential component of "sustainable development" in this country which can be translated into effec t ive man agement action and government policy.

References Ahlgren , I, T Frisk and L Kamp-Nielsen (1 988) E mpirical and theoretical models of phosph orus loadin g, r ete ntion and co nce ntration vs lake trophic sta te. Hydrobi ologi a 170 : 285303 Cosser, P R (1989) Nutrient conce nt.ration - fl ow r elationships a nd loads in the So uth Pin e Ri ve r ,So uth-easte rn Qu ee ns la nd. 1.

Phos phorus loads. Australian Jnl Mar and Freshwater R es, 40: 613-~0 Cullen, P and E M O'Loughlin (1982) Non point so ur ces of pollu t io n . p.437-453 in "Pr e d ict ionin wate r q u ality" ed s E M O' L o ug hlin and P C ull e n, Au stra li an Academy of Science, Canberra Harris , G P (1986) Phy to plank to n eco lo gy, Chapman and Hall, London Harris, G P (1994a) Nutrient load ings and algal

11

blooms in Australian waters - a discussion paper.LWRRDC Occasional paper No. 12/94, 99p.

Harris, G P (1994b) Pattern, process and prediction in aquatic ecology. A limnological view ofsome general ecological problems.

Freshwater Biology 32: 143-60 Harris, G P and Baxter, G (1995) Interannual variability in phytoplankton biomass and species composition in North Pine Dam, Brisbane. Freshwater Biology. (in prep) Janus, L L and R A Vollenweider (1981) The OECD cooperative program on eutrophication. Summary report, Canadian contribution. Scientific Series No . 131, National Water Research Institute, Canada Centre for Inland Waters, Burlington, Ontario Janus, L L and R A Vollenweider (1984) Phosphorus residence time in relation to trophicconditions in lakes. Verh Internat Verein. Limnol. 22: 179-184 Matveev, V (1995) The dynamics and relative strength of bottom-up vs top-down impacts in a community of subtropical lake plankton.

Oikos 72 (in press).

Mazumder, A (1994a) Phosphorus-chlorophyll r elationships under contrasting herbivory and thermal stratification: predictions and patterns. Canadian Jnl . Fisheries and Aquatic Sciences . 61: 390-400 Mazumder, A (1994b) Phosphorus-chlorophyll relationships under contrasting zooplankton community structure: potential mechanisms.

Canadian Jnl. Fisheries and Aquatic Sciences. 61: 401-7 Oliver, R L, B T Hart, G B Douglas and R Beckett (1993) Phosphorus speciation in the Murray and Darling Rivers. Water, 20(4): 2426 and 29 Reynolds, C S (1984) The ecology of freshwater phytoplankton. Cambridge University Press Simpson, H J, M A Cane, A L Herczeg, S E Zebiak and J H Simpson (1993) Annual river discharge in South-eastern Australia related to El Nino-Southern Oscillation forecasts of sea surface temperatures. Water Resources Research 29: 3671-3680 Steinberg, C E W and G Zimmermann (1988) Intermittent destratification: a therapy measur e against cyanobacteria in lakes.

Environmental Technology Letters 9: 337 350 Tailing, J F (1986) The seaso nality of phyto¡ plankton in African lakes. Hydrobiologia 138: 139-160 Thornton, J A and W Ras t (1993) A test of hypotheses relating to the comparative limnology and assessment of eutrophication in semi-arid man -made lak es. p. 1-24 in "Comparative Reservoir Limnology and Water Quality Management", M Straskraba, JG Tundisi and A Duncan (eds) Kluwer, Dord.recht Tundisi, J G, T Matsumura-Tundisi and M C Calijuri (1993) Limnology and management of res erv oirs in Brasil. p25-56 in "Comparative Rese rvoir Limnology and Water Quality Management", M Straskraba, J G Tundisi and A Duncan (eds) Kluwer, Dordrecht Vollenweider, R A and J Kerekes (1980) The loading concept as a basis for controlling eutrophication: philosophy and preliminary results of the OECD programme on eutrophication. Progress in Water Technology. 12: 538, IAWPR Pergamon Press

Managing Non-Point Sources of Phosphorus From Rural Areas P WCullen

Introduction Regional water quality planning requires a consideration of both point and non-point sources (single and diffuse sources), as well as the capacity of the receiving waters to handle the pollutant load without unacceptable change. While the assessment of loads from point sources is relatively straightforward, assessing the magnitude and importance of non-point sources is more difficult.

Nevertheless, it is now accepted that it is not reasonable to look at either one in isolation. An effective water quality management plan will require attention to each, and an acceptable solution may require attention to both sources.

Sources of Phosphorus When rain runs off land it transports phosphorus in both dissolved and particulate forms to water bodies. Non-point sources contain particulate material, comprising soil particles, plant material, animal excreta and other substances.

Runoff is the driving factor that cause phosphorus to move from catchment to water body.

In rural lands throughout much of Australia the rocks and consequently the soils are low in phosphorus, and phosphorus has been added to these soils to sustain a viable agriculture. This fertilizer can be lost if it is applied directly to waterways or streambanks, and if a runoff event occurs before the grain of fertiliser slakes down and the phosphorus bonds with soil particles. The grass and organic materials produced as a result of phosphorus applications are further sources of phosphorus, as is the animal excreta produced after stock eat the grass.Some soils are naturally higher in 12

phosphorus than most. Soils formed on basalt in the New England region are one example. These soils are thought to be important in the eutrophication of storages like Chaffey.

Mobilisation and Transport Pathways Rain is the driving force behind nonpoint sources of phosphorous. It and runoff provide the energy that detaches and transports particles of phosphorous.

Receiving waters are therefore subjected to pulses of contaminants, determined largely by rain. The longer the period between rains, the more material there is available to be washed off.

Generally phosphorus does not move through the subsoil, since it is precipitated as insoluble compounds or bound to clays. This mechanism does not seem to apply to sandy soils (eg. Peel-Harvey inlet), soils with many large channels (roots and wormholes seem important in some of the Mt Lofty work) and from soils that have received large amounts of phosphorus from waste discharge over a long period (abattoir paddocks at Blayney).

Observations on Phosphorus Exports Loads are more useful than concentration. When thinking about the contaminants that enter a receiving water it is important to think of loads not concentrations. It is possible to have a high concentration but if the amount of water involved is low, the amount or mass of contaminant is low. It may not matter. Load is calculated by multiplying the volume of water (in, say, ML) by the

concentration (in mg / L) and may be expressed as kg/yr or as kg/ha/yr.

Attempts to measure phosphorus export should be done at a flow gauging station, preferably one that has a long run of data so the period of concentration measurements can be seen in the long term flow context. However, we normally have a continuous record of stream .flow, but only intermittent measurements of concentration.

Since export takes place during runoff events, sampling needs to be based on flow, not time.

There is not much point taking a lot of concentration measurements during low, dry weather flow periods. The concentrations will not vary much; the loads themselves will be minor in comparison with what is moving during high flow events. The trade-off between reliability of load estimates vs cost of sample collection, transport and analysis is a critical issue.

Measurements of pollutant exports are very expensive since facilities to collect and analyse large numbers of samples must be maintained for the high runoff events. This requires a capability to get staff into the field within a few hours of the runoff starting if automatic data collection devices are to be kept operational. The costs of these studies should not be underestimated . It is important to collect data from a range of runoff events. Since it is important to measure exports under flood conditions it may be necessary to collect data for several years to catch such high flow events.

Flow is very much more important than concentration in estimating high flow nutrient loads.

WATER MAY/JUNE 1995

Table 1. Influence of Flow on Exports of phosphorus, Monkey Creek 1988-9 Sampling Period Flows over 2400 ML/d 1200 ML/d 600 ML/d 300 ML/d Entire

Days

%

No. 3 6 10

25 314

1 2 3 8 100

Flow

cumulative %

kg

cumulative %

21672 26407 29772 35984 52994

41 50 56 68 100

1764 1989 2123 2334 2874

61 69 74 81 100

Typically, concentrations increase two-five fold whereas the flow may increase by three or four orders of magnitude, eg: Baseflow, 12-2 0 Âľg P/L: Quickflow, 100-250 Âľg P/L. There is no doubt that under dry weather conditions sewage discharges may be dominant in a catchment but under wet conditions they may be trivial.

The importance of wet weather events can be clearly seen in Table 1.

These results show that 61% of the phosphorus and 41% of the water transported in Monkey Creek moves in 1% of the time during our study. This is not atypical of other studies. When considering the nutrient movements from the point and non-point sources of a catchment it is therefore misguided to consider only dry weather flow. While this is a nice simplifying assumption for tho se who can't understand probability, it will give a very biased view of the sources of phosphorus.

The Monkey Creek data set cost more than $350,000 to cover most storm events throughout the year. This included collecting more than 5000 concentration measurements as well as flow data from six stations. Measurement of nonpoint pollutants is technically difficult and costly.

Sediment Storage and Release.

One reason given for ignoring enormous flood flows of phosphorus is that they are bound to particulates and will settle to the bed of the lake or river under lower flows. This is true. The assumption that in this settled state they cannot contribute phosphorus back into the water column to stimulate algal growth is certainly wrong. Often where shallow lakes have not responded to reduction in external phosphorus load, the sediments have been found to be supplying phosphorus to the water column at critical periods. This is called internal loading.

The sediment release may not be significant on an annual basis, but may be critical when considered on a seasonal basis. In lakes such as Lake N orrviken in Sweden, a substantial release of phosphorus has been observed in summer, and this supports algal blooms during period s of low inflows and hence low washout. This process appears to occur in shallow, well mixed lakes (mean depth 1-6 m) . Understanding of the processes WATER MAY/JUNE 1995

PExport

ML

controlling phosphorus release from sediments under aerobic conditions is limited.

Nutrient inputs from catchments can be measured and modelled but as yet we have no useful models that predict the high sedimentation found in erodable Australian catchments. Our understanding of the release proces ses is inadequate, and the observation that significant fluxe s of phosphorus can be released from sediments in a period as short as a few weeks makes prediction difficult. This is likely to be important in Australia where the one in 20 flood event may transport enough phosphorus to maintain a eutrophic system over the following year. Lawrence (1993) has identified the importance of organic carbon in sediment, when sewage di scharges are present, in enhancing this microbial sediment release.

Assimilation - Does Phosphorus Disappear or Just Get Stored?

As we move down a river it is common for phos -horus to drop out of the water column. This occurs as particles settle in pools and dissolved phosphorus is taken up by macrophytes and attached algae (biofilms). Despite the fantasie s of some water quality modellers, no-one has discovered the refutation of the law of conservation of mass. The phosphorus does not disappear; it goes into a store from which it may be remobilise d by higher flows. This r emobilising is often what confuses people about first flush effects.

This process r equires care in defining what are the receiving waters of concern.

Bioavailability Much of the pho sphoru s in water is attached to soil and organic particles.

Even the soluble phosphorus from fertilizer and sewage will rapidly attach to exchange sites on suspended particles in turbid Australian waters. This attached phosphorus can also come off the particle and support algal growth. On the other hand, some of the phosphorus is of geological origin and is only going to be available at a much slower rate. It is an active area of research within the CRC for Freshwater Ecology to try and mea-

sure bioavailable phosphorus in waters.

It is argued that dissolved phosphorus better represents biologically available phosphorus. By the time we measure phosphorus in a stream much of it exists as particulate phosphoru s, especially during high flow. Some argue that this form is less available than the dissolved phosphorus coming from sewage. How realistic is it to compare 1000 kg of phosphorus coming from 35 sq km of catchment with 1000 kg coming from a sewage treatment works? Under laboratory conditions it has been shown that up to 47% of the total phosphorus in lake se diments can be extracted by phytoplankton in a period of 3-4 weeks under aerobic conditions (Rosich & Cullen, 1980).

As a general assumption, I believe particulate phosphorus s hould be thought of as largely available to algae.

If it stays in suspension it will, however, be available at a slower rate than dissolved phosphorus. If it is available more slowly to algae then it might slow the rate of algal growth without necessarily having much influence on the final biomass that develops in the long growing season typical of Australian waters. To cope with this situation, The National Capital Development Commision (1981) developed the concept of effective phosphorus which gives weightings to the various forms of phosphorus from different sources: Effective P - Sewage P + 0.3 Urban Runoff P + 0.1 Rural runoff P.

Tools for Predicting Phosphorus Exports The most simplistic approach to estimating phosphorus expor ts is to use export coefficients which give an estimate of the phosphorus released per hectare each year. Some commonly use d estimates are shown in Table 2 (Cullen & O'Loughlin, 1982). Given the information from our Monkey Creek work the simplistic use of mean annual exports of this sort should be done with care.

A computer version bas ed on this approach has been developed by CSIRO, called CMSS, which is based on these sor ts of mean annual exports. A manual of likely exports is available, and so once land uses are identified the export from a catchment is calculated .

A more sophisticated approach is to relate phosphorus exports to runoff voiumes . The "POLLUTE" model, the pollutant generation part of AQUALM, (Phillips et al,1992) does this on a daily runoff basis. This is based on data from the Canberra region. (Table 3). It allows one to take a long term rainfall record and, using rainfall-runoff models, to identify likely phosphorus exports over a long period (say 20-50 years) to see how particular data fits into the long term picture.

13

Table 2. Some Typical Planning Estimates of Non-point Phospho1-us · export, kg/ ha/yr Forests

< 0.1 kg

Poor quality grazing Intense Grazing

0.2 kg 0.6 kg

Urban Areas

1.2 kg

Table 3. Influence of rainfall on ea-port of phosphorus kg/100 ha per day Urban Rural

0.39R 0·' 0.115R 0·"

Where R is the rainfall in mm/day

Land Management Interventions Input Controls. Land use controls: Traditionally Australia has allowed rural landhold ers considerable freedom in determining land use. Currently, envir onmental r egulatory agencies implement controls over pollution from dairies and feedlots rather than r equiring controls over non-point sources.

Land Manage'n'Wnt: The techniques of conservation cropping and controlled stocking rates are important aspects of land management long recognised by the best farmers. These techniques need to be more widely used.

Fertilizer controls: Farmer s pay a lot of money for fertilizer and are interested in ways they can keep it on the land rather than wasting it. There seem to be so me basic goo d hou sekeeping principles (Cullen, 1991).

• Ensure fertili zer s are not applied directly to streams and buffer areas, and they are ap plied in ways that ensure they will be retained onsite rather than washed into waterways . Thi s may involve sub-surfac e application rath er than broadcasting.

• Consider the advantages of multiple small dressings.

• Evaluate rock phosphate and other slow release formulations of phosphatic fertilizer s to reduce loss.

• Educate the users of fertilizer to avoid applying fertilizer immediately befor e rainfall (that was thought to wash it into the soil, but we now understand it washes off).

Land disposal of wastes: Land disposal of effluen ts and other wastes is attractive in the context of ecologically sustainable development. Good hydrologic information and moni to rin g is required to ensure we are not just transferring problems as non-point sources or to groundwater.

Mobilisation and Transport Controls. Vegetation cover and grazing rates: We should encourage landholders 14

to adopt basic soil conservation management and ensure the maintenance of a vegetative cover on the land . Conservation cropping and effective control of grazing rates can achieve this.

Drought management: Drou ghts commonly end with "flooding rains" that wash enormous amounts of soil, phosphorus and organic matter into river s.

After the 1982 drought broke I saw farm dams with up to a metre of sheep dung floating on them, washed off the catchment in the first runoff event. Th ese large transfers of nutrients and organic matter to rivers and storages may well cause r aised nutrient levels for decades in those receiving waters, due to sediment release. This export of contaminants is much greater when the catchments have been denuded of vegetation, as occurs during drought.

If sustainability is to have any meaning in t he Australian context it must mean getting away from the notion that drought is so me unforeseen disaster, that is always claimed to be the worst in 100 years. The reality is we seem to have at least two to four years of drought every decade, and we had better start learning to live with this variable and unpredictable rainfall.

The key as pect in the drought context is keeping some vegetative cover on the land and on the river banks. In my view there are a number of land management practices that should be encouraged.

• We should encourage farmers who are hand feeding to stock to do so in small penned areas away from water courses that can be sacrificed. At present we get deve,getation on a landscape scale which ca uses major probl e ms late r. In my view, any Governmental assistance for supplementary feeding should be conditional upon such arrangements.

• Failing the above, we should at least try to protect so me vegetation on the paddocks adjacent to water courses.

• Given the improving capacity of the Bureau of Meteorology to give longrange forecasts we need to develop a better drought warning system. I can envisage say a three-stage alert system that would trigger the sor ts of management practices identified above. The trouble at present is that by the time we appreciate we are in a maj or drought, much of the dama ge ha s been done. A Stage 1 drought aler t might require farmers pullin g stoc k out of paddocks along water courses.

• A drought management plan at the property level should be developed and its existence and evidence of implementation should be a requirement for being eligible for any Government assistance in this area. Perhaps farmers in this situation should get earlier assistance since they would be incurring costs earlier.

There would be a significant public good in avoiding the damage we now incur.

Trappigg Strategies. Fencing an<i Buffer strips: Fence stream banks ir

sensitive catchments to prevent stod destroying streambank vegetation whicb leads to erosion and the loss of produc tive land due to scouring during flood s.

Water needs to be supp li ed to stod away from the str eamb ank . This will also reduce direct faecal contamination.

Ensure there is a reasonable , ungrazed buffer strip between these fences and the river, perhaps up to 10m in width. (eg. Weaver et al, 1994 ). WE should certainly look to reclaim Crown reserves along watercourses as a meam of improving water quality, as well as securing the valuable nature conservation benefits from s uch riparian reserves. We need to ensure these public land s are effectively managed so that weeds, fir e and vermin do not create more problems.

Wetlands: Farmers should be encouraged to develop water pollution control ponds on watercourses. These should be planted with aquatic macrophytes and fenced. These can be use d as drought fodder through direct grazing under controlled conditions or by harvesting the plant materia l, as well as providing emer ge ncy water. These would t r ap nutri ents and se dim e nt and provid e some drought r eserve.

Trapping and Recycling: Look to recycle land runoff for irrigation so as to use the fe rtilizers that would otherwise be lo st. Req uir e ani mal wastes from dairies or other intensive congregation zone to be treated using wetland pollution control ponds or other appropriate technologies.

Use with Caution! There is little expe rim e n ta l d ata from Australian sources to support these "best management practices". They are however, reasonable approaches to land management given our present understanding of pollutant generation and transfer processes. They await experimental validation and demonstration in a catchment context (Cullen 1994).

Conclusions

The export of phosphorus from nonpoint sources is a significant component of potential eutrophication. Management at the farm and catchment level is a fundamental element of water quality planning in many areas where eutrophication of water has been a concern. There are a number of approaches to good land management which now need to be demonstrated and evaluated in different areas.

It may well involve less cost to the community to r equii;e s uch land management than to have further investment in advanced sewage treatment in some catchments.

References Cull en , P W (1994) Nutri e nt Runoff from

WATER MAY/ JUNE 1995

Agricultural Land. Proc of 24th International Dairy Congress. Melbourne, Cullen, P W (1991) Land Use and Declining Water Quality. Aust.J.Soil & Water Conservation. 4. No 3 4-8.

Cullen, P.W. and O'Loughlin, E.M. (1982). NonPoint Sources of Pollution. In 'Prediction in Water Quality' . Ed. O'Loughlin and Cullen, Aust. Acad. of Science, Canberra.

Lawrence A I (1993) Establishing Nutrient

'Biogeochemis t ·y of Ancient and Modern Environments'.

Trudinger, P.A., Walter, M.R. and Ralph, B.J. (Eds). Aust. Acad. of Science, Canberra and Springer-Verlag, Berlin, pp. 117- 122.

Weaver D M, Pen L J, Reed A E G. (1994) Modifying the phosphorus cycle to achieve management objectives in the Oyster harbour catchment. Water 21,1 28-32

Targets. Algal Management Strategy.

Background paper No.3. Murray-Darling Basin Commission. Canberra.

Phillips B C, Lawrence A I, Bogliatzis T (1992) An Integrated Water Quali ty and Streamflow Model Suite. Int. Symp. on Urban Stormwater Management. Sydney.

Rosich, R.S. and Cullen, P .W. (1980) . Lake Sediments : Algal Availabil ity of Lake Burley Griffin Sediment Phosphorus. In

Dissolved Phosphorus Concentration in the Darling River BT Hart, M Grace, R Beckett, J Van Berke4 R Oliver, C Rees There is considerable research activity in Australia investigating the factors that cause blue-green algal blooms in lowland rivers, such as the MurrayDarling River system. This brief article reports some of the latest results from a collaborative study on the factors controlling the concentration of dissolved phosphorus in the Darling River.

Phosphorus is well known as one of the major factors, but certainly not the only one, that causes algal blooms in aquatic systems. The study is being undertaken by two groups within the CRCFE (WSC Monash University and Murray-Darling Freshwater Research Centre) and the CSIRO Division of Water Resources. It is funded by the Murray-Darling Basin Commission.

Forms of Phosphorus Phosphorus can exist in a river in many forms, the most common being the orthophosphate ion, dissolved organic forms, and phosphorus associated with solid materials (e.g. colloidal and particulate matter in the water column and bottom sediments). Orthophosphate is the most biological available form, although there is evidence to show that under certain conditions phosphorus in other bound forms may also become available (Oliver et al, 1993).

The role of phosphorus in lowland rivers in Australia has been little studied, despite the large number and importance of this type of river system in Australia. Australian lowland rivers differ from those well studied systems overseas in at least two respects - they have a much more variable flow regime, and are generally more turbid (Harris, 1994).

The CRCFE Darling River research program has focused on two aspects of phosphorus dynamics in lowland rivers - the development of better methods for measuring 'bioavailable' forms of phosphorus, and the factors controlling the concentration of 'bioavailable' phosphorus (emphasis on dissolved orthophosphate) in the river. We consider here some recent results on the latter aspect.

Speciation A new method for obtaining informaWATER MAY/JUNE 1995

-.

'dissolved' reactive phosphorus in the Darling are high in comparison with most other rivers, which are typically in the range 5-20 µg/L, and this suggests that it is unlikely that phosphorus would limit algal growth in this river.

Until now, the standard method for measuring 'dissolved' phosphorus has been to filter samples through a 0.45 µm filter. However, our studies show that there is often a large difference, up to 40 µg/L, between the 'dissolved' phosphorus concentrations in the <0.45 µm and <0.003 µm fractions. Thus, the standard <0.45 µm measurement is not a good indicator of the true dissolved phosphorus concentration, and in the Darling

tion on nutrient speciation in natural waters, based on the use of continuous flow centrifugation (CFC) and tangential flow filtration (TFF), has been developed . Water samples are fractionated into four fractions as shown in Figure 1.

Data typical for the Darling River at Bourke shows that most of the P is in the dissolved fraction (<0.003 m) and the large particulate fraction (> 1 m) (Figure 2). The relatively high P concentrations in the 'dissolved' fraction (45-126 µg/L) , are mostly present as reactive phosphorus (80 - 100%), and are therefore probably in the form of orthophosphate or very easily hydrolysed organic phosphorus compounds. The concentrations of

400

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3000

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,1000

250~-------------,

150

Feb 94

Figure 2. Total phosphorus concentration infour fractions (particulate, large colloida4 small colloidal and dissolved) separated from Darling River water samples collected from the Bourke weir pool.

Figure 1. Separation technique used for Darling River water samples (CFC - continuous flow centrifuge, cut off ca.

1 um; TFF - tangential flow filter (Millipore Minitan system))

200

Ott 93

Oct93

, _ _ _ _ _ Fraction C (colloids)

~

300

~

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> I µm fraction ol 1-0.2 µm fr:iction 0.2-0.003 µm fraction <0.003 µm frac1ion

300

400

500

P added ,. solution (µg/L)

Figure 3. Phosphorus adsorption isotherm for a Darling River sample taken from Bourke wei1· pool in November 1994.

0 0. 10

e

I

• • • •

0.30 r,1rllcle dh1meler (µm) 0.20

0.40

Figure 4. Surface adsorption density (SAD) vs particle size for a water samr ple collected from the DarlingRiver.

15

River would lead to a substantial overestimate of the available phosphorus.

The rather high concentration of phosphorus in the ' dissolved' frac tion was quite unexpected given the very high concentrations of colloidal and particulate matter in this river. We had expected that most of the dissolved reactive phosphorus would have been taken up by the particles, since t here have been many studi es sh owing that orthophosphate is rapidly and readily taken up by most naturally occurring solid matter (eg soils, sediments and suspended particulate matter), particularly those containing high concentrations of iron oxides (Fox, 1993). Our findings are therefore even more surprising given that (i) t he concentrations of hi ghly adsorbent iron oxides in the particulate matter are relatively high (3-8% as Fe), and (ii) the particulate matter does not appear to have very high total phosphorus conc entrations associated with it (360-840 µ/ g), suggesting that t here should be excess capacity to sorb phosphorus.

So the question we need to answer is: why is the colloidal and SPM in the Darling River such a poor adsorber of phosphorus?

Adsorption Three types of studi es are being undertaken to investigate the capacity of the colloidal and particulate matter to sorb pho sp horu s . Th e first invo lves adding increasing amounts of radiola-

belled orthophosphate (33 PO/ is used) to unfiltered Darling River water, equilibrating for 24 hours, fractionating using th e method depicted in Figure 1 but omitting the CFC step, and then determining the amount of 33 P remaining in solution. A typical result is shown in Figure 3. Despite the rather strange behaviour at low concentrations of added phosphorus, it is apparent t hat little orthophosphate was adsorbed by the colloidal and particulate matter (maximum ca. 200µg/g).

The second type of study is aimed at obtaining information on the amount of the phosphorus in each fraction that is easily exchangeable with phosphorus in t h e 'disso lved' fraction. Unfiltered Darling water is spiked with " PO 4·•(only picograms of phosphorus added, so there is little perturbation of the system), then this is fractionated and the activity of 33 P in each fraction determined. The rate of exchange was rapid, with equilibrium achieved after about 2-3 hours. For one sample taken in June 1994, only 10-15% of the total phosphorus in the colloidal and particulate fractions was ab le to exchange rapidly with dissolved phosphorus.

Recent work by Van Berke! (1994) has provided a possible ~Jue on the reason why the Darling River colloidal and particulate matter is such a poor adsorber of orthophosphate. He measured the surface adsorption density (SAD) distribution - the amount of phosphorus sorbed per unit area of particle surface as a function of particle size - for particulate

matter from\ithe Darling River, using a new separation technique called field flow fractionation (FFF - Beckett and Hart, 1993). Somewhat unexpectedly, he found that t he SAD was significantly increased when the organic matter was removed from the particles using hydrogen peroxide (Figure 4).

Currently, we are testing the hypothesis that natural organic material associated with the colloidal and particulate matter is responsible for the low sorption capacity of these particles, possibly by reducing the number of sorption sites on the hydrou s iron oxide (and other metal oxide) coatings.

References Beckett R and Hart B T (1993) The use of fieldflow fractionation techniques to characterise aquatic particles, co lloids and macromolecul es . In 'E nvironmen tal Particles, Vol 2' (Eds.J. Buffle and H. P . van Leeuwen), pp 165-205. Lewis Publishers, London.

Fox L E (1993) The chemistry of aquatic phosphate: inorganic pro cesses in rivers.

Hydrobiol.253, 1-16.

Harris G P (1994) Nutrient loadings and algal blooms in Australian water s - A discussion paper. LWRRDC Occasional Paper No 12/94, Canberra.

Oliver R L, Hart B T, Douglas G B and Beckett R (1993) Phosp hor us s pec iation in th e Murray and Darling Rivers. Chem. Australia 60, 392-397.

Van Berke! J (1994) The study of orthopho sphate adsorption onto natural colloidal particles., Honou ;·s t hes is, Chem istry Dept, Monash Univ, pp68.

Billabongs, Floodplains and the Health of Rivers T Hillman

Introduction For many of the world's larger river systems much of the total aquatic habitat is found away from the main str eam in the form of anabranches, backwa ters, cut-offs, and shallow floodway s. In Australia many of these floodplain water bodies, usually without significant flow, are referred to as billabongs - a word of Aboriginal derivation. The role of these ha bitats in the ecology of fl oodp lain rivers has been discussed by Welcomme (1979). Their particular significance in the highly variable and 'unpredictable' hydrological conditions of SE Australian rivers has also been noted (Hillman, 1992).

and time (Hillman 1986). It follows that much of the billabong biota is widely-tolerant and exhibit opportunistic responses to environmental change (Boon et al 1990). Small organisms appear to be particularly abundant and active in billabong communities. Boon (1991) indicated that the rate of bacterially-mediated

Interactions Between River and Floodplain Aquatic Ecosystems

The Nature of Billabong Ecosystems Billabongs are biologically quite distinct from their 'parent' rivers - at least in terms of their invertebrate communities (Hillman & Shiel, 1991). They are highly variable in terms of physical and chemical characteristic s both in space 16

decomposition was abo ut one hundred times greater in billabongs than in other aq uatic ecosystems. Similarly microinvertebrate biodiversity is significantly greater (one to two orders of magnitude) in billabongs than in equivalent river sites (Cranston & Hillman 1992).

Typically, then, billabongs are variable but highly productive systems supporting a large and diverse biomass dominated by microorganisms and microinvertebrates.

Floodwaters sweep thefloor efthe Barmah Forest

Although part of the biota (eg vertebrates other than fish, and adult insects) is capable of moving freely between the two systems, mose in teraction takes place when they are joined by water during appropriate flow conditions. The ecological dynamics of these periods of interaction are under active investigation currently and are critical to fu ture ecological management of river r esources.

WATER MAY/JUNE 1995

Response of floodplain systems to inundation. The supply of water from the river to the floodplain elicits a number of biological responses.

Inundation of flood-adapted terrestrial vegetation not only supplies necessary water but also acts to determine community structure (Bren & Gibbs 1986) along a gradient of flood frequency and duration.

In ephemeral wetlands organisms adapted to drought respond quickly to inundation. Studies of experimental inundation in the Barmah-Millewa Forest indicate that substantial communities of micro-invertebrates occur within a week of flooding (R Shiel pers. comm.) followed quickly by planktivorous macroinvertebrates (mainly mobile hemipterans and coleopterans) and the development of complex billabong foodwebs (Hillman & Nielsen 1995). Maher and Carpenter (1984) observed very high productivity in ephemeral waterbodies during the first year of inundation. In preliminary experiments there is some

indication that not only the rate of development but also community composition is influenced by temperature, implying that the time of year in which inundation occurs may modify the community response.

The biota of permanent billabongs also react to inputs of river water.

Dilution by the influx of river water and the resultant variability in water level probably contribute to maintaining temporal and spatial diversity of aquatic plant communities and the biota they support (Boon et al 1990). Tan and Shiel (1993) observed rapid shifts in species composition of billabong zooplankton and a significant increase in biomass within days of a four-fold increase in water volume. The increase in zooplankton densities combined with increased water volume indicates a significant jump in prod uctivity following inundation. This response is currently being explored experimentally.

Floodplain Inputs to the River.

Whereas the floodplain derives mainly

Figure 1. Frequency ofRiver Murray flows exceeding various levels expressed as weekly means during 1974-1990. Observed flows are compared with flows estimated to have occun-ed in the absence ofHume Dam hcHdlng 20000Ml/doy

bctâ&#x20AC;˘dlnt 2'000 MlJdoy

bc11dln11 JOOOOMlJdor

I

11 1: Table 1: Likely ecological response to flow events and impact of human intervention Flow Event

Response within maJor components of floodplain river ecosystem: Terrestrial floodplain aquatic River floodplain

Impact of:

River Regulation

Levees

Major flood

General supply of water.

Removal of flood prone plant species determination of community structure.

Recharge of most water bodies.

"Re-setting at maximum capacity.

Impact of allochthonous material of terrestrial origin.

Nil

Re-direction catastrophic break-through floodplain alienation.

Minor flood s

As above on reduced scale.

As above on reduced scale.

Connection of higher billabongs

Allochthonous material from floodways

Reduced frequency

Floodplain alienation

High flows

Nil

Recharge and connection of billabongs joined below bank-line

Access to resources for larval fish.

River Inocculation.

Seasonal displacement at some sites

Floodplain alienation .

WATER MAY/JUNE 1995

physical resour1._es from the river a growing body of evidence indicates that the floodplain contributes significant biological resources to the parent river ecosystem both during floods and at times when flows are sufficient to put the main stream in contact with billabongs.

Floods. The significance of flows which over-top the river banks was identified by Welcomme (1979) and has been refined in the "flood pulse" concept of Junk et al. (1989). Over-bank flows, in addition to connecting floodplain water bodies to the river, have the potential to sweep organi<c material from the floodplain to the mainstream providing a significant allochthonous energy supply to the riverine ecosystem. On the Murray this input is likely to come from floodplain forests and large, macrophyte-dominated, wetlands. Bacon (pers. comm.) indicated that litter fall in the BarmahMillewa forest is equivalent to about four tonnes/ha/year at full canopy cover. On the Darling River, much of which lacks the well-defined floodplain of the Murray, such inputs could come from well vegetated anabranches and floodways - particularly following the exfoliation of native trees during summer. In both cases the potential for floodplains to provide this input is highly dependent on land management as well as flow pattern.

High Flows. High flows which do not significantly exceed the channel capacity may also have a significant role in river-floodplain interactions. As with floods, fish movement and reproduction may be stimulated (Cadwallader, 1986).

The hypothesis that the dense populations of billabong microinvertebrates, made accessible to the¡ river by these flows, represents a significant food resource for larval native fish is attractive, but has yet to be tested experimentally. Research on fish larvae (Gehrke 1991) indicate that the relationship between high flows and fish recruitment may be complicated.

The temporary connection between stream and billabong does represent the potential for interaction between the biologically rich and diverse floodplain systems and the riverine ecosystem. Apart from any active migration between the two, passive movement from billabong to stream during the decline of the hydrograph may represent a significant inoculation of bacteria, algae, and micro invertebrates. The ecology of these interactions will be the subject of research at the CRCFE, however, it is clear that any effect of such inoculations on the health of the river ecosystem would be dependent, inter alia, on ~onditions at that time in the billabongs involved - ranging from the input of an algal bloom to a complex of grazing and decomposing organisms.

17

Impact of River Management Apart from land manageme-n t issues which effect floodplains directly, there are three aspects of river management which impinge on river-floodplain interactions; water abstraction, flow regulation, and floodplain alienation.

Abstraction. Approximately three quarters of Australia's water consumption involves waters of the MurrayDarling; a system which receives only 4% of the continent's total runoff (Anon.

1987). At least half of the average annual flow of most of the major streams in the Murray-Darling system are allocated for off-stream use. Although this situation has its most profound effect during dry periods it can reduce the frequency of natural high flows - particularly where "excess flows" are allocated (permission to remove water only when flows exceed a set level).

River Regulation. Management of the waters of the Murray-Darling as a human resource has involved the collection and storage of water - mostly in the catchment - and its release in a temporal pattern which mimic s downstream human requirements as nearly as practicable . The highly variable nature of annual flows (Anon. 1987) has resulted in the need for large storages to achieve management aims (McMahon, 1975). It also means that large floods are virtually unaffected by river regulation. In much of the river system, particularly near storages, the pattern of other than floodflows is significantly altered. Figure 1 shows an analysis of river flows in the Murray at Albury in the period 19741990 comparing observed events (under the influence of Hume Dam) with flows calculated to have occurred in the absence of Hume Dam (the total of flows for Murray above Hume, Mitta Mitta and Kiewa Rivers). The data represent the frequency of flow events in which weekly average flow exceeded 20,000 ML/day, 26,000 ML/day (bank full at Albury) 30,000 ML/day (significant floodplain inundation), and 50,000 ML/day (flood).

The data show that substantial floods are little effected by regulation; that minor floods are reduced in frequency (from 22 to nine) though their seasonal pattern remains similar; that for all flows exceeding channel capacity (26,000 ML/day) there is some reduction in frequency and a tendency for them to occur in summer/autumn under regulation .

Flows of 20,000 ML/day or greater are less likely to occur in winter/spring but more likely to occur in summer/autumn with Hume Dam in place, though their total frequency is increased from 37 to 46 for the 17 years.

Envisaging these various flow rates as the lower limits at which numbers of billabongs are connected to the river, the potential for river regulation to disrupt the pattern of billabong/river interaction 18

K'iewa River snaking across a flood p"lain is apparent. The likely significance of this disruption to the viability of the river ecosystem is currently being investigated.

Floodplain Alienation: Levees.

In addition to modified flow regimes interaction between floodplain and river can be disrupted by physical barriers.

Small anabranches and flood channels are frequently blocked to improve access to floodplain land during high flows .

Along parts of the Darling, billabongs are blocked off to encourage stock to water at the main channel rather than become bogged attempting to reach receding billabong water. The most usual barriers to river-billabong interaction are levees. Built to hold back major floods, levees exclude all lesser flows as well. A significant part of levee construction took place last century, stimulated by three major floods (1852, 1867, 18970) and ha s continued since Federation, under state control. Levees are built primarily to protect property and to "reclaim" flood-prone land; including billabongs. Because levees tend to force floodwaters to move to other parts of the fl odplain, there is a tendency for incremental construction on each bank of the river which eventually leads to channelisation and total alienation of the floodplain . A better understanding of floodplain river ecology should lead to more enlightened policies on levee construction providing essential protection whilst enhancing river/floodplain interaction under high flows.

Floodplains and Environmental Flows The design of environmental flows for the Murray-Darling syste m is an urgent issue particularly in view of possible over-allocation of the resource through past management policies. The issue is also complex and may be further complicated by factors such as the special role of variability, unpredictability, drought, etc in the Australian environment which might make simple rules for river management inappropriate and possibly counter-productive. Even the purpose of environmental flows is not alway clear - whether they are intended to conserve a full range of riverine ecosystems or whether they are intended merely to sustain those components of the system which will prevent its continued decline as an anthropocentric

resource. These issues are beyond the scope of this paper. However, whatever their purpose or complexity, environmental flows will need to address the preservation of river/floodplain interactions.

Table 1 summarises aspects of various components of the floodplain river ecosystem in relation to river flows. It also suggests likely consequences of river regulation and floodplain alienation.

Major floods do not warrant further consideration as they are not significantly amenable to regulation. Minor floods which result in sheet inundation of at least part of the floodplain (influencing terrestrial plant communities, recharging and connecting water bodies and transporting allochthonous organic material to the river) are also unlikely to be produced in isolation as an environmental allocation. However, allocations as a "top-up" of appropriate natural events, as investigated by MDBC for the Barmah-Millewa forest (Anon. 1992) may be effective and achievable.

High flow events, produced by "topup s" or by varying the pattern rather than the total quantity of release, may represent highly valuable environmental flows in sustaining vital river/floodplain interactions. Research into these interactions - notably tqeir potential for carbon transport, fish recruitment and biological "inoculation" of the river - is required urgently to examine the effectiveness of such flows and their essential characteristics. Such characteristics might need to include season, peak-flow, and duration and shape of declining hydrograph.

There is every reason to believe that river/floodplain interactions represent a vital component of the Murray-Darling ecosystem and that their protection is an essential (though not sufficient) part of the long-ter m management of the resource.

References Anonymous, 1987 . Murray -Dar lin g Basin Environmental Resources Study. MurrayDarling Basin Ministerial Co uncil. SPCC: Sydney.

Anonymous, 1992. Barmah-Mi ll ewa Forest water management plan. Prepared for MDBC by Maunsell & Partner s. MDBC: Canberra.

Boon, P I, 1991. Bacterial assemblages in rivers and billabongs of so uth-eastern Australia.

Microbial. Ecol. 22:27-52.

Boon, P I, Frankenberg, J, Hillman, T J, Oliver, R Land Shiel, R J , 1990.

Billabongs . In: N Mackay and D Eastburn (Eds) The Murray. MDBC; Canberra. 182198.

Bren, L J and Gibbs, N L, 1986. Relationships between flood frequency , vegetation and topography in a River Redgum forest.

Aust. For. Res. 16:357-70.

Cadwallader, P L, 1986. Flow regulation in the Murray River system and its effects on the native fi sh fauna. In : I C Campbell (ed.)

'Strea m Protection: the management of rivers for in stream use s'. Water Studie s

WATER MAY/J UNE 1995

Centre, CIT:Melbourne, 115-133.

Cranston, P S and Hillman, T J, 1992. Rapid assessment of biodiversity using 'Biological Diversity Techniqu es'. Aust. Biol. 5: 144~4. .

Gehrke, P C, 1991. Avoidance of inundated floodplain habitat by larvae of golden perch (Macquaria ambigua Richardson); influence of water quality or food distribution?

AustJ Mar Freshwater Res. 42:707-719.

Hillman, T J and Nielsen, D, 1995. Chironomid assemblages of temporal and permanent water bodies in a flo odplain for est. In : Proceedings of 12th International

Symposium Chironomidae. (In press.)

Hillman, T J and Shiel, R J, 1991. Macro- and microinvertebrates in Australian billabongs.

Int. Ver. Theqr. Angew. Limnol. Verh.

Hillman, T J , 1982. The River Murray and Man. Proc. 17th Assembly Aust. Freshw.

Fisherman. 21-26.

Hillm an, T J, 1986. Billabongs . In : P DeDeckker and W D William s (Eds) 'Limnology in Australia. CSIRO and Dr W Junk: Melbourne and Dordrecht. 457-470.

Junk, W J , Bayley, P B and Sparks, R E, 1989.

The flood pulse concept in river -floodplain systems. Special Pub. Can. J. Fish. Aquat.

Sci. 106: 110-127.

Maher, M and Carp~nter, S M, 1984. Benthic studies of waterfowl breeding habitat in sou t h-western New So ut h Wales: II Chironomid population s. Aust. J. Mar. Freshwater Res. 35:97-110.

McMahon, T A, 1975. Preliminary estimation of reservoir storage for Australian streams.

Civil Engineering Trans . 1976. 55-59.

Tan, L W and Shiel, T J, 1993. Responses of billabong rotifer communities to inundation.

Hydrobiologia.

Welcomme, R L, 1979. 'Fisheries Ecology of Floodplain Rivers'. Longman: London.

Urban Runoff - A Resource to be Managed A I Lawrence

Abstract Community expectations in respect to the planning and manage ment of urban s tormwater and associated drainage corridors are undergoing significant change, with a growing awareness of both the extent of impacts of stormwater discharges on downstream environmental values, and of the resource values of stormwater and associated open space systems being foregone.

This paper outlines the management responses to these changes, the information needs generated by these changes, and the research programs being undertaken by the CRC for Freshwater Ecology and CRC for Catchment Hydrology in response to these needs.

Background Urban stormwater, long considered a nuisance that required collection and transfer out of the urban area in the cheapest possible manner, is increasingly being recognised as a valuable resource, simply begging the application of more innovative and better coordinated approaches in order to secure the comprehensive range of benefits it offers.

The potential for use of urban stormwater for groundwater recharge in urban areas has been recognised in Perth and Adelaide. Re-use of urban stormwater in the ACT has reached the limits of sustainable supply in some urban catchments, requiring the of control of urban stormwater removal, including the consideration of environmental flow requirements. Urban stormwater discharges, properly managed in quality and peak flow terms, provide an important environmental flow return to streams, offsetting the impact of upstream water supply diversions.

In recent years, there has been a recognition of the significant role of natural drainage corridors in contributing important open space, landscape, recreation, conservation and movement values. Consequently, there has emerged a community concern to recover and protect these values in ongoing urban development and redevelopment.

WATER MAY/JUNE 1995

Th e imp a cts of uncontroll ed discharge of urban stormwater, high in suspend ed solid s, nu trients and organic material, on receiving waters is now identified by the community and pollution control agencies as unacceptable, and requiring management action to redress.

Finally, the high costs associated with extending and replacing traditional stormwater infrastructure, particularly in tight economic times, are unpalatable to the community which expects the adoption of service provision strategies which best secure broad economic, social and environmental objectives.

Management Implications Intervention in land and water resource development and management processes is required in order to secure the economic, social and environmental benefits of an approach to urban stormwater based on resource management. Intervention may be required in terms of land development and infrastructure controls, guidelines and coordination nece ssary t o ensur e that the urban form and location, and infrastructure planning and design is undertaken in a manner capable of securing: • the resource benefits of total water cycle based provision of urban services; • the economic, social and environmental benefits of multi-purpose design and management of drainage corridors; • the protection of downstream environmental and use values.

In particular, there is a nee d to address the increasing incidenc e of downstream impacts (flooding, water pollution) associated with expansion of urban land development in the catchment, and concerns regarding the long term implications of climate change.

The adoption of integrated land and watercycle planning and provision of services based on the total water cycle r equire s implementation at both the block and at the major drainage corridor levels. At the block level, measures comprise: • the use of vegetated areas and infiltration pits, trenches a nd swales, and porou s pavements to intercept runoff and pollutants, and recharge soil mois-

ture and groundwater; • the use of tanks for detention of runoff and grey water for re-use; • mulching and xeriscaping to minimise external water demand .

At the main drainage corridor level, measures comprise: • retention of vegetated waterways and riparian zones to stabilise surfaces and retard flow and intercept pollutants; • use of gross pollutant traps, necessary to limit loading of trash and sediment to sustainable levels in respect to the vegetated waterways, wetlands and ponds; • integration of wetlands and ponds to enhance pollution interception, open space and landscape values; • co-location of sportsgrounds to enhance retardation capacity and exploit hydrozone; • re-use of stormwater for irrigation of open space.,.

The national adoption of ecologically sustainable development and bio-diversity goals requires the identification of resource use and management practices which safeguard the sustainability of urban waterway and downstream environmental and use values.

The adoption of an approach based on total or integrated catchment management facilitates the incorporation of catchment wide consideration of the full range of values and interests across the affected communities, and effective coordination of land and drainage planning and management across the catchment.

The 'management strategy plan' drafting process also provide s an effective vehicle for community partnership with government agencies in determining the long term objectives, and the most environmentally, socially and economically acceptable means of attaining them.

The NSW Department of Planning now requires that its Regiona l Environmental Plans address the impact of land uses on water quality, and the land use, location and management practices appropriate to n{inimising these impacts. NSW has established a number of Catchment Dra inage Authorities where drainage and pollution problems ar e particularly acute.

A number of State and Local Government agencies have published 19

Urban Stormwater Pollution Control Guidelines, either as a basis for encouraging better practice, or as the pasis of approvals or licensing. In NSW, a Stormwater Task Force, chaired by the Environment Protection Authority, is currently drafting a "Best Management Practices Manual", which will provide guidance on the selection of management practices appropriate to particular local drainage and environment contexts.

The Murray Darling Basin Commission Algal Management Strategy for the Murray Darling Basin (MBDC 1994) adopts a catchment management strategy approach to resolution of flow and nutrient export issues across subcatchments of the Basin. The Strategy requires the development of guidelines for improved management practices to contro l nutrient exports, including sewage treatment and effluent re-use, and urban stormwater management.

The Agricu ltural & Resource Management Council of Australia & New Zealand (ARMCANZ) - Australian & New Zealand Environment & Consultative Council (ANZECC) Draft Guidelines for Urban Stormwater Management (1994) propose the adoption of a hierarchy of strategies/master plans, as the basis of coordinated and integrated management of drainage, water quality and ecology, open space, recreation and water supply.

Information & Technology Needs The implementation of these changed planning and management approaches confronts the water manager with a wide range of information needs.

Broadly, the information and technology needs comprise: • Guidance on the determination of the environmental values and their associated water quali ty and flow guidelines against which ecological sustainability is to be assessed; • Guidance on the translation of the water quality and flow guidelines back to sustainable loads in respect to the problem pollutants/flows; • Guidance on total or integrated catchment strategy planning procedures; • The translation of National, State & Local Government related policies and procedures into local performance criteria and management practices; • Information on the range of management measures in relation to protection of downstream environmental values, and guidance on the design of integrated suite of management measures; • Information and models describing the bio-physical processes, including a need for water quality and ecology predictive models, and enhanced flood estimation predictive models; • Need for guidance on appropriate water quality/ecology monitoring and assessment programs; • Need for open space/landscape design

20

and performance assessment guidelines; • Need for recreation design and performance assessment guidelines; • Need for water supply design and performance assessment guidelines; • Need for elaboration of economic analysis methodologies which are TCM based, include externalities, and consideration of non-market costs and benefits; • Implications of climate change for urban stormwater design and infrastructure provision; • Strategies, technologies and assessment methods guiding decisions on aging infrastructure replacement, and the restoration of urban waterways; • Listing of performance indicators and bench-marking procedures.

Research Responding to the Information & Technology Needs The CRC for Freshwater Ecology and the CRC for Catchment Hydrology are jointly undertaking research directed towards responding to a number of these information and research needs.

Research areas include: • Water quality and ecological assessment: Development of water quality and ecological assessment techniques, including the assessment of physical, chemical and biological indicators, and sediment chemical and biological indicators.

• Pollution predictive models: Land use and management practice based predictive export models; Pollutant interception technologies and design models; Transport and interception based models; Receiving water quality and ecology response models and sustainable loads.

• Environmental flows: Assessment of environmental flows/physical factors in relation to ·aquatic ecology composition and structure; Runoff and flow estimation models, including consideration of scale, retention and retardation components, and in-channel routing.

• Development of guidelines: Aquatic ecosystem classification system and related water quality and flow guidelines; Range of management practices and criteria guiding application; Waterway, wetland, pond, gross pollutant trap design guidelines; Waterway restoration guidelines.

The results of this research will be made available to the industry through publication of papers and guidelines, the incorporation into Decisions Support Systems, and the convening of workshops, as well as by way of direct advice to water organisations.

Conclusion Growing community awareness of the resource values of urban stormwater and associated open space systems, and the potential impact of urban stormwater discharges on downstream environmental values, is requiring a significant shift in management approaches. The scope of the implications of these changes for management is substantial,

requiring new knowledge and tools in order to translate ecologically based management objectives into sustainable land and water use and management practices. Current research being undertaken by the CRC for Freshwater Ecology, and the CRC for Catchment Hydrology, is making an important contribution to these new knowledge and analytical tools needs.

References ACT Planning Authority (1989 - 1993), A range of stormwater pollution controlguidelines.

ANZECC (1992), Australian Water Quality Guidelines for Fl·esh and Marine Waters.

Australian Environment Council (1988), Water Pollution Control Guide for Urban Runoff Quality Management, Report No 23.

ARMCANZ/ANZECC, (1994), Draft Guidelines for Urban Stormwater Management, November Development.

Commonwealth of Australia (1992), National Strategy for Ecologically Sustainable Commonwealth Department of Health, Housing and Community Services (1992), AMCORDUrban: Guidelines for Urban Housing.

Commonwealth Environment Protection Agency (1993), Urban Stormwater: A Resource too Valuable to Waste.

CSIRO Division of Water Resources (1992), Urban Stormwater: Impacts on the Environment.

NSW Department of Planning (1993), Better Drainage: Guidelines for the Multiple Use of Drainage Systems.

Environmental Consulting Australia in association with John Botting and Associates Pty Ltd and the Centr e for South Australian Economic Studies (1991), Metropolitan Adelaide Stormwater: Options for Management, for Engineering and Water Supply Dej"'1rtment.

Environmental Protection Authority, Water Authority of Western Australia, and Department of Planning & Urban Development (1993), Water Sensitive Urban (Residential) Design Guidelines.

Lawrence A I & Phillip s B (1993), 'Urban Stormwater Pollution Management Practices in Australia', in Proceedings, 6th International Conference on Urban Storm Drainage.

MDBC (1993), Algal Management Strategy, Technical Advisory Group Report, 'Paper No.7 - Stormwater'.

MDBC (1994), Algal Management Strategy for the Murray Darling Basin.

National Capital Planning Authority for Better Cities Program (1993), Designing Subdivisions to Save and Manage Water.

NSW EPA Taskforce, Urban Stormwater Manual, in drafting.

NSW Government (1986), Floodplain Development Manual.

NSW Government White Paper (1994), Review of Management and Regulation of Water in NSW.

NSW Planning Department (1992), Outdoor Recreation and Open Space : Planning Guidelines for Local Government.

State Pollution Control Commission (1986), Pollution Control Manual for Urban Stormwater Sydney CoastAl Councils (1992), Draft Stormwater Pollution Control Code for Local Government.

The feature on Freshwater Ecology is continued on page 25 WATER MAY/JUNE 1995

Carp: The Prospects for Control?'

J H Harris

Introduction For the past decade in rural southeastern Australia, the debate about carp has shifted from 'is there a problem' to 'how can the problem be controlled?'

Until recently, science contributed little more than opinions - often conflicting - to this community debate. There have been numerous theoretical analyses of the role (roil?) of carp in our waters, but very little new knowledge has been produced other than the Victorian work summarised by Hume et al. (1983), which left many uncertainties, and recent preliminary experiments by Roberts et al (1995). At least seven Australian scientific institutions are presently studying carp in Australia (University of New South Wales, CSIRO Division of Water Resources, Mitchell and Wagga campuses of Charles Sturt University, University of Adelaide and, in the CRCFE, University of Canberra and NSW Fisheries Research Institute) and they are all trying to remedy the uncertainties and gaps in our knowledge about carp ecology. However, most of the people confronted with the problem in their daily lives - the landowners and others living beside carp-infested rivers - have long ago concluded that carp are indeed a profound ecological problem (Nannestad 1994). Their concern is leading to strong pressures on management agencies to find effective methods to control this alien pest.

Many adverse impacts of carp have been suggested as justifying their control (Tilzey 1980; Hume et al 1983; Fletcher 1986; Morison 1989; Morison & Hume 1990; Lawrence 1989; Nannestad 1994; Gehrke & Harris 1994; Harris

1995), but the evidence is, for the moment, inconclusive. In summary, the adverse effects are mainly those arising from the carp's characteristic bottomfeeding behaviour: increasing water turbidity; destroying aquatic plant beds; liberating nutrients from sediment, promoting algal blooms; damaging artificial wetlands built for water-quality control; undermining the banks of streams and irrigation channels.

More-direct interactions with native aquatic fauna, such as predation on small life forms and competition for food, space and other resources, have also been suggested (Hume et al 1983, Cadwallader & Lawrence 1990). While hypotheses about such effects are presently being tested on many fronts, it is already clear that the majority of rivers in south-eastern Australia are now inhabited by an extraordinarily large biomass of carp, especially in the inland, lowland reaches (Figure 1; Gehrke et al 1995; NSW Fisheries, unpublished data).

A Definition of Carp Uncertainty about the identity and naming of carp confuses the debate.

Carp, Cyprinus carpio, is a member of the Cyprinidae, a family of fish alien to Australia. It has often been named as 'common carp' or 'European carp', but neither of these names are recommended, especially the latter, as the species is native to Asia rather than Europe.

Seve:r;.al distinct strains add to the confusion. Shearer and Mulley (1978) noted the existence since colonial settlement of ornamental, non-invasive strains in Sydney ponds (the 'Prospect' strain) and rice-growing areas (the 'Yanco' strain).

Darling

Parco Carp 35.6%

Carp 7.7%

Others 92.3%

Others 64.4%

Murray

Murrumbidgee

Carp 91.6%

Carp 91.8%

Others 8.4%

Others 8.2%

Figure 1. Relative dominance of carp in preliminary catches from the Murray, Murrumbidgee, Paroo and Darling river systems during a study of the recruitment ecology of native fish (Gehrke et al 1995). .

WATER MAY/JUNE 1995

They also described the early-1960s origins in Victoria of the prolific, invasive 'Boolara' strain that now dominates so many rivers . A recent addition to the problem is the highly-selected, colourful koi strain of ornamental C. carpio, which is proving to be a similarly invasive, threatening fish in the Shoalhaven, Richmond and other rivers in New South Wales (Harris 1994). Within the Boolara strain, there are also clear morphological types such as 'mirror carp' or 'leather carp', so-called because of differences in their dermal scales. To complicate matters further , the only other widespread cyprinid invader of Australian water s, the goldfish, Carassius auratus, has hybridised with carp (Shearer & Mulley 1978), especially in the Riverina region. So 'carp' encompasses a multitude of fins.

Possible Control Methods As with other established alien vertebrate pests such as goats, pigs, canetoads, starlings, Indian mynas or rabbits, eradication seems impossible with existing technology. But if eradication is impossible, at least an acceptable level of control is certainly feasible. Either 'direct control' or 'biological control' methods are potentially available to manage carp populations.

Direct control. In early stages of carp inva sio n of a waterway, the approach to control by fisheries authorities has often involved fish poisons such as rotenone or lime (Figure 2). For example, early populations of Boolara strain carp in Victoria and Tasmania were poisoned (Shearer & Mulley 1978), and this drastic method is still applied where confined noxious fish threaten new areas (Hall 1988; NSW Fisheries, unpublished data) . But poisoning is seldom applied because of risks to other aquatic fauna, and it is generally used in highly modified environments such as water storages.

Water-level manipulations can also play a part in direct control. Netting of the outlets of floodplain wetlands in South Australia showed that large-scale emigrations of carp occur when water levels are drawn down, and selective population reduction is possible at these times because carp emigrate at night and early in the draw-down, while native fish mostly move during the day, and later in the draw-down (B. Pierce, personal communication, 1994). The drawing-down of water storages after the spring spawning period has also been suggested as a way to destroy the eggmasses of carp after their deposition in littoral shallows, but it does not appear to have been attempted, probably

25

because of the long spawning season in pressure a~ are well adapted to cope warm Australian waters. In some reguwith predation, it may prove impracticalated storages, complete draining every ble to control them in this way, unless three to four years could be valuable, as part of a broader plan. This negative concarp reach breeding maturity at this age. clusion is reinforced by the continuing . But the most frequently proposed declines observed among stocks of both ~irec~ method to suppress carp populanati~e (e.g Murray cod) and alien (eg tions mvolves targeted fishing. Over-harr~dfm perch, Percafluviatilis) predatory vesting of fish populations can lead to fish that share habitats with carp 'growth overfishing', with disappearance (Rowland 1989; Derwent 1994). of larger, older individuals, and/or it Spring Viraemia infection. The m_ay cause ':ecruitment overfishing', Figure 2. A mass of carp - the Kai most prominent of the biological control with populations collapsing because the strain in this case - killed by poisoning in methods so far promoted has been the breeding stock is suppressed. Brown an ornamental pond in Sydney which proposed introduction of a virus (1994) discussed the significance of histhey were damaging, and threatening to Rhabdovir?fs-carpio, which causes th~ to_rica} o~erfis?ing in the Murrumbidgee disease Spring Viraemia in carp. Hume River s fisheries. The likelihood of over- invade a small stream et al. (1983) recorded the Victorian ~shin~ varies with the type of fish (espeGovernment's investigation into this procially its fecundity, breeding and other Notwithstanding these restrictions posal for a myxomatosis-like solution. on the potential for fisheries to control behaviour, and growth rate) . Also imporPreliminary results indicated that tant are the spread of fishing effort carp generally, some controls are availSpring Viraemia has caused seasonal ac~oss 0e po~ulation, whether the popuable at the local level. In enclosed waters epizootic outbreaks among carp in such as irrigation systems, populations lat1on 1s confmed in some way and of Europe for a long period of time, and could be controlled by harvesting course, _the intensity of fishing. C~rp that no other species have been shown to populat10ns are generally resistant to (Brown & Harris 1994). Isolated lakes be affected. The virulence of the infecwith dominant carp populations such as overfishing; undoubtedly this attribute is tion does not seem to have declined no significant in its status as the world's Lake Cowal in the Lachlan River floodresistance to infection has b~en most widely distributed fish. plain or Barrenbox Swamp near Griffith observed, infection is transmitted can sometimes sustain useful commerNevertheless, carp populations are relathrough the water so that no living veccial fisheries for carp if tightly controlled tively confined in many waters such as tor is required, and the disease apparent,. floodplain lakes or impoundments and (Derwent 1994). Because carp migrate ly remains a potent control over carp the fishways built on weirs to provid~ their poor image among rural com:nunities helps to ensure the popularity of passage for native fish offer an addition- abundance in Europe.

The Victorian project tested the sus'Carpathons' and other local attempts at al potential tool for local control. weirs ceptibility to the virus of six native eradication. Political attention is focused such as Euston (Murray R.), on commercial fishing, either with tradiTorr~mbarry (Murray) and Boggabil!a Australian fish plus goldfish at the W:y~ridge virology laboratory in tional gear or newer electric-fishing tech(Macmtyre R.) have permanent weir Bn~am. _None showed susceptibility. nology, as a means of carp control. staff, and traps are fitted to their fishWhilst this was an encouraging start to ways for censusing fish movement.

Small, declining commercial fisheries assessing the risks to Australian fauna of exist in inland rivers of south-eastern Some of these sites are already used for the proposed virus introduction (Howes Australia (Lawrence 1989), and carp has carp destruction; up to 1200 large carp 1993), a comprehensive and rigorous per day have been harvested from the become an increasingly dominant conasse~sment of risk would obviously be Torrumbarry t:ap (Mallen-Cooper, perstituent of their catch (Pease & Scribner r_eqmred as part of any further investiga1993). The potential for commercial har- sonal commumcation 1994). There is tion of the possibilities of viral control. vesting to provide large-scale carp conpotential to replicate this operation at Furthermore, many national and intertrol is restricted by three factors: other major weirs. While it has been sugnational agreements and regulations gov• The present market value of carp is g~sted that '_d ifferentiating' fishways ern such introductions. While much low_- only around $0.70/kg, so there is litmight be designed to serve native fish tle mcentive for commercial fishermen. but prevent carp dispersal the results of remains to be done to evaluate the proposal, and Morison (1989) doubted its But values could radically improve if swimming-speed and 'behavioural practi~ali~ because of the difficulty of markets for live fish could be found and research show too much similarity ~ss:ssmg risks, the available knowledge exploited, as occurred recently with eels between native fish and carp and this 1~d1ca_tes that an effective program of goal is impracticable in A~stralian whose value increased ten-fold (Peas~ and Scribner 1993). streams (Mallen-Cooper 1993; Harris & b1olog1cal control based on introduction of Spring Viraemia is a possibility that • Carp are now very widely distributed Mallen-Cooper 1994). deserves further, prompt and thorough a~d migratory, so that local populations e· I investigation. will always be replenished after highIO ogical Control Methods flow events in rivers.

Fish stocking. Various methods of Genetic manipulation. Genetic manipulation techniques are being develbiological control of carp have been pro• Wa~er and Jackson (1993) reported oped to control other vertebrate pests that eight percent of the Australian posed or attempted. Frustrated anglers and may be applicable to fish. Bradley freshwater fish fauna are threatened have tried, so far unsuccessfully, to manwith extinction. Carp occupy the habiage carp by stocking large numbers of (1994) and Tyndale-Biscoe (1994) described how techniques of immunocontats of most of these threatened species predatory native fish, especially golden ~rac ep ti on, which induce the body's perch (Macquaria ambigua) or Murray and al~o exist side-by-side with man; other fishes that comprise the stock of cod (Maccullochella peelii) (NSW immune system to attack the reproduc~ive c~lls of its o;,.;n species, are being freshwater fish biodiversity and valued Fisheries, unpublished data). These mvest1gated as controls for rabbits and native species. It is clearly imperative attempts have been encouraged by many foxes. Low-virulence, host-specific for fisheries authorities to conserve casual observations that native predators recombinant viruses are planned to disthese resources, and this responsibility are extensively feeding on carp, and by seminate suitable antigens among the precludes the possibility of widespread the ready availability of artificially proptarget populations. No work has been agated ~oung native fish. But, as carp commercial fishing that is sufficiently done to evaluate the applicability of this intense to control carp. evolved m the face of intense predation system to fish, but such an innovative, 26

WATER MAY/JUNE 1995

minimally intrusive method of carp control would have great environmental and economic advantages over the traditional direct control methods. Again, like the Spring Viraemia proposal, the potential for immunocontraceptive control of carp deserves investigation.

Preventing New Infestations Disappointingly, carp are still being deliberately or accidentally introduced to new waters. New populations have appeared in the past few years in New South Wales in streams and water-supply dams at Sydney, Moss Vale, Casino, Captains Flat and Yass (NSW Fisheries, unpublished data). A small minority of anglers, especially those with cultural backgrounds in which carp are a favoured species, have been suspected of stocking carp into waters lacking recreational fisheries. In recent weeks an apparent re-introduction of carp to Tasmania has been discovered in Lake Crescent (Hobart Mercury, 3 February 1995), sharply emphasising the risks of continuing spread.

There are many human factors involved in range extensions of carp.

Fish hatcheries sometimes disseminated unintended species among liberations of propagated fi sh, until scrutiny over stocking practices was increased following controversy over such incidents.

Furthermore, few hatcheries or display ponds have sufficient security to completely prevent the escape of fish into natural waterways, and koi carp, at least, have invaded rivers in this way (NSW Fisheries, unpubli shed data).

Because of evidence that the use of live fish as angling bait has been responsible for establishing populations of carp, goldfish and oriental weatherloach (Misgurnus anguillicaudatus) in new waters, fisheries regulations now forbid this type of bait (Derwent 1994).

These incidences of the development of new pest-fish infestations through human intervention emphasise the important need for community education programs and fisheries legislation that is both effective and consistent between states, in achieving carp control.

Sustainable Management of Rivers: The Best Response Invading species are more likely to succeed in disturbed systems (Courtney & Hensley 1980). Field experience with carp in Australian waters is underscoring the importance of sustainable-development principles for rivers (e.g. CSIRO 1992) as a critical element in control.

For example, workers in sampling programs soon learn that carp do relatively poorly in rivers with strong flow; they congregate only in patches of slack water. Furthermore, Mallen-Cooper's (1993) research in the Murray River showed that, while migrating native fish WATER MAY/J UNE 1995

respond well to small-scale flow variability, carp are favoured by the static flow conditions typical of the present irrigation-supply regime of the Murray. In addition, early results of work on the recruitment of inland fish (Gehrke et al.

1995) showed that carp dominate the fauna of highly regulated rivers such as the Murray and Murrumbidgee to a much greater extent than less-regulated rivers such as the Darling and Paroo (Figure 1).

There are also biological considerations as well as these abiotic aspects of su stainabl e development of rivers.

Under present conditions, native predators may not be able to suppress carp populations to low levels of abundance, but it is reasonable to assume that, in healthier communities with abundant, diverse native species, a dynamic balance would develop which would help to limit the population densities of carp. It follows that the potential for population limitation by native predators cannot be realised unless good river-management is applied, and the needs of native fish are cared for. These needs have often been identified, at least in a qualititative way. Good river management involves a range of essential aspects: • Supplying proper environmental flows.

• Drawing downstream releases from the surface waters of dams, rather than from the cold bottom waters.

• Minimising catchment erosion.

• Retaining and nurturing riparian vegetation.

• Removing barriers to fish passage or overcoming them with fishways.

• Halting desnagging programs, and perhaps even reversing them.

• Halting in-stream mining of sand, gravel and other minerals.

• Implementing effective programs of pollution abatement.

It is hard to avoid the conclusion that carp, like blue-green algae, are merely another potent signal from our rivers that inappropriate management practices must be put right.

Acknowledgements Jane Roberts, Peter Gehrke and Elizabeth Gordon-Werner provided helpful advice and suggestion s, and, with Brian Pierce, kindly gave permission to refer to their unpublished material.

References Bradley, M P (1994) Experimental strategie s for the development of an immunocontraceptive vaccin e for the European red fox, Vulpes vulpes. Reproduction, Fertility and Development. 6, 307-317.

Brown , P (1994) The Murrumbidg ee Riv er Fishery: A historical perspective. In: 'The Murrumbidgee, Past and Present' (J Roberts and R Oliver, Eds .) pp. 20-26.

(CSIRO Divi sion of Water Resources, Griffith NSW.) Brown , P & Harris , J (1994) Carp in the Murrumbid gee Irri gation Area.

UnpubliilPed report by NSW Fisheries fo1 the Murrumbidgee Irri gation Areas anc Districts Managem ent Board and NS~ Department of Water Resources.

Cadwallader, P & Lawrence B (1990) Rive1 Life: Fish. In: 'The Murray'. (N. McKay & D. Eastburn, Eds) pp.317-336. (Murray Darling Basin Commission, Canberra.)

Courtney W R & Hensley D A (1980) Specia problems associated with monitoring exotic fish. In: 'Biological Monitoring of Fish' (C F. Hocutt & J R Stauffer, eds). pp 281-308 Lexington Books, Lexington Massachusetts.

CSIRO (1992) Towards Healthy Rivers. CSIRC Division of Water Resources Consultanc~ Report No. 92/44.

Derwent L (1~94) Commercial and r ecreationa. fishin g ·or carp in NSW. Current manage ment and options. In: Proceedings of thE Forum on European Carp . Wagga Wagg, NSW, 20 June 1994. (C. Nannestad, Ed .) p~ 43-49.

(Murrumbidgee Catchmen1 Manage ment Committee, Wagga Wagg, NSW).

Fletcher A R (1986) Effects of introduced fish in Australia. In: 'Limnology in Australia.'(P. De Dekker & W.D. Williams, Eds) pp.231250. (CSIRO, Melbourne & W. Junk , Dordrecht.)

Gehrke P C, Brown P, Schiller C B, Moffatt D B, & Bruce A M (1995) River r egulation and fish communities in the Murray-Darlin g River system, Australia. Regulated Rivers: Research and Management. (In review.)

Gehrke PC & Harris J H (1994) The role of fish in cya nobacterial blooms in Australia.

Australian Jnl Mar and Freshwater Res 46, (6) 905-915.

Hall D A (1988) The eradication of European carp and goldfish from Leigh Creek retention dam. Sµ,fish 12(4), 15-16.

Harris J H (1994) Carp in Australia: The Role of Research. In: 'Proceedings of the Forum on European Carp'. Wagga Wagga NSW, 20 Juie 1994. (C Nannestad, Ed.) pp 17 - 20.

(Murrumbidgee Catchment Management Committee, Wagga Wagga NSW).

Harris J H (1995) Fish/habitat interactions. In: 'Geomorprphology and River Health in New South Wales ' . Proceedings of a conference at Macquarie University, 7 October 1994 (G J Brierley, Ed.) (in press).

Harris, J H & Mallen-Cooper, M (1994). Fishpassage development in the rehabilitation of fi s h eries in mainland so uth- easte rn Australia. In: 'Rehabilitation of Freshwater Fisheries' (I.G . Cowx, ed.) pp 185-193.

(Fish ing News Books: Oxford.)

Howes D W (1993) Scientific Officer's Report.

Pro ceed in gs of the 28th Ass em bly of Australian Freshwater Fishermen.

(Australian Freshwater Fishermens Assembly Inc., Canberra). 19-23.

Hume D J, Fletcher A R & Morison A K (1983) Carp Program Report No . 10 Final Report.

Fisheries and Wildlife Division, Melbourn e.

Lawrence B W (Ed) (1989) Proceedings of the Workshop on Native Fish Management.

Canberra 16-17 June 1988. (Murray-Darl ing Basin Commission, Canberra.)

Mallen-Cooper M (1993) Habitat changes and decline s of fre shwater fi sh in Australia : what is the evidence and do we need more?

In: 'Sustainable Fisheries through Sustaining Fish Habitat' . (D A Hancock, ed) pp. 11 8-23. ,Bureau of Resourc e SciencesProceedings, AGPS, Canberra.

Morison A K (1989) Management of introduced species in the Murray-Darling Basin. In: 'Proceedin gs of the Workshop on Nativ e Fish Management'. pp. 149-162. (MurrayDarling Basin Commission, Canberra.)

Morison A K & Hum e D (1990) Carp (Cyprinus carpio L .) in Australia. In:

27

'Australian Society for Fish Biology Workshop : Introduced and Translocated fishes and their Ecological Effects'. Bureau of Rural Resources Proceedings No. 8. (DA Pollard, Ed.) pp .110-113. (Aus t ralian Government Publishing Service, Canberra.)

Nannestad C (Ed) (1994) Proceedings of the Forum on European Carp. Wagga Wagga NSW 20 June 1994. 67pp. (Murrumbidgee Catchment Management Committee, Wagga WaggaNSW).

Pease B C & Scribner E A (1993) The New S~uth Wales Comm ercial Fi sheries

Statistics 1990/91. NSW Fisheries, Sydney.

Roberts J, Oswald L, Chick A J, & Thompson _P (1995) Tl;!e effects of carp, Cyprinus carpio, an exotic benthivorous fish on ecological structure and processes in experimental ponds. Freshwater Biology (submitted).

Rowland S J (1989) Aspects of the history and fishery of the Murray cod, Maccullochella peelii (Mitchell) (Percichthyidae). Proc Linnaean Society of NSW, 111, 201-13.

Shearer K D & Mulley J C (1978) The introduction and distribution of carp, Cyprinus carpio Linnaeus, in Australia. Australian Jn l

Mar and F'r~hwater Res. 29, 551-563.

Tilzey RD J (1980) Introduced Fish. In: 'An ecological Basis for Water Resourc e Management' (W.D. Williams, ed.) pp. 271279. (ANU Press, Canberra.)

Tyndale-Biscoe C H (1994) Virus-ve<;tored immunocontrace ption of feral animals .

R eproduction, Fertility and Development. 6, 281-287.

Wager R & Jackson P (1993) The Actio~ Plan for Australian Freshwater Fishes.

Australian Nature Conservation Agency, Canberra.

Invertebrate Communities in Victorian Running Waters R Marchant, S Talman, R Norris

Introduction The modern approach to assessing a river's "health" is based not only on chemical measurements of water quality but also on an evaluation of biological quality, by classification and ~re_diction.

The composition of the benth1c mvertebrate community has been widely used for this latter purpose. If the composition of these communities at undisturbed sites can be predicted, then comparisons of the numbers and types of taxa that are observed to occur at a given site with those that ought to occur in the absence of disturbance can be made. Such predictions can be looked upon as the baseline biological conditions against which the current conditions are being compared.

Predictive Systems A predictive system of this kind has been designed for the invertebrate fauna of English rivers (Wright et al. 1993). It is called RIVPACS (River InVertebrate Prediction And Classification System) and has been successfully used to assess the impacts of organic and other types of pollution, and river impoundment ?n lotic ecosystems in the UK. In Australia, the Commonwealth EPA is currently funding a project known as the Monitoring River Health Initiative (MRHI) which aims to produce a system similar to RIVPACS for each state. This project is based on identifications ~ken to the family level at sites where obVJous disturbances to the lotic habitat are absent. Knowledge of these invertebrate communities is more advanced in some states and in Victoria specimens can currently be identified to at least the genus level and in many cases to the species level. Also, genus and species level data at a range of generally undisturbed sit~s on Victorian streams are already available as a result of surveys undertaken by the Environment Protection Authority of Victoria (EPA). We have made a preliminary attempt at constructing a predictive system using these EPA data.

Victorian Data Data were available on invertebrate 28

communities at 55 sites from six river basins in Victoria: South Gippsland, Barwon, Otways, Campaspe, Ovens and Snowy. (The South Gippsland and Otways basins included sever~l catchments whereas all other basms contained 'single catchments; full site details are given by Butcher 1991). At each site up to two habitats were sampled: t~e bank or slow-flowing zone and the mam channel or fast-flowing zone; at a number of the deeper downstream reaches, only bank samples could be taken.

Samples were taken with hand nets (250 mm mesh) by sweeping the net along the bank or by kicking up the stream bed in front of the net in the main channel. In both habitats a collection period of 10 minutes was used. Collected material was then sorted Jive in the field for 30 minutes and returned to the laboratory for identification. In addition, a number of physical and chemical variables were measured on all sampling occasions: dissolved oxygen (DO), electrical conductivity (EC), pH, water temperature (temp), turbidity (turb) and current velocity (vel). Sampling occurred in spring and autumn for two years (1990 and 1991, 4 sets of samples) in all basins and for three years (1990-92) in two (6 sets of samples, Barwon and Campaspe).

Invertebrate data were assembled on a database (Paradox 3.0) and information from the different sampling occasions was averaged to produce one list of taxa (and their abundances per sample) for each site. Data from the two habitats were kept separate. (In what follows only data from the banks are analys_ed as samples from this habitat are available for all sites). A total of 769 taxa were identified; these were recorded mostly as species or genera but some groups were only recorded at higher ta~onom~c levels, e.g. Oligochaeta, Hydracarma. Six of the 55 sites were excluded from analysis as it seemed possible that some disturbance to the river had occurred at these. Rare taxa were also excluded; those that occurred at fewer than three of the sites were omitted thus reducing the number of taxa to 416.

Analysis The first step in the analysis was to subject the data (after log tr~n.sfor_mation) to ordination and class1f1cat1on.

Ordination of the sites was carried out using Hybrid Multidimensional Scaling (SSH) and Detrended Correspondence Analysis (DCA). Site classificatio~ was accomplished using Two-Way INd1cator SPecies ANalysis (TWINSPAN) or Unweighted Pair Group arithMetic Averaging (UPGMA). Programs for all these routines were contained within the PATN (Belbin 1993) software package for multivariate analysis of ecological data. To interpret the ordinations 23 variables were correlated with the ordination space using a form _of multip!e regression, the Principle Axis Correlation routine (PCC) in PATN. These variables included the mean values for the physical and chemical measurements itemised previously and additional variables derived from field observations, maps, and discharge or meteorological records: altitude, di stance _to source mean annual discharge (and its annual' CV), width, depth, latitude, longitude, slope, mean particle size of the substratum, heterogeneity of the substratum macrophyte cover, air temperature, rip;rian vegetation and adjacent land use (a categorical variable).

Both methods of ordination showed that two underlying gradients existed in community composition: a longitud!nal or downstream gradient and a gradient based on the actual size of the river at a site. The first gradient was indicated by strong correlations of the ordinations with variables such as altitude, DO, EC, temp and turb; these all vary markedly along the course of a river and ca_n b~ seen as different aspects of the long1tud1nal environmental variation that is present in all rivers. The second gradient was displayed by high correlations with mean annual discharge and width; and distinguished communities at sites with high values for these, e.g. sites in the Snowy basin, from communities at other sites. Longitudinal gradients have been found in other ordination analyses of WATER MAY/JUNE 1995

community composition of Victorian lotic invertebrates (Marchant et al 1994); but a gradient corresponding to- river size has not.

Classification of the data by TWIN SP AN gave four groups of sites; UPGMA gave only two groups and was thus considered le ss successful. The environmental characteristics of the four TWINSPAN groups largely repeated the trends already established by the ordinations. This was confirmed by subjecting the environmental and physical and chemical variables to Step-wise Discriminant Analysis (DA in the SAS software package). A subset of six of the 23 variables provided maximum discrimination between the four TWIN SP AN groups: EC, width, altitude, latitude, substratum heterogeneity, distance to source.

Prediction The methods of Moss et al (1987) were then used to transform the results from the DA into a predictive system that would give lists of taxa, and their probabilities of occurrence, for a site specified only by measurements on the six variables above. Five sites were removed at random from the 49 available to serve as test s ites. The TWINSP AN and DA analyses (using the same six variables) were repeated on the smaller (44 site) data set and the DA equations (part of the DA output incorporating the six environmental measurements as predictor variables) were used to predict which of the four resulting TWIN SP AN groups the five test sites most probably fell into. It was then possible to predict the probability of occurrence of a taxon at a test site from knowled ge of the frequency of occurrence of taxa in each of the TWIN SPAN groups.

The number and type of taxa observed at a site was compared with those expected and the result expressed as a ratio of numbers observed to numbers expected. For undisturbed sites,

such as the five test sites picked above, the ratio should be close to 1.0; for disturbed sites the ratio should progressively decrease as the degree of disturbance increases. In this case the ratio varied from 0.8 to 1.3 (mean of 1.0) for the five test sites, indicating that all were undisturbed, as expected. These procedures were repeated for the six sites that were omitted originally from all analyses because it was thought that they might be disturbed. For five of these sites the ratios varied from 0.7 to 1.2 indicating that these sites were not as disturbed as initially thought from the site descriptions given by Butcher (1991). (R. Butcher confirmed that these sites were ge nerally in good condition). One of these sites, however, had a ratio of 0.2 suggesting that indeed it was impaired.

In fact this particular site was only sampled once (rather than 4-6 times as the other sites) because it seemed obviously disturbed by saline discharges and other factors. The lower ratio may thus be partially caused by under sampling rather than disturbance, although this seems unlikely. If the above information had been gathered during a routine survey of river sites, a manager would conclude that further investigation of the site with the low ratio was clearly warranted.

Applications Obviously the system outlined above is preliminary. The greatest need is to test it on a range of sites that are disturbed by identifiable factors (or combination thereof) e.g. sewage pollution, input of heavy metals, regulated flows, to determine the sensitivity of the ratio of observed to expected taxa. It will then be possible to assign different ranges of the ratio to different levels of impairment, e.g. >0.8 no disturbance, 0.6-0.8 some disturbance, 0.4-0.6 persistent disturbance, <0.4 degraded. Such a banding system is used with the ratios derived from the English RIVPACS system.

From the results of nationwide invertebrate sampling in the UK it is now possi-

ble for autho'llities to calculate the percentage of river sites within the various bands and thus state with some confidence the extent and severity of disturbance to rivers. Naturally, we are some way from being able to do this in Victoria; but our early results are encouraging and indicate that it should be po ssible to construct a useful RIVp ACS-like system for streams and rivers in this region.

Acknowledgments This study was ¡made possible by the cooperation -of the Victorian EPA who allowed us to analyse their data. We are grateful to them and in particular to L. Metzeling (EPA) who arranged the transfer of data. The field work was carried out by R. Butcher and others from the Rural Water Corporation of Victoria on behalf of the EPA. We are indebted to her for answering our many enquiries about the sites. The project is a cooperative one between the Victorian EPA, Museum of Victoria and the CRC for Freshwater Ecology. Funding of staff directly engaged on the project and computing is supplied by the CRCFE.

References Belbin, L (1993). PATN - Pattern Analysis Package . (CSIRO Division of Wildlife and Rangelands Research: Canberra).

Butcher, R (1991). Biological assessment and surveillance network: fir st interim report May 1990 to November 1990.(State Water Laboratory of Victoria: Melbourne).

Marchant, R, Barmuta, L A, and Chessman, B C (1994, . Preliminary study of the ordination and classification of macroinvertebrate communities from running waters in Victoria, Australia. Australian Jnl Mar & F'reshwal;er Res 45, 945-62.

Moss, D, Furse, M T, Wright, j F and Armitage, P D (1987). The prediction of the macroinvertebrate fauna of unpolluted runningwater sites in Great Britain using environmental data. F'reshwal;er Biology 17, 41-52.

Wright, J F, Furse, M T, and Armitage, P D (1993). RIVPACS- a technique for evaluating the biological quality of rivers in the UK European Water Pollution Control 3, 15-25.

Some Current Research Projects Lifecycle of the Toxic Blue Green Alga Anabaena Circinalis WvanDok

Objective Some filamentous types of bluegreen algae have specialised cells, called akinetes, which are thought to be a 'resting cell', like a seed. Akinetes develop at intervals along the chain of cells which make up the filament and when mature, are released. They may germinate straight away, or settle to the stream or WATER MAY/JUNE 1995

reservoir sediment surface, perhaps to germinate at a later time.

The broad objective of the research is to assess how much the life cycle of Anabaena circinalis , a toxic blue-green alga, depends on the resuspension of akinetes from the sediment to start seasonal growths. However, before this question can be answered it is necessary to determine the factors which induce akinetes to form and to germinate. If these conditions are known it may be possible to manipulate stream or reservoir conditions to minimise germination.

Results A study of natural populations of A. circinalis sampled from Hay Weir pool on the Murrumbidgee River, during the summer of 1991/92, revealed that attached akinete concentration correlated well with cell concentration (r"-0.753 p<0.01). The maximum akinete concentration of 1 100 akinetes mL/1 coincided with maximum cell concentration of 27 000 cells mL/1. Attached akinete concentrations in the Hay Weir pool samples never exceeded 3 per 60 cells with most filaments being 30-60 cells long.

29

As water depth decreases, the potential for resuspension increases. In Hay Weir pool, at a flow rate of up to 500 ML/d in the river, the critical depth for resuspension of akinetes into the top 2 m of water was approximately 6m.

Laboratory studies have determined that akinetes develop from A. circinalis as a response to phosphorus limitation.

It is hypothesised that phosphorus inside the cell, above a threshhold concentration, represses the genes which code for akinete development, and that the ratio of phosphorus: nitrogen: carbon is the critical factor.

Laboratory studies have also shown that akinetes, which have reserves of carbon and nitrogen, but not of phosphoru s, need phosphorus to germinate.

Nitrogen has no effect on germination.

The final objective is to test a new hypothesis which challenges the premise that the primary fuction of akinetes is dormancy.

In practical terms for the water supply operator, it may be that artificial aeration systems could help to suppress algal blooms by keeping phosphorus chemically bound, and unavailable for germination of akinetes.

Benthic Community Metabolosm in an Upland River System S Treadwell

Objective Stream communities use energy inputs from sunlight, and both autochthonous organic matter, from within the system, and allochthonous matter, such as detritus, from outside the system. The process of energy use, or metabolism, in a stream segment can provide important information in determining the structure and function of the stream ecosystem.

Dissolved oxygen, which provides an indication of photosynthetic activity and thus primary production, was recorded in each chamber every five minutes.

Photosynthetically activated radiation (PAR), benthic and transported organic matter, benthic chlorophyll a, and stream physico-chemical parameters were also measured.

Annual means for gross primary productivity, community respiration and net daily metabolism ranged from 0.05 to 10.7, 0.7 to 14.8 and -0.15 to -8.0 g02.m2.day-1 respectively. Gross primary production and community respiration tended to increase as stream size increased and net daily metabolism became more negative indicating an increase in net energy consumption as streams became larger. There were no significant seasonal patterns, although gross primary production tended to be higher in summer and autumn.

Community respiration rates measured in this study tended to be higher than respiration rates measured in previous chamber studies where intact colonised trays have been used and thus hyporheic respiration excluded. This study indicates respiration in the hyporheic zone, the stream bed itself, to be a significant component of community respiration, which, if included in the calculation of net daily metabolism suggests that most streams tend be net consumers of energy or heterotrophic.

Factors that influenced primary prod uctivity and respiration were stream size, benthic chlorophyll a concentration and nutrient concentrations.

Water Quality in the Threadbo river: Impacts of Nutrients on Periphyton Growth and Macroinvertebrates GBrown

Method

Objective

Benthic community metabolism was studied at four sites in the Acheron River basin situated in the Victorian Central Highlands. Metabolism was measured at each site using in,.situ perspex chambers (3 clear, 2 dark) over 24-48 hour periods twice a season. The chambers were clamped to plastic trays that had been buried at each site and had been allowed to colonise with benthic organisms for four weeks. The trays had their bottoms removed to allow for vertical colonisation and to allow a more natural flow of stream water through the substrate. Removal of the tray bottoms also allowed for respiration occurring in the hyporheic zone to be accounted for in the measurement of community respiration . Chamber volumes ranged from three to 30 litres depending on stream size.

Despite being a major sourc e of water for much of south-eastern Australia, the aquatic ecosystems of the Australian Alps have been a largely neglected as a field of study.

30

Investigations on the Threadho River on the growth of algae, etc. Electrified wire is threaded through certain channels w eliminate grazing by aquatic insects

Biomonitming work being conducted by the CRCFE in Pip ers Cree k, Kosciusko National Park

Determining the ecological consequences of a particular human impact requires some fundamental knowledge of unperturbed ecosystem structure and function, but it is difficult to establish the effects of these impacts on high mountain streams because so few remain unaltered. In an attempt to address this knowledge gap, a project aimed at establishing relationships amongst the l:iiota which are responding to chemical and physical features of their environment has been initiated. An understanding of these relationships will provide biological standards which will enable: the setting of sewage effluent discharge criteria: establishment of catchment management controls to protect aquatic ecosystems: the assessment of reasons for changes in biota commonly used to assess impacts.

Method The experiment is being conducted in situ in the Thredbo River using 18 independent channels that have no adverse influence on physical conditions.

Channels are constructed from 3m lengths of 30cm diameter PVC pipe halves, with 50cm high polyethylene walls. Within each channel, clay halfpavers embedded in natural substrata provide a standardised sampling unit for periphyton and macroinvertebrates, which are sampled about two weeks after installation.

Several unsuccessful attempts using nutrient-diffusing substrata have been made to establish which nutrients, or combinations, are limiting in the Thredbo River. Th~ lack of success using this well-documented technique has led to several controlled laboratory experiments which questions its usefulness in providing nutrient limitation information.

Without specific knowledge, nutrient WATER MAY/JUNE 1995

manipulation has involved the addition of tr eated efflu ent, because algae ar e known to respond to this sour.ce of nutrients. By comparing the composition of the effluent with that of the river water , infer ences regarding nutrient limitation may be possible, allowing any observed community structure differ ences to be interpreted better .

After initial trials with insecticides and nets, macroinvertebrates have been successfully exclud ed from designated channels through the novel use of electricity. Preliminary r esults indicate that macroinvertebrate grazing of autochthonous material is a major energy pathway in this system.

Problems of standard setting, monitorin g and imp act assess m en t exi st nationwide, so the approach advocated in this project and the r esults obtained will provid e biologi cal information which might be used as standards needed as a basis for formulating criteria to manage wate r qu ali ty in upl a nd river s in Austr alia.

The Role of Yabbies as consumers in Billabong Ecology J Jordan P S Lake Objective The aim of this research has been to

examine the r ole of the freshwater crayfi sh, Cherax destructor, in structuring the detritus and macrophyte-based fo od chains of billabongs on the Ovens River floodplain, nor th-eastern Victoria. As an oppor t unistic omnivore, C. des tructor may have complex effects on the fate of energy and nutrients within many aquatic habitats. Within the Ovens River billabongs, C. destructor is likely to have the most influence thro ugh its effects on aquatic macrophytes .

Method Alt h ough detritus is r egard ed by many as t he maj or foo d so urce of C. destructor (see Lake and Sokol 1986 and refer ences therein), results of labor atory and field experiments indicate that, within the Ovens River billabongs, allochthonous detritus is not an impor tant food for this cr ayfish. Litter from the River Red-gum, Eucalyptus camaldu lensis, forms a major component of the coarse p ar ticul ate detrit us in all t hese billabongs. During contr oll ed laboratory experiments, C. destructor consumed an average of only 0.8 g (wet weight) of E. cama ldu lensis leaf ma terial ov er 10 weeks. Not sur prisingly, this impact was n ot statistically s ignificant wh en th e experiment was conducted in situ. It is unlikely, therefor e, that C. destructor plays a significant role in the processing of allochthonous leaf material.

.,

The impatt of C. destructor on live aquatic macr ophytes, however, may well influence the dynamics of a billabong's pla nt assemblages. In the labor ator y, using experimen tal plant and animal densities equivalent to those r ecorded during billabong surveys, C. destructor caused significant reductions in both the biomass and density of the three macrophyte species, Myriophyllum crispatum, Potamogeton tricarinatus and Juncus usitatus. Results from field experiments suggest that, under more natural conditions, crayfi sh do not cause an over all decr ease in plant density, but instead, they may keep the natural incr ease in plant number s in check.

Clearly, the consumption or destruction of aquatic macr ophytes and their asso ciated epiphytes may have significant indirect effects on macr ophyte-associated macr oinver tebrates and on r ates of nu trient cycling within billabongs.

These issues are currently being examined.

Reference Lake, P S and Sokol, A (1986). "Ecology of the yabby, Cher~ destructor, Clark (Crustacea: Parastacidae) and its potential as a sentinel animal for merc ury and lead pollu t ion. " Austral ian Water Resources Co un cil Tec hni cal Pape r No . 87 (A ustrali an Government Publishing Service, Canberra).

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The arrangements Tubemakers Water have with Envirex supersedes previous arrangements between William Baby and Envirex.

Tubemakers Water is the source of spare parts for all the Envirex equipment installed by William Baby.

For more information please contact Tubemakers Water: Telephone Q2 929 6166 Facsimile 02 922 7881 WATER M AY/JUNE 1995

31

HEALTH

HEALTH-RELATED WATER MICROBIOLOGY: AUSTRALIA LEADS: BUT WHERE NEXT? NJ Ashbolt* Introduction The state-of-the-art in microbiology for the water industry has largely been in a time capsule since the middle of this century, since reliance on coliform bacteria as an indicator of faecal contamination and disinfection efficacy ha s changed little in the last forty years (ANZECC, 1992; NHMRC and ARMCANZ, 1994).

While coliform standards have clearly aided in the provision of safe water in developed countries, epidemiological studies of waterborne illness in such countries indicate that the common aetiological agents are more likely to be viruses and parasitic protozoa than the pathogenic bacteria that faecal coliforms attempt to indicate (Seyfried et al., 1985; Kay et al., 1994; Moore et al., 1994) .

Furthermore, the recent literature illustrates the poor correlations between waterborne ~uman viruses and faecal coliforms in waters (Loh et al., 1979; Deuter et al., 1991; Grohmann et al., 1993; Harrington et al., 1993).

Concentrations of major groups of faecal microorganisms and their removal by treatment are given in Table 1.

This lack of a relationship between coliforms and pathogens relates in part to the sporadic presence and poor ability to detect pathogens in sewage/effluents.

In addition, there are problems in sampling (Fleisher, 1990), and many pathogens survive longer than the faecal indicator bacteria determined by culturing methods (Evison, 1988), with viruses or parasites present when indicator bacteria are absent (Hughes et al., 1991; Pontius, 1993). Table 2 lists a range of pathogens and survival times. A further complication is the formation of non-culturable but viable indicator bacteria which are not enumerated by standard methods and result in considerable underestimation of pathogen/faeces presence (Byrd et al., 1991; Green et al., 1991).

Australian Input As we turn to the next century, however, there are significant improvements in sight. Thanks to recent advances in molecular microbiology, developments in direct rapid pathogen detection are now becoming available. Properly directed, these methods will allow a sound micro-

32

biological basis for setting water quality standards. One of t he most advanced groups in the world to trial these new technologies was established by Sydney Water through their Australian Water Technologies (AWT En Sight) laboratories and their principal collaborators at Macquarie University and The University of New South Wales.

Progress by the Sydney group and reports from the IA WQ conference in Budapest (IA WQ, 1994) are presented here to update the water industry on the significant advances in health-related water microbiology that have occured over the la st few years. It should be noted, however, that while the Sydney team has run three international workshop s on "Water Microbiology for the 21st Century" in Sydney, Seattle, USA and Nottingham, UK, and has also played a significant role in an international Water Colloquium in Ecuador ("Global Issues in Water Microbiology", April, 1995) sponsored by the American Academy of Microbiology, continued financing of their work is proving to be almost i~ possible.

International Developments.

The Health-Related Water Microbiology was the first IAWQ specialist group and again showed its strength by presenting 56 oral and many more poster papers at last year's Budapest meeting. (IAWQ, 1994). The three Australian oral papers were from work coordinated by AWT-EnSight. Three major themes were covered in the conference, the highlights of which are reviewed below.

Health Effects and Risk Assessment A number of potentially important microbial groups in recreational waters were covered. Starting with a general epidemiological pilot study into the health effects of triathletes swimming in water with median E. coli, faecal streptococci, F-specific RNA phages and entero+reoviruses (six other groups were also determined) of 170/l00mL, 13/l00mL, 56/l00mL and 0.22 pfu/L respectively, the Dutch authors failed to shown any statistically significant effect except for general illness from the third-

sixth day after exposure. Nevertheless, the methodology was considered suitable for larger numbers than those of this pilot study (314 cases versus 81 controls) which is anticipated by follow up events.

The presenter (Dr. Medema) suggested that a higher prevalence of gastrointestinal illness resulted in the case group.

This unfounded comment seemed somewhat reminiscent of Pierre Payment's filtered water versus tap water study 1 which unfortunately was not discussed at the meeting.

In contrast to most epidemiological studies, Dr. Roger Fujioka's group from Hawaii demonstrated a clear relationship between fiftythree 4 month-16 year old "swimmers" and the incidence of Staphylococcus aureus skin infection.

The association was further supported by matching antibiotic resistance patterns from iso.Jates obtained from patients and seawaters.

Another group of opportunistic pathogens and indicators, environmental aeromon"tds, were elucida ted by the group from AWT-EnSight, Sydney.

Elegant PCR typing of aeromonads from seawater, river water, urban runoff and sewage effluents was developed by the group (Dorsch et al., 1994) which clearly showed that the majority of environmental aeromonads were not readily phenotyped . Nonetheless, A. hydrophila and A. veronii biotype sobria predominate in fresh river waters, and these species contained the highest proportion of potential virulence factor s. This is considered important in The Netherlands and Canada, where aeromonads are now monitored as part of the drinking water standards.

Legionella spp. are also ubiquitous in waters and Bruce Roll from Roger Fujioka's laboratory showed an order of magnitude increase in sensitivity to their detection by using PCR compared to cell culture. As with the aeromonads, legione llas were reported to grow in sewage effluents and chlorinated effluents, but the primary pathogenic species, L. pneumophila, appeared only as far as post secondary treatment and was not detected in aerosols associated with secondary sewage treatment. * School of Civil Engineering, Un iversity of New South Wales, Sydney, NSW 2052

WATER MAY/JUNE 1995

Growth of faecal indicators and Shi,gella sonnie was reported in drinking water by Dr. Kott from Haifa, Israel, and Vidar Lund (Norway) included Yersinia enterocolitica, a problem group in cool waters. These data were supportive of the work carried out by Dr. Anne Camper (not presented) in that rechlorina ted tap water further encouraged regrowth and potential survival of these bacteria in biofilms in the distribution system. Tap water was also identified by Dr. Laurenti et al. to be responsible for Pseudomonas aeruginosa nosocomial infections in neonatal intensive care units in Rome. It was emphasised that nosocomally acquired legionellosis has also been sourced to tap water and point of use filters.

Adding to this increasing worry about opportunistic bacterial pathogens, Prof. Betty Olsen's laboratory in Irvine, California is assessing the presence of such organisms in groundwaters recharged or impacted by sewage effluents, using 168 ribosomal RNA directed gene probes and sequencing. In addition, she suggested the use of Legionella sp. for determination of AOC rather than pseudomonads or aeromonads to better assess regrowth potential of the problem legionellae.

However, Prof. Chuck Haas (Philadelphia, Pennsylvania) along with Dr. Joan Rose (Tampa, Florida) has been pushing a different approach to assess risks, that of Quantitative Risk Assessment (QRA). He presented an impelling analysis to demonstrate that with 20 laboratories per 10,000 people (common in the USA), the likelihood of detecting an outbreak was about 1:1000.

If fact with fewer laboratories per capita in smaller communities the detection likelihood increased to 1: 100-1: 1000.

Based on QRA, which relies on likely concentrations in source waters, accepted dose response models and Monte Carlo simulations, he placed a plea for others to try the methodologies. Dr. Rose presented data to indicate that taking severity and mortality into consideration, bacteria and virus risk was 1,00010,000 fold greater than for the parasite Giardia. Using the Enhanced Surface Water Treatment Rule proposal to base pathogen removals on Giardia, she recommended that for every log reduction of cysts, 7 and 8 log reductions would be needed for rotavirus and bacterial pathogens (salmonellae and campylobacters) respectively. Rose and Sobs ey (1993) have also used QRA to demonstrate the life-time risks of viral infection due to consumption of raw oysters.

However, putting this QRA methodology into practice is not always straight forw ard . Dr. Bertina Genthe (CSIR, Dur ba n) attempted to use Haas' s approach to estimate risk from their monitor ing data. Unfortunately, she end ed up reporting that larger sample WATER MAY/J UNE 1995

sizes are required to reduce the number of non-detects (of viruses and parasites) and that there is a need for addition models to move on from ones based on ingestion to include inhalation and dermal exposures.

Virus and Parasite Detection With the realisation that parasites and viruses are generally assumed to be the major waterborne pathogens, a number of laboratories world-wide are focusing on methods to detect these microorganisms. Starting with the viruses, Dr. Bertina Genthe and Marian Wolfaardt (South Africa) , Dr . Gary Grohmann (Sydney), Dr. David Green (Auckland), Dr. Rosa Pinto (Spain), Dr . Robert Girones (Barcelona), Dr. Wyn-Jones and Dr. David Lees (U.K) and Prof. Chuck Gerba (Arizona) all presented progress with viral gene amplification and identification using the polymerase chain reaction (PCR) with samples from waters and wastewaters. However, some groups still only report positive results from seeded environmental samples.

What is clear from the work presented in Budapest was that sample clean up is still a major issue and there is not one universal method available for the removal of PCR inhibitors from environmental samples. Nonetheless, common pretreatments are appearing based around ultrafiltration and column chromatography, along with some proprietary nucleic acid cleaning agents.

Further progress was presented by the Sydney and Barcelona groups by combining cell culture with PCR or molecular hybridisation. In addition, during the last fe w months, AWT EnSight have developed a general cleanup strategy for viral PCR of environmental samples.

(For further information on these environmental virology methods contact Dr. Grohmann (AWT-EnSight, 02-334 0880).

Dr. Rivka Kfir (CSIR, Pretoria) attempted to recover parasites and viruses with the one concentration method, a flat bed ultrafilter (50,000 Dalton cutoff).

While recoveries of Cryptosporidium oocysts and Giardia cysts were not great, they were as good as the standard methods using Cuno-wynd or Filtrite cartridge concentrators (up to about 11 % recovery). Hence there is potential to recover viruses and parasites in one go, which is also under evaluation at the laboratories of AWT-EnSight, Sydney.

Nonetheless, both the Sydney and South African groups suggest the application of hollow fibre rather than flat bed ultrafiltration, as the latter results in poor virus recoveries.

Perhaps the most progressive leap in methodology was presented by th e Australian-centred group with its presentation of flow cytometric sorting and potential enumeration of viable parasites from environmental samples Goint work

from Macq{tarie University, A WTEnSight and Thames Water Utilities).

Recoveries for Giardia and Cryptosporidium with UK and Australian waters was reported at 7080% and 40-60% respectively with the flow cytometry assisted method.

Viability assessment by flow cytometry of 188 rRNA oligonucleotide fluorescentlabelled material showed a nearly perfect correlation with excystation of Cryptosporidium oocysts. Hence, it is not surprising that seven flow cytometers are now in use by the UK water industry and under evaluation in The Netherlands and US . The latter is to be supported by the American Water Works Association Research Foundation (A WWRF) with three major grants being offered for parasite work for 199698.

Considerable discussion followed the flow cytometry paper, and focused on the likely poor quality (some would say useless) data to be obtained throughout the USA during the Enhanced Information Collection Rule monitoring of parasites now due to start late 1995, but using the Filtrite cartridge standard method. See Clancy's inter laboratory trial for an indication of how variable (from no detection to 11 % recoveries) this data is likely to be (Clancy, 1994).

The recent outbreaks of cryp tosporidiosis has generated considerable interest in viability methods and sources of oocysts worldwide. Dr. Stadterman (Pittsbur~ h, PA) reported a 99.9% inactivation of seeded Cryptosporidium oocysts following 24h anaerobic sewage digestion and 98.6% removal during primary and secondary sewage treatment in laboratory models. Interest in Cryptosporidium in Latin America was reported by Joan Rose, where oocysts were present at <1-48/1001 in drinking waters, 16-1,390/1001 in sewage and <180/ l00L in surface waters using the Filtrite standard method. Clearly, higher and more consistent densities will be reported as improved methods are implemented for parasite detection.

Alternative "Health-Related" Indicators A range of papers covered disinfection methods (ranging from combinations of chlorine dioxide-chlorine to silver and radiant energy on hydrogen peroxide). Methods to assess the process efficacy were generally based on removal of bacterial and bacteriophage indicators.

While nothing new was reported with this legitimate use of indicator organisms, there were seve:a1 papers pushing the concept of bacteriophages as surrogates for human enteric viruses in soils and waters (i.e. as index organisms).

Prof. Mark Sobsey's (Chapel Hill, North Carolina) work with hepatitis A, polio, echo and the virus "index" MS2 (a F-spe-

33

cific RNA bacteriophage) supported the case by presenting data to show MS2 survived as long as the hardiest human viru s tested (echovirus) in soi ls and groundwaters and desorbed from soils more r eadily than most human viruses.

He has subsequently published this and r elated work (Schwab et al. , 1995).

Some caution set in with work presented by Prof. Willie Grabow (Pretoria) and Prof. Joel Jofre (Barcelona). Grabow investigated the prevalence of somatic, F-specific and Bacteroides fragilis strain HSP40 bacteriophages in a range of animal and human faecal samples. B. fragilis phages were absent from primate, mammalian and avian faeces, but present in 13% of human samples. In contrast, somatic coliphages were detected in 54% of human, 56% of seabirds; and Fspecific phages in 26% of human, 90% of domestic animals, 76% of monkey and baboon, 63% of higher primate, and 20% of seagull faeces. With somatic and Fspecific phage titres of 4.5x 106 a nd 3.2x10 4 per gram respectively, these phages may be poor indices of human enteric pathogens. Mounting support for the use and further testing of the apparently human specific B. fragi lis HSP40 phage followed with evidence from Dr. Rob ert Armon (Israel) and Jofre with drinkin g waters and Dr. Paul Jagals (Bloemfontein, South Africa) with receiving waters.

Jofre's work was particularly interesting, showing that B. fragilis phages are more r esistant to water treatment (including chlorination) t han eit h er somatic or F-specific phages, but still less resistant than Clostridium perfringens.

There is a problem, however , current methods for B. fragilis phages indicate they are 2-3 lo gs less num erou s in sources and raw waters that the other phages. He nc e, improv ed detection methods are the focus of J ofre's group in Barcelona. Nonetheless, one is left wondering that perhaps more effort should be directed to dete ction of an enteric virus like adenovirus or reovirus, shown to be consistently present in human faeces around the world.

Returning to bacteria, we were reminded that none of the faecal indicator /index organi sms help predict the presence of native bacterial pathogens such as Leptospira and Vibrio species, particularly in tropical/sub-tropical waters. Dr. Fujioka's group has developed selective media for the r esolution of pathogenic from saprophytic Leptospira found in soils and waters. Thi s work from Hawaii indicated that L eptospira were derived from soil contamination of waterways.

Dr. Gary Toranzos's molecular and culture study of marine Vibrio spp. from Puerto Rico is relevant to diseases such as vibriosis and V. parahaemolyticus/vulnificus gastroenteritis from consump_tion of contaminated seafoo d . Henc e

34

Table 1 Key Faecal Microorganisms in Sewage and 'typical % Removals by

Treatn'?ent Processes E. coli

Source

Salmonella -

Enteric

GiardiaCyBtti

CampylobactN

Vll'U.8e8 Raw Sewage (L-1)

10'-10'

40,000

100-15,000

5,200-22, 700

50-90, 27-96 91-99 99.99-99. 99999

50-90, 15 96-99 99.99-100

0-30 30-75, 76-99 99.8-99.99

55 99 99.8

%Removal by: Primary treatment Secondary treatment Tertiary (ponds/chlorine)

Data from McNeil! (1985), pp. 48, 77, Holler (1988) and Yanko (1993) for bacteria and viruses; Giardia data (Long & Ashbolt, 1994).

Table 2 Major Potential Pathogens/Indicators in the Aquatic Environment Group of Organism

Source(s)

Symptom(s)

Survival

an./human faeces human faeces human faeces human faeces human faeces human faeces human faeces human faeces an./human faeces an./human faeces

CCoFGHR G G G B CDE-M FHR S C E-MFGRP.S H C FE-MP R None known G

T99.9 50 d Unknown Unknown Unknown 2 d-46 wk 2 d -46 wk > 24 d 2-130 d >4d 2-34 d

an./human faeces an./human faeces an./human faeces an./human fa eces an./human faeces sea water an./human faeces an./human faeces seawater, faeces an ./h uman faeces

GSW G-F G indicator organism indicator organ ism S W "indigenous" G-F Bloody diarrhoea GW Appendicitis-li ke G

12h - 5d <15->70 d "indigenous" /<6d daysweeks

an./human fa eces faeces an./human faeces

Wate.ry diar r hoea F G/dysentery Diarrhoea/bloating

(probably month s) Unknown Unknown

an./human faeces an.fhuman faeces

Roundworm Tapeworm

Unknown Unknown

Alexandrium spp.

Gambierdiscus toxicus

ballast/sea water sea water

"indigenous" "indigenous"

Gymnodinium spp.

ballast/sea water

PSP ciguatera shellfish poisoning PSP

Viruses Adenovirus Astrovirus Calicivirus ( inc. Norwalk) Coronavirus Coxsackie A&B Echovirus Hepatitis A Poliovirus Reovirus Rotovirus

BacteriaT90 Aeromonas spp.

Campylobacter jejuni E n terotoxigenic E. coli faecal coliforms faecal streptococci Mycobacteriurn marinum Salmonella spp.

Shigella spp.

Vibrio spp.

Yersinia enterocolit:ica

"indigenous" Poor 5 h-2 d 2 h -2 d 2 h - 12 d

Protozoa Cryptosporidiurn parvum Ent.amoeba histolytica Giardia intestinalis

Helminths Ascaris spp.

Taenia spp.

Dinoflagellat.e.s

"indigenous"

F'rom Akin et al., 1976; Blawat et al., 1976; McNeill, 1985; Evison, 1988; Hallegraeff, 1992; Chung & Sobsey, 1999.

C-carditis, Co-conjunctivit:is, Ffever, D-diabetes, E-M-encephalitis-1neningitis, G-gastroenteritis, G-Fgastro+fever, H-hepat:itis, P-parcilysis, PSP-paralytic shellfish poisoning, R-respiratory infection, Sskin infection, W- wound infection.

T90 or T99.9 times for 1 or Slog reduction in numbers respectively at 10-25C.

Table 3 Likely Target Microorganisms for Future Routine Monitoring of Water

Quality Microbial Group

Indicator/Index Microorganism and Method(s)

Human Virus

Adenoviru s/-Reoviru s in all waters; by PCR or flow cytome try Parasite Giardia for r ece nt sewage pollution, Cryptosporidittrn for more distant faecal pollution and reclaimed waters; by flow cytometry or immunological methods faecal coliforms for recent ge neral fa ecal pollution; Clostridium perfringens for human faecal inpact; Aeromonas spp. for drinking waters; Legionella spp. in reclaimed water; cyanobacteria in freshwaters, Vibrio spp. in marine waters; by culture/PCR/hybridisation with gene probes and fl ow cytometry

Bacteria

with the current push for direct molecular identification of faecal pathogens, we should not loose sight of the other indigenous waterborne pathogens now within our grasp to monitor.

New Microbiological Standards With the advent of molecular detection methods for pathogens (Enriquez et WATER MAY/JUNE 1995

al., 1993; Dorsch et al., 1994; Tsai, et al., 1994; Vesey et al., 1994), it is timely to reassess the Australian microbiological standards. The European community took the other extreme stance back in 1976 by providing guidelines, but not methods to meet, no viruses in 90% of 10L samples and no salmonellae in 90% of 1-L samples of primary recreational waters (Council of the European Communities, 1976). This approach has stimulated method development, but limited virus analysis to the readily cultivated but numerically less significant enterovirus group and in the case for Spain, various viruses that infect bacteria (bacteriophages).

The epidemiolo gical evid ence for accepting the enterococci standard proposed by Cabelli for marine waters (Cabelli et al., 1979) has also been put in doubt (Fleisher, 1991). Furthermore, the longer survival of enterococci in marine waters compared to faecal coliforms is of little consequence when in their absence, enteric viruses are present in either seawater or shellfish (Schaiberger et al., 1982).

On the other hand, the sewage indicator bacterium, Clostridium pe1f1-ingens is significantly elevated at sewage/sludge disposal sites (Ashbolt et al., 1993; Hill et al., 1993). This bacterium may indicate the presence of long lived faecal microorganisms as illustrated by elevated levels hundreds of kilometers downcurrent of a sewage sludge dump site (Hill et al., 1993). Currently no standards exist for Clostridium perfringens, although a Hawaiian (Fujioka pers. comm.) and the Sydney (Harrington et al., 199 3) epidemiological studies were evaluating its usefulness as a pathogen index organism.

As a predominantly human fa ecal indicator, Clostridium perfringens has not been shown to be a useful surrogate for Cryptosporidium in Sydney's pristine catchments, indicating animal rather than human faecal contamination.

Hence, it is important to know your water's catchment when selecting an appropriate array of indicator/pathogen index microorganisms. Similarly, when using reclaimed water, bacteria resistant to chlorination and able to regrow in the reticulation system, such as Legionella spp. may become important to monitor using molecular methods that will detect injured cells (Palmer et al., 1995).

The general direction is for an array of microbial groups to be monitored, dependent on catchment characteristics.

Possible microorganisms that will be routinely monitored next century are given in Table 3. Molecular methods are being developed than will enable such a range of microbial groups to be measured in the one sample preparation.

WATER MAY/JUNE 1995

Conclusions Traditional bacterial indicators do not reliably reflect the presence or absence of enteric pathogens in waters or sediments. Hence, despite little epidemiological evidence (or data) of health problems from Australian waters, a rational basis to monitor the microbiological status awaits further trial of novel molecular based methods being pioneered in this country.

Enteric viruses and parasite cysts should be regarded as indicators of faecal contamination, since they are probably more closely related to the causative agents of infections acquired from waters rather than faecal coliforms or enterococci. The presence of viruses to bacteria such as coliphages may be useful surrogates for enteric human virus survival in seeding experiments and disinfection studies, but their presence may be misleading for receiving waters.

Chlorine resistant pathogens, such as Cryptosporidium and Legionella spp. may be of particular concern in reclaimed waters. Molecular methods are the only tools available for these difficult to culture microorganisms, particularly for bacteria following chlorine stress.

Author Dr. Nicholas Ashbolt is Associate Professor in the Schoo l of Water Engineering at the University of New South Wales since 1994. Previously he was a principal Scientist for four years with Sydney Water's AWT EnSight, and there stabli shed extensive links with the universities of NSW and Macquarie.

The collaboration continues, and the group have established a world lead with their work on molecular identification of pathogens and indicator bacteria by the polymerase chain reaction and flow cytometry.

References Ak in , E.W. , Hill , W.F., Jr. , Cline, G.B. and Benton, W.H. (1976). The loss of poliovirus I infectivity in marin e waters. Wat. Res. 10, 59-64.

ANZECC (1992). Austra li an Water Quality Guidelines for Marine and Freshwaters. 1st ed . Vol. Draft 9 September, 1992.

Melbourn e, Australian & New Zealand Environment & Conservation Council.

Ashbo lt, N.J ., Kueh, C.S.W. and Grohmann, G.S. (1993). Significance of specifi c bacterial pathogens in the assessment of polluted receiving water of Sydney. Wat. Sci. Technol.

27(3-4), 449-452.

Blawat, F. , Potajallo, U ., Dabrowski, J. , Towianska, A. and Jarnuszkiewicz, I. (1976).

Survival of so me viruses in the sea-water sam ples collected from the gulf of Gdansk.

Preliminary studi es. Bull. Inst. Mar. Trop.

Med. Gdynia 27(3-4).331-339. In: Viruses in Water, Renovated and other Waters ¡ 1977 Literature Abstracts. (Ed: Berg, G.) USEPA Environ. Res . Center, Cincinnati, Ohio.

Byrd, J .J. , Xu, H.-S. and Colwell, R.R. (1991).

Viable but ~ on-culturable bacteria in drinking water. Appl. Environ. Microbiol. 67, 875878.

Cabelli, V.J ., Dufour, A.P., Levin, M.A. , McCabe, L.J. and Haberman, P.W. (1979).

Relationship of microbial indicators to health at marine bathing beaches. Am. J. Public Health 69:690-696.

Chung, H. and Sobsey, M.D. (1993).

Comparative survival of indicator viruses and enteric viruses in seawater and sediments.

Wat. Sci. Technol. 27(3-4), 425-428.

Clancy, J.L., Gollnitz, W.D. and Tabib, Z. (1994 ).

Laboratory ex peri e nce: monitoring for Giardia and Cryptosoridium. In: Proc.

Water Quality Technolo gy Conference, November 7-11, Miami, Florida, Part II. (Ed: AWWA) American Water Works Association, Denver, Colorado, pp:1713-1731.

Council of the European Communities (1976).

Council Dire ctive of 8 December 1975 Concerning the Quality of Bathing Water (76/160/EEC). Off J. Eur. Communit. 19, L31/1-7.

Deuter, A., Gale, P., Irving, T.E., Jolly, P.K., Munro, D. and Pike, E .B. (1991). Viruses in Surface Waters - Occurrence and Environmental Control. FR 0213. Marlow, UK, Foundation for Water Research/WRc. 63 pages.

Dorsc h, M., Cox, P.T., Ashbolt, N.J . and Goodman, A.E . (1994). Rapid identification of Aeromonas species using 16S rDNA targeted oligonucleotide probes: a molecular genetics approach for scr eening environmental isolates. J. Appl. Bact., 77:122-126.

Evison, L.M. (1988). Comparative studies on the survival of indicator organisms and pathogens in fresh and sea water. Wat. Sci. Technol. 20(11-12), 309-315.

Fleisher, J.M. (1990). Th e effects of mea surement error on previously reported mathematical relationships between indicator organism density and swimming-assoc iated illn ess: a quantitative estimate of the resulting bias.

Int. J. Epidemiol. 19, 1100-1106.

Fleisher, J.M. (1991). A reanalysis of data supporting US federal bacteriological water quality criteria governing marine r ec reational waters. Res. J. Wat. Pollut. Control Fed. 63, 259-265.

Green, D.H., Loutit, M.W. and Lewis, G.D. (1991) . Gene probes and polymerase chain reaction for assessing the microbiological quality of waters. In: Coastal Engineering Climate for Change. Proc. 10th Australasian Conf. Coasta l and Ocean Eng in eering, Auckland, New Zealand, 2-6 December, 1991.

(Eds: Bell, R.G., Hume, T.M. and Healy, T.R.) Water Quality Centre Publication. 21, DSIR, Hamilton, pp:399-403.

Grohmann, G.S., Ashbolt, N.J., Genova, M. , Logan, G., Cox, P. and Kueh, C.S.W. (1993).

Detection of viruses in coastal and river water systems in Sydney Australia. Wat. Sci. Technol. 27(3-4), 457-461.

Hallegraeff, G.M. (1992). Harmful algal blooms in the Australian region. Mar. Pollut. Bull.

26, 5-8.

Harrington, J ., Wilcox, D., Giles, P., Ashbolt, N., Evans, J. and Kirton, C. (1993). The health of Sydney surfers: an epidemiological study.

Wat. Sci. Technol. 27(3-4), 175-182.

Hill, R.T., Knight, I.T., Anikis, M.S. and Colwell, R.R . (1993). Benthio distribution ofsewage sludge indicated by Clostridium perfringens at a deep-ocean dump site. Appl. Environ.

Microbiol. 69, 47-51.

Hii ll er, C. (1988). Long-te rm study of occurrenc e, di str ibution and reduction of Campylobacter sp. in the sewage system and wa stewater treatment plant of a big town.

Wat. Sci. Technol. 20(11-12), 529-531.

35

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Hughes, M.S., Cqyle, P.V. and Connolly, J.H. (1992). Enteroviruses in recreational waters of Northern Ireland. Epidem. Inf. 108, 529536.

IAWQ (1994). Proc . Health-Related Water Microbiology, 24-29 July, 1994, Budapest, IA WQ 17th Biennial International Conference. Conference Preprint Book 3.

IAWQ, Budapest.

Kay, D., Fleisher, J.M., Salmon, R.L., Jones, F., Wy er, M.D. , Godfre e, A.F., ZelenauchJacq uotte, Z. and Shore, R. (1994).

Predicting likelihood of gastroenteritis from sea bathing: results from randomised exposure. Lancet 344(4927):905-909.

Lon g, J. and Ashbolt N.J. (1994). In: Microbiological Quality of Sewage Treatment Plant Effluents. A WT Science & Environment 94/123, Water Board, Sydney.

McNeill, A.R. (Ed.) (1985). Microbiological water quality criteria: a revi ew for Austra li a.

Australian Water Resource Council Te chnical Report No. 85 . Canberra, Australian Government Publishing Service.

561 pages.

Moore , A.C., H erwaldt, B.L., Cra un , G.F., Calderon, R.L., Highsmith, A.K. and Juranek, D.D. (1994). Waterborne disease in the United States, 1991 and 1992. J A WWA 86, 87-99.

NH&MRC and ARMCANZ (1994). Austalian Drinking Water Guidelines. Draft June, 1994, National Health and Medical Research Council, Ag riculural and Reso urc e Management Council of Australia and New Zealand, Canberra.

Palmer, C.J., Bonilla, G.F., Roll, B., PaszkoKolva , C., Sangermano, L.R. and Fuj ioka, R.S. (1995). Detection of L egionella species in reclaimed water and air wi t h the EnviroAmp L eg'ionella PCR kit and direct fluorescent antibody staining. Appl. Environ.

Microbial. 61:407-412.

Pontius, F.W. (1993). Protecting the publi c again s Cryptosporidium . J A WWA 85: 18,22, 122-123.

Rose, J.B. and Sobsey, M.D. (1993). Quantitative risk as sessmen t for viral contamination of shellfish and coastal waters. J. Fd. Protect.

66, 1043-1050.

Schaiberger, G.E. , Edmo nd, T.D. and Gerba, C.P. (1982). Distribution of enteroviruses in sediments contiguous wi th a deep marin e sewage outfall. Wat. Res. 16, 1425-1428.

Seyfried, D.L. , Tobin, R.S ., Brown, W.E. and Ness, P.F. (1985). A prospective study of swimming-related illness. II. Morbidity and the microbiological quality of water. Amer. J. Pub. Health 76, 1071-1075.

Schwab, K.J. , de Leon, R. and Sobsey, M.D. (1995). Concentration and purification of beef extract mock eluates from water sample s for the detection of enterovir uses, hepatitis A vir us, and Norwalk virus by reverse transcription-PCR. Appl. Environ.

Microbial. 61:531-537.

Tsai, Y.-U., Tran, B., Sangermano, L.R. and Palmer, C.J. (1994). Detection of poliovirus, hepatitis A virus, and rotavirus from sewage and ocean water by triplex reverse transcriptase PCR. Appl. Environ. Microb ia l. 60, 2400-2407.

Yanko, W.A. (1993). Ana lysis of 10 years of virus monitoring data from Lo s Ange les county treatment plants meeting California wasewater r ec lamation criteria. Wat. Environ. Res. 66, 221-226.

Vesey, G., Hutton, P ., Champion, A., Ashbolt, N., Williams, K.L. , Warton, A. and Veal, D. (1994). Application of flow cytometric method s for the ro utin e detection of Cryptosporidium and Giardia in water.

Cytometry 16, 1-6.

WATER MAY/JUNE 1995

TECHNOLOGY

PARTICLE COUNTING IN WATER TREATMENT BA Murray* Keywords Particle counters, water treatment, particulates, filtration, Giardia, Cryptosporidium

Abstract Particle counters determine the number and size distribution of particulate matter in a water sample, in contrast to turbidimeters which give a general measure of the scattering of light by whatever particles are present. Overseas they are gaining acceptance as process monitoring instruments that have proven to be useful tools for optimising water treatment plant (WTP) performance. In Australia, particle counters have been used, to date, mostly as analytical tools in research and development projects, but they are being considered for process monitoring and optimisation tools. The potential as warning devices for the filter breakthrough of particulates which may include the pathogenic Cryptosporidium and Giardia cysts is also being considered.

Particulates in Water Treatment The science of water treatment is based on the physico-chemical reactions of dissolved compounds and of particulates. Colloidal impurities in a raw water are first coagulated and the particulates formed are then flocculated to the right size for clarification and/or filtration.

The process of filtration centres on the behaviour of the particulates - their size, their number, their physical properties, their chemical properties.

Because the particulates in a water are such a crucial component of that water, particle distribution analysis of the water by particle counting must therefore lead to an improved understanding of the water and its treatment.

The optimisation of floe size and particle removal for a given filtration system can lead to improved water quality, longer filter run times and to significant reductions in chemical dosing requirements and thereby to a reduction in backwashing and sludge handling system requirements.

Turbidimetry Particulates have not, of course, been ignored in water treatment prior to parWATER MAY/JUNE 1995

ticle counting. Turbidimeters have traditionally been used to monitor filter performance and to chart raw water quality in order to enable coagulation requirements to be predicted. Currently, treated water guidelines are based on turbidity measurement.

Turbidity is a measure of water clarity and is measured by the amount of light scattered by the sample into a sensor placed at an angle to the light source.

It is an indirect measurement of particulates in the water. Turbidimeters have been shown to be insensitive to changes in particle fluctuations in the low end of the range. In the high end of the range, high turbidities can be associated with a huge range of particle distributions. In water treatment large differences in particle size and distribution can be associated with relatively small changes in turbidity. This is because light scattering is a function of particle shape, size, number and refractivity so there is no direct correlation between turbidity and particle numbers, although similar trends are often observed for a given water type.

Particle Counting Methods for counting particles are based on the determination of the number and size distribution of the particles in the water by passing the sample through a small orifice and monitoring either the scattering or obscuration of a colliminated beam of light by each individual particle. Counters are made up of a sensor, a signal processing counter and usually a computer or data logger to store the data produced.

Figure 1 shows a schematic diagram of a particle counter and counting system. Particle counters may be arranged to sample on-line, usually at frequent intervals, or as discrete batch samplers.

l

Water flow generated by

on-lme pressure or sample~

Colllma1ed IIQhl

0

Laser diode hgh1 source

0

Sample cell

Outpul s1gnal 10 counter

Figure 1. Principle of the light extimtion particle counier (from Cross & Rossi, 1992)

On-line particle counting provide s ar immediate picture of particulates in c process stream and many more samplei can be processed than would ever be pos sible by discrete sampling. Discrete sam ple particle counting however has thE advantage of greater flexibility in thal the number of sampling points is on!) restricted by the sampler's imagination.

Portable particle counters are no'" available that can be installed on-line anc later moved to other locations or used tc measure particle distributions in bater samples either in the field or in the labo ratory. A bar-coding scanner can also bE included to enable sampling regimes tc be programmed and sampling details tc be recorded from bar-code labels at eacr sampling point. The information frorr the particle counter can be processed analysed and plotted by software eithe1 contained within the particle countin~ equipment or in a separate personal com puter. Particle counting software usuall) provide s plots of variou s parameten inducting particle counts, particle volumE and surface area. Such software can alsc convert the data into ASCII format f01 exporting to other software such as thE various spreadsheeting or graphics pro grams.

Figure 2 is a photograph of a particlE counting system, including a PC, usec for research and development at thE Prospect Pilot Plant.

Calibration

Calibration is an important but ye1 imperfect part of particle counting Mono-dispersed latex beads, in a rangE of sizes covered by a particular particlE counter, are normally used for calibra tion in the water industry. The calibra tion sphere s should be to US Nationa Institute of Standards and Te s tin g Specifications. This calibration methoc has generally been found to be satisfacto ry, however, the difference between thE various shapes and refractivity associat ed with the many particles and organ isms that occur in water and the near perfect, opaque ' spheres of the late:ii beads, can lead to discrepancies. Fo1 example, the cysts of the two pathogem Cryptosporidium and Giardia have size, of 4 to 6 Âľm and 9 to 15 Âľm respectively * City Water T echnology Pty Ltd, 4 Cal g, Avenue, Normanhurst NSW 2076

37

when sized under the microscope, but they are usually sized by extinction sensors as 2 to 4 Âľm and 4 to 6 Âľm respectively, due to the refractivity of the particles. In such cases known calibration spikes of the relevant particulates should be run through the counter under laboratory conditions so that their characteristics can be established.

Particle counters can be inter-calibrated to ensure that comparable results are obtained from different instruments using different sensors. In Australia, calibration of sensors with spheres down to 1 Âľm diameter is available either on-site or in the manufacturer's laboratory.

Maintenance Particle counters have similar maintenance requirements to turbidimeters.

The particle counting system for filtered water should be flushed out at intervals of around six months, but more regularly for raw water particle counters, particularly during periods of dirty water.

Isopropanol or ethanol can be used to flush the system. Laser diode sensors will normally last at least 100,000 hours of operation (11.5 years of continuous operation).

Costs When used as a research tool particle counters are more complicated than turbidimeters and require a higher level of operator skill and training. However, when installed on-line in a WTP and connected to data processing software with associated alarms and operating guidelines they require no more attention or skill than on-line turbidimeters. The capital cost of particle counters varies depending on the configuration of counters provided and the type of equipment but is typically at least three times the cost of a turbidimeter. Multiple sensors can be connected to each particle counter thus reducing costs. In most cases particle counters would be installed in addition to turbidimeters, not instead of them.

Benefits The cost benefits of particle counting can include: a reduction in chemical consumption in the WTP by optimising chemical doses, a reduction in electrical consumption by optimising mixing energy and maximising filter run times (thereby reducing backwashing requirements), reductions in plant equipment requirements by optimising designs in pilot plant studies prior to design, reduced plant maintenance due to improved plant operation. Other benefits, such as the use of a particle counter as an indicator for possible pathogen breakthrough in filters, do not have a readily calculable cost benefit. These benefits may not all apply in each case and some of these benefits can be

38

achieved to some extent with other methods of process monitoring. However many researchers write that the benefits of particle counting are greater than for other process monitoring methods.

Applications of Particle Counting Process Optimisation. Particle counting can be used for the optimisation of many water treatment plant processes. Particle count and size distribution is usually best monitored after filtration.

The effect of adjusting the various operating parameters is then optimised in terms of filtered water quality and run time. In direct or contact filtration, the optimum floe size for ideal bed penetration in the filter media could be determined and monitored.

Particle counting can also be employed to measure the volume of material deposited in a filter, which may be correlated to filter head loss and turbidity breakthrough. It can be calculated from the difference between particle volume in the filter influent and filter effluent.

Depending on the characteristics of the particles in suspension, particle volume or particle surface area, calculated from the particle count and distribution, can be related to suspended solids concentration.

Warning of Pathogen Breakthrough. After recent concern about microbiological contamination of disinfected water supplies overseas (eg Leland et al, 1993), particle counters have been shown to have a further use.

For example, in Milwaukee, USA, over 300,000 people became ill and deaths of patients with immune deficiencies were attributed to a waterborne Crypto-sporidium outbreak (Washington Post, 1993).

Particle counters were immediately installed on water treatment plants serving the city in an effort to reduce the risks (Rossi, 1993).

Giardia cysts and Cryptosporidium oocysts are resistant to normal methods of disinfection and are best removed from the water by effective coagulation and filtration prior to disinfection. By optimising the performance of a water treatment plant in terms of particle removal the risk of breakthrough of pathogens such as Giardia and Cryptosporidium is minimised. Further, particle counters can provide an alarm indicating possible contamination of the water supply when unusual particle counts are experienced in certain size ranges such as those corresponding to pathogens of concern. A few cysts could pass into the consumer's water supply undetected but a spike of cysts from a source of contamination could be identified.

Normal methods for the analysis of . these micro-organisms takes at least a

day. With ins~ntaneous feed-back from a particle counter, action can be taken before any contamination problem gets out of hand. In the case of the water treatment plant, the operator can clean the filters and/or modify his process parameters when the number of particles exiting the plant, particularly those in the size range of the pathogens, increases.

Recent studies overseas have shown that Cryptosporidium and Giardia cyst breakthrough can be related to deterioration in plant performance or unusually high cyst leyels in the filter influent Filter breakthrough of cysts may occur with either poor coagulation or poor filtration. Poor coagulation is particularly likely during a rapid change in water quality such as after a storm in the catchment when many pathogens are reaching the WTP in large numbers. Poor filtration is usually associated with the ripening time at the start of a filter run or with particle breakthrough towards the end of a run. Cyst breakthrough into the reticulated water has also been attributed to backwash water being recycled from the sludge dewatering area where cysts may have concentrated.

In Australia, though many of the water catchment areas are relatively protected and uninhabited, those that may receive raw or treated sewage are at risk. Farm runoff can also be a problem as Cryptosporidium is known to infect most mammals, young animals being most susceptible. However, no known waterbo:im e outbreaks of giardiasis or cryptosporidiosis have yet been recorded in Australia's public water supplies. One waterborne outbreak affecting 90 people was recorded in a private water supply in Victoria and was attributed to sewage contamination of the water.

Suggested Guidelines. A proposed target level for total particle

Figure 2. The counter system used for the Prospect Pilot Plant.

WATER MAY/JUNE 1995

counts, after full treatment including coagulation and filtration, could be 20 particles per mL for particles greater than 2 µm in size. Such a level will only be achieved with a well operated treatment plant running on good quality raw water. Even then this level will be exceeded during filter ripening and towards the end of a filter run. However it is a readily achievable target for many WTPs and the risks of contamination of the water supply to consumers would be greatly reduced if backwashing were automatically set to occur when the total particle count in a filter's effluent exceeded 20 particles/mL. A similar target has been set at some WTPs in the USA. A more general water treatment guideline for total particle counts could be that 200 particles/ mL should not be exceeded for 95 % of samples. Such a figure would allow for poor quality raw water and the operational problems associated with rapid changes in flow rates and water quality.

A survey of particle counts in the treated water of twenty WTPs in California, Utah and Nevada, USA (Tate and Trussel 1978) found that treated water particle counts ranged between 7 and 726 particles/ mL with a median of 50 particles/ mL in the 2.5 to 150 µm size range. In the same survey the treated water turbidity ranged between 0.05 and 0.75 NTU with a median of 0.20 NTU.

ed water. The 60 ML/d Ashley Valley WTP, also in Utah has had an on-line particle counter since 1987.

Particle Counting in Australia

Australia, while apparently on the forefront of world water treatment technology in many other areas, appears to be lagging behind in the utilisation of particle counters. Inhibitors to the wider use of particle counters have been water treatment guidelines based on turbidity, the cost of the equipment, perceived maintenance and calibration difficulties and uncertainties about the technology and processing of data. Most of these problems have been resolved or reduced as particle counting technology has developed.

In Australia, particle counters have so far been used mostly as analytical tools in research and development projects, but are starting to gain acceptance as process monitoring instruments and tools for optimising water treatment plant performance . Particle counting was first employed in pilot plant work for the Wyong WTP (NSW) in 1978 by James Montgomery Consulting Engineers and then in further pilot plant work at Newcastle. The NSW Public Works Department then bought this particle counter and experimented with particle counting as a monitoring tool for laboratory scale research in the early 1980s. Particle counting has been carried out by the Sydney Water Board since the Some Applications Overseas early 1980s when investigations were There are many WTPs in the USA made into the relationship between turusing on-line particle counting, and they bidity and particle count. Since then the are reported as showing significant Water Board has carried out particle potential as a tool for operating WTPs at counting in a number of research protheir peak levels of performance and jects aimed at characterising the waters in Sydney's supply (Water Board, 1993). assuring the quality of the treated water.

In many cases the authorities have The Australian Nuclear Science and reported that they have led to significant Technology Organisation (ANSTO) also savings in operating costs. The Alfred used particle counters in investigating Merritt Smith Treatment Facility, a 1500 the physico-chemical reactions of iron ML/day plant in the Southern Nevada and manganese in water treatment in Water System, used a laboratory particle the mid 1980s.

Sydney Water Corporation counter with a small pilot scale plant to Recent Research. In research carried optimise the chemical dosing (Hutchinson 1985). They now use five on- out at the Prospect Pilot and Prototype line particle counters connected to 25 Plants, particle removal efficiency in the sensors. Particle counters have been 2 to 350 µm size range was found to be used at the 160 ML/d Utah Valley WTP in the order of 99% ( 2 log removal) for since the late 1970s to monitor the treat- deep bed, coarse media dual and monomedia filters . The particle counter Particles 2 - 350 um (/ml) Turbidity (NTU) was found to be a .... . , , . , 1,000 10 ., . useful tool in process monitoring (Entwisle and Murray 1993: Murray 1993). A typical result is demonstrated in Figure 3, where 0.01 10 15 20 2s 30 3r5_ _4..:.. o _ _ _ __ the particle count 5 0 is compared to Run Time (h) \ - Turbidity + Counts I turbidity meaFigure 3. Comparison of turbidity and particl,e count surement during L___ _ _ __

_ __ __

WATER MAY/JUNE 1995

_ __ __

_

a run at the J>rospect Pilot Plant.

Particulate breakthrough occured long before turbidity breakthrough. The removal efficiency of Cryptosporidium and its oocysts, by the process of coagulation and high rate filtration, was found to be in the order of 99.99 % (4 log removal) with ·a deep, coarse, dual media filter using filter aid. Starting and stopping the filter did not release any Cryptosporidium oocysts from the filter.

Such a removal efficiency, however, was achieved under closely monitored and controlled research conditions.

Hunter Water Corporation.

Recent Research. Trials were conducted at the direct filtration WTP at Grahamstown (Bailey 1993). HWC were considering employing increased offpeak pumping from the WTP which would result in sudden large flow changes through the plant. The effect of such step changes on the performance of their relatively shallow dual media filters was of concern particularly in terms of pathogen breakthrough. The study found that particle removal efficiency in the 4 to 10 µm range, the range in which Cryptosporidium and Giardia cysts were expected to be found, was generally between 96 and 98 % (1.5 log removal) during periods of satisfactory operation of the filters. Gradual increases in the filtration rate generally resulted in a slight decrease in particle removal efficiency.

Sharp changes , in the filtration rate reduced particle removal efficiencies to as low as 78% (0.7 log removal). Filters in the early stages of a filter run were more susceptible to abrupt flow changes than those in the middle stages of a run.

Filters in the latter stages of a run gave variable results depending on whether particle breakthrough had already begun. Further tests showed that the greater the step change of flow rate the greater the deterioration in particle removal efficiency.

Increasing the dose of a nonionic polymer filter aid improved the capacity of a filter to withstand significant flow changes at the start of a run. Thus polymer as filter aid may be used to control particle breakthrough during step changes in flow rates. Increasing the depth of filter coal in the 1.45 mm effective size dual media filter (from 570 mm to 750 mm) resulted in a substantial improvement in particle removal efficiency.

The report concluded that a particle counter was necessary, in addition to a turbidimeter, to successfully optimise the plant's performance with regard to cyst removal. Particle breakthrough was also identified well in advance of turbidity breakthrough. A particle counter was subsequently purchased in 1994 and, to the· author's knowledge, is the first in Australia to be installed on-line. It is being used to optimise the performance of each process unit of the Grahamstown WTP. It should be noted that particle 39

removal efficiencies in excess of 99.99% were also measured on the Dungog WTP with good quality raw water. Dungog WTP is a contact filtration plant having medium depth, coarse, dual media filters (Bailey, HWC 1993).

The Future Rational standards or guidelines for particle counts need to be introduced into the water industry to enable this useful tool to be properly utilised. This would enable the performance of WTPs in general to be improved and any risks associated with pathogens in the water supply to be minimised Once sufficient data have been gathered, an absolute maximum particle count allowable in a given number of samples may be considered. In the future on-line particle counters could be set up to sound alarms at certain set points, within specified size ranges, leading to immediate backwashing and subsequent adjustments in coagulation conditions, filter aid dose and/or filtration rate.

Hargesheimer, Lewis , Yentsch (1992) and others have speculated that WTPs worldwide will be fitted with integrated on-line particle counting systems that will continuously characterise the water, into, out of and throughout the WTP. Information about the raw water particle distribution will be used, with other analytical results, to update the WTP's computer data bank. This data

bank will be regularly consulted by a coagulation control system to optimise coagulant doses. Multiple, inter-calibrated particle sensors will monitor water at various stages of the treatment process leading to the fine tuning of process parameters. Drinking water guidelines will include particle count standards.

Industry-wide standards for quality assurance and inter-calibration will exist, enabling the meaningful comparison of results between water treatment plants and between different instruments.

Manufacturers of particle counters and water treatment professionals will develop particle counting systems specifically suited to water treatment applications.

Conclusions In drinking water treatment applications, particle counting is an innovative technology with significant potential. It provides detailed information about the effectiveness of water treatment processes. Two dimensional information is provided about the particles, that is, size and number. This information can be used to generate further information about a water sample such as size distributions and estimated particle volume or surface area distributions and totals.

This is far more information than could be obtained from the one-dimensional turbidimeter, but less than from laboratory cytometry, which, however, is a costly and slow procedure. Turbidity is

Hiac/Royco On-Line Particle Monitoring System + Allows real-time reporting of filter operation and efficiency + Reduces chemical treatment costs + Optimises backwash procedures Roband Dynamics represents the Hiac/Royco Division of Pacific Scientific, worldwide leaders in the development and application of particle counting techniques. They provide complete customer service including:

+ Installation

+ Operator training

+ System maintenance

+ Regular calibration services.

Roband Dynamics Pty Ltd 23 Ben Boyd Road Neutral Bay NSW 2089 Telephone (02) 956 6022 Facsimile (02) 956 6044 40

not always ingicative of particle concentrations at the low levels necessary to assure public health.

The development of particle counters capable of measuring ever larger particle concentrations and wider size ranges is expanding the applications for this technique . Particle counters have been shown to be useful as a means of indicating possible contamination of water supplies by pathogens such as Giardia and Cryptosporidium. With instantaneous feed back from a particle counter action can be taken before any contamination problem gets out of hand.

The capital cost of particle counters versus turbidimeters must be taken into account, although the gap has been closing over recent years. Laboratory scale testing may be useful along with a cost benefit analysis to determine if significant operating cost savings would be made in any application or if substantial benefits would minimise the risk of the operating authority to public liability.

Acknowledgments The author thanks Roband Dynamics Pty Ltd, Pacific Scientific Pty Ltd, Hunter Water Corporation and the Sydney Water Corporation for their contributions and permission to use information on their research work.

Author Bruce Murr~y is an independent consultant/ contractor. He has specialised in water and wastewater treatment processes and has concentrated on research- and concept development. He has recently produced a booklet on particle counting with Roband Dynamics.

References Bailey D (1993) 'Grahamstown Water Treatment Plant, Stage 2, particle counting trials' (Hunter Water Corporation, July 1993) Cross J, Rossi P (1992) 'Using particle counters to optimise the performance of municipal water treatment plants' Hiac-Royco, Silver Spring, MD. USA Entwisle TM, Murray B A (1993) Particle counting in contact filtration. 15th Federal AWWA Convention, 1088-1092.

Hargesheimer EE, Lewis CM and Yentsch CM (1992) Evaluation of particle counting as a measure of treatment plant performance.

AWWA Research Foundation Hutchinson C W (1985) On-Line particle counting improves filter efficiency. J Water Engineering and Management, 132(7) 20-25.

Leland D, McAnulty J, Keene W , Stevens G (1993). A Cryptosporidiosis outbreak in a filtered water supply. JA WWA, June pp 34-42 Murray B A (1993) 'Prospect WTW - pilot and prototype plant studies, November 1991 to November 1992' (AWT/ Water Board, March 1993 Rossi P (1993) 'Particle counters - The new tool for monitoring drinking water quality and plant performance' Hiac/Royco UK. Tate C H and Trussel R R (1978). The use of . particle counting in developing plant design criteria. JA WWA 70 (12) 691-698 The Washington Post (1993) Dec 9.

Water Board (1993) 'Prospect Prototype Plant res ea rch and development project, November - December, 1992' (Water Board, May 1993)

WATER MAY/JUNE 1995

TECHNICAL NOTE WATER TREATMENT SLUDGE - A RESOURCE, NOT A WASTE TM Skene, J M Oades

Abstract Alum sludge from water treatment plants in South Australia, after drying, has been found to be an excellent medium for horticulture. Further research is proceeding.

Introduction Water purification by flocculation and filtration inevitably leads to the byproduct, sludge. Disposal of this sludge is becoming increasingly expensive and difficult as landfill sites reach their capacities and the urban sprawl prevents the establishment of new disposal sites close to the treatment plants. In South Australia the Happy Valley Water Filtration Plant produces more than 10 000 tonne of sludge, at 25% solids, each year. The problems of disposal of this material led in 1993 to the establishment of a collaborative project beween the EWS&D and the Department of Soil Science of the University of Adelaide.

Properties of Sludge Water treatment sludge was found to have some interesting and valuable properties. Dried sludge from Morgan Water Treatment Plant consists of nearly 90% clay w/w and is high in organic carbon (around 8% w/w) and nitrogen (around 2% w/w/). When the material is subjected to a few drying and wetting cycles it crumbles down to a fine gravel-like consistency. This characteristic in soils is known as "self-mulching". Interestingly, sludge which had been mechanically dewatered by filter press to 20% solids, as distinct from slow drying in lagoons, crumbles down to the same consistency on its first drying.

"Self-mulching " soils will regain their structure on wetting and drying even after having their structure completly destroyed by 'puddling'. Such loose, friable soils drain freely and are easily explored by plant roots. The sludge had the added advantage of a high water-holding capacity. All this suggested that it would make an excellent medium for growing plants.

stems and leaves were dried, weighed, ground and subjected to various chemical analyses. Two types of sludge were used in this experiment: alum sludge, and sludge where polyDADMAC, a polyelectrolyte, had been used as flocculant.

The effect of the various mixtures is shown in Figure 1.

Discounting the trials with no added fertiliser, in general there were no significant differences in dry-weight production, except for the two 100% sludge trials. The extra nitrogen from the polyelectrolyte was probably the reason for the excellent result for this sludge, but the immobilisation of phosphorus by the alum sludge needed to be countered by extra fertiliser.

Analyses of the stem and leaf matter showed no evidence of aluminium toxicity, or any abnormally high concentrations of any elements.

Field Trials Sludge from the Morgan Water Filtration Plant was used to grow vegetables and fruits under irrigation. A bed of sludge approximately 50 m x 25 m x 200 mm deep was prepared during August 1993. In September, seeds of sweet corn, watermelons, butternut pumpkins, butter beans and lebanese cucumbers were sown in rows approximately 40 m long.

o

,.

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Poly()AOMAC sludge

Alums!udg1

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weight (g per pot)

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WATER MAY/JUNE 1995

Conclusions and the Future Research to date suggests that water treatment-sludge could be used very successfully as a plant growth medium, and as such is a valuable resource and should not be regarded as a waste.

The Botanic Gardens in Adelaide have become involved in the project, through their need for clean fill in the landscaping taking place at a former Bus Depot in Hackney. The use of sludge by an organisation with such a high public profile, coupled with positive publicity, could mean future demand could outstrip supply. It would neatly solve the financial problems of waste disposal.

Research is continuing to enable guidelines for the management of the sludge to be established.

t...._J 100%

Treatment

Figure 1. The effect of treatment on dry matterproduction

Pot Trials Sludge was mixed with sand in 2%, 4%, 10% and 100% proportions. An appropriate, and equal, amount of fertiliser was added to all but one pair of the mixes. Broad beans were then grown in these mixtures and the whole plants, except roots, harvested at flowering. The

Complete Mineral Mix was applied during sowing at the rates recommended on the packaging. Irrigation was by overhead sprinkling of River Murray water.

All crops germinated within 5 weeks, started producing in late November and harvesting was continued until February 1994. All crops grew extremely well (Figure 2 is a photograph of a healthy crop of sweet corn.)

Samples of the vegetables and fruits analysed by ICP (inductively-coupled plasma emission spectroscopy) showed that they conformed to Standard A-12 of the Australian Food Standards Code, March 1993.

In another experiment the survival of composting worms was investigated.

Fifty worms were added to pots of both polyDADMAC and alum sludge .

Vegetable scraps were added and the pots kept moist for 20 days. Not only did the worms survive but they multiplied.

Many worm cocoons and juvenile worms were also found.

Acknowledgments The authors thank Geoff Gilmore, Peter Tarrant, the staff of Morgan Water Filtration Plant, and Neil Kleinig in particular for the management of the field site. The financial support by the EWS&D for this work and the ongoing project is gratefully acknowledged.

Authors

Figure 2 A healthy crop ofsweet corn

Trudi Skene is currently a PhD studen~ and Professor Malcolm Oades is a Reader in the Department of Soil Science, University of Adelaide, Waite Campus, Glen Osmond SA 5064.

41