Water Journal May - June 1998

water

Volume 25 No 3 May/ June 1998 Journal Australia n Water & Wastewater Associat ion

Editorial Board F R Bishop, C hairman B N Anderson , G Cawston, M R Chapman P Draayers, W J Dulfer, GA Holder M Muntisov, P Nadebaum, J D Parker AJ Priestley,] Rissman

General Editor

CONTENTS From the Federal President .............................................. ................. ............ 2 From the Executive Director ............... .... ....................................................... 4 MY POINT OF VIEW

Margaret Metz AWWA Federal Office (see address below)

The Next Millennium-Are We Ready For It? .................... ... .. ....................... 3

Features Editor

T Flapper

E A (Bob) Swinton 4 Pleasant View Cres, Wheelers Hill Vic 3150 T el/ Fax (03) 9560 4752

Branch Correspondents ACT - Ian Bergman Tel (06) 248 3133 Fax (06) 248 3806 New South W ales - Mitchell Laginestta Tel (02) 9412 9974 Fax (02) 9412 9676 Northern Territory - Bill Bean Tel (08) 8924 7201 Fax (08) 8941 0703 Queensland - Tom Belgrove Tel (07) 3810 7967 Fax (07) 3810 7964 South Austcalia - Angela Colliver Tel (08) 8227 1111 Fax (08) 8227 1100 Tasmania - Ed Kleywegt Tel (036) 238 2841 Fax (036) 234 7109 Victoria - Mike Muntisov Tel (03) 9600 1100 Fax (03) 9600 1300 Western Australia - Jane O liver Tel (09) 420 2462 Fax (09) 420 3178

Advertising & Administration AWWA Federal O ffice Advertising: Angela Makris Graphic Design: Eliz.abeth Wan PO Box 388 Artam1on NSW 1570 Level 2, 44 Hampden Road, Artam1on Tel (02) 9413 1288 Fax (02) 9413 1047 Email: info@awwa.asn.au

Water (ISSN 0310 • 0367) is published six times per year:January, March, May,July, September, November by

Australian Water & Wastewater Inc ARBN 054 253 066

Federal President Greg Cawston

CRC

Water is sent to all members of A WWA as one of the privileges of membership. Non- members can obtain Water on subscription at an annual subscription rate ofS39 (surface mail).

ECOLOGY

P C ullen Should We Care About Mlcrofauna? ............................. ........ ..... ... ....... ... .... 11

RShiel The Campaspe River Project ...................................... ... ... ... ... .... ...... ........... 13

J Growns Blue-green Algae and Artiflcal Destratlficatlon ............... .. ........... ............ 15·

J W hittington, B S Sherman, R

L O liver

Invasion of an Exotic Freshwater Snail ......... ...... .................... ... .......... ... .. 17

S Schreiber Cyanobacterial Blooms In the Darling River .......................... ... ...... .......... 18

R L O liver, C M Rees, MR Grace, B T Hart, G Caitcheon, J Olley

Salinity: A Threat to Our Streams and Wetlands ....... ........................... ..... 20

P Bailey, N Warwick Flooding: The Lifeblood of Our Billa bongs .................... ..... ............... ....... .. 22

D Nielsen New Risk-based Water Quality Guidelines ............................................... . 24

B T H art, W Maher, I Lawrence Guidelines for Designing Pollution Control Ponds .... ............ ................... 25

I Lawrence, P Breen Assessing Water Quality in Kosciuszko National Park Using AusRivAS 28

R H Norris, J Simpson, K Beggs NSW Rivers Need Urgent Restoration ............................. .. ........... .............. 31

J H arris, P

Gehrke, S H artley

Where Do Carp Prosper? .......................................... ... ... ........ ..... ..... ... ..... ... . 33

P D river WATER ·, A Moblle Water Treatment Plant for Small Town Water Supplies .. ..... 34

N H ealey Radon-222 Concentrations In Potable Groundwater in Australia ........... 37

A L H erczeg, J C Dighton

Executive Director

Subscriptions

FRESHWATER

Introduction to CRC for Freshwater Ecology Special Feature .. .. . ... ... ... . .. . 9 Transferring Knowledge-The CRC Approach .. ...................................... .... 10

WASTEWATER

Chris D avis Australian Water & Wastewater Association assumes no responsibility for opinions or statements of facts expressed by contributors or advertisers and editorials do not necessarily represent the official policy of the organisation.

Display and classifi ed advertisements are included as an infom1ation service to readers and are reviewed by the Editor before publication to ensure their relevance to the water environment and to the objectives of the Association. All material in Water is copyright and should not be reproduced wholly or in pare without the written permission of the Editor.

FOR

•

·, On-line Process Monitoring of Nutrients In BNR Plants ....................... 38

I D McKelvie , G J C ross, TE H arris, B T H art ENVIRONMENT Reducing Phosphorus In Aquatic Systems Using Modified Clays .......... . 42

G B D ouglas, D N Coad, J A Adeney BUSINESS ·, Privatisation-Who Decides? ............................. ....... ... ... ..... .... ..... .... ...... 44

R Loo, C Porter Who WIii Train Our Future Water Engineers? ....... ... ... ... ............................ 46

L Reeder DEPARTMENTS International Afflllates ............................ .............. ... ... ........... .. .. ... ............ .. .. 5 From the Bottom of the Well ... .... ......................................... ........... ... ........... 2 Meetings ... ....................................... .. ... ... .... ........................................ .......... 48 New Products ................ .......... ... .. .... ........ ... .... ...................... ........ ........ ..... ... 47 OUR COVER: Read about th e fresh water New Zealand snail Potamopyrgus

antipodarum invading o ur waters (page 17). Photo co1trtesy of Sabine Schreiber, Cooperative R esearch C entre for Freshwater Ecology .

FRESHWATER

ECOLOGY

Significant declines in abundance, Multiplicity of Species range o r distribution of birds, fish, In terms of biodiversity, it is not amphibians and macroinvertebrates in possible to provide a comprehensive list Australian and Murray-Darling aquatic of the microfauna of any inland ecosystems have been reported. How- Australian waters. Whilst protists ever, the complex co mmunities of largely remain unknown, rotifers are microinvertebrates which provide the better studied, albeit for a very small food web links between bacteria/algae number of habitats, primarily billabongs and higher order consumers have been or reservoirs of the middle reaches of virtually ignored (see Figure 1). the Rive r Murray. More than 100 After bacteria and phytoplankton, species of rotifer have been recorded microfauna- protists, rotifers and from single net tows in billabongs, microcrustaceans-are commonly the w here densities may exceed 75,000 most abundant organisms in inland individuals per litre, making them a Australian waters. Their rapid genera- significant and dynamic component of tion times and high population densities both biomass and biodiversity. produce dynamic grazing/p redation Billabong microcrustacean commuimpacts on their preferred food items, nities commonly are less diverseproviding in turn a rich food source for 20-40 species may occur together on a those organisms that eat plankton. given sampling date. High species T here is some evidence that higher diversity is possible because the various orde r co nsumers were cued, pre- components have evolved to partition regulation at least, to use the rich plank- the available resources. Some taxa are so ton 'soup' of sheltered billabongs as specialised that they feed on only a nursery and feeding refuges. single species of alga-others are generRecent studies by NSW Fisheries alists, grazing anything they can catch of suggest a strong correlation between the an appropriate size (see Figures 2, 3). diversity of microfauna and that of Transposing such species numbers native fish. Microfauna are more sensi- into the compartments in Figure 1 illustive to changes in water quality than trates the complexity of microfaunal higher organisms such as macroinverte- food webs-in the ancient, highly brates or fish. Protists are, after all, compartmented, niche-rich billabong single-celled, and rotifers generally only ecosystem, many hundreds and potenca . 1000 cells. Rapid response times tially thousands of species may occur, make them ideal environmental indica- particularly in spring and autumn. tors of the 'health ' of aquatic ecoReservoirs, with their general lack of systems-a value not presently used in submerged and emergent vegetation Australia. and rapid fluctuations in level, do not

support a microfaunal assemblage of the complexity of that found in billabongs.

Rive rs provide a more extrem e environment again for aquatic microfauna, with a consequent reduction in biomass and diversity. Those microfauna persisting from upstream impoundments or flushed in from backwaters or the floodplain in times of high flow generally are only a small fraction of the reservoir or billabong plankton or littoral assemblage.

Australian inland rivers are unusual in the global sense because thei r slow flows and frequent impediment by locks and weirs provide a sequence of lakelike or billabong-like habitats in which a diverse microfaunal community may be partly represented.

The Seedbank In inland river systems the floodplain is critical to the maintenance of microfa unal assemblages-it is the seedbank or genetic repository.

As is seen in island populations, adj acent billabongs commonly have different dominants, reflecting a mosaic of environmental cu es, and w hi ch species em erges from the seedbank at any given time depends on the required (or supplied) stimuli.

Successional events may be very rapid, particularly at break of season, when inflows of water into billabongs provide cues to emergence from resting stages. Figure 4 shows differing responses of rotifer species to such a

WATER MAY/JUNE 1998

11

FRESHWATER

ECOLOGY

Figure 2 A live-in special ised herbivore, Ascomorphe/la volvocicola eats Volvox, a colonial f lagellate, from t he inside out

j,, ! ¡ 1~

12

WATER MAY/JUNE 1998

3

IL.;

Figure 1 Simplified microfaunal food web from Murray-Darling waters. Except for fish , each compartment may contain scores to hundreds of species on any sampling occasion (from Shiel & Green (1992) Viet. Nat. 109)

flood event. The dynamics of these events are hours and days.

The preliminary results of flooding experiments in Barmah-Millewa Forest and artificial billabongs near AlburyW odonga suggest that timing of inundation is not critical-'something' will be cued whatever time of year flooding occurs and regardless of duration.

What is critical to the seedbank is that flooding does occur-not necessarily annual floods, or even regular floods, but occasional inundation. T he persistence of cysts, resting eggs, winter eggs or other diapausing stages is unknown and may be remarkable-up to tens or scores of years-but they are finite.

As has been demonstrated for macroinvertebrate emergence from floodplain sediments, the longer a particular section of floodplain remains dry, the less likely its full complement of microfaunal resting stages is to break dormancy on subsequent re-wetting.

The commitment of some of the river flow to environmental needs is the first positive step in conservmg seedbank diversity, but the urgent need to conserve the floodplain is also critical. Loss offloodplain habitats, or loss of access to them, is a primary causal factor in the existing decline in range or abundance of floodplain biota. Some of the more heavily used floodplains of the Murray- Darling Basin have lost more than half of their billabongs and wetlands to agriculture, horticulture and other activities or to general degradation.

Given that some of the groups of

4

3 2

2

Figure 3 The centropagid calano id copepod, Boecke/la triarticu/ata, a more generalist grazer, from the 1991 Darling River Anabaena circinalis bloom. The filaments are the cyanobacteria, which the copepod ca n graze

microfauna mentioned have a high degree of endemism-more than 80% for some of the microcrustacea- the implication must be that we have already lost a proportion of our indigenous microfauna. If we continue to degrade floodplains and diminish the remaining seedbank it is certain that more will be lost. The declines we now see at the top of food chains (e.g. our fish) are surely a reflection of what is happening, unseen and unremarked, at the bottom of food chains.

We Must Care!

It should be evident that the answer to the question posed in the title of this p aper is an unequivocal 'yes!'

The unseen microbiota of our inland waters are a necessary component of all

10 20 March 1990

Taxa are (l¡R from top) Brachionus /yratus, Fillnia pej/eri, Lecane bu/fa, Brachionus falcatus, Filinia opoliensis, Proa/ides tentacu/atus (From Shiel (1996) GeoJournal 40)

Figure 4 Population density of selected rotifer species demonstrating specifically different responses t o summer intrusion of river water (indi cated by vertical broken line) into Ryan's #1 Billabong near Albury

aquatic ecosystems. Any of 2ur activities which act directly or indirectly to reduce their diversity may have farreaching ramifications that include removing their grazing influence on bacte rial or algal populations and removing them as food items for macroinvertebrates and higher order consumers.

Microfauna may be low on the systematic scale, but they are no less important to the Australian aquatic enviro nment than the 'warm and cuddlies' are to our terrestrial ecosystems.

Author Dr Russ Shiel is at the MurrayDarling Freshwater Research Centre in Albury.

FRESHWATER

THE

ECOLOGY

CAMPASPE RIVER

PROJECT

J Growns

T he allocation of wate r for is p iped fro m Lak e Eppalock to Ben digo but m ost of the diversion is environm ental flows in Australian regulated rivers is the subj ec t of for irrigation during summer and many debates. The complexi ty of autumn. river ecosystems, lack of clear obj ecFrom October to January water is released and diverted to irrigation tives and short history of scientific studies of environmental flows mean ch annels at the Campaspe W eir. that there is no single, clearly defined From February to April extra water is pro cess by w hich environme ntal released from Lake Eppalock and flows can be determined. Whilst a allowed to pass ove r the Campaspe quick solution to the problem is W eir and is diverted to the W aranga unlikely, it is clear that large-scale The Campaspe River Is being studied to Western Main C hannel at the experimen tal manipulations of flow balance human, Irrigation and ecologlcal Campaspe Siphon. w ill be necessary to test wh ether needs for water Under the presen t release regime specific release regimes produ ce the only a small environmental allocathe collec tion of baseline data and tion of 10-1 5 ML/day is released from desired results.

T he Campaspe River Project is the imple men tatio n of changes in the Lake Eppalo ck after the irrigatio n first such large- scale experimental mani- release regime, and three years fo r more season fi nishes in April until winter pulation to be performed in Australia. It data collection after the flow change rains have filled the lake. In late winter is a collab orative project between the begins in May 1998. in about 50% of years, heavy rain can CRC for Freshw ater Ecology, includcause the dam to overflow, leadi ng to ing Monash University and the The Campaspe River increased flows which pass all the way T he Campaspe River is in n orthern down the river (see Figure 1).

Murray-Darling Freshwater R esearch Centre, and Gou lburn- Murray W ater, central Victoria. It flows north to meet There are currently three hydrologithe Marine and Freshwater R esources the Murray River at Echuca and drains cally distinct sections of the Campasp e Institute, Snobs Creek and the C RC fo r an area of about 3400 km2 . The chann el River below Lake Eppalock. Be tween Catchment H ydrology. T he project, is deeply in cised and does not have Lake Eppalock and Campaspe W eir w hich is funded by Land and W ater significant wetland or billabong systems. there are relatively constan t moderate Before regulation there w ould have flows in summer/autumn and constant R esources R esearch and D evelopmen t Corp oration, Environme n t Australia been generally low flows in summer and very low flow for mu ch o f w inter and the CRC for Freshwater Ecology, the river may often have dried to a series until Lake Eppalock spills. Between should provide a model for similar of pools. However, occasional rain Campaspe W eir to Campaspe Siphon wo uld have flu shed the river in there are constant low flows in summer future experime nts. summer. In w inter there would have with increased bu t still relatively Negotiating and Developing been higher and variable flows for much constant flows in March and April and of the period from M ay to Novemb er constant low flow for much of w inter the Project until Lake Eppalock spills. Below the When developing the experimental (see Figure 1).

The main storage o n the system , C ampaspe Siphon there are constant design, a compromise had to be reached between scientific issues and the n eeds Lake Eppalock, was completed in 1962 low flows fo r most of th e yc!ar until and has a capacity of 312,000 ML. Lake Eppalock spills in late winter. of water users.

About 114,000 ML is diverted annually From May to O ctob er 1998, 25% of Goulburn-M urray W ater (G-MW) is from th e Campaspe' s mean annual daily inflow to Lake Eppalock will be the Victo rian Governme n t water au tho rity that manages Lake Eppalo ck. discharge of 314,000 ML. Some water released downstream so long as Lake Eppalock is at least 64% full. Th e W hile little could be done abo ut releases w ill pass down th e full the high summer flows destin ed length of the river and will be in for the irrigators, ch anges to 1~00 excess of any abstraction from the winte r flows were able to b e nver. n egotiated through detailed modelling analyses and extensive The Studies discussions w ith G-MW. i : ; ~·=···= · ~·1=···~--·~ ·J" ---~··1~-----·-- --·-~·-··· _···T · ·_... · _...·~ / -·--+-·~ ~ \ -~..~ _..._...r,._..

The support of the irrigators River regulation has been A s 0 N D J F M A M was obtained through ex ten sive Month show n to severely affec t the consultation, during w hich th e ecology of riverine ecosystems - - shows pre-regulation flows ·· ··· ·· shows regulated conditions concerns of sec uri ty of su pply all over the world, particularly were addressed. downstream of deep reservoirs Figure 1 The project was then formalwhich release very cold an d Median mean monthly flows in t he Campaspe River ised to run for five years-two for below Rochester sometimes chemically unfavour-

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WATER MAY/ JUNE 1998

·'

13

FRESHWATER able water and also below hydroelectric dams which cause wild fluctuations in flow rates over short periods.

The effects include changes in benthic algal communities, zooplankton and fish but most work has been done on macroinvertebrates including shrimp, larval and ad ult insects, worms, molluscs and mites. The general pattern detected is that species ric hness is greatly reduced for varying distances below dams and the species composition is changed.

Fish Before regulation the Campaspe River supported a dive rse community of native fish species, although it is not certain that they completed their life cycle in th e river. Over the last two years regular sampling has shown that very few species of native fi sh now occur in the Campaspe and none in large n umbers. However, introduced carp and mosquito fish are plentiful.

Continued sampling of adult fish will show w hether fish stocks recover in the long term. Many fish are long-lived and it will take several years for the adult populations to build up, even if they can start breeding successfully shortly after th e flow change. H owever, focusing on larval fish may give more rapid indicati ons of improved spawning and recruitment.

To strengthen the co nclusions fro m this work a similar but less regulated stream, the Broken River, is being sampled. During the last two years, larvae of four species of native fish have been collected from the Carupaspe.

This compares with eight species from the Broken and confirms the poor status of the Campaspe.

Macroinvertebrates The invertebrate component of the Campaspe project focuses on shrimp and on invertebrates living on red river gum snags which support a diverse and abundant macroi nvertebrate com m unity compared with the soft sediments.

A me thod has been developed which will allow these invertebrate comm unities to be effectively sampled for the first time-significantly adding to our knowledge o f the macroinvertebrate ecology oflowland rivers.

Preliminary samples have shown that regulation of the Campaspe has had significant effects on the macroinverteb rate co111111unities living on the snags.

A dramatic differe nce b etween the highly regulated uppe r section of the Campaspe and other areas is the presence of thick, dense mats of the

14

WATER MAY/JUNE 1 998

ECOLOGY

native moss Fissiden s fontanus covering most of the snags. Invertebrate density and diversity is much higher on these snags than those elsewhere. Although this may seem to be desirable, it has to be recognised that the character of the river h as been changed to make it more similar to a cool upland stream . The consequences of this for other compon ents of the ecosystem are unknown.

T he Campaspe River is not used for hydro- electricity, nor does it release very cold hypolimnetic water, so its effects are likely to be less marked than some larger dams that have b een studied . However, data loggers in place over the last two summers have shown that the water temperature in the upper section of the Campaspe i111111ediately

Dr Jane Growns sampling for macroInvertebrates In the Broken River

below Lake Eppalock is consistently 4- 5° C below that in the Broken River.

Also , the diurnal variation is a degree or so less in the Campaspe over summer and maximum temperatures are reached later in the season than in the Broken River. T hese temperature differen ces are probably sufficient to cause significan t changes i n i nve rtebrate metabolism , growth and rep roductive success.

The other major impact of the dam is the irrigation flow regime. T he flows have basically been reversed and are now moderate in sumn1er and low in early winter. They are also much less variable than they were before regulation. Many invertebrates, such as blackfly and some caddisfly and chironomid larvae, are filter feeders and rely on water current and plankton to survive.

These animals will be favo ured in the upper section of the Campaspe du ring the irrigation season but will probably suffer ca tastrophic stranding when the water levels drop. T he changed flow regime will affect the composition and

abundance of algae in the biofilm growing on the surface of sediments and snags and this will affect those grazing invertebrates. Some algae are less palatable and nutritious than others and the quality of diet can affect the growth of invertebrates.

Another fac tor that may be related to th e changed flow regime is the distribution and abundance of three species of shrimp which require differing habitats ranging from slow to rapid flows.

After the Flow Change Although the su111111er flow regime will not be changed, it is possible that improving the winter flows may significantly improve the ecology of the river.

Winter is a critical time of year for fis h, as it is when they develop gonadal tissue and prepare for breeding in summer.

If winter conditions improve, tli.is may increase successful breeding and recruitment of native fish .

R ainfall permitting, the rapid decrease in river level when irrigation flows are cut off sh ould be improved.

This should reduce the problem of massive invertebrate stranding. Macroinvertebrates are not very active during winter, although some larvae do continue to grow slowly and are ready to emerge as adults when temperatures rise.

More water in th e river in winter w ill certainly provi de more and bet ter macroinvertebrate habitat that should support greater nu mbers of animals, which should , in turn, provide mo re food fo r the fish. However , changing winter flows is unlikely to return the macroinvertebrate com m unity in the upper section of the Campaspe to that of a typical lowland river.

Conclusion Whether or not the environmental flow releases have a beneficial effect, the results from the Campaspe pr oject will provide useful information for managers and significantly co ntribute to o u r unde rstanding of th e ecology of lowland rivers in Australia.

This proj ec t demonstrates that largescale, long- term collaborative projects to test theories about environmen tal flows can be developed successfully wh en all parties are willing to take the time and effo rt to co nsult, negotiate and think creatively abou t solutions to problems.

Author Dr Jane Growns is a R esearch Fellow with the CRCFE and Department of Biological Sciences, Monash University at the MDFRC, Albury.

FRESHWATER

The CR C for Freshwater Ecology is addressing the apparent failure of artificial destratification to con trol bluegreen algal growth in a major research project at C haffey Dam, a 64,000 ML storage on the Peel Rive r, near Tamworth, New South Wales. The p roject, w hich includes scientists from CSIRO Land and Water, MurrayDarling Freshwater R esearch Centre, University of Canberra, Monash U niversity and NSW D epartment of Land and Water Conservation, has used a multidisciplinary approach to study the physical, chemical and biological processes operating in Chaffey Dam and how they are affected by artificial destratification. This article focuses on the part of the project which examines the influence of artificial destratification on blue-green algal blooms.

Why Might Artlficlal Mixing Control Blue-green Algal Growth?

In stratified waterbodi es the buoyancy of blue-green algae such as M icrocystis and Anabaena species provides a competitive advantage over non- buoyant algae. It is argued that because artificial mixing deepens the surface mixed layer it nullifies the advantage of buoyancy and favours the growth of algae such as diatoms that harvest and use light efficiently. If the depth of surface mixing relative to the depth of light pene tration is great enough, the algal population may be

ECOLOGY

starved of light and the standing crop will be reduced.

By increasing the supply of oxygen to the hypolimnion, destratification also may suppress the release of P from the sediments that can occur under anoxic conditions. Since algal biomass is freque ntly restricted by the availability of P, artificial destratification may restrict the total algal standing crop by reducing the release of P from the sediment.

The outcome of destratification is likely to depend upon whether the biomass of algae is light- or n utrientlimited. For example, if the growth of algae is limited by the availability of light, deepening the surface layer is likely to reduce algal biomass. If, however, the growth of algae is limited by the availability of nutrient, deepening the surface layer may not have a significant effect on algal biomass and may even increase it.

CRC Project at Chaffey Dam Between 1995 and 1997 five periods of artificial destratification of between 11 and 36 days duration were undertaken at Chaffey D am. On each of these occasions 100 L /s of compressed air was injected through a pipe located a few metres above the bottom to form 10 plumes in the water column. The resultant circulation consisted of two gyres that flowed away from the plume at the intrusion depth with return flows both above and below the level of the intrusion (see Figure 1).

Temperature and Oxygen Effects Within two weeks of turning on the compressor a quasi-equilibrium linear vertical temperature gradient was approached, represe nting a balance between surface heat transfers, absorption of solar radiation and the artificially enhanced downward advection of heat.

As the op eration of the compressor contin ued, the temp erature difference between the surface and the bottom remained approximately constant during the spring, when the reservoir was heating up, whereas i t decreased slowly in summer and autumn.

T he vertical distribution of dissolved oxygen also assumed a linear quasiequilibrium gradient, but i:,e quired longer, at least three weeks, to do so.

Typically the DO at the bottom of the water column was maintained at 50-60% of saturation and at the surface at 70-80% of saturation. The equilibrium represents a balance between airwater exchange, in-situ photosynthetic production (near the surface), in-situ demand for oxygen and the vertical transport of oxygen resulting from the increased circulation.

By maintaining higher hypolimnetic dissolved oxygen concentrations during 1995-1996, destratification effectively eliminated the enhanced release of phosphorus from the sediments to the water column. When the reservoir was allowed to stratify normally, approximately 285 kg of phosphorus was

WATER MAY/ JUNE 1998

15

FRESHWATER

ECOLOGY

20m Bubble plume

Upper circulation

Chaffey Reservoi r Surface Layer Depth 0 ,------,------,-..----~--:.--"7"7r:--i

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Lower circulation Compressor line

Fluid entrainment into plume

Figure 1 Circulation prod uced by artificial destratificatio n

released each mon th under anoxi c conditions. Operation of the compressor reduced this to 38 kg a month.

Controlling Algal Growth by Deepening the Surface Layer It is often assumed that by reducing the temperature differe nce between the top and bottom of the water column to some small value, say 0.5° C, the water colum n is 'mixed.' Vertical profiles of tempe rature, dissolved o.x.-ygen and chlo rophyll fluorescence at Chaffey Dam have shown quite dramatically how very small temperature changes can significantly impede vertical transport. For example, on one occasion there was a temperature change of less than 0.05° C at a depth of 4.5 m, yet 90% of the chlorophyll was situated above this depth. A small oxycline coincided with the temperature step as well. While this is an extreme example, temperature steps of 0.1-0.2° C are a common feature in the water column.

Figure 2 shows smoothed hourly surface layer depths w here the bottom of the surface layer is defi ned as the level where the wate r column is 0.2° C colder than the surface. The solid bar shows the period of compressor operation. Operation of the comp ressor halved the temperature difference from top to bottom in a fortnight, but had no effect on the surface layer thickness and so would not influe nce the depth to which algae were mixed. Significant deepening of the surface layer occurred on only two occasions as a result of unseasonably high heat losses and strong winds. As soon as normal weather conditions returned, the surface layer shoaled back to 3- 5 m depth despite the much weaker overall thermal stratification.

improve either algal abundance or the elimination of blue-green algae. O n d ifferent occasions algal abu ndance increased, decreased o r remained constant following operation of the compressor.

T he following example highlights the potential problem of artificial mixing alleviating n u trient limitation of algal growth wh en used inappropriately.

Initially, t he reservoir was strongly stratified with low concentrations of inorganic N (<0.02 mg/L) and filterable reactive P (frP), (0.004 mg/L) in the surface layer and very high concentrations offrp (0.415 mg/L) in the anoxic hypolimnion. Ch lorophyll-a concentration i n the surface layer was 0.02 mg/L and the algal community was comprised of a number of algae, including t he blue-green algae Anabaena circinalis and the green algae Oocystis

16

WATER MAY/JUNE 1 99 8

8-1

15-1

22·1 1996

29·1

5-2

12-2

shows the period of compressor operation

Figure 2 Surface layer dept h versus time at Chaffey Dam

sp. While frp was low in the surface water, algal bioassays and in- situ p hysiological assays indicated algal growth rate was N -limited. Since, however, Anabaena has the capacity to fix N 2 , its biomass would be limited by the availability of P . H owever, destratification lifted the frP and consequently the algal communi ty doubled over 35 days, becoming dominated by the blue-green alga A nabaena w hich persisted at a high abundance for four weeks after artificial destra tifica tion.

This trial reinforces the need to understand w hat is limiting the growth of algae before artificial mixing, since mixing can potentially increase algal growth in stratified , nu trient- limited waterbodies.

Long-term Effects on Algae A lo ng- term algal monitoring program has been under taken at C haffey Dam by the New South Wales Department o f Land an d Water Conservation. Most (79%) of the interannual variability in algal abundance was explai n ed by the maximum hypolimnetic P concentration measu red during the previous sum mer. Summers in which artificial destratification was atte mp ted, even for relatively sh ort periods, had lower t han ave rage hypolim netic P concentrations and also lower algal abundance in the following year. H owever, blue-green algal and dinoflagellate blooms still occurred in late sum mer and autum n in years w here artificial destratifica tion was attempted.

Are Bubble Plume Systems the Answer?

Short-term Effects on Algae Given that operation of the comp ressor did not alter the thickness of the surface layer, i t is not surprising that artificial destratification did no t

-

___,_~~~=:Dlltl~~-~~..=~~=

Blue-green algal bloom on Chaffey Dam near Tamworth

T he system at Chaffey Dam was clearly incapable o f produ cing a completely mixed water column. Even continuo us ope ration would be unlikely to help because the hot, calm climate typical of the area was able to heat up the surface layer nearly as fast as

FRESHWATER

ECOLOGY as the system only needs to be operated for a fraction of the time of the present system.

Past design practices and operating criteria for destratification systems have implicitly assumed the availability of sufficient wind energy to completely mix a reservoir once the destratification system had reduced the temperature differential to less than half a degree or so. C learly, this assumption must be revisited for storages located in hot, calm climates such as Chaffey D am.

the enhanced circulation could 'pump' the heat downwards. It seems likely that to accomplish complete mixing, the temperature differential would have to be reduced to less than 0.2° C because of the occurrence of extended calm periods. As long as a surface layer persists, noxious blue-green algae will be able to exploit their ability to float and inhabit the surface layer, growing until the available nutrient supply is exhausted.

Controlling the release of nutrients from the sediments does help to reduce th e m aximum biomass achieved by the algae in the reservoir. However, measurements of the external nutrient load to the reservoir provided by the Peel River shows that in normal-to-wet years the external total phosphorus load can be up to 10 times greater than the

net annual internal phosphorus load.

The external frP load alone may be comparable to, and frequently larger than, the internal phosphorus load.

Destratification will have little effect on blue-green algal biomass when external sources dominate the supply of frp and a shallow surface layer persists.

The only way to improve the destratification system's ability to light-limi t algal growth would be to vastly increase the compressor airflow rate and the n umber of plumes. Computer sim ulations have indicated an airflow rate of more than 15 times the present l00L/s may be required to eliminate the surface layer. Such a large system for a 64,000 ML dam may prove to be prohibitively expensive even though the operating costs may not be significantly different

The aquatic New Zealand snail Potamopyrgus antipodarum invaded Australian waters around 1870 (Ponder, 1988). It is n ow common in many lakes and streams in south-eastern Australia, where high population densities can occasionally block water pipes and distribution systems. It has also been fou nd to be an intermediate host of a parasitic trematode, Micropha1lus sp., both in New Zealand and Australia.

The aims of this project have been to identify the environmental fac tors related to the distribution of this snail in streams in southe rn Victoria, to relate its reproductive biology in fo ur South Gippsland streams to population densities, and to identify potential interactions of the sn ail with native invertebrate fauna.

Sampling at 73 stream sites in southern Victoria in 1994 revealed that the distribution of P. antipodarum was correlated to the degree of catchment disturbance, e.g. by agricultural and forestry activities, and flow variability.

However, w ater quality parameters such as nutrients, salinity, pH, temperature and calcium content were not related.

A two-year examinatio n in four South G ippsland streams revealed that, contrary to invading populations in som e European locations, densities remained stable, both in high-density and low- density populations. A detailed description of the snail's life-history in these streams will allow an assessment of the importance of reproductive strategies in maintaining high p opulation densities.

INVASION OF AN EXOTIC

Authors Dr John Whittington is at the M urray-Darling Freshwater Research Centre (MDFRC) in Alb ury. Dr Bradford Sherman is at CSIRO Land and Water in Canberra. Dr Rod Oliver is also at the MDFRC in Albury.

FRESHWATER SNAIL S Schreiber

Potamopyrgus antlpodarum

As P. antipodarum is a relatively sedentary fres hwater invertebrate, it was possible to carry out field experiments investigating the interaction between the snail and native invertebrates. As streams are su bject to disturbances through high flows, resulting m small ba re patches availab le for recolonisation, these experiments were carried out during such colonisation.

It was fou nd that high densities of P. antipodarum did not have a negative impact on colonising fa una. The only impact detected was an early doubling in the d ensities of the midge, Polypedilum, w hich can often be found in nutrient- rich waters.

The reasons for this increase are not clear, but it is possible that the presence of the snails resu lted in a small-scale increase in nutrients through snail faecal material, which may have attracted the midge.

Previous reports have suggested that P. antipodarum may have substantial negative effects on native snails in the same family, Hydrobiidae, but as native hydrobiids were not collected during the experiment it was not pQssible to test this suggestion.

This research has shown that P. antipodarum is an exotic species that thrives in degraded systems, w here it can maintain high population densities.

However, it also is able to maintain populations in streams with diverse native invertebrate communities. An examination of its in te raction with native invertebrates at one site in such a stream did not reveal strong negative effects.

Author Sabine Schreiber is a PhD student with the CRC for Freshwater Ecology at t he Depart men t of Biological Sciences, Monash University, Clayton.

WATER MAY/ JUNE 1998

11

FRESHWATER

ECOLOGY

CYANOBACTERIAL BLOOMS IN THE

DARLING RIVER R L Oliver, C M Rees, M R Grace, B T Hart, G Caitcheon, J Olley

This recently completed three-year Turbidity field study investigated the factors No significant correlation existed controlling algal growth in the Darling between flow and turbidity. Even at low River. The project was funded by the flows, the river could remain turbid.

Murray-Darling Basin Commissio n 's However, under low-flow conditions Natural Resources Management Strategy saline groundwater intrusions n ear (NRMS). The NSW D epartment of Bourke raised the con centrations of Land and Water Conservation sup2+ and Ca 2+ and caused rapid particle Mg ported the project by providing access coagulation and settling. Improved ligh t to invaluable monitoring data. penetration initiated the growth of The project addressed three key cyanobacteria, especially if linked with questions: An underwater sensor measuring the increased thermal stratification. By • what are the environmental condi- amount of llght In the Darllng River relating light penetration to turbidity tions that initia te the growth of megali tres/day (ML/day) and reached and turbidity to electrical conductivity cyanobacteria in the Darling River?

• w hat nutrient is in shortest supply unacceptable levels at discharges below it was fo und that cyanobacterial growth relative to the needs of the organisms ca . 500 ML/day. These results are was stimulated in .the weir pool w hen and likely to determine the extent of the comparable with findings at Maude turbidity fell below ca. 100 N TU and Weir on the Murrumbidgee Rive r. that this occurred w hen electrical biomass increase?

• what are the major sources of phos- H owever, not all low flow p eriods were conductivity was greater than ca. 300 associated w ith high cyanobacte rial µ S/cm. phorus supply to the system ? numbers. This confirmed that o ther environmental factors also influence cell Nutrient Ratios The Fleld Site growth.

The D arling River has high concenFlowing rivers often contain a small trations of phosphorus and moderate amount of phytoplankton, but w here Thermal Stratification concentrations of nitrogen . T he cyanoflow is retarded by impoundments, Reduced water mixing advantages bacterial blooms occurring in the river extensive phytoplankton populations can develop in the associated pools. buoyant, bloom- forming cyanobacteria are dominated by nitrogen-fixing Most of the majo r rivers in the Murray- that can move vertically to increase species. This suggests that phosphorus Darling Basin have their flow modified their light supply. In contrast, other could play a major role in determining by small, in- stream weirs used to supply phy toplankton that are denser than the maximum biomass of cyanobacterial water to towns and fo r irrigation. The water are lost to the population through blooms and that reducing the phosBourke township weir was selected as sinking. The two large cyan obacterial phorus supply could reduce the magnithe major field site for this project and blooms observed during the study tude of these blooms. A major part of periodic sampling was done along the occurred wh en thermal stratification the study was aimed at identify: ng phosrive r. During the three-year study was intense and persistent due to low phorus sources to assess the potential of significan t cyanobacte rial populations flows. this strategy. (>5000 cells/ ml) occurred on only two D espite the Redfield ratio which occasions. Smaller populations appeared Light suggests that when N:P rati os are at intermittent in tervals, providing a Assuming well mixed conditions, the greater than 16: 1 P is the controlling useful data set to analyse the association relationship between tu rbidity and nutrient, the D arling River data between growth and environmental attenuation of light was determi ned demonstrated that total nitrogen to total conditions. from data collected in the historical phosphorus ratios were poor predictors monitoring program. Theory suggests of future nutrient limitation because Flows penetration oflight less than 20-30% of much of the phosphorus is strongly Phytoplankton biomass can increase depth is indicative of light-limiting bound to particles and u navailable for in weir pools w hen the rate at which conditions. This was supported by the algal growth. However, ratios based on populations are flushed out is less than data from the D arling River. However, dissolved n utrients provided reasonable their growth rate. A comparison of flow the converse was not always true and predictions and are applicable to field data and cyanobacterial nu mbers for the the p hytoplankton di d not respond conditions provided re- supply is not weir pool at Bourke showed that during late winter of 1995 even though occurring. Although nutrient ratios and cyanobacterial biomass increased w h en flow was extremely low and the light growth bioassays can predict w hat discharge rates were below ca. 1000 climate seemed suitable. nutrient w ill event ually limit algal

18

WATER MAY/JUNE 1 998

FRESHWATER growth, they do not clearly identify a possible limitation at the time of sampling.

Nitrogen and Phosphorus Results from both dissolved nutrient analyses and bioassays indicated that nitrogen was most often in shortest supply in the D arling River. The physiological assay indicated an immediate n utrient limitation o n only two occasions-both times to nitrogen. The iden tification of nit rogen limitation is consistent with the dominance of nitrogen-fixing cyanobacterial blooms.

Total ph osph orus con centrations varied between 50 and 450 µgP/L and were usually in excess of 100 µ gP/L. Con centrati ons o f algal-available p h osphorus (0 .003 µ m fil tered and particle- associated combined) were also usually high and sufficient to support significant phytoplankton populations.

However, during the large cyanobacterial bloom of November-Decembe r 1995 the concentration of filterable phosphorus (<0.003 µm) was reduced to <Sµ gP/L for three weeks. D uring this time the concentration of the available phosph orus associated with particles remained uncha nged b u t th e total ph osphoru s concen tra tion increased from 45 to 84 µgP/L. T his suggests the bottom sediments were supplying phosphoru s to the overlying water and that the biomass peak would depend on this phosphorus supply. U nfo rtunately, the bloom was dispersed by increased flow before its maximum was attained and we were unable to demonstrate direct nutrient control of the biomass peak.

In a large river system such as the Darling where sediment is repeatedly stored and transported, p hosph orus cycling becomes an imp ortant factor.

T his means that the phospho ru s in bioavailable form is related to both immediate and historical bioch emical conditions and may not directly equate with the fo rm of phosphorus in the original source. Given the difficulty of trying to track the available phosphorus fraction, most effort was aimed at identi fying the likely on gm of sediment-associated phosphorus which accounts for a large percentage of the phosphorus load.

The natural magnetic, chemical, and radion u clide properties of so il and sediment in the river basin were used to trace the origin of the clay and very fine silt. It was concluded that mo re than 20% of the fi ne sediment (<10µ m) in the Darling River originates from naturally phosphorus- rich basalt soils found in the uplands o f the major

ECOLOGY

eastern tributaries. The particleassociated phosphorus concentrations in the main c hannel sediment are relatively low and are consistent with those in natural soils of the region, indicating a mix of 40% basalt- derived soil and 60% from soils developed on oth er rock types. This shows that natu ral soil sources alone could account for the sediment-associated phosphorus in the Darling River.

Sediment cores collected from the main chann el at the Namoi Rive r indicated that phosphorus concentrations have not changed significantly in the last 200 years. There is no evidence at these sites that anthropogenic

phosphorus is only a small fraction of the sediment phosphorus load and algal populations show periods of phosphorus limitation, ta rgeted nutrient reduction strategies at particular river reaches may be advantageous.

A significant amount of bioavailable P in the river may be released from bottom sediments by dissolution processes operating over large spatial and temporal scales. W hile di rect interven tion to reduce p hosphorus delivery may be difficult, maintaining flow is likely to reduce the dissolution of P from bottom sediment by sustaining oxic conditions. T he question of how muc h phosphorus is released from bottom sediments under different flow conditions needs to be answered .

Furthe r studi es are required o n phosphorus cycling to address these questions.

Conclusions

Professor Barry Hart taking bottle samples from the Darllng River

phosphorus (e.g. from fertilisers, sewage treatment p la n ts e tc.) has had a detectable impact on sediment-bound P concentrations.

Because of the potentially lo ng residence times of sediment in the river system and the fact that most sediment is moved during a few large storm events, it will be difficult to find a management strategy that will have a significant i mpact on the delivery of sediment- associated phosphorus. H owever, the connection between sedimentbou nd p hosph o ru s and bi oavailable phosphorus is poorly understood and sediment- bound forms are not the only source ofbioavailable phosphoru s to the system. Point sources such as sewage treatment plants and diffuse sou rces of an thropogenic p hosphoru s are traditionally considered to supply p hosphorus in fo rms that become readily bioavailable to algae. T heir significance is difficult to assess when the bioavailability of the major natural source of phosphorus is unknown. If bioavailable

The results have demonstrated a sequence of events that are responsible for the occurrence of cyanobacterial blooms in the Darling River. R educed flow leads to i ncreased residence times in the weir pools and increases the likelihood of thermal stratification of the water colum n. Reduced discharges we re found to be responsible for increases in saline inflows that precipitated turbidity and improved light penetration. T hese events initiated the growth of cyanobacteria.

Flow management is a major tool for regulating the occurrence of blooms.

H igh flows also assist in keeping the bottom sediments oxygenated and decrease the likelihood of nutrien t release into the overlying water. The direct co n trol of diffuse sedime n tbound phosphorus loads to the river is more diffic ult and it is unclear how effective t his strategy would be in reducing algal blooms. Fu rthet' work is required to describe the connections between phosphoru s loads associated with sediments and bioavailable concentrations.

Acknowledgements Original research contributions were made to this study by Peter Wallbrink, Gary H an cock, David Short and C hristine Rees.

Authors Rod Oliver and Christine Rees are at the M DFRC in Albury. Mike Grace and Barry Hart are at the Water Studies Centre at Monash University. Gary Caltcheon and Jon Olley are at CSIRO Land and Water, Canberra.

WATER MAY/JUNE 1998

19

FRESHWATER

Salinity of soils and water, or 'primaty salinisation' is a natural characteristic of arid climates wo rldwide.

Australia is estimated to have 29 million hectares of naturally saline land, 14 million hectares of whic h are salt marshes, salt lakes and salt flatsimportant ecosystems in t heir own right. The focus of this study is secondary salinisati on, which occurs when salt is stored in the soil profile or when groundwater is mobilised as a result of land clearing and irrigation.

The economic costs to agriculture are significant.

Our streams, rivers and wetlands are also suffering from the effects of salt as saline groun dwater seeps into waterco urses and salin e groundwater is discharged into them . The extent and severity of these less immediate 'instream' effec ts have been largely ignored.

ECOLOGY

nine open-ended channels (see Figure 1), each with substrate- filled trays that had been colonised by invertebrates over the previous month.

In the first experiment salt concentrations were increased to 1000 mg/L and 2000 mg/L for six days in six channels, while the other three channels acted as controls. Comparisons of the abundance and diversity of the invertebrates and their extent of recovery after six days were made between the low and high dose and control channels.

In the second experiment salt concentration in three channels was increased to 2000 mg/L continuously fo r five days, w hile three other channels

Salt Sensitivity Research With funding from the Land and Water Resources Research Development Corporation, for the past four years we have been conducting research designed to quantify the effects of inc reasing salinity on the biota of wetlands and streams. The aims of the project are to: â&#x20AC;˘ develop a database of the salt sensitivity of freshwater wetland and rive rine plants and animals â&#x20AC;˘ study th e effects of salinity on wetland and riveri ne plants and animals â&#x20AC;˘ formulate management plans to help resource managers minimise the damage caused to wetlands and rivers by increasi ng salinity.

River Experiments Experime nts at Hughes Creek near Seymour in Central Victoria focused on the effects of increasing salini ty on invertebrate communities. Parallel to the stream flow we constructed a nest of

20

WATER MAY/ JUN E 1998

Healthy Potamogeton trlcarlnatus

were raised to 3500 mg/L for fo ur separate 10-h our periods. In this way we attempted to ascertain whether short releases of high concentration or 'acute' saline water differed in effect to a longduration moderate concentration or 'chronic' release.

Whilst minimal effects were observed at 1000 mg/L, salt concentration at 2000 mg/L adversely affected th e abundance of some invertebrates, particularly snails. For some taxa, conditions such as stream flow and depth modified the effects. The release

schedule affected more taxa and the acute release was more deleterious.

T hese results indicate that how and when we release saline water to the environment is crucial if we want to minimise impacts on aquatic p lants and animals.

Wetlands Experiments Experiments were carried o ut at Raftery State Forest Wetland on the Goulburn River near Shepparton in Victoria to study the effects of increasing salinity on wetland plants and animals. Raftery Wetland is an ephemeral floodplain wetland which remains wet for four to six months after flooding and slowly dries up over summer. Two distinct phases are observed during a typical non-drought yea r-a 'dry' phase during which the wetland has a sward of graceful swamp wallaby grass, introduced weeds and an animal community dominated by a variety of terrestrial insects, and a 'wet' phase after flooding which can occur in any month but normally happens between July and September.

Water ribbons, floating pondweed, common spikerush and water milfoil lie dormant over t he dry phase. These plants emerge and grow quickly during the wet phase, flowering and se tting seed or forming new underground tubers in which they store energy and nutrients, and regrow when the wetland is flooded again the following year (see Figures 2, 3).

Aquatic inve rtebrates dominated initially by crustaceans that have lain dormant over th e dry phase quickly emerge. These are followed by other animal colonisers such as winged adult insects and adult frogs that arrive at various times, lay their eggs and contribute to the abundan t and diverse animal commu nity that inhabits the wetland and forms the food web that supports fish and waterbirds.

FRESHWATER The wetland is currently unaffected by salt, but it may be threatened in future due to its location in the Shepparton Irrigation Area. Field experiments were carried out simulating an increase in salt concentration to levels found in the groundwater of the Goulburn Valley. Similar concentrations are likely to be experienced by the wetland if it is either inundated with rising groundwater tables or flooded with saline water that is pumped into the river or wetland system.

During the dry phase from March to July we constructed nine 10 m x 10 m, 50 cm high artificial po nds in t he wetland. Each pond was lined with a plastic sheet designed to lie flat on the ground until the wetland flooded, when the sheets were pulled up to enclose an undisturbed 100 1112 of wetland. T he salt concentration in six of the enclosures was increased-three to 600 mg/L (low salt enclosures) and three to 1800 mg/L (high salt enclosures).

Measurements were made of conductivity, pH, plant growth, diversi ty and insect and oth er animal numbers. Experiments were carried out in the laboratory and glasshouse to refine the effects of salt on the plants and animals found.

As the water evaporated, the concentration of salt increased by more than threefold-an important factor that must be taken into account w h en considering ephemeral wetlands.

Accompanying this inc rease in sal t concentration we observed a significant decrease in the pH of the water. In the low salt enclosures, pH decreased by 1. 4 units to almost pH 5.6, w hile in the high salt enclosures there was a threeunit reduction to pH 4. Similar synergistic results are likely in other low - buffered wetlands of south-east Australia, the initial survey results from 20 sites across Victoria supporting this hypothesis. Such acidic conditions are likely to be as deleterious to animals and plants, if not more so, than those caused by salt.

As we tlands contain a range of plant species, it was expected that there would be a range of responses to salt.

This was proved by detailed observations, particularly on the reduced viability of the reproductive organs, seeds and tubers of most of the native plants.

Generally high salinity reduced the abundances of all the animal groups examined, particularly drago nflies, water beetles, snails and crustaceans.

At the same time, the abundances of salt-tolerant larval species such as mosquitoes (Culicidae) and some midge

ECOLOGY

Open-ended channels used In salt experiments at Hughes Creek

flies (Chironominae) increased sÂľb stantially, by as much as 400%. Such increases in abundance were noticeable at concentrations as low as 750-1 250 mg/L. The implications of our findi ngs for this and similar wetland ecosystems are significant. In particular, the crucial role of wetland macrophytes in underpinning the ongoing health o f th ese systems cannot be understated.

Macrophytes form an architectural matrix within the ecosystem by providing sh elter and food for invertebrates, fish and nesting platforms for bi rds.

They also form an important surface for the growth of epiphytes, wh ich are a diverse, nutritionally-rich food source for many animals. T heir abscised tissue or 'detritus' is a major nutrient and source of carbon for the wetland and parent river.

The immediate loss of biomass of sensitive macrophytes, as recorded in this study, wou ld lead to a reduction in plant cover, food availability and alterations in nutrient quality and cycling.

Poor growth of salt- sensitive plants would lead to the wetland eventually being dominated by salt-tolerant species.

Significant loss of abu ndance of a large n umber of invertebrate animals will lead to reduced food availability for other taxa including fish and waterbirds.

The mo re salt-tolerant species will dominate, leading to reduced animal diversi ty. Substantial mcreases in numbers of particular groups such as mosquitoes and some midges have obvious public h ealth and nuisance implications.

strategies to m1111mise damage to aquatic environments caused by salt.

The simplest strategy is to avoid disposing saline water to rivers when the flooding of ephemeral wetlands is likely.

At a more sophisticated level, the timing of inundation of the wetland with saline water can be controlled during the sensitive growth stages of wetland plants. The type and reproductive stages of the plants could be simply assessed by visiting the wetlands to see whether flowers have appeared and seeds have set and by digging around to see if storage tubers have formed for the growing season. It may be safer to inundate the wetland with saline water after these sensitive growth stages and cause minimal impact.

Water managers need to be aware that the salt concentrations of the water they send down a river might treble or quadruple wh en it reaches an ephemeral wetland during its drying phase.

The effects of salinity in streams may be i ncreased by not only release schedules but prevailing physical conditions such as flow and depth and, in all likelihood, the chemical or nutrient status of the system.

Through this work we have been able to more clearly understand the factors contributing to the loss of riverine and wetland plants and animals.

However, this work has concentrated on one stream and wetland type. Wh ile the management principles may apply to other such systems, more need to be studi ed. Most importantly, further research is needed to assist water managers to make decisions that protect Australia's valuable wetlands.

Conclusion We now have a better idea of how some of the wetland species of the Murray-Darling Basin are affected by salt. Using this knowledge, we are now working with managers to formulate

Authors Dr Paul Bailey and Nigel Warwick are based at the Department of Biological Sciences, Monash University, Clayton VIC 3168, tel. (03) 9905 1422.

WATER MAY/J UNE 1998

21

FRESHWATER

ECOLOGY

FLOODING THE

LIFEBLOOD OF OUR BILLABONGS D Nielsen

Research into floodplain systems and the role of floods is increasing, but its focus has been on the role of eph emeral wetlands and the response of dormant plant and animal stages residing in the dry sediment. T he emergence of these organisms in response to inundation contribu tes to the overall p roductivity and species diversity of the floodplain.

While it is clear that permanent floodplain waterbodies play a vital role in the productivity and 'health' of our river systems, the ecology of these wetland ecosystems remains poorly understood.

Experimental Billabongs The response of permanent waterbodies to flooding was investigated using 16 identical artificial billabongs on the floodplain of the River M urray, near Albury-Wodonga . T he experimental billabongs were profiled to give a shallow ephemeral area and deeper permanent area and were planted with Myriophyllum and Vallisneria sp ecies.

A divider down the middle of each billabong prevented movement of zooplankton while allowing mixing of water between the two halves. Into one half of each billabong, a com mon native plankon- eating fish, carp gudgeon (Hypseleotris spp.) was added to investigate the effect of predation in determ111111g co m m unity structure in Australian billabongs.

Four patterns of flooding representing p ast and c urrent water management practices were imposed on the experimental billabongs.

Manipulated • P ermanent- highe r water levels caused by the construction of dams and weirs downstream of billabongs have resulted in many of them becoming permanently inundated • Summer flood-irrigation releases from dam s du ring summer have changed the seaso n and duration of flooding • Winter flood-if environmental flows were imposed these would most likely be released la te w inte r-early spring, the best period fo r the floodplain and associated biota

22

WATER MAY/JUNE 1998

Daryl Nielsen examining a water sample

Control • U nflooded-many billabongs, especially those high on the floodplain, are infrequently inundated and their water levels fluctuate naturally, mostly because of rainfall and evap oration The experimental billabongs were sampled over two years fo r zooplankton, macroinve rte brates and macrophytes. During this period four floods occurred-two in w inter/spring and two in summer.

Results T he results of the experiment indicated that flooding does affect billabong productivity in a variety of ways.

Although productivity of invertebrates increased following disturbance by flooding, a change in the season of inundation does not appear to alter this response .

Permane n t flooding of floodplain wa terbodies inhibits environmental cues fo r some taxa, which may lead to a loss of diversity on the floodplain.

Competition between invertebrate predators and plankton-eating fish in the experimental billabongs has implications for the structure of communities at lower trophic levels. Variable topdown pressure may create differing successional patterns and ultimately different communities at these levels.

A shift to summer flooding, with associated changes in hydrological regime, resulted in reduced species diversity in plant communities. Similar reduction in plant species diversity in n atural billabongs could lead to further changes in ecosystem trophic levels by reducing primary produ cers and/or habitat structure.

River regulation has significantly changed the hydrology of many floodplain wetlands. Some previously temporary billabongs h ave become permanently flooded, while others now have little or no contact with the associated river channel. As a result of releases from upstream water storages over the summer months for irrigation, other billabongs recei ve summe r floods instead of the winter floods they would previously have received under natural flow conditions.

Conclusion The results of this two-year experiment indicate that the wetting and drying cycle has an important role in mainta111111g species diversity and productivity in our floodplain wetlands.

Permane nt flooding, by masking environmental cues, may reduce species diversity and the long-term viability of many invertebrate and plant taxa, as well as reducing the overall productivi ty. T he seasonality of floods, w hile not appearing to affect the productivity of invertebrates, reduces the diversity of plant taxa and productivity of wetlands, with consequent changes in the ecological systems that depend on them .

Variation in p redation and competition pressure across floodplain waterbodies will assist in maintaining species diversity by altering successio nal patterns that will eventually form different communities.

Author Daryl Nielsen is based at the Murray-Darling Freshwater Research Centre in Albury, working for a PhD through C harles Sturt University. H e especially thanks FJ Smith for her help collecting and identifying samples.

FRESHWATER

ECOLOGY

NEW RISK-BASED

WATER QUALITY GUIDELINES B T Hart, W Maher, I Lawrence

The Australian continent encompasses a diverse range of ecosystems-from the Murrumbidgee River to lowland streams such as the Darling River. Management guidelines are being developed for each ecosystem type

Deteriorating water quality and degradation of the nation's rivers are key environmental issues in Australia and have led to calls for improved management of these precious natural reso urces. If Australia's inland and marine water resources are to be effectively improved through the 1990s and beyond, it is important that the improved management be ecologically based.

The ava ilability of water quality guidelines relevant to ecosystem protection will be vital. U nfortunately, current guidelines suffer from one major deficiency in that they focus almost exclusively on physico-chemical indicators, and do not include information on biological or ecological indicators. It should be noted, however, that the 1992 ANZECC guidelines did for the first time introduce biological indicators.

This paper summarises a new riskbased approach being used to upgrade the 1992 ANZECC water quality

24

WATER MAY/ JUNE 1998

guidelines for ecosystem protection.

The draft guidelines are due to be released for public comment in the first half of 1998.

Risk-based Approach for Ecosystem Types The Australian continent encompasses a wide range of climatic and geographic regions and a diverse range of aquatic ecosystems. This makes it desirable for management guidelines to be developed that are specific to each ecosystem type.

The new guidelines consider seven types-upland rivers; ecosystem lowland rivers; lakes and reservoirs; wetlands; estuaries; coastal; and marine-a vast improvement on the two broad ecosystem types (freshwater and marine) addressed in the current gu ide lines. Despite the attempt to expand the number of ecosystem types considered, there is often a lack of knowledge on what lives in them and how the ecosystems function.

To help address these difficulties, a risk-based approach has been developed which should provide a more realistic and effective means of protecting the biodiversity or ecological integrity of aquatic ecosystems than the previous 'magic' numb~rs. This approach is based on ecological risk assessment (ERA) methodology, a process for determining the level of risk posed by stressors such as chemicals, n utrients to the survival and h ealth of aquatic ecosystems.

The risk- based approach was developed in response to the difficulties of assessing the impact of multiple stressors on complex ecosystems. It was first discussed at a workshop with input from Peter Culle n, Chris Bell, Bill Dennison, Graeme Batley, Graham H arris, Graeme McBride, J ohn Parslow, Eric Pyle and Wendy van Dok. The approach was further developed and assisted by discussions with J ohn C hapman, C hris H umphries, Kevin McAlpine and other members of the ANZECC Guidelines update team.

Packages for Ecosystem Problems The n ew guidelines will focus more on ecosystem problems rather than on single indicators. This is because problems are rarely caused by one stressor alone. T he influence of environmental fac tors which could also cause stress to the ecosystem may modify the effect of the stressor.

Guideline ' packages' have been developed for each ecosystem issue and type. These comprise key performance indicators and appropriate trigger levels as well as a protocol for further investigation if the trigger level is exceeded.

Key performance indicators for each ecosystem have been defined and trigger levels are the concentrations below those indicators that signal there

FRESHWATER

ECOLOGY expensive options are needed. The new guidelines provide a number of case studies to help managers use the guidelines.

Ecosystem management issues for which guideline packages are being developed include: • effects due to toxicants such as heavy metals and toxic organics in the water column • effects due to toxicants in the sediments • nuisance growths of aquatic plants • maintenance of dissolved oxygen • effects du e to suspended particulate matter, salinity, temperature and pH • effects due to changes in flow (for rivers and wetlands).

Testltght

conditions(IUrbidityl

NO

Test flow

\-------l conditions

Conceptual model assumes cyanobacterial growth is cont rolled by: nutrients (TP - total phosphorus: TN - total nitrogen), light climate (turbidity used as surrogate) and flow conditions in the river.

Authors

Figure 2 Decision tree for assessing the risk of cyanobacterial blooms in lowland rivers caused by irrigation ret urn drainage.

is a risk that adverse bi ologi cal or ecological effects will occu r. They are the levels that 'trigger' the need fo r continued monitoring in the case o flow risk situations, or further ecosystemspecific investigations in the case of high risk situations. They are both ecosystem-specific and issue- specific.

For situations where the problem is serious, it is possible to develop complex (and quite expensive) models.

Examples include Port Phillip Bay, the Hawkesbury- N ep ean Rive r and the coastal waters off Perth. H owever, for the majority of situations where this type of fu nding is not available, less

Professor Barry T Hart is based at the Water Studies Centre at Monash University. BIii Maher an d Ian Lawrence are at the University of Canberra.

Note This article p reviews the new ANZECC risk-based water quality guidelines. A full paper will appear in a futu re issue cf Water when the draft guidelines have been released.

GUIDELINES FOR

DESIGNING

POLLUTION CONTROL PONDS I Lawrence, P Breen Simpl e empi ri cal models for the design of stormwater pollution control ponds have been used in Australia over the past 15 years. Concerns are growing about the appropriateness of these models for locations with differen t climates, hydrology and soils and the long- term performa nce of ponds as pollutant traps is being questioned.

In 1994 the CRC fo r Freshwater Ecology initiated a pollution control pond research project aimed at better understanding the physical, chemical and biological p rocesses associated with pollutant interception. Drawing on the results of this research, a model and guidelines for the design of pollution control ponds and w etlands have been

produced and are now available from the CRC. The term 'p onds' is used to describe p redominantly open waterbodies with depths of2-3 m , while 'wetlands' refers to shallow waterbodies of up to 1 m w hich contain aquatic plants.

Pollution in Ponds U rban runoff typically co n tains extremely high levels (1000- 3000 mg/L) of fine suspended particles. The particles constitute an extremely large surface area for adsorption of othe r pollutants and a substrate fo r biological growth akin to a fluidised bed reactor used in wastewater treatmen t.

The primary and overwhelming

response of ponds to discharges is rapid adsorption of many metals, nutrients, organics and bacteria onto the surface of these fi ne suspended p articles, followed by their removal from the water colum n by coagulation and physical sedimentation of particles.

Once settled to the sediments of ponds, the bi ologi cally available components of the organic material promote heterotrophic bacterial growth and the bottom sediments become anaerobic. This leads to the reductio n of ferric iron to ferrous iron, releasing phosphorus and other metals previously bound- up with the insoluble ferric iron.

T he soluble phosphorus and metals are in a highly bioavailable form and can be

WATER MAY/J UNE 1998

25

FRESHWATER

ECOLOGY

----+• --+

OXYGEN

---+• -+

_I____.,

Online GPT and pond

Online GPT and Wetland

INFLOW

----+• --+ BIOFILM

t

OXIDATION ZONE

~~tVED _ _ _...;._

~

REDUCTION ZONE

OXIDATION ZONE

----+• --+ Figure 1 Water quality and ecological processes in pools, ponds and lakes

26

WATER MAY/JUNE 1998

On-line GPT and pond/wetland

_.

GROUNDWATER

rapidly used by pond algae. These processes are illustrated in Figure 1.

Under the conditions of hot summer days and the low wind typical of mu ch of the Australian continent, mixing in ponds is weak, resulting in stratification of even, shallow ponds. The sedimen ts receive even less oxygen, while the elevated temp erature of pond water accelerates the microbial decomposition rates. While algal growth can generate oxygen, in the case of a stratified and turbid pond, the blue-green algae will dominate and photosynthesis will be limited to the upper water layer.

For Australian conditions, the level of organic carbon (or BOD) l9ading per square metre of pond sediments is critical in terms of limiting the remobilisation of sedimented material. R esearch indicates that while pond sediments may provide a long-term sink for pollutants, under conditions of poor mixing and extreme loading of organic matter, there is a potential for ponds to act as reactors, with nutrients transferring from abiotic to biotic fo rm, and the discharge of an increased BOD (high algal bioma~s). Under extreme conditions ponds can exacerbate the impacts of stormwater discharge.

There were two othe r significant findings: • the w ide range of labile carbon conte nt (BOD) of various orgamc carbon sources • a common condition of microbial growth limited by lack of non-adsorbed (bioavailable) P .

There is a tenfold difference between the availability of carbon from sewage eilluent and carbon from macrophytes and eucalypts. This understanding partly explains the greater impact of sewage eilluen t than non-point sources on eutrophication levels.

Experiments have shown that the strength of bonding of P to fe rric iron in

___.

L+.

On-line GPT, Pond and Wetland

t

Ill

On-line GPT and Pond, off-line Wetland

Figure 2 Treatment train options

oxidised sediments may limit the level of P available for bacterial growth. This understanding may provide an explanation for the sudden switch in ponds and lakes from macrophyte- dominated systems to algal-dominated systems, if the sedime nt bonding sites become saturated as a result of P loading from sewage discharges.

Baseflows are typically low in suspended solid s. The discharge of sewage to ponds under these conditions would create a situation of high bioavailability of nutrients for direct uptake by algae. Except wh ere grazing levels may be sufficient to limit algal growth, ponds do not perform well under these conditions.

It was concluded that in the case of pond systems, macrophytes provide two functions: the calming of flow during storm inflow events; and the direct transfer of oxygen to the rhizosphere root zones, offsetting sediment-reducing processes when oxygen transfer throu gh the wate r column may be limited.

Pollution in Wetlands Wetlands do not perform well in terms of interception of suspended solids occurring under storm event or high flow conditions unless a high wetland area per hectare of catchment is provided. Analyses indicate that 90% to 99% of nutrients are stored in the sediments, with minor amou nts in the water column and macrophytes. In the case of wetlands with inflows low in suspended solids, the literature indicates that the transformation and transfer of dissolved and colloidal nutrients occur primarily in the benthic algae-biofilm zone and in the epiphytic growth zones on the macrophytes and other surfaces.

Storm events can scour these out of the wetland, with the p otential for loss of wetland efficiency and the discharge of

organic material high in nutrients and BOD.

Pond Design Guideline~ Drawing on this understanding of the dominant physical, chemical and biological processes characteri~ing ponds and wetlands, the guidelines provide a number of principles guiding the selection of treatment trains appropriate to the site hydrology and pollutant characteristics. Figure 2 illustrates this point.

E ach of the major intercep tion, transformation and transfer processes have been addressed, and models provided for estimating the overall significance of each component for the discharge characteristics (flow distribution, suspended solids and grading, BOD) of sites selected by th~ user. This information enables designs to b e finetuned in terms of volume, surface area, depth, soil substratum and selection and design of planting. The computational models also facilitate a more rigorous assessment of the performance and stru ctures o f existing ponds and wetlands.

The guidelines also include a computer-based pond water quality model comprising five submodelsmass balances/advection; adsorption and sedimentation; sediment redox and pollutant release; algal growth; and mixing/oxygen transfer. The submodels are interlinked to account for feedback processes. The model is run on a daily time step basis, with a facility to load historical runoff and wate r quality (monitored or rainfall runoff estimates) data for the selected site.

Authors Ian Lawrence is based at the University of Canberra. Dr Peter Breen is at the Water Studies Centre at Monash University.

FRESHWATER

ASSESSING

ECOLOGY

WATER QUALITY IN

KOSCIUSZKO NATIONAL PARK USING

AUSRIVAS

RH Norris, J Simpson, K Beggs Responding to a call for biological measures of water quality in the 1992 ANZECC Water Quality Guidelines, the N ational River H ealth Program and the CRC for Freshwater Ecology have developed AusRivAS (Australian River Assessment System), a set of compu ter models that provide rapid biological methods for assessing water quality.

New procedures for sampling, analysing and reporting biological data are contained in the system. The methods are standardised, easy to use and rapid.

Once established, they avoid many of the problems of confounded statistical designs. T he upper Snowy Catchment of the Kosciuszko National Park was used in a study by the CRC for Freshwater Ecology to investigate the use of AusRivAS as a water quality assessment tool.

Kosciuszko National Park The project faced specific difficulties in that ski resorts lie in the heads of catchments and there are few suitable reference sites for biological monitoring purposes in the short sections upstream of the resort. The general area for selection is also small and there are strong seasonal influences with associated changes in visitor uses.

The Snowy Mountains H ydroelectric Scheme has impacted on water quality and aquatic ecosystems in several ways. Most obvious are those ca used by the altered hydrology of the river system, but other less obvious effects arise from conservation measures to preven t sedime n tation o f dams.

Several sewage treatment plants pose significant threats to the ecological integrity of rivers and streams in the Park. The Thredbo WWTP provides tertiary effluent treatment and nutrient removal, while at the time of the study the Charlottes Pass and Perisher Blue plants provided secondary efflu ent treatment with no nutrient removal.

28

WATER MAY/JUNE 1998

University of Canberra students conducting blologlcal monitoring In the headwaters of the Snowy River, Koscluszko National Park

Materials and Methods Nineteen reference sites were selected in the Thredbo and upper Snowy Rive r sub- catchme nts (see Figure 1). T en test sites were located downstream of ski resorts and their treated sewage discharges. Sampling was conducted qu arterly over two years from May 1994 until November 1996 (11 occasions), to account for the low number of reference sites and strong seasonal changes.

Sampling methods followed those prescribed for the National River Health Program.

The deviation between the number of taxa expected (calculated by the model) and the number of taxa that were observed (collected in the field) was expressed as the ratio of observed/ expected taxa (0/E), and used as an indication of biological impairment at a test site.

Results Water Quality Characteristics Water quality variables measured in the study area were generally within the recommended guidelines for maintaining ecosystem health determined by

Maher et al. in Review of ACT Water Quality and Ecological Guidelines.

(1994). Exceptions were total p hosphorus at sites downstream of the three treated effluent inflows. Sites 013, 014, 107, 123 and 124 all experienced elevated total phosphorus levels (>0.03 mg/L) on at least one sampling occasion. Site 107 had t he highest recorded total phosphorus level of 2.0 mg/L. Site 162 downstream from Sawpit Creek campground also had elevated total phosphorus le vels on three occasions. Interestingly, site 129 has no sewage input upstream but also had elevated total phosphorus levels on five sampling occasions and elevated total nitrogen levels on one sampling occasion.

Several test sites had pH levels below 6, w hich is outside recommended levels for maintaining ecosystem health.

However, low pH values were also common at reference sites. Values for pH in the 5 to 6 range appear to be normal for the alpine streams of the study area.

Taxa Ratios and Impairment Bands Assessments of the test sites classed 38 sites/occasions as equivalent to reference (band A), 40 sites/occasions as

FRESHWATER

ECOLOGY

sawpit Ck.

N

t

'--'

0

q 020 01 4 \

0

+

* â&#x20AC;˘

1km

Reference

2Fails 3-5 Fails > 6Fails

Figure 1 Location of test and reference sites in the Kosciuszko National Park, NSW. Sites ranked using biological assessment by AusRivAS for sam pling from 1994-96

in an average O /E ratio equivalent to referen ce.

One reason w hy previous studies were less sensitive in detecting impairment caused by the treated effluent inflow and carpark runoff was the lack of suitable invertebrate data for comparison. The AusRivAS models predict what the invertebrate community at a test site should look like in the absence of impact, based on the 139 reference sites/occasions . The predicted taxa provide a 'target community' containing specific taxa with w hich to make comparisons and therefore also a measure of impairment.

In addition, the AusRivAS output shows that the invertebrate communities found at sites downstream of the treated effiuent inflow are different from those that would be expected if the treated effiuent inflow was removed. The AusRivAS model demonstrates that the impact from the treated efiluent inflow is producing a shift in the invertebrate communi ty composition rather than a simple loss of taxa .

Discussion If only physical and chemical data Previous studies on the Thredbo were used in conjunction with national River using physical/chemical data in water quality guidelines to assess the statisti cally confounded upstream/ alpine rivers and streams in Kosciuszko dow nstream designs found that treated National Park, 23 sites/occasions would efiluent inflow caused little or no have failed these criteria , but there biological impairment of the river. The would have been no indication of the results from the present study indicate severity of the impact. This figure there are several taxa missing below the jumped to 48 sites/occasions that failed treated effluent inflows that would be to meet reference conditions when the expected to occur if there was no input biological data and the AusRivAS of treated effluent. The impairment is, model were used. The severity of the however, mild and sites downstream of impairment was also provided, and a the treated effluent inflow only experi- target community of invertebrates that enced minor impairment on less than should have been present at each site. half of the sampling occasions, resulting This information could not have been

below reference (band B) and 8 sites/occasions as well below reference (band C). One site/occasion (12, November 1995) was outside the experience of the model and no assessm ent co uld be provided. Site 123 (below Perisher Blue) was consistently the most impaired site, with the lowest average O /E ratio for all sampling occasions (Table 2). Site 124 had the highest average O /E ratio for all sampling occasions (0. 92), but still had four incidences of mild impairment.

Site 129 was again of note, being impaired on eight of the 11 sampling occasions.

Sites/occasions with low O /E scores (106, 107 , 123 and 129) were commonly dominated by nutrienttolerant taxa such as oligochaetes, C hirono minae midge larvae and Elimidae beetle larvae. These sites were also commonly m1ssmg nutrientsensitive taxa such as Calocide caddisfly larvae and Scirtidae beetle larvae predicted to occur at such sites.

Sampllng macrolnvertebrates from a stream edge below Perisher Blue ski resort In Koscluszko Natlonal Park

obtained from traditional physical/ chemical assessm ent and enabled predictions to be made that test sites that were equivalent to reference could be expected to have h igher O/E ratios if the impact was removed.

Conclusion AusRivAS predictive models offer a number of advantages over traditional water quality assessment techniques for the assessment of alpine catchments.

The standardised methods allow spatial and temporal comparisons that are rarely possible between studies using other techniques. They are also quick and because the impairment of the biota is measured direc tly, sampling for specific pollutants is not required. The existence of a reference site database allows the sampling of new test sites without the need for new or modified experiments. The prediction of a target community provides managers w ith a goal to aim for and the banding system allows them to monitor the progress of remediation measures.

Acknowledgements This study was made possible by the cooperation ofNSW Parks and Wildlife and Kosciuszko Thredbo Pty Ltd. Funding, facilities and technical support were provided by the CRC for Freshwater Ecology and the University of Canberra.

Authors Richard Norris, Justen Simpson and Kerry Beggs are at the University of Canberra. AusRivAS is available at http://AusRivA S.canberra.edu.au/ ausrivas

WATER MAY/ JUNE 1998

29

FRESHWATER

In New South Wales, as in other parts of Australia, there are conflicts over the use of water, degraded riverine environments, damaged catchments, declining natural resources and threatened biodiversity. In this context, the NSW Rivers Survey was designed to improve our understanding of how rivers and their aquatic life are faring in the 1990s. The survey aimed to: • study the distribution, diversity and abundance of the native fish of NSW nvers • determine the abundance, distribution and habitat use of carp and other alien species in NSW rivers • develop understanding of the ecological effects of river regulation and establish hypotheses for further study of environmental streamflows • establish and test a standardised predictive model for monitoring river health using fish community assessment • establish a standardised survey structure for use in other studies.

NSW Rivers Survey Over two years four surveys were conducted in 80 randomly chosen sites representing five examples each of montane, slopes, regulated and unregulated lowland river reaches in the Murray, Darling, and north and south coast regions. Intensive but minimally

ECOLOGY

destructive sampling with five different fishing-gear types, including electrofishing, was designed to ensure that all fish species present at each site were represented in the samples.

Routine sampling recorded a total of 50,438 fish (including both 'caught' and 'observed' data) belonging to 55 species.

A total of 39 native freshwater species (i.e. those species recognised as regularly occurring above tidal limits for a significant part of their lifecycle) from 25 genera and 19 families were recorded, together with 10 estuarine species. Six species of alien fish (i.e. those species introduced from overseas and now established in the wild) were caught, comprising 18.4% of the total catch of fish.

Despite the survey having spanned major climatic variations, beginning in drought then passing through a wet period, there was surprisingly little temporal variation in fish catches other than a marked seasonal increase in numbers in the two summer samples.

Serious Degradation The State's degraded riverine ecosystems are rapidly losing their biodiversity.

Degradation is especially evident in the Murray region, in rivers regulated for water supply, inland lowland rivers

and montane areas. As indicators of river ecosystem condition, the fish are in severe decline, with the survey finding only 39 of the 55 species of native freshwater fish recognised as occurring in NSW and 29% of the fish fa una not detected.

The threatened conservation status of 11 NSW species was confirmed, and the status of previously abundant fish such as freshwater catfish should be reviewed. There were high levels of visible abnormalities in many species, with up to 25% of fish showing evidence of parasites and diseases.

The Murray River system gives cause for particular alarm. Only 4.4% of the total NSW catch of native fish came from the Murray region (including the Lachlan and Murrumbidgee systems).

The Darling ecological region produced almost 10 times as many native fish.

Native fish species constituted only 20% of the catch from regulated rivers in the Murray region.

Despite intensive fishing with the most efficient types of sampling gear for a total of 220 person-days over a twoyear period in 20 randomly chosen Murray-region sites, not a single Murray cod or freshwater catfish was caught, although more than 50 of each species were found at Darling-region sites. Relatively high catches of Murray cod are taken by anglers and commer-

WATER MAY/JUNE 1998

31

FRESHWATER

The Murray cod-Australia's most celebrated freshwater fishabsent from the Murray sites In the NSW Rivers Survey

cial fi shers targeting remnant populations in some key Murray- region habitats, bu t ou r results emp hasise that the populations of this keystone species are now fragmented and patchy, and their overall abundance is worryingly low.

The alien pest species, carp, is the domin an t fi sh of the M urray and Darling river systems and is threatening a number of coastal systems. Carp are aided by various human modifications of rivers, especially flow regulation. At one si te in the lowland reaches of the Boga n River, there was an average of one carp for every square me tre of river surface area.

Index of Biotic Integrity Efforts to manage and restore rivers need effective tools to measure the ' health' of rivers.

The Index of Biotic Integriry (IBI) was assessed for this indicator role, using 'metrics' of species richn ess, abundance, community structure, and the health of individual fish. The 80 sites of the NSW Rivers Survey spread through the full range of qualitative IBI rankings from 'Excellent' to 'Very poor' and 'No fish.'

T h e assumptio ns underlying the index were generally m et and it performed satisfactorily. Several recommendations were made to enhance the performance o f the IBI as a rapid, efficient and sensitive ecological tool and work is under way to complete validatio n.

ECOLOGY

Results of the NSW Rivers Survey Indicated that the shortfinned eel was not as abundant or widespread as expected

exhibited only negative effects. Flow regulation has reduced the resilien ce of native fish communities to invasion by alien fish species. Enhanced river flows in NSW can be expected to help rehabilitate fish communities.

Invasion of Allen Fish T he six alien species captured were redfin perch , gambusia, goldfish, brown trout, rainbow trou t and common carp.

Distributions of each of the alien species captured during the survey could be explained by their temperature tole rances and by attri butes of the habitats.

All inland rivers had higher carp biomass densities than the coastal rivers (see the article by D river in this fea ture).

Urgent Restoration Needed The NSW Rive rs Survey reco mmends further research to ensure that

managemen t d ecisions are based o n good information and a strengthening of policies by natural resource agencies to e nsure th at river management continues to be based on high- quality science.

The survey's primary recommendation involves accepting that riverin e heritage in NSW is in a generally degraded condition and in urgent need of restoration. What is required is the restoration o f river- ecosystem compone nts, especially flow and the rmal regimes and river catchments, particularly in the riparian zones .

A recognition that fish stocks are da maged and threatened by habitat degradation, recreational and commercial fishing prac tices, disease, alien species and fragmentation of populations is also critical to the health of NSW rive rs. T hreaten ed species include freshwater catfish , M urray cod and sh ort-fi nned eels. T h ere is an urgent need to control carp and restore fish passage at dams and weirs.

Knowledge gaps need to be filled if rive r health is to be su ccessfully res to red. T he research required includes testing e nvironmental flow regimes in regulated rivers, developing better tools to measure chan~s in water regimes, d eveloping knowledge on parasitic, viral and other fish diseases, imp lem enting programs to pro tect threatened fish and studying thermally polluted rivers below dams and floodplai n wetland s.

Effects of River Regulation

Authors

Significant differences occurred in the composition of fish communities be tween 'regulated ' or 'unregulated' river types, although communities in each region retained a unique regional character. Three abu ndant alien species and seven native species showed positive or mixed responses to river regulation, whereas 13 native species

John Harris, Peter Gehrke and Simon Hartley are with the CRC

32

WATER MAY/ JUNE 1 998

Five fishing-gear types Including gee traps (pictured) were used during the sampling work to ensure that all fish species were covered In the survey

for Freshwater Ecology based at the NSW Fisheries Research Institute in C ronulla. Support was also provided for the NSW Rivers Survey by the NSW R esource and Conservation Assessment Council and the NSW D epartment of State D evelopment.

FRESHWATER

Common carp (Cyprinus carpio L) often dominate the fi sh catch in waterbodies and are often associated with degraded waterways. The more carp, the greater t he impa cts on aquatic vegetation and water quality. However, the influence of large-scale effects on carp abundance are poorly understood.

These include natural effects such as changes in stream channel structure and human activities such as land clearance and river regulation.

There is an immediate need to understand this broader context becau se the methods of controlling carp that are currently being considered may be costly or have unknown and possibly undesirable environmental impactsenvironmental rehabilitation, poisoning, physical removal, in trodu ction of pathogens and molecular approaches.

One exte nsively debated 'control method,' comme rcial harvesting, is already under way and about to expand in scale. The success of control methods will depend on other, larger- scale influences on carp population dynamics.

The project su mmari sed in this article studied the distribution of carp in New South Wales rivers.

ECOLOGY

height and distance of nearby dams were derived from maps or government agencies.

Bio mass density (kg site - 1 ) was estimated using known length-weight relationships, the number of carp at each site and a subsample of the lengthdistribution.

To test our predictions regarding environmental conditi ons and carp, the presence of ca rp and ca rp biomass densities were related to the environmental variables. Because of their ecological differences, the coastal rivers and inland rivers were analysed separately.

Distribution Affected by Dams, Agriculture Inland rivers had higher carp densities and far more sites with carp than coastal rivers. Carp were found in all inland sites below an altitude of ca.

500 m ASL. In the coastal sites, carp

Carp Control

Carp Distribution Study Data collected from th e NSW Rivers Survey (CRC for Freshwater Ecology and NSW Fisheries R esearch Institute, Cronulla) were used for this assessment.

Eighty randomly selected sites including rivers in the Murray, Darling and north and south coast regions were sa mpled across New South Wales during the two-year survey.

A suite of fish-sampling techniques standardised for major habitat typ es were used at each site. Habitat characteristics such as flow, depth, width, substrate, abundance of aquatic vegetation and standard water quality measures were recorded. Other variables such as climatic conditions, altitude, agricultu ral land value and the wall

to ca. 500 m ASL. These slightly higher carp biomass densities in the inland rivers were associated w ith an abundance of riffie habitat and coarse particles in the substratum (e.g. gravel).

This association w ith co nditio ns indicating high energy flows was unexpected as optimal carp spawning is reliant o n shallow, vegetated, slow flowing habitat. The recorded concentrations of carp were probably a result of th e upstream migration of adult carp from sp awning habitats and barriers to fish dispersal. Adult carp most likely m igrated from spawning habitats including lowland sites (below ca. 200 m ASL) and artificial lakes in midaltitudes (ca. 200-500 m ASL). Both dams and natural river features would have acted as barrie rs to dispersal.

Across NSW, higher carp biomass densities were associated wi th the effects of dams and agriculture.

Alteration of flows and water temperatures, p hysical barriers to fi sh migratio n, carp spawning habitat created in artificial lakes and agricultural effects on water quality were all linked to higher carp biomass densities.

Electroflshlng for carp Moodemere, Victoria

on

Lake

were only found within an altitudinal range of 0-60 m ASL and within regu lated rivers. The differences between the coastal and inland rivers were attributed to the relative rarity of spawning habi tat in coastal rivers.

Carp biomass densities in the inland rivers were fou nd to increase slightly (r2 = 0.18) with altitude for altitudes up

T his study indicated large-scale influe nces on the distribution of carp and ca rp biomass densities. Barriers to migration, human impacts such as flow regulation, and the downstream availabili ty o f low-gradient, low-velocity spawning habitat were all considered important influences on carp population dynamics.

The results suggest that carp control activities need to consider the implications of the availability of spawning habitat, adult migration from these spawning areas and the effects of agricultu re and river regulation.

Author Patrick Driver 1s a PhD student at the University of Canberra.

WATER MAY/JUNE 1998

33

m

WATER

A MOBILE WATER TREATMENT PLANT

FOR SMALL TOWN ¡ WATER SUPPLIES N Healey This article is an edi ted and updated version of a paper that was presented at the 60th Annual W ater Industry Engineers and Operators Conference, Bairnsdale, 1997 , where it was awarded the Actizyme prize for the best paper by an operator.

Abstract Since the reforms to the wa ter industry in Victoria began there has been a continuous process of change and upgrading of wa ter and wastewater treatment plants to meet the n ew standards required by the Victorian Government. One of the major problem s facing all rural water authorities is to consistently meet W odd H ealth Organization (WHO) requirements for water supplies by 2000. This is particularly difficult for small towns with populations fewer than 500 people.

This paper details successful trials using a mobile chemical di spen sing system called the N eutra-Mill to achieve flocculation and sedimentation in small reservoirs in a cost-effective manner. The trials resulted in the purchase of a N eutra-Mill by Goulburn Valley Water as their preferred system for water treatment in small towns.

The auth or manages the Western Region, w hich comprises eleven townships: Tatura, Stanhope, Kyabram, M errigum, Rushworth, Colbinabbin, Tongala, Corop, Murchison, Girgarre and Toolamba.

Of these eleven towns, only three currently have fully treated water.

Tatura has a 12 ML/d DAFF plant that was completed in March 1997, and Tongala and Murchi son both have conventional water treatment plants.

Kyabram has a 15 ML/d DAFF plant under construction , Rushworth is to receive a new 3 ML/d plant in the near future and Toolamba's method of treatment is yet to be decided.

The remainder-Stanhope, M errigum, Colbinabbin, Corop and Girgarre - have reasonably turbid water supplied via the Goulburn-Murray Water rural channel system, with disinfection as the only form of water treatment.

These five towns presented a challenge to Goulburn Valley Water in providing WHO quality water by 2000 in a cost-effective manner. All have small populations, w hich means that the per capita price of supplying fully treated water would be very high.

The Goulburn Valley Water business plan allowed for capital expenditure of $50,000 to $80,000 per site to supply

Key Words Water treatment, flocculation, sedimentation, reservoir dosing

Introduction Goulburn Valley Water was formed in M arch 1994 following the merger of three neighbouring W ater Boards. By late 1994 to early 1995, further mergers brought the total number of towns and cities supplied with potable water under Goulburn Valley Water's control to 29.

34

WATER MAY/ JUNE 1998

Figure 1 The portab le Neutra-Mi ll unit, weighing 750 kg, is readily transported to sites as required

treatment plants, but the capital cost of conventional sedimentation and flocculation plants for these sites remains prohibitive. Most rural water authorities face similar financial problems in supplying suitable quality water to small townships.

The Neutra-MIII At the 1996 Australian Water and W astewater Operators Association Conference in Geelong, the portable Neutra-Mill was displayed by Earth Sys tems Pty Ltd, an environmental research and consulting organisation with specialist expertise in water treatment.

Experience with the system at that time was mainly in treating small to large acidic waterbodies at mine sites across Australia and Indonesia, where the system dispensed a variety of reagents, mainly hydrated lime, to raise pH. Discussions were held about whether the system could be used for the treatment of small town water supplies and it was agreed to run trials on storage reservoirs for the five towns listed above with Goulburn Valley Water supplying the ch emicals and Earth Systems supplying a Neutra-Mill at no charge.

The N eutra-Mill consists of a rotating, cylindrical, stainless steel chamber supported between four pontoons (see Figure 1) . The chamber rotates around a central axis, and is powered by an electric motor, gear box and pulley assembly . Dispensing rates from the chamber are controlled by varying the speed of rotation. ' The chamb er has large centrally located apertures at either end to permit the free flow of water and reagent solutions through and out of the chamber. The feed hopper delivers the reagents into one end of the chamber,

WATER and an impeller directs reagent solutions out the other end . The ro tating action of the chamber perfo rms the mixing, di ssolution and di sp ersion of the reagents, facilitating their release in a plume of fine suspension or concen trated solution.

The N eutra-Mill is designed to retain in the chamber reagent particles that are too coarse to dissolve or fo rm a su spen sion until they h ave bee n thoroughly disaggregated . This provides a higher reagent efficiency with a much lower energy input than compared with conventional chemical dispen sing and water treatment system s.

In one if its com mon uses, such as pH adjustm ent , a unit is gen erally moored on shore adj acent to the treatment reagents to be dispensed . In these applications the reagents may also be continuou sly or batch loaded into the chamber using a bulk storage and delivery system . In rem ote locations the unit may be powered by a small 5 KVA generator located on the bank via a floating submersible power cable.

Figure 2 Dep loyment of a Neutra-Mi ll unit into a reservoir. Alt ernati ve ly it can be ro lled off its trai ler

reservoir water quality after treatment at this do se rate were very encouraging, but there appeared to be roo m fo r improving the respon se time for achieving full clarifica tion.

The Girgarre reservoir (20 ML) was also treated using the same method.

Progressive changes to the raw water from pre-treatment to the final water quality and the time period are detailed in Table 1 for the Girga rre reservoir.

The colour was fine, pH could have been a little higher and turbidity could have been a little lower. The aluminium levels were below guideline levels.

T he second method was u sed fo r trials on the M errigum storage w hich has a capacity of 10 M L. In this method the Neutra-Mill pump was used.

Agricultural sprays were m ounted on the unit and the suspension was aerially dispersed over the surface of the water body, ra ther than moving the N eutraMill itself across the reservoir. The Neutra-Mill was only m oved a few times to achieve coverage of the reservoir with the alum solution .

As M ethod 2 achieved a m ore even coverage of the surface of the reservoir, it was expec ted that trea ting the supply in this way would achieve better results.

The water quality res ults in T able 2 support this expectation .

Whilst M ethod 1 took up to fo ur hours of m anual operation to treat app roximately 20 ML of water (Girgarre), M ethod 2 took up to six ho urs to treat 10 ML (M errigum). The water quality results following treatm ent using M ethod 2 were excellent, but thi s technique was too time co n suming given limited human resources (see Table 2).

A report outlining the results of the trials and recommending the purchase of the Neutra-Mill tQgether with a low noise generator and an electric outboard m otor was accepted by Goulburn Valley W ater m anage m ent . A budge t of $40,000 was approved and the N eutraMill was purchased at a base cost of $34,000 .

On-site Operation by Goulburn Valley Water

Following purchase, the N eutra-Mill was m odified to suit the specific requirem ents of Goulburn Valley W ater by attaching an outboard m otor so that the unit could be driven around the waterbody by an on-board operator. A Conduct of Trlals 4.6 KVA generator silen ce d to 65 The concept of the trials was to use decibels was purchased , along with a 3 the existing water impoundment as the kno t, 12 volt, electric outboard m o tor. wa ter treatment plant. R ath er than A local engineering firm constructed passing the raw wa ter through a plant m ounting brackets on the pontoon fo r where chemicals such as alum and lime the mo tor and generator. T hese modifiare dispensed and the resulting products cations were m anufac tured in stainless removed via sedimentation , flotation, steel in line with the other components filtration in a separate storage, it was of the unit. The unit was then successintended to move the the N eutra-Mill fully tes ted fo r manoe uvrability and chemical dispen sing system thro ugh the operation on a n earby storage. water impoundment w hilst dispensing The Neutra-Mill is currently transthe alum and lime reagent. ported to a waterbody requiring treatIt was hoped that this would initiate m ent on the back of a combined small flocculatio n and sedimentation and crane-tip truck and lowered into the allow the floe to settle to the base of the water (see Figure 2) . The light weight of storage . In this way the entire contents the unit-750 kg-m eans that backof a water storage would be treated to hoes can be used in o ther situation s and the standards required in one treatment the unit can even be rolled off a trailer. session , allowing the chemical dosing Once the ge nerato r and outb oard equipment to be moved to ano ther site. m otor are attached and the unit is tested T wo m ethods of dispen sing the and adjusted, bags of alum and lime trea tment reagents were are loaded o n board and devise d . The first involved operation comm ences. using ropes to m ove the R ecent trials have show n N eutra-Mill across the surface that optimu m results are of the waterb ody w hile it achieved w hen the alum and dispensed alum. The unit was lime are evenly di stributed guided from the bank to the over the entire surface of the centre of the reservoir a waterbody. T his is achieved number of times to achieve a by driving the operating grid-like coverage.

N eutra-Mill around the outer T his m ethod was u sed edge of the wa terbody and initially at Stanhope Storage then covering the rem ainder N o. 2, a rec tangular 12 ML of the storage in a ,grid pattern. reservoir. J ar testing of the raw A 10 ML sto rage can be water using granulated alum treated in as little as two hours and hydrated lime fo r pH using the self propelled system . correction at a ratio of alum Treatment of the Stanhope to lime of 3: 1 yielded an Figure 3 Three stages of water treatm ent at Stanhope showing Storage N o. 1 reservoir u sing optimum dose rate of 12 mg/L th e source channel in the foreground , the midd le pond after the self prop elled system of alum. The fi nal results of three months settl ing and the far pond a week after treatment began on 22 M ay 1997 . The WATER MAY/ JUNE 1998

35

WATER Table 2 Method 2 at Merrigum (10 ML)

Table 1 Method 1 at Girgarre (20 ML) Date

pH

Colour (Hazen)

Turbidity (NTU)

Aluminium (mg.L)

Date

pH

27.11.96 28.11.96 29.11.96 30.11.96 1.12.96 2.12.96 3.12.96 4.12.96 5.12.96 6.12.96 10.12.96 11.12.96

7.3 6 6.3 6.5 6.7 6.9 7 7.2 7.6 7.5 6.9 6.9

65 39 39 34 30 25 22 22 17 15 14 6

33 19 17 15 15 10 11 10 11 11 5 6

Nil 0.03 0.11 0.01 0.01 0.01 0.05 0.05 0.03 0.03 0.00 0.02

28.11.96 29.11.96 30.11.96 1.12.96

7.6 7.16 7 7.3

pH

Colou r (Hazen)

Turbidity (NTU)

22.5.97 23.5.97 26.5.97 27.5.97 28.5.97

7.3 7.3 6.5 6.5 7.25

6.6 3.2 2.7 0.5 0.4

33 15 13 6 1

Colour (NTU)

Turbidity (mg. L)

7 6.8 6.8 6.8 6.9

2.5 0.01 1.5 1.5 0.8

10 8 5 6 4

23.5.97 26.5.97 28.5.97 30.5.97 2.6.97

reservoir has a capacity of 12 ML and a depth of 4 m. The desired final water quality was achieved in a shorter p eriod (see Table 3) than in the initial trials (see Figure 3). A follow- up was required some days later to adjust the pH due to a minor operator error.

Stanhope Storage No 2. was treated again, using the self propelled method.

The results were excellent (see Table 4).

Several other small town supplies are now routinely treated (see Tables 5, 6).

Other Uses The Neutra-Mill is now routinely used to treat a number of storages, the largest of these with a capacity of 40 ML. Goulburn Valley Water has also used the unit as an emerge ncy response system. For example, problems were encountered with the water treatment plant at Tongala when a bearing collapsed on a paddle-stirrer in the flocculator.

The plant is fed from a 30 ML holding reservoir. The Neutra-Mill was rapidly mobilised and used to treat the water in this holding storage using an expedient alum dosing rate.

Within twelve hours the water had clarified to the required levels and was passed through the treatment plant for 36

WATER MAY/J UNE 1998

30 11

3.12.96 4.12.96 5.12.96 6.12.96

7.3 7.5 7.5 7.5

10.12.96

6.9

8 11 14 11 5

11.12.96

6.7

2

8 8 10 7 9 14 13 1 2

Aluminium (mg.L) Nil 0.36 0.11 0.1 0.07 0.01 0.00 0.07 0.04 0.02 0.0

Table 4 Stanhope No. 2 Storage (10 ML) Aluminium (mg.L)

0.03 0.05 0.00 0.00

pH (Hazen)

52 18 18 15 16

7.4

Date

pH (Hazen)

Colour (NTU)

Turbidity (mg.L)

30.5.97 2.6.97 6.6.97

7.5 7.1 7.1

4.4 0.1 0.1

22 0 0

Aluminium

0.02 0.03 0.00 0.00

Aluminium

0.00 0.00

Table 6 Colbinabbin Storage (13 ML) Date

pH (Hazen)

Colour (NTU)

Turbidity (mg.L)

21.5.97 22.5.97 23.5.9 7 26.5.97 28.5.97 30.5.97 2.6.97

7.4 7.3 7.3 7.4 7.5 7.4 7.2

3.4 2.1 0.9 1 .1 1 .3 1 0.7

16 11 8 6 4 3 0

Table 5 Merrigum Storage (10 ML) Date

Turbidity (NTU)

2.12.96

Table 3 Stanhope Storage No. 1 (10 ML) Date

Colour (Hazen)

final filtration and disinfection. This resulted in no disruption of supply to commercial and household consumers and the water treatment plant was repaired two days later.

This example highlighted the potential of the N eutra-Mill to be transported to areas on an as-needed basis to assist with water management.

Several other potential applications include: • preventing algal blooms by stripping n u trients or treating algae with an algacide or by flocculation and sedimentation • pre-treating high turbidity raw water in storages prior to treatment in conventional plants • lowering suspended solids in wastewater such as sewage and agricultural effiuent • supplementing conventional potable water and sewage treatment plants.

Conclusions The Neutra-Mill provides wate r authorities which are managing small town supplies with many advantages.

The benefits of the Neutra-Mill for Goulburn Valley Water include: • a single cost-effective water treat-

Aluminium

0.03 0.00 0.01 0.00 0.01 0.00

ment process for multiple small towns • the ability of small town water supplies to comply with WHO water quality guidelines well in advance of the 2000 target and on a more consistent basis than ever before • the ability to deliver to customers in these regions a quality product • the ability to deliver the system to a site where water treatment is required on an as-needed basis.

The self propelled, portable NeutraMill is now Goulburn Valley Water's preferred method for treating water in small towns.

Acknowledgements The author freely acknowledges the cooperation t hroughout the project of Michael Leak e, Environmental Scientist/Product Services Manage r with the research and consul ting company w hich developed the NeutraMill: Earth Systems Pty Ltd, Suite 209, Princes Tower, 1 Princes Street, Kew VIC 3101.

Author Nell Healey is Area Manage r, Western R egion, Goulburn Valley Water, Ross Street, T atura VIC 3616.

WAYE R

RADON-222 CONCENTRATIONS IN POTABLE GROUNDWATER IN AUSTRALIA A L Herczeg, J C Dighton Summary

100

A considerable amount of controversy exists concerning the level, or even necessity, of drinking water guidelines for dissolved radon- 222.

Radon-222 has a half life of 3.8 days, and has been the subject of a great deal of research in North America and Europe with respect to its contribution to indoor radon gas concentrations where water is sourced from groundwater supplies.

Because radon readily escapes when in contact with the atmosphere, radon222 in surface water supplies is usually negligible. In 1981, the US EPA suggested an interim maximum perrnissible level of 11 Becquerels/Litre (1 Bq/L = 1 disintegration per second) , although this was later revised to an 'action level' 147 Bq/L pending a National Academy of Sciences Toxicity Assessment of drinking water radon.

The current Australian AR.MCANZ/ NHMRC recommended value is 100 Bq/L, which is more in keeping with European standards. This study set out to measure radon-222 concentrations in some of Australia's groundwater supplies, as well as assess any areas or lithological aquifer types that may have high radon concentrations.

Survey A total of 230 analyses of radon-222

90 80

70

Unconsolidated and sandstone

Limestone

â&#x20AC;˘

Fractured rocks

60 50

40 30 20

I,

10

Ii 10

20

30

40

50

60

70

80

90

100 >100

Rn-222 Bq/L

Figure 1 Radon concentration by rock type

dissolved in groundwater from mainland Australia were compiled. These include 155 new analyses and 75 analyses from Western Australia previously published by Thorpe P M. (Radon- 222 levels in Perth's scheme water sources, Hydrogeology Report No. 1991/44, Geological Survey ofWestern Australia, 1991). Measured radon concentrations range from <0.5 Becquerels per litre (1 Bq/L = 1 disintegration per second) to 334 Bq/L. The data are log normally distributed with a median of 13.4 Bq/L and an arithmetic mean of 30.2 Bq/L. The highest concentrations were recorded in fractured rock aquifers (median = 33.9 Bq/L; mean= 53.4), while limestone aquifers have very low concentrations and are more nearly normal distributed (median=4.6 Bq/L; mea n=5 .0 Bq/L. Eighteen samples

Table 1 Radon in water from various rock types (Bq/L) Fractured rock

Unconsolidated

Limestone

All data

Median

33.9

10.2

4.6

13.4

Mean

53.4

13.6

5

30.2

Standard deviation

58.7

13

3

45

Geometrical mean

30.4

8.4

4.1

Median (Bq/L) Mean (Bq/L) Standard deviation (Bq/L) Variance

2 .1

2.16

0.27

3.2

Variance

3442

168.5

9

2026

103

103

24

230

Conclusion If these 230 samples are considered representative of radon concentrations in groundwater supplies as a whole, the contribution of radon from groundwater to indoor radon is a negligible health risk based on the UNSCEAR criteria.

Acknowledgement This work was partly funded by the NHMRC Public Health Small Grants Scheme.

Authors Dr Andrew Herczeg is a Research Scien tist and John Dighton is a Senior Technical Officer at the Centre for Groundwater Studies in CSIRO Land and Water, Private Bag 2, Glen Osmond SA 5064. Both authors work in several research areas concerning naturally occurring stable and radioactive isotopes in groundwater.

Table 2 Incidence of radon in groundwater in various States of Australia

Skewness

Skewness

n

D â&#x20AC;˘

exceed the drinking water guideline value of 100 Bq/L, but only four of those by more than a factor of 1.5.

These were all located in fractured rock aquifers and none are directly reticulated into public or private water supplies (Table 1). The incidence in the various States is summarised in Table 2.

Minimum Maximum No. of samples

WA

SA

VIC

NT

NSW

Qld

11.8 22.7 29.6

20.6 42.5 57.5

4.3 9.6 9.4

22.7 25.2 11.3

9.1 30.6 65.9

13 14.1 9.7

3.15 873 0.9 171 75

2.4 3301 1.3 334 97

1.5 88 2.5 28.9 11

1.1 128 11.8 47.3 11

2.8 4338 0.1 220 11

1.2 95 2.8 40.4 25

WATER MAY/JUNE 1998

37

m

WASTEWATER

ON-LINE PROCESS MONITORING OF NUTRIENTS IN BNR PLANTS I D McKelvie, G J Cross, T E Harris, B T Hart relatively large volumes of reagent and/or sample, and are capable of This paper describes a new on-line limited sample analysis rates. system for monitoring nutrients includFlow Injection Analysis (FIA), an ing phosphate, nitrate and ammonia in automated sample handling and analysis biological nutrient removal (BNR) technique w hich is readily applicable to plants. The system has been specifically process monitoring, has the capacity to developed for use in continuous pilot overcome most of these deficiencies plants, w here only very small volumes (see Figure 1). The inherent advantages of sample are available for analysis. The of FIA for process analysis include: strategies adopted for the frequent • rapid analysis times automated sampling and analysis of • minimal sample and reagent these small volumes, the instrument consumption design, and the control and communi- • the ability to condition samples, cation features are reported. Possible continuously clean manifolds and refuture application of the system to the condition sensors on-line analysis of other control para- • potential for multiple, simultaneous meters, for example volatile fatty acids, analyses is also discussed.

• ability to calibrate frequently, without removal of the sensing element or Introduction disturbance of the analysis manifold The on-line monitoring of waste- (unlike dip probes) wa ter treatment plants, particularly • relatively inexpensive instrumentawhere the information is to be used for tion costs enhanced process control, is not a trivial • easy miniaturisation and interfacing exercise. The current method for into SCADA and PLC systems. monitoring biological nutrient removal Instruments based on FIA have been plants typically involves taking grab used increasingly for bioprocess and samples and analysing these in a labora- water quality monitoring (Andrew et al., 1994; Forman 'Despite its demonstrated advantages as a et al., 1991). process monitoring tool, there has been Pedersen et al., (1990) showed that limited application of FIA in wastewater the use of FIA in wastewater process process monitoring' monitoring led to tory for nutrients such as phosphate, enhanced process control with an nitrate and ammonia. The rather small accompanying improvement in nitroamount of information that can be gen and phosphorus removal efficiency.

D espite its demonstrated advantages achieved in this way limits the understanding of the microbial processes as a process monitoring tool, there involved in BNR processes, and conse- has been limited application of FIA quently makes the improved process in wastewater process monitoring (Pedersen et al., 1990; Benson et al., control of such plants difficult.

More information could be achieved 1996a). This can be attributed to sceptiwith automated on- line analysers. The cism regarding the ability of such continuous monitoring of parameters systems to handle samples with high such as dissolved oxygen, pH and Eh is suspended solids concentrations, and relatively common, although this type the potential for problems such as of monitoring requires regular off-line the formation of biofilms on sensor calibration to minimise instrument drift This paper is an updated version caused by biofilm formation (or poisonof the paper On -lin e Process ing) of the sensor surface.

Monitoring of Nutrients in BNR A number of automated batch and Treatment Plants published by continuous flow analysers that p ermit AWWA in the BNR3 Conference either continuous or frequent on-line Proceedings, Brisbane, 1997. analysis are now commercially available.

However, most of these systems use

Abstract

38

WATER MAY/JUNE 1998

surfaces, blockage of the small bore tubes used for reagent and sample transport, bubble entrapment in photometer flow cells, detector drift, limited linear range, and a general lack of reliability.

This paper describes how the Water Studies Centre at Monash University has addressed many of these issues in developing and deploying an Aut9mated Flow Inj ection Monitoring System (AFIMS) for nutrient analysis in a continuous BNR pilot plant.

Monitoring System Architecture The monitoring system architecture consists of three main components: a sample pretreatment unit, one or more analysis units located at the plant, and a host computer situated in a control room which supervises the pretreatment and analysis units over a remote RS-485 network (see Figure 2). The host computer also has an Internet connection, allowing the system to be controlled, configured and monitored from remote locations.

Each analysis module is 'stand alone' and comprises a reagent pump, injection valve, reagent selection valves and a pump priming switch, as well as an LCD display that provides the operator with status messages, analyte concentration values and error diagn~ tics. In a similar manner, the sample pretreatment module has front panel mountings for supply and feed pumps, a small cross- flow membrane filter and an LCD display.

The sample pretreatment module and each of the analysis modules is based on a generic design, using an embedded 68HC11 microcontroller board and a custom- designed interface board with a range of 12-bit A/ D , D /A, relay controls and digital inputs.

Each analysis module has its own detector board coupled to the interface board, the detector type being dictated by the chemistry used in the analysis module. For example, a spectrophotometric detector board is used for the reactive phosphorus analyser, while one option for the analysis of nitrate uses an ion-selective electrode with a potentiometric detector board.

WASTEWATER

Calibration standards

Switching valve

Pump

Sample conditioning Reagents ---11-----+----;

Reaction manifold

Detector

Waste

FIA computer

Local output Remote output

Figure 1 Conceptual flow inj ection analysis system for wastewater process monitoring (adapted from Andrew et al., 1994)

that the analyser could handle the high solids concentrations of the wastewaters (ca. 8,000-10,000 mg/L), the very small volumes of liquid (preferably <30 mL/ hr) that could be taken from the plant, and the potential for biofilm formation in the flow injection system.

The automated dilution-filtrati on system is shown in Figure 3.

Automated dilution of samples was possible because the analytical detection limits achi evable using solid state p hotometric detectors are typically 50-100 times lower than the typical concentrations of nutrients encountered in wastewaters. Therefore, we have used dilution facto rs of ca. 25-100 to minimise difficulties associated with biofouling and suspended solids cake formation on the cross-flow filtration devices used (Vigneswaran e t al., 1989).

Ana lysis modules Module 1 Sample pretreatment module

Sewage sample Dilutor unit

Module 2

Module n

Host computer

Internet connection

Figure 2 Total sampling and ana lysis system

System Design Considerations: Sample Pretreatment Common objections to the application of FIA in on-line analysis have been the potential blockage of the narrow-bore manifold tubing used , damage to injection valves by particulate material in the sample, and deposition of biofilms that can coat a range of surfaces resulting in impaired performance of optical or electrochemical detection devices. These problems can be particularly severe with wastewater samples, which are generally characterised by high co ncentrati ons of suspended solids and contain large numbers of microorganisms.

However, if the wastewater samples are suitably pretreated (e.g. by filtration), small volumes of particle- free samples can be readily analysed by an FIA system. Further, between analysis cycles the detectors can be calibrated and reconditioned if n ecessary, and the

system can be thoroughly rinsed. In this way, the analysis is essentially performed in a chemically controlled environment, unlike that w hich prevails wh en dip- type devices (e.g. DO probes) are employed . Additionally, the use of narrow- bore manifold tubing enables rapid sample throughput and ensures that the reage n t and wash solution requirem ents are minimal. H ence, the miniature characteri stics of the FIA system are advantageous, rather than a handicap , in on-line monitoring applications.

The particular situation which stimulated the development of the online instrument reported here was the requirement fo r frequent analysis of nu trients in a small continuous BNR pilot plant operated by Sydney Water Corporation. A new sample pretreatme nt system , which involves both automated dilution and prefiltration through a 0.2 m filter, was developed so

Detectors and Detection Chemistries The major considerations in selecting a detection system are reliability, relatively fast sample throughput, a proven detection chemistry, low toxicity of reagents and by-products, and ease of conversion to a flow injection method.

Phosphate and Ammonia From the wide range of potentiometric (Katsu et al., 1992), amperometric (Harden et al. , 1984; Hinkamp et al. , 1990) or enzymatic (Yao et al., 1990) methods that have been published for the d ete rmination of phosphate, we have elected to use a conventional photometric method , based on th e formation of phospho-molybde num blue (McKelvie et al., 1995). A simple solid state detector, using a referenced red light emitting diode (LED) w ith max at ca. 650 nm, and a photodiode with a log amplifier (D asgupta et al. , 1993) is used. This detector has-a linear, rather than Z-shaped flow cell configuration, and despite a short optical path length of ca. 1 mm, has a detection limit of approximately 5 g P/L. T his configuration is favoured because it shows little tendency to e ntrap gas bubbles.

Ammonia has been determined using a similar photometric d etection system .

Nitrate A conventional nitrate electrode in a wall-j et configured flow cell was initially used for nitrate detection. This configuration has been shown to be successful for analysis of nitrate in low chloride environments. However, in dilu ted wastewaters we found the relatively high chloride con centrations interfered with the nitrate electrode.

This finding required that we shift across to the standard cadmium reduction method, with a similar sp ectrophotometric detector to the one described WATER MAY/JUNE 1998

39

WASTEWATER above, but using a green LED with max at ca. 565 nm.

T his combination of a robust detection chemistry with a sensitive low- cost detector, a preconditioned sample and a high rate of sample t hroughput has meant that FIA can be successfully used for on-line analysis. T he concerns over sample handling (particususpended larly high solid concentrations) and small volumes o f sam ple have been satisfactorily addressed.

suite on the Linux operating system.

T he control daemon initiates a sample pretreatment cycle, followed by the analyses, at regular. intervals (typically every five minutes). After the analyses are complete, the concentration data is retrieved, archived, charted and fed via a TCP/IP interface to the WIZCON Fill valve Potable water

Reagent Stablllty and Consumption

I

operator should a problem occur in any of the analysis modules, e.g. malfunctioning injection valve.

The AFIMS software allows the user to control the system w hile displaying a strip chart of concentration profiles versus time and a status log of calibration times, concentration values and any error events. An HTML- based on- li ne help system with information such as an extensive user guide, trouble- shooting c harts, maintenance details and materials safety informa ti on is incorporated in the softwa re.

A key specifica tion in Level Future Directions the system design was a sensor T he modular design of low de mand fo r system the on- line instru men t mainte nance, including ma kes it possible ¡t o t he re placement of Overflow 'add on ' other analysis reagents, wh ere the limitmodules. Other modules ing factor is the stability of t hat could be added to t he reagent over an the system, but are no t extended period of time.

Waste needed fo r th e reported An examination of reagent Analysis application to the BNR stabilities quoted in some Cross flow module pilot plant, are those for of the standard analytical filtration total ph osphorus and total methods suggests that the \ -....1....-a~ Waste nitrogen, both of which reage n t life times in th e published literature are Figure 3 Automat ed dilution-f iltration system used with FIA systems to would incorporate an on- line digestio n step typically very con servative. det ermine soluble phosphate , nitrate and ammonia (Benson et al., 1994). T he For exa mple, the storage of tin (II) chloride in the phospho- PLC program that controls the pilot next module we expect to add to the system is one for t he monitoring of molybdenum blue method is cited as plant.

A Java applet has been written to volatile fatty acids (VFAs) . seven days, w hereas fi eld trials by Be nson e t al. demonstrated stable contro l th e daemon via any J avastorage over three weeks, even whe n com plian t web browse r, such as Acknowledgements stored at 300° C (Benson et al. , 19966). N etscape Navigator o r Sun's H otJava.

T his p roject is funded by a Generic Each of th e detec ti o n systems T he applet allows the user to check the Industrial Research and Development selected has been tested to ensure that status o f the analyser sys te m , run grant from the Commonwealth Departall reagents are stable fo r a minimu m of di agnostics o n the various components, ment o f Industry, Scie nce and T echseven days . Additio nally, analytical start/stop the analysis cycle, and view a nology. We gratefully acknowledge methods that have minimal consump- strip chart of the parameter concentra- assista nce from our project partners at tion of reagents have been selected tions. By making t he client a Java the University of Q ueensland, Sydney w here possible. By carefully selecting apple t, the control software has the Water C o rporation and the NSW the m ost approp riate methods we have advantages o f platform indep endence D epartment of La nd and Wa ter been able to develop an on-line system and ease of use from remote locations.

Conservation. that only requires operator maintenance User Frlendllness on a weekly basis. O ther fac tors, su ch as References the use of potable water as the diluent The primary opposition o f plant (which is feasible because o f the consid- operators to automated analysers, based Andrew K N, Blundell N J, Price D, Worsfold P J (1994). Flow Injection e rable di fferen ces in co ncentration on expen sive failu res in the past, are Techniques for Water Monitoring, Anal. between potable and wastewater nutri- twofold: a lack of robustness, and Chem, 66, 916A-922A. ent co ncentratio ns) h ave also bee n un friendly user in te rfaces. Conse- Benson R L, McKelvie I D, Hart B T, exploited. que ntly both hardware and software Hamilton I C (1994). Determination of Total Phosphorus in W aters and have been designed with an emphasis User Interface and Software Wastewaters by On -line Microwaveon robust, longer unattended operation induced Digestion and Flow Injection T he sample pretreatment unit and by a non-chemist. Full diagnostic and Analysis. A nal. Chim. A cta., 291 , each analyser has an emb edded error reporting capabilities are used 233-2 40. controller running software that handles in conjunction with well p roven the operatio n of each module as well as chemistries to achieve reliable perfor- Benson R L, Truong Y B, McKelvie I D, Hart B T, Bryant G, Hilkmann W m odule diagnostic functions. Each of man ce. System safeguards include (1996a) . Moni toring of Dissolved these modul es is linked via an RS-485 packet checksums fo r verification of Reactive Phosphorus in Wastewaters by network to a host compu ter that super- network traffic integrity, reagent-level Flow Injection Analysis. Part 2. On-line vises and coordinates the op eration of sensors, on- board voltage monitors and Monitoring System. Water Res.. , 30, the modules. The computer is a temperature probes that gu ard against 1965-1971. standard Pentium-class P C running a overheating. In- built diagnostics pro- Benson R L, Truong YB, McKelvie I D and Hart B T (1996b). Monitoring of custom-designed Python/C software vide intelligent information to the plant 40

WATER MAY/ JUNE 1998

WASTEWATER (1995). T ech niques for the QuantifiDissolved Reactive Phosphorus in Wastewaters by Flow lnjection Analysis. cation and Speciation of Phosphorus Part 1. Method D evelopment and in Natural Waters. Anal. Proc., 32, Validation. Water Res., 30, 1959-1964.

437-445.

Dasgupta PK, Bellamy HS , Liu H , Lopez] Pedersen K M, Kummel M and s-eberg H L, Loree E L, Morris K, Petersen K, Mir, (1990). Monitoring and Control of KA (1993) . Light Emitting D iode Based Biological R emoval of P hosphorus and Flow-T hrough Optical Absorption Nitrogen by Flow Injection Analysers in a Detectors. Talanta., 40, 53-74.

Municipal Pilot-Scale Waste-Water Fom1an L W, Thomas B D, Jacobson F S Treatment Plant. Anal. Chim. A cta. , 238, (1991) . O n-line Monitoring and Control 191-199. of Fermentation Processes by Flow- Vigneswaran S, Ben A.in R (Ed.) (1989).

Injection Analysis. Ai1al. Chim . Acta., Water, Wastewater and Sludge Filt1~1tion.

249, 101-11 2.

C R C Press, Inc., Boca Raton, Flotida.

H arden S M , Nonidez W K (1984). Worsfold P J , Clinch JR, Casey, H (1987).

Determination of Orthophosphate by Spectrophotometric Field M onitor for Flow Injection Analysis with AmperoWater Quality Parameters. The Determetric Detection. Anal. Chem., 56, 1nination of Phosphate. Anal. Chim.

2218-2223.

Acta. , 197, 43- 50.

Hart B T , McKelvie I D and Benson R L Yao T, Kobayashi N , Wasa T (1990).

(1993). R eal-time Instrumentation for Amperometric Flow- inj ection System Monitoring Water Q uality: an Australian with an Immobilized Enzyme Reactor for Perspective. Trends Anal. Chem. , 12, the Highly Selective Detection of 403-412.

Phosphate and On-line Ampli fication by Hinkamp S and Schwede G (1990).

Substrate Recycling. Anal. Chim . A cta., Determination of T otal Phosphorus in 238 , 339-43.

Waters with Amperomettic Detection by Coupling of Flow-Injection Analysis with Continuo us Microwave Oven Authors Digestion. Anal. Chim. A cta., 236 , The authors all work at the Water 345- 351.

Stud ies Centre and C hemistry DepartKatsu T and Kayamoto T (1992). ment, M onash U niversity, Caulfield Potentiometric Determina tion of InCampus, PO Box 197, Caulfield East organic Phosphate Using a SalicylateVIC 3145. Dr Ian McKelvie is a Senior sensitive Membrane E lectrode and an Alkaline Phosphatase Enzyme. A nal. Lecturer in chemistry and leads the . Flow Injection Resea rch Group. Dr Chim. Acta. , 265 , 1-4.

McKelvie I D , Peat D M W, Worsfold P J Graeme Cross is a R esearch Fellow

who has had a leading role in the design of th e hardware and software of the systems described. Tom Harris is an electronic e ngineer with extensive experience in the design and manufacture of water quality instrumentation.

Professor Barry Hart is Professor of Environmental Chemistry and D irector of the Water Studies Centre.

Worldwide Web of Water Following are a number of useful internet addresses relati ng to water which members are invited to visit: • http://www.awwa.asa.au (Australian Wate r and Wastewater Association) • http://www.aW\va.org (Ame ri can Water Works Association) • http://WW\v.iawq.org.uk (International Association o f Water Q uality • h ttp ://www.iawq.org.uk/li nks. htm (the IAWQ guide to the best water sites on the web) • http://www.wef.org (Water Environment Federation) • h ttp://in ternet.0°CU .comr dalden/ index.

• h tml (P ubli c H ealth Inspector H ome Page by D onna Alden)

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41

ENVIRONMENT research, development and p otential applications of the modified clay and related materials.

Research

Summary T he sediment remediation project at CSIRO Division of Land and Water in Western Australia is addressing the biologically available phosphorus stored in sedime nts-one of the most common problems in controlling algal blooms in Australia's waterways. The project has evaluated a range of existing and novel sediment remediation technologies for both their short- and medium- term effectiven ess in reducing nutrient availability.

Various types of clay minerals can be modified to create and/or increase their capacity for ad sorbing or binding phosphorus. It is envisaged that these modified natural materials could be 42

WATER M AY/JUNE 1998

placed in a variety of aquatic environments where they adsorb phospho rus from both bottom sedime nts and/or from the water column.

Labo ratory tests showed that a modified clay was able to reduce the con centration of phosphorus dissolved in water by more than 90% under a range of salinities. Application of the same material to sediment cores from the Swan Rive r also demonstrated a similar phosphorus reduction over a period of seven days. A major field trial of a modified clay in Lake Monger, Western Australia has demonstrated a reduction of p hosphorus over one month.

Provisional patents broadly cover the

Release of phosphoru s stored in sediments h as often nullified efforts to control the P concentration in the water column, thereby exerting some control on algal blooms.

At the start of the sedimen t remediation project a literature review of a range of existing and novel sediment remediation techniques was conducted (Douglas and Coad, 1996). The review included an evaluation of both physical (e.g. aeration, dredging) and chemical (e.g. alum, red mud) techniqu es and/or materials in terms of their potential or documented effectiveness in reducing nutrient (P and/or N ) availability in aquatic environments.

It became apparen t that no single techniqu e was universally applicable to effectively reduce loadings of P and/or N in the wide range of physico-chemical conditions commonly en countered in aquatic environments. In particular, there was a paucity of tools available to counter in ternal loadings in aquatic environmen ts such as the Swan River estuary as a consequen ce of nutrient regeneration processes from bottom sedimen ts (Douglas et al. , 1996, 1997b). T he flu x of these nutrients may also be enhanced by local grou ndwater ÂŁlow from bottom sediments (Linderfelt et al. , 1997; Turner et al. , 1996).

A two-year series of laboratory and field trials o f sediment remed iation m aterials was conducted to ide n tify materials that may have the potential to reduce the con centration of available nu trients in aquatic system s (D ouglas et al. , 1997a). Specifically, the nutrient binding properties of 14 ~aterials or derivatives identified in a review of potential sediment remediation materials were evaluated . R esults from the batch-test experimen ts suggest that derivatives of a natu ral clay had a capacity to significantly redu ce the concentration of PO4-P in solu tion over a range o f salini ties. H oweve r, few materials had , on the basis of the batchtest exp erimen ts, a demonstrated capacity to adsorb significant N H 3-N from solution.

Further investigatio n of the most promising sediment remediation material involved a rigorous assessmen t of p hysico-chemical properties . The modified clays were tested u nder a wide range of simulated environmental conditions using small-scale batch tests to determine their robu stness in the adsorption of phosphorus in response to variation of a combination of environ-

ENVIRONMENT mental factors (pH, salinity, dissolved organic carbon and dissolved oxygen).

Further trials were conducted in a variety of aquatic environments in the Swan River, both on sediment cores in the laboratory and in large tanks or 'mesocosms' in a major field trial in the upper estuary. Results from core experiments indicate dissolved P could be reduced over one to th ree weeks, while results from the mesocosm trial indicate that dissolved P could be reduced over three days.

In late 1997 and early 1998 , a major 3-6 month trial of the modified clay was begun, using two ca. 5 m diameter macrocosms (see picture) . The trials are being undertaken in Lake Monger, a large suburban lake in Pe rth which exp eriences persistent algal blooms over the spring/summer months. So far, we have achieved a reduction of dissolved phosphorus of over 90% in the experimental mesocosm (modified clay added) compared to the co n trol mesocosm (untreated) over approximately one month of the trial.

The technique has p otential to be a valuable addition to the armoury of algal control methods, and national and international paten ts (in partnership with the Water and Rivers Commission/Swan River Trust) have been applied for.

Positioning control and experimental mesocosms In Lake Monger

Groundwaters and Saline Surface Water in a Seasonal Estuary: The Swan River System. Progress report prepared for the Western Australian Estuarine Research Foundation. CSIRO Land and Water.

Turner J V, Linderfelt W , Townley L R, (1996). Interaction Between Shallow Groundwaters and Saline Surface Water in a Seasonal Estuary. In Hamilton D P (Ed.). An Integrated Ecological Model of Catchment H ydrology and Water

References Douglas GB, Hamilton DP, Gerritse R G, Adeney J A, (1996). An Investigation of Water Q uality at Two Sites in the Swan River Estuary, 1993/4. CSIRO Division of Water Resources Report (96-2).

Douglas GB, Coad D N, (1996). R eview of Estuarine Sediment R emediation Techniques.

Confidential Report prepared for Water and Rivers Commission. CSIRO Division ofWater R esources R eport (96-11). R evised October 1997.

Douglas G B, Coad, D N , Adeney J A, (1997a) . Sediment R emediation Project: Laboratory and Field Trials. Confidential report prepared for Water and Rivers Commission. CSIRO Land and Water Report (97-58).

Douglas GB, Hamilton D P, Gerritse R G, Adeney J A , Coad D N (1997b).

Sediment Geochemistry, Nutrient Fluxes and Water Quality in the Swan River Estuary, W estern Australia. In Davis, J R (Ed.), Managing Algal Blooms, Outcomes from CS IRO's Multi-Divisional Blue-Green Algal Program, pp. 15-30.

Douglas G B, Coad D N (1998). Sediment Nutrient Fluxes and Ox")'gen Demand in the Swan River Estuary, W estern Australia. Confidential report for Water and Rivers Commission. CSIRO Land and Water R eport (in prep .).

Linderfelt W G, Turner JV, Townely LR, Bartle GA, Watson GD , Woodbury RJ (1997). Interaction Between Shallow

Quality for the Swan and Canning Rivers, pp. 28-35.

Authors Dr Grant Dougl~s. Senio r Research Scientist, Dean Coad , Experimental Scientist and John Adeney , Senior Experimental Scientist are based at CSIRO Land and Water, Floreat Western Australia, Private Bag, PO Floreat WA 6014, fax (08) 9387 821 1.

SPECIALISING IN ENVIRONMENTAL SERVICES ..,._ Environmental Audit/Site Investigations ..,._ Contamination Assessment & Remediation ..,._ Environmental Risk Assessment ..,._ Hazardous/Industrial Waste Management ..,._ Solid Waste Management ..,._ Information Management ..,._ Environmental Impact Statements ..,._ Environmental Management Planning & System Development

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B

BUSINESS

PRIVATISATION-WHO DECIDES? R Loo, C Porter During a session on corporati sation and privatisation at the AWWA Sydney convention two years ago two questions were asked: Why should our communities give up ownership of their essential services? and What benefits would flow to our communities?

There was a deafening silence. Not one of the eminent people o n th e panel assembled to describe the virtues of change was prepared to stand up and say the community would be nefit from lower charges, lower taxes or better service. Not one was even prepared to say there was a chance the com m unity would benefi t.

T he priva ti sa ti o n heavies we re m obilised aga in at th e AWW A M elbo urne convention last year and from what they were saying, we are sure to be priva tised and globalised w ithin five years. But who is behi nd these pushes? W e susp ect eco nomists, politicians and lawyers. And why? For whose benefi t?

The authors are sure there are savings and profits to be made, since Australia's wate r age ncies are very 'liquid' and profitable monopolies with good cash flows and positive growth prospects.

However, we are concerned th at ou r communities won't get a fair proportion of the savings.

Whose Interests?

In our practice, if we have a reco mmendation to make to change the d irection of a compan y or its activities, we need to convince th e company executives that the change w ill be fo r the benefi t of the company and its shareholde rs. H ow then does the water industry proceed down the privatisation path wi thout anyone being prepared to state that it will benefit the conununity, the shareholders and the owners of th e existing assets?

If the co mmuni ty won't be nefit, then are the democratic processes of this wo rld being misu sed to assist th e greedy? T he autho rs must admit to possession o f only marginal respect for the economists and lawyers of this world. Economists, and others of that ilk, appear to be con ti nuously getting it wrong, yet their revised predictions are reported ad infinitum in the daily media.

It would help if the media had more of a collective memory on expert advice. When an expert regularly gets 44

WATER MAY/ JUNE 1998

their forecas t wrong it might help if the press stopped calling them an expert and in fac t stopped publishing their fo recasts altogether.

The current globalisation of operating and main tenance functions is, we are sure, the work oflawyers, politicians and economists. In our view this serves little p urpo se other than to move community monies into private coffers.

Lawyers appear to see great advantages for themselves in locating BOOT or operating schemes as far away as possible from their homeland. Do they see a bright future in unravelling the international legalities in due course?

We cannot see that any scientific pe rson would se ri ou sly entertain the proposition that the French or English are better managers or opera tors of our fac ilities. The scientific co mmuni ty in Australia tries to understand and overcome our problems. In o rder to better understand our problems we like to conununicate and discuss our experiences wi th people from all parts of th e world and vice versa. Such co mmuni cation assists us all to adva nce.

H oweve r, very few of us would be silly enough to put ou r hand up and say chat we know more about problems in Germany, for exa mpl e, or that we can operate their systems more efficien tly.

T hat is a nonsense. U nless you live and practise in a cou ntry for qui te a few years you can not fu lly appreciate the diffi cu lti es o f another climate and culture.

This globalisation of operatio ns is purely a device, in our view, for the very ri ch to rip some more off gullible govern ments and communities.

Engineers Outnumbered We have in this cou ntry a disproportionate number of lav,ryers and accountants or econo mists compared to engineers.

For each engineer in Sweden the re are only 0.1 5 lawyers and accountants and in J apan only 0.02. H owever, we in Australia are blessed with 1.5 lawyers and accountants per engineer. Is it any wonder that most of us are dictated to and controlled and directed by financial theory rather than co m mon sense?

Why sho uld any enginee r even contemplate suggesting a no n- proven solu tion to a problem with the everpresent threat of 'the lawyers' hanging over our heads? What and w here are the

rewards for aiming at improvements to ou r current knowledge base?

Negligence or Legitimate Risk?

Almost all engineering and scie ntific advan ces are und erpin ned by ' riskbased' decision-making, yet our legal system does not appear to be capable of recognising this fact. Risk should no t be conside red as, o r related to, negligence.

As engineers, we are confro nted by just as many, if not more, complex pro blem s than the bean- countii1g professions. U sually we are able to come up w ith solutions that are acceptable for at least 10-30 years until further research advances our knowledge and ofte n a better way for the future is identified.

W e have managed to send m en to th e moon and spaceships to Mars, increased the life expectancy of the maj ority of people on Ea rth , and ass isted the health professionals to devise ways of overcomi ng health problem s and even body part failures. Sure, we have made mistakes, but we are conti nuo u sly learning and advancing and trying to contribute to the advan cem ent of fu ture ge neratio ns.

Lawye rs, economists and accountants survive and multiply by co mplicating our laws, lives, businesses and governments so that we mu st make use of the ir services. Yet for some unfa th oma ble reason our communities continue to dance to their tunes.

The Long View Economists seem to be forcing the view that engin eers can only commit fu nds for work that ca n be shown to stand up to cost-benefit analysis.

Whilst this is a reasonable objective, what seems to be unreasonable is that, for the sake of expediency and simplification, we are often told to ignore areas of benefi t that we perceive to exist but wh ich are very difficult to quantify.

Long- term cost-bene fi t item s or more wide-ranging co nsiderati ons are not considered or are dismissed by manageme nt as ' political matters of no concern to engineers.'

Again, in theory this may be correct, bu t since politicia ns and some of our new high-flying contracted executives appear to have o nly a fo ur-year memory span, if we don't raise and consider these aspects, w ho will?

We are failing in ou r professional

BUSINESS duty if we do not raise our concerns for the community to consider. We must not let our concerns be obliterated from project considerations by economists who can see SSS savings if certain projects can be delayed or curtailed provided the long-term aspects can be removed from any debate.

Similarly, politicians in power have no desire to enter a debate on long-term considerations if it is going to benefit a future government and muddy the budget they have devised to ensure their own re-election.

BOOT Schemes We have always had niggling doubts about the logic and sense of BOOT schemes where private industry takes over control or provides basic essential community needs for a set number of years. From the government economists' point of view, as long as the contract states that the facilities handed over at the end of the contract period must be in good condition, then based on this premise if the benefit/cost ratio works out positive, they are happy to let the BOOT happen.

Based on the assumption that bean counters will remain in charge of our destinies for the next 15 years, how will the BOOT scheme operator's accountantjustify expenditure during the latter

years of the contract to maintain the facility in a serviceable condition?

Every decision to refurbish or renew is almost certain to have a detrimental effect on the BOOT company's bottom line. Will they have the courage to stand up and tell the shareholders that this expenditure is part of the BOOT contract conditions and that it must be made even though it means their company may lose money for the next five to seven years and not pay a dividend?

Today's Executives and 'Performance Indicators' Most of today's executives have performance-based contracts that measure their performance by a series of indicators.

These indicators assume a greater importance than reality. It's not what you see that's important-it's the indicators. After all, paper indicators waste less time, don't argue, don't question and are an excellent means of proving what a good job you arc doing.

Our problem with this is that we suspect some of our community's assets, facilities and expertise are currently being run down intentionally to make the indicators look ve1y favourable.

With no job security these days, the manager or executive will have moved

on long before this action is ever exposed, with another even more lucrative contract tucked under their arm.

Reality Check As a nation, we seem to be substituting appearance for reality. Anyone who dares to challenge official policy and the dubious economics on which it is based can be assured of a spirited counter attack. With the steady loss of job security, experienced and competent public servants are afraid to speak.

And the lawyers wait, like vultures, to pounce on any engineering initiative that does not succeed, even though they are the profession least competent to decide what is a reasonable risk. The economists, politicians and lawyers have taken over from the practising scientists and engineers in the water and wastewater industries as they havC elsewhere. As a result, the public is fed only half truths. Perhaps George Orwell's Nineteen Eighty-Four wasn't so far off the mark after all!

Authors Rein Loo is a principal of Rein Loo and Associates, Consulting Engineers Water Management, Perth, WA. Colin Porter is former Director of the Victorian and WA Environment Protection Authorities.

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BUSINESS

WHO WILL TRAIN OUR FUTURE

WATER ENGINEERS? L Reeder The reform of the public sector and the new role of the private sector in providing services that in the past were the province of government are b ringing about fu ndamental changes in the delivery of engineering services.

Recent reforms in workplace structu re inclu de downsizing of large government organisations, privatisation and co n tracting out. Overlaying all these changes is the implementation of competition policy.

In the past engineers gained the industry experience t hat took them from academically qualified to experienced practitioners in large government utilities and departments. To date there has been almost no research into how these changes will impact on fu tu re training opportµnit ies for engineers and what industry training will be required.

Whilst there are efficiency gains to be made from the workplace c hanges, there are also factors which need to be monitored if we are to minimise the disadvantages and maximise the advantages of the reforms.

There are already issues being raised in relation to the impact of contracting out and downsizing on adequate levels

April to examine the impact of the changes in the water and electricity sectors and the road authorities. The workshop comprised representatives of government, the private sector, unio ns and academia from the three sectors and aimed to gain a clearer perspective from each of the sectors w ith a view to identifying future policy responses.

Questions addressed included: • what are the structural changes in the workforce which have occurred in the last ten years?

• how are th ese impacting on t he training opportunities for engineers and technologists?

• will industry train to the exten t the public sector has in the past?

• if not, what are the forecasts for sho rtfalls in training?

• will companies of all sizes undertake training, or will it fail to the larger companies who have the financial and human resources to put into training?

• will work done under contracts provide training opportunities?

• w hat are the barriers to SMEs providing on-the-job training?

Selected industry represen tatives gave a paper of five to ten minutes providing information on 'In the past engineers gained the the changes in their particular sector and identifying industry experience that took the impact of structural them from academically qualified· workplace changes on training. These papers included to experienced practitioners in figures on what percentages large government utilities and of work in particular sectors is now being done on either departments' a contract basis or within privatised or corporatised of technical expertise within organisa- utilities. They also identified the tions. In some circumstances the changes to the employment of recent contracting process can favour large graduates.

T here was discussio n about the firms over smaller ones, thereby eroding the opportunities for the local compa- followi ng issues: nies and decreasing competition.

• identification of the changes in the How responsive the private sector workplace which have impacted on will be in undertaking training on an training opportunities fo r technology increased scale is still to be determined. into the future However, indications are that the re may • clarification of the implications for be problems. training opportunities for technology In order to investigate these issues into the future the Institution of Engineers in conj unc- • identification of a series of recomtion w ith the D epartment ofEducation, mendations to address issues raised Employment, Training and Youth • the most appropriate ways of achievAffairs held a one- day workshop m ing recommendations, including the 46

WATER MAY/ JUNE 1998

identification of ways in which the Department and industry could work cooperatively.

Whilst there is still debate amongst economists about the linkages between advances in knowledge and long- run growth, there is also an increasing recogni tion that national resources of skill and k nowledge are the m ost important assets in a modern economy.

In continuing the trends to privatisation, contracting out and downsizing of government services, there exists an assumption that the private sector will be providing Australia's future employment and training opportunities. In particular the Government seems to be pinning its hopes on small to medium sized enterprises (SMEs) as the generators of jobs in the fu ture. Currently the small business sector employs a total of 49% of the workforce.

A report of the Small B usiness Research Program w ithin the D epartm ent oflndustry, Science and Tourism found that the larger the firm the more it spent on training.

Only one in ten micro firms (firms of less than 5 people) and one in three firms employing 5-9 people undertake some formal training. In contrast, about 80 per cent of enterprises employing more than 100 people undertake some formal training of em ployees.

These results are perhaps riot surprising given that small- to medium-sized enterprises have difficulty in taking qualified workers offiine to provide training to new graduates. T his, of course, is not true of all SMEs, but overall the barriers to training for SMEs are considerable.

A recent evaluation of the training guarantee levy found that fi rms were reluctant to provide training opportunities for their employees in circumstances where there was no prospect of an employer seeing tangible short-term gains in profitability from an increased training effort, or where the short-term costs greatly exceeded the minimum expenditure requiremen t.

The Institution of Engineers' own membership figures highlight the massive switch that has occurred from the public to the private sector. In the past up to 70% of members were

BUSINESS employed in the public sector and around 30% in the private. Today these figures are all but reversed, with 27% in the public sector and 56% in the private sector.

Defining the barriers to the private sector undertaking training on an increased scale is one of the issues the workshop canvassed.

Training is by and large a long-term solution to fill employment opportunities as they occur. If training opportunities are not being provided to the extent they have in the past, forward planning to anticipate skills shortages should be carried out.

If we cannot determine where shortage will occur thFee to four years out, industry may become increasingly reliant on immigrant labour in the absence of skilled graduates. As one example, South Australia is about to offer a package: of incentives to skilled British workers to emigrate to fill the current shortfall in information technology and precision engineering skills places-overall 8,000 places by 2000.

Of course, these issues are not simply confined to the water industry. A recent discussion paper released by the Western Australian Chamber of Minerals and Energy included research results from a survey of its members.

With a response rate of 60%, the survey found that only 16% of respondents had employed new graduates in the past year, preferring instead yo ung professionals with at least 2-3 years experience.

It is assumed that the trend to contracting out will also continue to provide employment opportunities, and by and large it will. However, a recent report on the mining industry from the Wes tern Australian D ep artment of Training found that, with the industry trend toward the use of contractors, many companies are no longer taking on apprentices.

Recent evidence shows that contractors do not view the provision of training as their responsibility. Whilst industry assumed that the training component would also be picked up by the contractors, from the contractors' point of view the high competition and shortterm nature of mining contracts (1-2 years) made it difficult to take on longterm trainees (4-year apprenticeship indentures).

It was estimated that skilled contractors now comprise approximately onethird of the mining workforce. More investigation needs to be undertaken to identify similar trends in the water sector.

It is not only at the professional level that concerns are being raised. The Utilities ITAB has also released a

Commonalities Project report on a study w hich raised similar concerns to those already outlined. This report found that, 'In the past most utilities enterprises supported extensive training divisions which provided a range of generic, industry and enterprise specific training. Out sourcing of work reduces opportunities for water utilities employees to obtain on-the-job training and the experience/knowledge gained through job rotation. A consequence is that while employees are now expected to be more multi- skilled than ever before, they are not always being given the training nor acquiring the necessary experience.'

The report concluded, 'The evidence would suggest that a skills shortage will emerge in the near future if strategies are not identified and implemented to fill the training gap caused by the contracting out of services and the closing down of many in-house facilities.'

Currently Australia-wide industries are benefiting from 'ready made' consultants who were formerly senior officers in public sector organisations and utilities. Where similar technically qualified and exp erienced consultants will come from in the future is not clear.

In its report Engineering the Transition to Competitive Utilities the Institution of Engineers found evidence that many senior executives of industry associations and government departments are concerned about the future.

In public hearings Dr John Langford of the Australian Water Association warned, 'A lot of people are corning to me and asking where our skill base is coming from. I am worried about the generation of our skill base from here on, because in my view we've stopped training in the water industry and unless we start doing something about it reasonably soo n, we've got a big problem. But nobody wants to listen to problems you're going to have in five or ten years time.'

The changes which have occurred in recent times and that are still occurring are bringing fundamental changes to the nature of the workforce. It is important that the efficiency gains of these changes are not offset by poorly monitored implementation strategies for employment and training.

The private sector has forcefully argued that it should be given the chance to undertake work that in the past has been done by governments.

Having now been given opportunities to take the commercial advantages, it is vital that there is a recognition that much of this work also involved responsibilities. Employment and training opportunities are an integral part of that responsibility.

Equally, there will always be a role for government in addressing market failures, and adequate levels of training may well fall into the category of market failure.

More research is required to determine the extent to which contracting out and privatisation will result in adequate employment and training opportunities.

Policy solutions need to be developed to address any shortfall, not only for the individuals involved but for Australia's future as a whole.

We need to know what proportion of those employers w ho find it difficult to recruit appropriately skilled staff resort to training as a solution, since this would be one of the most important tests of industry's commitment to training reform.

This is an issue on which the Institution of Engineers is pleased to work with government to ensure that adequate training opportunities for engineers are provided into the future.

A final rep ort of the workshop outcomes will be available by the middle of the year.

Author Lynne Reeder is Associate Director (Public Policy), Institution of Engineers, Australia, 11 National Circuit, Barton ACT 2600 .

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WATER MAY/JUNE 1998

47.