Water Journal March - April 1995 by australianwater

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AUSTRALIAN WATER & WASTEWATER ASSOCIATION

Volume 22, No 1 March/April 1995 Editor E A (Bob) Swinton

Editorial Correspondence 4 Pleasant View Crescent Glen Waverley Vic 3150 Tel/Fax (03) 560 4752

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

inside front cove r

2 4

MY POINT OF VIEW Water Reform - Rearranging the Deckchairs?

John Pigram

FEATURES Water Markets and Trading Developments in Victoria

D Stringer

Increased Efficiency in the Water Industry?

G Watson

Testing an Effluent for Tainting of Fish - The Latrobe Valley Ocean Outfall

Editorial Board F R Bishop, Chairman B N Anden!On, G Cawston, M R Chapman P Draayers, W J Dulfer, GA Holder MMuntisov, P Nadebaum, JD Parker A J Prieatley, J Rissman

Branch Correspondents Aar -Alan Wade Tel (06) 207 2350 Fax (06) 248 3364

New South Wales - Mit.chell Laginestra Tel (02) 412 9974 Fax (02) 412 9876 Northern Territory - Ian Smith Tel (089) 82 7244 Fax (089) 41 0703 Tel (07) 835 '0222 Fax (07) 8326335

Stochastic Data Generation: Yield Assessment of Mt Bennet Dam, NT

South Australia - Phil Thomas Tel (08) 259 0244 Fax (08) 259 0228

Tasmania - Dao Norath

J Paiva

Tel,(002) 332 596 Fax (002) 347 559

A Norwegian Suspended-Carrier Biofilm Process

SM HJones

Victoria - Mike Muntisov Tel (03) 600 1100 Fax (03) 600 1300

Western Australia -Alan MaU8

Treatment of Primary Tank Skimmings in Perth K Catlee, M Domurad, G Munns

Tel (09) 420 2465 Fax (09) 420 3178

WATER {ISSN 0310-0367)

Ozwater 95 Supplement

insert

REPORTS IAWQ Budapest July 1994 IAWQ 4th International Conference on Wetland Systems

is published six times per year January, March, May, July, September, November by

Australian Water & Wastewater Inc ARBN 054 253 066 PO Box 388 Artarmon NSW 2064

Federal President Richard Marke

DEPARTMENTS 31

6 32 inside back cover

OUR COVER. Our photograph shows the filter gallery of the newly-commissioned Yan Yean Water Treatment Plant, north of Melbourne. This plant is the first BOO project in the water field in Australia, and was the culmination of a cooperative project. Design and construction was managed by Transfield Construction, which in turn sub-contracted design to CMPS&F Environmental. North West Water Australia is responsible for operation for the 25 year contract (see Water December 1993). Construction and commissioning was a 'fast track' job. Engineering design commenced in February 1993, and completed by November. In parallel, siteworks began in April, so that civil and structural works were completed by January 1994. Detail installation proceeded until plant commissioning started in June. A series of quality tests, with only minor glitches appearing, resulted in the contracted supply of treated water to Melbourne Water Corporation commencing in October 1994.

Photo courtuy ofNorth Wut WatM-Auatralia.

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

Queensland - ~dsay Chapple

P R L Mosse, J Kowarsky

Industry News International Affiliates Products Meetings

Advertising Sales & Administration Margaret Bat.ea

Executive Director Cb.rill Davis 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 classified advertisements are included as an informational services 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,copy right and should not be reproduced wholly or in part without the written permission of the Editor.

Subscriptions Water is sent to all members of the AWWA as one of the privileges of membership. Non members can obtain Water on subscription at an annual subscription rate of $35 (surface mail).

MANAGEMENT

WATER MARKETS AND TRADING DEVELOPMENTS IN VICTORIA D Stringer* Abstract There is a major potential for 'finding' new water for high value use without building financially and environmentally costly new dams. This is by re-allocation, not by bureaucratic edict, but by the use of market mechanisms. However, this is by no means a simple matter. None-theless there is little doubt that such trade will, in the future, be relevant not just to the irrigation sector but to urban agencies, particularly for rapidly developing areas. This paper outlines the problems and the prospects as seen from the Victorian point of view.

Tradeable Water Rights? There has been plenty of press recently about water trading in rural areas. This is as a result of two things, the first being the current drought conditions, which are, (or have been), severe, particularly in New So ut h Wales and Queensland. This very unfortunate, but predictable, condition has focussed attention on the fact that Victorian irrigators have access to high security water and relatively plentiful supplies. The second is that there has been a lot of talk (but very little action) in the interstate arena about interstate water trading. Views expressed in recent te levision programmes have indicated, more or less directly, that the "red tape" attitudes in Victoria are all that stands between the salvation of farmers in other States (read access to Victorian water) and ruination. What is the reality? It is helpful to examine this issue in a structured context. Hopefully then the lessons of history become clear and a much more rational system can be developed. The developm,ent of water markets is a significant component of the Victorian Government's current water refo1.,n program. Indeed, it is likely to be far more fundamenta l and enduring than some of the ins titutional arrangements around the nation. Using market mechanisms to allocate water is preferab le to employing the more traditional "command and control" approach, und er which so me "wise" bureaucrat(s) usually decided amongst WATER MARCH/APRIL 1995

competing uses for new, free water. Perhaps more importantly in an era where there is practically no public finance, no scope to divert more water directly from rivers and limited environmental scope to build expensive new dams, a water market provides a means of "finding" water for high value use s without incurring the financial and environmental costs of new infrastructure. That is, the market is a way of reallocating water we already harness. Reallocation is one of the major challenges for water resource management in a mature phase. The water industry has very strong natural monopoly characteristics, so creating a market in water is a means of introducing competition into the industry. A market should help to stimulate the water industry to achieve best international practices in an increasingly competitive world. Thu s the potential benefits are substantial. An old saying goes: "water move s downhill and towards money". In theory, creating a market in water should be a relatively easy matter of removing any restrictions on trade. In practice there are some quite substantial issues to be resolved. Unless it is in bottles, water is a somewhat elusive commodity. Security of supply is subject to the vagaries of the weather. The timing of delivery along rivers, pipelines and channe ls often depends on the behaviour of other users. There are important environmental matters to be addressed before commercial imperatives are given a freer rein. Irrigation water makes up 80% of consumptive use in Victoria. After six years of very cautious moves, a limited irrigation water market does now ex ist. However there are sub stantial constraints and the market does not extend to urban supply where growth is pushing demand. There is little doubt that trade will be increasingly important for urban agencies, and particularly for rapid ly urbanising areas.

irrigation water entitlements were originally allocated by formula and thereafter locked to particu lar parcels of land. Water rights are the basic entitlement in public irrigation systems. They are paid for whether used or not. In addition water is available each year as "sales", and as a percentage of water right. Sales water is paid for only if used. Temporary transfers of water rights have been allowed since 1988, and permanent transfers since 1991, after years of debate about third party effects. This broke the traditional rigid nexus between land and water. Last year temporary trade amounted to 44,000 ML or about 2.5% of the total of 2 million ML 'in the State. Part of this represents people putting their toe in the water, waiting for the permanent market to became better established. In some cases, farmers use the temporary market while they are developing their farms, planning to buy permanent entitlements later. In other cases, temporary transfers simply cater for uncertainty. Unused water rights are often offered for temporary transfer at a price below cost - which provides a cheap alternative to "sales". Permanent trade in 1994 amounted to a little less than 6,000 ML, that is a third of one percent. While this level of trade is low, in that year water resowÂˇces in the South were virtually unlimited. Demand was low as it was a wet year with substantial early season flooding. A fairer test of the significance of the existing market is more likely to occur when resources are tight, demand is high and people are more aware of the possibility of a continuing drou ght. Th e demand for water from NSW has risen sharply this year in light of the drought conditions, but Victorian farmers are wary of selling in case they need it too, even as an insurance policy. In general water is tending to move away from badly salinised, mixed farming land in the mid-Murray area (Kerang and Pyramid Hill). It is moving to dairying and horticultural areas where the

Trade at Present

*Director, Office of Water Reform Departm e nt of Conservation and Natura l Resources, 232 Victoria Parade, Melbourne.

In Victoria, as elsewhere in Australia,

returns are higher, ie upstream to Cohuna, Rochester and Shepparton, or downstream to Sunraysia. On top of the 6,000 ML traded (reallocated) between irrigators last year, 12,000 ML was auctioned by the Rural Water Corporation for private irrigation development (diversion licences) along the Murray. This auction, which included probably the last "new" water and some reallocation, was arranged on the basis of a salinity management plan. It created keen interest. 4,000 ML of water was sold with annual licence charges the same as for existing licensed water ($5 per ML). This brought an average of $440 per ML. 8,000 ML of new water was sold with annual charges equal to full cost recovery including 4% rate of return on assets ($20 per ML plus a capital charge for salinity of $112.50 per ML) This water fetched an average of $200 per ML. 99% of the water went to the lower Murray around Sunraysia. About half the water was snapped up by big export-oriented viticulturalists like Mildara and Penfolds, who plan to establish greenfields operations. There is still unmet demand from such high value-adding enterprises. At the time of writing, consideration is being given to a one year (temporary) sale of 20,000 ML of Victorian Murray water reserved (but not required this year) for environmental purposes. Proposals are for sale by tender with Victorian, NSW and SA farmers eligible to bid on an unsubsidised basis.

Barriers to Trade It has not been possible to transfer water between public irrigation districts and licensed private diverters, or in some districts to trade at all. These barriers and barriers to trade between the main systems in northern Victoria - the Goulburn and the Murray systems - should be removed in the short term. Initially these new trading opportunities are proposed on a megalitre for megalitre basis. However, proper exchange rates (to maintain the securities of different sorts of entitlements) and translation factors (to allow for losses in different locations) will need to be resolved and introduced fairly soon thereafter. Another barrier is the inability to trade directly between irrigators and urban agencies. One large irrigator might use 3,000 ML, a quarter of the supply for a city the size of Shepparton. Exchange rates are also necessary in this situation. Other impediments in the present situation are less obvious but very significant. In northern Victoria, irrigation usage has been trending up for many years, as farmers introduce more permanent pasture. Irrigators are using increasing quantities of "sales" water, which is frequently offered on an unlimited basis, not just near the end of the season, but as early as December. In the peak usage season of 12

1990/91 more than a quarter of all irrigators in the main Goulburn-Murray district used in. excess of 200% of water right. It is likely that this growth will be capped in the course of defining rights more carefully. Growth in usage is a major concern in the Murray Darling Basin for environmental reasons. Increased usage is also reducing the security of water entitlements and the timely delivery of entitlements. Although not the reason for capping use, this action will have the effect of stimulating trade in water.

A More Open Market The evidence suggests that, even with a better and expanded framework, trade will be quite small in terms of quantities of water - perhaps no more than 1 or 2% a year. However even such limited trade is likely to provide very significant economic benefits, especially over time. As demonstrated by the recent auction of water to export-oriented viticultural is ts in Swan Hill, relatively small amounts of water can be the basis for important new value-adding industrial developments. Trade will also facilitate the gradual restructuring of irrigated agriculture to higher value-adding production in more suitable, less salinised locations. As many as a third of irrigators have been described by the Australian Bureau of Agricultural and Resource Economics as unviable, whether or not water prices move to full cost recovery. In the coming decades, developments in world markets are likely only to increase the pressure for relocation and restructuring. Equally important as the benefits to be derived from more open trading between geographical locations are the benefits from allowing irrigators to have some choice over the reliability of their entitlements. At present the standard of security is set centrally. Victorian storages are operated relatively conservatively, and the high security water by and large suits the extensive permanent plantings. Pushing decisions down towards the end-users is a critical part of moving away from the old "command and control" approach. While some enterprises might well plan for even high security, others could possibly do much better from a lower security, higher yield service. There are indications that the productivity of dairying could ri se by as much as 14%, if such choices were available to farmers. Already there are some irrigators buying up additional water rights to increase the security of their water, and then selling their annual "sales" entitlement to other farmers with different requirements or judgements about risk. (The present system of selling sales water is one aspect of the existing trading system which probably needs to be reined in, as it is leading to greater

water use overalQ_. In the urban sector also, the aim is to maximise choices available to end-users. In the Melbourne area, for example, the emphasis is to provide the three new regional retailers with the maximum practicable control over their own water, rather than have this control with the headworks operator. An effective market in water should, by exposing both irrigated agriculture and urban water sectors to a fuller set of price signals, lead to significant increases in efficiency and less regulation. The need for capital funds for infrastructure should be lessened, and ultimately the pressure on the environment should be alleviated. In years to come, major urban centres like Melbourne and Geelong should be able to obtain additional water, not by building new dams but by financing actions to save water (for example improving existing works or smarter operating systems) in the north of the State.

Clear Entitlements For trade to be maximised, entitlements need to be explicit, exclusive and enforceable property rights, not too dependent on what the system operator or other right-holders choose to do (i.e. they must be as "unattentuated" as possible). In practice, the feasibility of unattenuated rights m~st be tested. Capacity shares. The most attractive form of entitlement is a "capacity share", i. e. the right-holder effectively "owns" a share of a storage and of the inflows into it. This form of entitlement has the great advantage that it enables right-holders to make their own decisions about risks - basically the trade-off between yield and reliability in a system which "carries-over" from one year to the next. Capacity shares are most feasible on relatively simple systems, for example where there is only one storage and not too many users. Thus they can work well in circumstances like the Lal Lal Reservoir, which supplies Geelong and Ballarat. In northern Victoria the system is very complex, integrating many storages on a number of different rivers. The feasibility of introducing capacity shares for large groups of irrigators (about 1000 in a group) in this system has recently been tested. An irrigator group such as Boort (right at the western end of the Goulburn system) gets a lot of its water from the local Loddon River storages in wet years, but in dry spells turns ,to the larger carryover capacity at Lake Eildon on the Goulburn River. If Boort were given a share of Eildon, the share would be under-utilised in most years. But if Boort were not given a share of Eildon, it would occasionally be in serious trouble. WATER MARCH/APRIL 1995

Moreover the congestion on the main channel bringing water to Boort from Eildon is an overriding constraint on how much water can be delivered. Thus a capacity share system would need to include rights to use key channels, which is theoretically possible but can become quite complicated. (An embryonic form of sharing is already in place on the channel supplying Boort). If capacity shares were to be extended to the individual irrigators in this multi-river system, the difficulties in defining fixed shares and dealing with channel constraints is compounded many times. Practical operations make such a system hopelessly complex and costly. The conclusion is that capacity shares would work in northern Victoria, but only if they were introduced on a scale large enough to internalise channel capacity constraints. Delivery entitlements. Attention has turned to treating irrigators' entitlements as delivery entitlements, that is, entitlements defined in terms of a fixed volume with a specified security. This is more or less how they are thought of now, except that the optional "sales" right in particular is very poorly specified. Urban authorities will also usually have delivery entitlements, particularly where they take their bulk supplies from large integrated supply systems, so the following comments also apply in these cases. The security of delivery entitlements is assessed by modelling the water supply system. However, in practice, security also depends on the performance and decisions of the Headworks manager. Water supply system modelling is very complex, so that monitoring, verifying and enforcing can be very difficult. To make the security more transparent, it was initially proposed to insert in entitlements a restriction policy which related volume to be delivered to water levels in the storage(s). This achieved a tighter definition of the entitlements, but at the expense of making the operating policy for the storage very rigid and attenuating entitlements. A way around this which is currently being explored is to use abnormally low inflows - which are independent of storage operating decisions - as the trigger for restriction measures. So far over 80% of the variance in water availability can be explained using inflows (together with other independent variables such as summer rainfall). However, whether specifying restriction policies using inflows will be the best answer is not clear at the time of writing. If a storage-based restriction system is needed, a means of reviewing the operating policy will be necessary so that the policy can respond to requirements of entitlement holders and to smarter operating regimes. For example, the restricWATER MARCH/APRIL 1995

tions policy could be set out in a schedule, with a set process for renegotiating it.

Different Products Better defined entitlements at individual level will open up the possibility of offering entitlements with different security levels. By means of exchange or trade between these different products, an entitlement-holder then could choose the best mix of yield and security to meet specific needs and risk tolerances. Providing irrigators with the option of splitting their existing entitlements into high security and medium security rights which could be tradeable independently may be feasible. To an extent this builds on the existing temporary transfers. However while the turnaround time for temporary transfer is being cut significantly to (48 hours), transaction costs are still a problem if such transfers are to be relied on to provide real irrigator choice. At this stage a range of rights of different security levels is believed to provide more control to the user than a simple arrangement whereby "next year's" water can be used now or "this year's" water can be carried over. However the value of such an overdraws/underdraws arrangement is currently being assessed. On a broader level, different products based on the time of supply (for example, flow rates, time of day, time of season) also holds promise, particularly as an adjunct to a trading system.

Bulk Entitlements The clearer definition of individual irrigators' rights requires spelling out exactly what water is available for all uses. This is being done through work to convert authorities' existing, often vague, rights to clearly specified bulk entitlements. This is a conversion process, not one which tries to reallocate water. Basically bulk entitlements will not be readily tradeable, because they will be associated with obligations to supply water to irrigators and townspeople. However they can be an important vehicle to provide incentives for reducing losses in water systems. Water thus saved could be traded. The details of how bulk entitlements will fit together with irrigator customer groups or retailing organisation are still being considered. Environmental requirements are being clarified as part of this conversion process and, in time, it is planned to establish explicit environmental allocations rather than using surrogates like minimum flows at specified locations. To sum up this work on entitlements, the strategy being developed involves: providing clear boundaries between different uses - irrigation water, urban water and water for the environment through the definition of bulk entitlements; looking at the benefits and the

costs of providing bulk entitlements in capacity sharelcform down to the level of irrigator groups or large urban retailers; making the entitlements of individual irrigators, or of small towns in integrated systems, much more concretely defined, if not by using storage inflows then by using appropriately adjustable system operating policies; enabling entitlements to be split into different securities which can be traded independently, so that entitlement holders can choose their own risk levels.

Regulation A regulatory framework is needed which will spell out very clearly the circumstances in which trade can take place. This must be in a form which is readily understandable to potential traders and which allows trades to be made quickly. For these reason s approvals should be as automatic as possible, as long as some basic conditions are met. It is important to the success of the market that there is adequate monitoring and checking of third-party effects of trade, such as on the security of other entitlements and on the congestion of channels. Assessments will need to made of savings of water, enabling bulk entitlement holders to trade surplus water. A "register" of entitlements will also be necessary. Considerable water system modelling expertise will be needed for this work and the degree of regulation necessary will depend, in part, on the degree of "attenu~.tfon" in the definition of rights.

Interstate Trade While Victorian water entitlements have high security, NSW uses much more of its water each year out of the Murray-Darling system, but runs a far higher risk of shortages. This may suit opportunistic annual cropping such as rice-growing. It also means that there is a real potential for beneficial trades between Victoria, NSW (and possibly S.A.). However different levels of subsidies must not be allowed to distort outcomes and trade must not result in increase d water use in the Murray Darling Basin. These are the key issues in resolving interstate trade. Up until now there has only been one event approximating an interstate trade, the sale two years ago to NSW irrigators, of options to 1050 ML at $1 per megalitre. It rained and the options were not taken up. As mentioned above, consideration is currently being given to temporary interstate trade in Victorian surplus environmental water. If this eventuates it should highlight and stimulate the need for resolution of the key interstate trading barriers. Basic requirements for interstate trade are that bulk entitlements to irrigation water and more clearly specified 13

"sale s" entitlements, are establi shed. Without these there can be some greyness about ownership of water. Future trade would be far better at irrigator-to-irrigator level rather than between bulk entitlement holders. A basic commonality across State borders in the way irrigators' entitlements are defined is also desirable.

Specialist Consultants & Analysts

Conclusion In present circumstances, with high security of water in Victoria and no general local shortages, the effects of widening the market in water, while generally beneficial, are not likely to be dramatic in the short term. However in the medium term many millions of dollars can be saved in infrastructure and substantial environmenta l benefits can accrue. Importantly, irrigated agriculture can be made more sustainable. On the other hand development of the water market will not solve all water resource management problems. Rather, it promises to become a major tool. The major benefits will flow from better resource allocation , in particular across the lower Murray Darling Basin, as the water resource is allowed to move and usage to adjust in response to emerging international market opportunities. This means that sub sidies should not determine where water is demanded, but that land capability and an appropriate level of water input will determine the hi ghest economic advantage for Australia. States' borders are not brick walls, and trade into and out of regions should allow all to prosper. Proper recognition of environm ental valu es both through the explicit allocation of water to those purposes, and through proper pricing of third party effects, will ensure the long term sustainability of irrigated agricu lture and the communities which depend on it. Multilateral acceptance of water trading and "common currency" definitions are necessary preconditions to gaining this benefit. Victoria's program is about establishing the level playing field where all players have maximum choices and the best chance of scoring goals.

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MANAGEMENT

INCREASED EFFICIENCY IN THE WATER INDUSTRY? G Watson* Abstract Increased efficiency is espoused as the answer to sustainable improvements in living standards. What this means for the water industry is the establishment of some form of workable competition. The paper summarises the models of institutional management of water resources in Australia. This is followed with a discussion of the barriers to the evolution of an efficient competitive market structure within the water industry. International experience in the use of privatisation in an attempt to increase efficiency in this sector is examined. One tool used to simulate competition in a natural monopoly is benchmarking. Its various forms, uses and limitations are discussed. The absence of homogeneity and the existence of joint costs within the multi-product water sector leads one to question the validity of this tool as a measure of efficiency or regulation.

Introduction Historically, the water industry began in Australia in private hands, but the failure of the market system showed the need for public sector involvement and control in the industry. From these tumultuous beginnings, water policy in Australia proceeded as a tool of economic and social development, through its twin roles of improving health and providing a key resource for agricultural and industrial development. For maximum overall economic output costs should be at a minimum for the level of output that consumers want. On the demand side consumers will be efficient in their consumption if the price they pay is correct. The theoretical requirement of price in an economic system is to set a measure equating benefit and cost. Here cost means full social costs net of any benefits. For water the costs would include, for example, storage, treatment and reticulation through to the loss of environmental amenity through pollution. From this should be netted, for example, the increased productivity of labour through better health. On the supply side to assure minimum costs a 'contestable market' is required - one where there is a real threat of effective competitors, who can take your business away. WATER MARCH/APRIL 1995

The language of change in the public sector often distorts the reality of what is happening. Proponents of public sector change argue that the economic and social foundation of current institutional forms no longer apply. They point out that functions should be more effective/ efficient. Effectiveness focuses on the degree to which the purpose or objective of the service has been accomplished with these resources. An efficient operation minimizes the amount of resources expended for a given quantity of services The past effectiveness of water authorities is irrelevant to the current debate. Current effectiveness should be measured against their mission statements. Efficiency is gauged by reference to costs. Walker (1993) used private sector accounting methods to estimate the efficiency of water authorities. He found the average rate of return on equity to be 10% and on assets 9% (page 192). He concludes (page 203) that, for operating margins of around 38.5%, "For a high-volume business, using long-lived assets, these margins are remarkably high ." He concedes that these are average figures and that there may be a case for improvements in the efficiency and effectiveness with which individual water authorities manage their physical, financial and human resources. Overall, they are highly profitable investments in terms of private sector accounting practices. Kearney and Daly (1993) demonstrated that public funding of infrastructure within the Australian context enhances private productivity and crowds-in private investment over time. Thus, the belief that the public sector does not produce wealth but only assists in producing wealth is erroneous. Discussion over the last decade should have centred on finding economically sust,ainable solutions to funding the public enterprise capital base. It has been distorted into an argument against the very existence of public enterprises. The function of water as a resource basic to material and social wellbeing dictates that its integrity must not be jeopardised. Institutionally the structure of a reformed water industry must recognise the autonomy of individual regions with-

out compromi sing interregional spillovers. In this way system risk can be reduced through pooling while retaining the option of using market power or external benefits as a social justice tool. Risks of major investment and disasters, such as flood and drought, should be shared by a large population, preferably the whole nation. Monopoly power can be used to transfer income to groups where social benefit is greater than the private costs. Although some would call this cross-subsidisation (or CSOs) such direct intervention can be more effective and less costly than indirect intervention through the taxation system.

Australian Water Institutions The following is a concise summary of the institutional organisation of water service providers on a state by state basis (as at the date of writing). Queensland. Water, sewerage and drainage is principally managed on a local gove~ nmE;)nt basis. The _supply of water is administered by stat 3 water authorities. The fu~ctions of the 'most powerful municipal unit, the Brisbane City Council, are the mo.st extensive in Australia. Local government boundaries, raw water and consumer supply, tourism and erratic rapid regional development are likely to be the source of great conflict. The institutional arrangement has the potential for escalating this. New South Wales. Originally, water administration in New South Wales by the statutory authority/local government model was the most complex in Australia. However, reform is proceeding. The Hunter Water Corporation was established in January 1992. The (Sydney) Water Board should by corporatised by the time this paper is published. The Public Works Department faces a diminishing role in the management of water in this state. Whereas it was once the water program administrator it is now confined to the management of two bulk water supply schemes and advising local government on' managing their water investments. Victoria. In the 1980's the Victorian Government commenced a major reform * University of Western Sydney, Macarthur,

PO Box 555 Campbelltown NSW 2560

on a hitherto fragmented and uncoordinated water sector. The process involved amalgamation, where possible, on a regional or catchment basis. In Âˇ1989 the Latrobe Regional Water Authority was established as a model authority, merging bulk water supply, reticulation and river management. At the start of 1995 Melbourne Water was split into five separate legal entities. The first step in the reform was to establish clear, consistent, stable objectives as a necessary condition for efficient operation. The next step involved the establishment of Melbourne Water Corporation as wholesale supplier of quality water, and wholesale waste receptor, treater and disposer. For an interim period it will also provide drainage. Three separate retail corporations, with geographic boundaries which almost mirror the preceding met,. ropolitan regions, provide water and sewerage services at a retail level. They will bill the end users and be responsible to them. A separate Melbourne Parks and Waterways Corporation is responsible for water-based recreation and stream management.. The Office of the Water Regulator General will set prices and manage licences. While the Water Industry Bill initially makes provision for three water and sewerage operating licences, there is scope for up to five types of licences covering operation of headworks to retail of water, sewerage collection, treatment and drainage. Tasmania. The state authorities provide bulk water schemes and control all the irrigation sector. Urban water, sewerage and drainage services are provided by the local government sector. Differences of opinion over the ownership of the bulk water supplies are a reflection of the growing conflict between resources management and water consumption. Australian Capital Territory. The Australian Capital Territory Electricity and Water Authority was formed in 1988 to gain efficiencies of scope in management, foster an efficiency-oriented culture and gain efficiencies from regionalisa tion of operations. It supplies water and sewerage services, owning and operating the infrastructure. It has responsibility for preventing water pollution in the Murrumbidgee. Northern Territory. The Power and Water Authority was established in 1987. It includes a Directorate of Water Resources with clear demarcation between water resource management and provision of water and sewerage services. Drainage is generally undertaken by local government authorities South Australia. On the surface the Department of Engineering and Water Supply administered the whole spectrum of the water industry. In practice local governments undertook drainage and non-metropolitan sewerage 16

with the support of state government grants. The potential for conflict between the objectives of regulator and service provider are Âˇ acknowledged and separation is under way. However, the benefits of direct involvement in policy are seen as greater than any losses of efficiency. Western Australia. The Water Authority of Western Australia has a virtual monopoly in that state. It is charged with managing water resources and providing water services. Its failure to attract private capital in the 1980's to sewer backlog areas may be an indication of the reluctance of private funds in Australia for investment in water infrastructure. In view of the Western Australia case other states cannot be complacent as their infrastructure ages and water supply sources are compromised. This is especially true of the increasing areas of marginalised land where the community is increasingly under a variety of stresses. General. Currently ownership, control, management and operation of the core water assets are still within the public sector realm in Australia. In New South Wales and Victoria the situation is witness to a pressure for change. What is required, however, is reform. Sustaining and improving environmental values and lifting the water industry performance standards requires increased industry regulation with centralised co-ordination. Ownership, control, management and operation are separable issues but require a coordinated approach. There exists the potential for great conflict in the allocation of water to different uses within the current institutional framework of many states. New South Wales is the only state with the appropriate independent regulatory framework to ensure authorities (or corporations) meet economic, social and environmental objectives.

Can Competion Help? Watson and Johnson (1993) indicated that recourse to the 'invisible hand' of the market to overcome the industries problems is simplistic. For efficient outcomes in the market model it is necessary that there be a contest for customers in the market, conducted on the basis of the price charged or quality of service. To meet the contestability requirement the private and social costs and benefits must equate. This cannot occur if there are strong monopoly characteristics, as with water. One of the assumptions of the competition model is a homogeneous good. Water supply is heterogeneous in time, space and quality characteristics. Different users and uses of water will require or tolerate different water qualities and supply guarantees. The very nature of water services forms a barrier to competition based on homogeneity. The institutional structure within which a market-based system can fine-

tune water management will need to be designed to reflect this heterogeneity. In practice contestability can be created through explicit competition in noncore, non-monopoly sections. There are many successful examples already in the water industry. Just two are the leasing of maintenance of treatment plants by the (Sydney)Water Board, and out-sourcing of a whole range of functions by Melbourne Water: However, where the core business remains a natural monopoly then price regulation and performance indicators have to be used to simulate the information and sanctions of the market, whether or not the entity remains in government or is transferred to private control..

Is Privatisation an Advantage? The hoped-for benefits of privatisation are that the discipline of the market on the water entity will enable consumers to enjoy lower prices, enhanced water quality and the benefits of share ownership. Benefits for the government would be reduction of public borrowing and public debt. The trade unions would lose their monopoly power, thereby removing a historical source of high costs. The economy would enjoy reduced prices and costs through more efficient technical and distributive allocation of resources and therefore a higher standard of living. For the water service entities themselves the hopes are for simplified objectives, investment not politically restrained and reduced information collection and reporting. â&#x20AC;˘ However, Johnson (1993) (Chapter 8) indicated that these conclusions are not borne out by international experience (see below). Watson and Whelan (1990) defined the processes of privatisation, corporatisation and commerialisation of the Australian water institutions, and their paper suggested that the most effective management structure is one in which the corporate culture is changed to meet new efficiency objectives without losing the benefits of control over operational outcomes. The claim that privatisation is the solution to reform has serious consequences for the long-term management of the water industry.There are a number of critical issues in the appropriate management of water resources. The values of water resources must be sustained. Water policy makers and water service authorities seem to have fallen behind the current social consensus on the importance of environmental quality. A sustainable renewable resource such as water in a fit state and, sufficient for the growing claims on its uses is one important environmental quality. Definitions of sustainable development which allow the replacement of natural capital with built capital ignore the possibility nf jeopardising the system through depletion of one WATER MARCH/APRIL 1995

essential resource below its minimum level. This point of view assumes that future generations will rank their enjoyment of a extra unit of water output above its cost in opportunities foregone such as the aesthetic value of the water environment. Neither Rre markets well enough developed to recognise those values inherent in the natural environment that are important for the economic welfare of people and the sustainability of the environment. These are are values which private ownership will have difficulty in identifying. Where there are short term gains but the risk is shared with the rest of society, or even passed on to other generations, the risk becomes irrelevant to private investment and pricing calculations. Rix (1993) presented further evidence against privatisation which is often missing from the political debate. He maintained that 'rational economic language' denies motivation based on collective ideals. The debate is couched in terms of a paternalistic government identifying merit goods rather than responding to public pressure. The result, he found, is a fall from favour of the 'public good'. Democratic social policy choices afforded by public ownership are excluded from the debate. He questioned governments' right to transfer assets which they only hold in trust.

Privatisation British Style It may be to our benefit that Australia has been slow to reform its water industry since it could avoid the mistakes made by Britain. Privatisation puts a mask over the industry. Any move from a public service provider to provision of an economic good under managed competition is still a move from public monopoly to private monopoly. The next few paragraphs judge the British experience against the reservations about privatisation, and to a lesser degree corpora tisa tion, discussed in Watson and Whelan(1990). They are drawn from the research done by Johnson (1993). Their Regulator requires increased information from companies to accurately estimate their efficiency dividend. There has been significant deficiency between agreed plans and actual investment. The split between the monopoly (regulated) and commercial (unregulated) activities is difficult to monitor due to joint costs and cross-subsidisation between core and non-<:ore activities. There has been an increase in the complexity of the objectives. This is due to overlapping in the sets determined directly by the government and indirectly by the regulator(s). In the event, improved customer service has not resulted from market competition but fr om incr ease d regulation. Notwithstanding this, consumers have no WATER MARCH/ APR IL 1995

choice in suppliers or price. Average prices have increased 12.8% in 1990/91 and 14.8% in 1991/92. The requirements to adhere to environmental standards have become more uncertain. However, there have been benefits, including forced reform of environmental regulatory structures and functions, and facilitation of public scrutiny in investment. The Regulator is also at arms length from the political arena and from the Treasury on price and performance. The major authorities were privatised debt-free. While their debt/equity ratio remains low any large capital borrowing will get preferential treatment. The capital market will not exercise any discipline until their debt/equity ratio reaches the level of comparable corporate borrowers. The remaining smaller statutory authorities did not receive similar debt writeoffs. This has created distortions in the market for water capital. Stock market discipline is questionable as there are many shareholders with limited knowledge of the industry and low individual voting power. Foreign ownership has increased from an average of 14% to over 60% in one region. Local councils are challenging the legality of transfer of large amounts of land which were held in public ownership by the water authorities to the private ownership of the companies. In fact Governments themselves do not own the assets. They act as steward for the people. Why should some citizens be able to buy at a reduced price what the community as a whole all already owns? Paddon and Carman(1994) give overwhelming evidence for the conclusion that privatisation discounts the value of assets. Corporatisation and especially privatisation change ownership of assets. It is argued that this will reduce the principal/agent problem and remove political interference. Watson and Whelan (1990) however, argued that these aims may not be achieved. Change of ownership may prejudice decisions of future democratically elected governments, since governments a1'e reluctant to direct laws against specific companies or persons . Thus there is less likelihood of regaining sections of the industry into public ownership or directing individual water companies to undertake tasks not required by others. This is a grave long-term consequence of the current ideology.

Benchmarking One technique .which is promulgated as providing a simulation of competition in the water industry is benchmarking. One of the most important challenges facing Australian organisations today is the achievement of international standards of performance. Globalisation of markets has increased the pace and nature of change in technology and consumer tastes. Competition on the basis of

costs now\includes a multifaceted notio of quality and time. "The Best Practic Program, announced in the Feden Government's March 1991 Economi Statement, aims to accelerate the intri duction and dissemination of a new worl place culture based on international bei practice .. promotes benchmarking as a important tool in driving cultural chang within the workplace" (Nationc Industries Extension Service, NIE~ 1993). Benchmarking should be part of a integrated set of tools. Organisations tha undertake. strategic planning find it eas er to adopt benchmarking. This i because better utilisation of existing teer nology and the adaptation of the mos appropriate advanced technology has t do with the corporate culture. Benchmarking may be either interna or external, or to do with numbers or pe1 formance. Numbers establish the size o the gap but they give no informatio1 about the critical success factors in th, process. For example you can benchmarl the figures of profit margins or rates o return, or alternatively you can analys, and compare the process of how you pre duce your product. Successful bench marking is a process of rigorous implE mentation of improved business procesE es which requires a consultative/partici pative culture in the documentation of ; clear widely pwned strategic plan. The NIES found it "important tha the benchmarking process is customisec to the needs, capabilities, and culture o the individual enterprise." It requirec "understanding the trends in your indus try - local and international - and thE broad effect on your competitiveness Each step of the benchmarking process ii unique and "depends on -the size of thE company, industrial relations climate, thE attitude of management, and understand ing of competitive position." The searer for good benchmark partners is a stei: that can be very time consuming. Then is no guarantee that the hived-off sectiom of a water authority will be suitable men tors for each other or for enterprises ir different environments. Eggleton (1994) defines benchmark ing as "the continuous practice of system atically comparing one's own activitie E and products (or services) against those of best practice, in an attempt to achieve competitive superiority through the adopÂˇ tion, adaptation and implementation oJ those practices." It was found that benchmarking could most easily be used in independent domains with routine technologies where performance is output specific. (ie. those areas of the water enterprise which are easily earmarked as separate cost centres or subject to outside tenders for services. Examples are fleet management, mailed payments processing, safety surveillance of headworks, data processing and unit maintenance). 17

The performance of every business process should be measured. A critical mistake made in the past is to choose the key performance indicators and try to fit business processes to these. It is better to choose the critical success factors and fit the performance indicators to these. If the correct processes are chosen, then the considerable time and effort put into benchmarking can lead to improved results.

Benchmarking to Regulate the Water Industry? Efficiency requires two important aspects of the operation to be in place at the same time. There must be clear, consistent and stable objectives and a contestable market. Governments have made a lot of progress on the first issue in the last decade in the water industry. Resort to the use of benchmarking recognises that the second condition is not so easily implemented. A concise definition of performance is required. Economic theory suggests that efficiency can be achieved if the unit price for a commodity is related to cost. The theory assumes that the cost base is a minimum. The idea of 'competition by comparison', however, is void of any economic foundation, or for that matter any empirical support that it can lead to an efficient outcome. Mayer (1994) contends that the scope of direct competition between water providers is limited by geographical and natural monopoly considerations. In his view the proposed practice of benchmarking as a regulatory tool is a means by which prices are set on the basis of minimum or average industry costs. There is a view that this mirrors competition. It in no way identifies the industry minimum cost. What makes the approach unworkable is that under the present proposal if a water entity scores badly there will undoubtedly be excuses. Vital repairs, poor weather, drought, contracting customer base - the plausible reasons are endless. The most convincing argument for not meeting benchmarks is that the entity is adhering to its mission. In serving its own customers each water provider will encounter different customer preferences. These could range from easy bill paying, to high reliability potable water or even to demanding pristine receiving waters. Staunton and Hagan (1988) studied Annual Reports and summarised the 'mission statements' of major Australian water authorities into concepts which might be employed to derive objectives and measuring systems. The study aimed to find commonalities in the objectives. In regard to relevance and reliability of common performance measures they found "no clear nexus between indicators and efficiency" (page 14). Their reason was because the "content of the performance measures was as varied as the geograph18

ic areas for which the authorities are responsible." They conclude that the current debate .confuses low cost resources use with efficient use. The debates on the appropriate institutional structure of water enterprises, discussed above, confused outcomes with processes. The same confusion is being repeated with measurements of performance. Variously termed "performance indicators/benchmarking/yardsticks", the usefulness of comparing outcomes has been confused with the process necessary to achieve those outcomes. Quantity figures fail to show how to get better. Each water provider has different customer densities, expectations, different infrastructure age spectrum and natural resource endowments. Of equal importance is the absence of a set of criteria on which to judge the impact of different operating environments on the performance outcomes. For benchmarking to be an effective regulatory tool a quantified model of the characteristics that contribute to variations in entity performance is needed. Perhaps we should be asking 'why sho uld costs be the same?', rather than 'how do we make costs the same?' "Differences in perspective usually cause coexistence of contradictory stances. Each group approaches the performance measurement task with different objectives." (Erlwards,1986). To be effective the regulator must shadowmanage the entity. The regulator and the regulated will very probably have a different perspective on efficiency. Commonalities and/or differences in meeting the benchmark criteria will be in the eye of the beholder. Even more complicated will be the decisions the regulator has to make as the environment gains more weight in the equation . This is because environmental properties are largely intangible making their valuations subj ective and therefore practically impossible to quantify in dollar terms.

Benchmarking in Practice Benchmarking has been carried out by individual water providers for many years and lately there has been a move to examining the practices used by commercia_l firms. The Eggleton study concluded that benchmarking works well in routine technologies where the output is definable, measurable and independent of other domains. In a heterogeneous market of interrelated outcomes it may not be possible to define the best practice and thereby define minimum costs. Often best practice is found outside the industry or the country. Even if it exists there is no guarantee that commercial firms will co-operate in sharing their valuable corporate knowledge, the basis of their profits. Finally, even assuming that an efficient benchmark exists and can be identified there is the final barrier of successful transferral.

With.in thi context benchmarking can continue to be used as it already is. Managers in the true spirit of public service search for, compare, adapt and implement best practices. They strive to adopt processes that will yield efficient and effective outcomes; just as private managers do in the search for profits. Any success in reducing costs and increasing benefits in the use of benchmarking as simulating competition will not flow from any yardstick power but from the will of managers to comply.

Conclusion It is accep.ted that further reform of the water industry can be of benefit to the national economy. Provision of infrastructure and pooling of risk on both the supply and demand sides are important factors. Increasing liberalisation of individual autonomy is leading to decentralisation, but the circular nature of the water cycle and its inter-relationship with development should limit such decentralisation to no smaller than the regional catchment basin. However the monopolistic and heterogeneous nature of the water industry makes it impracticable to increase efficiency by a truly contestable market. The concept of privatisation of the water utilities is being discussed in some areas, but experience overseas indicates that this is a dangerous approach. Exceptions exist in those function s which are non-monopolistic, and which can be out-sourced or subject to competitive bidding. For the core businesses, price regulation and performance indicators have to be used to simulate the sanctions of the market. Price regulation by means of benchmarking is likely to prove costly to both the regulators and the regulated, and would become even more difficult as the intangible factors of the environment become more significant. Performance indicators have little relevance in the core functions due to the profound geographical and climatological differences across our continent, nor do they guarantee identification of minimum costs.

References In 'Water in Au s tralia - Mana gin g Economic Env ironmental and Community Reform ', Michael Johnson and Stephen Rix (eds) Pluto Press, Leichhardt, NSW Johnson M (1993) The water industry over seas - Lessons for Australia (Chapter 8) Johnson M, Rix S(1993) Better water ways (Chapter 13) Kea rney C, Daly K, (1993) Water and the Australian economy: capital stru cture and financing strategies (Chapter 7) Rix S (1993) The political context of public sector reform debate (Chapter 9) Walker R G (1993) Evaluating the finan cial performance of Australian water authorities (Chapter 10) Watson G, Johnson M (1993) Pricing: Cheap wa te r or an e nvironmental perspective (Chapter 11) WATER MARCH/APRIL 1995

Edwards J B (1986) 'The Use of Performance Measures', Nationa l Assoc iatio n of Accountants, Montvale, VA. USA. Eggleton I (1994) 'Benchmarking for the Water Industry', UWRAA, Research Report No . 7 Mayer C (1994) The regul atio n of the water ind ustry: An in ter im assessment, in 'Regul ating Utilities: The Way Forwar d' , Institute of Economic Affairs, London. National Industry Exte nsion Service, (1993) ' Austr ali an Best Practice Demonstr ation Program (Benchmarking Self Help Manual)', AGPS, Canberra. Paddon M and Carman M (1994) ' Paying t he P r ice of Privatisation: T he Federal Governments FAC Privatisation Proposal in 1994', P ubli c Secto r Researc h Ce n t r e, University of NSW. Staun to n JJ and Hagan LL (1988) 'Fin ancial Gu ide lines and Perfor mance Meas ures' University of New England, Armidale, NSW Watson G and Whelan S (1990) Privatisation Corporatisation for the Water Industry Water 17 5, pp22-28

â&#x20AC;˘

IE Aust

The 23rd Hydrology and Water Resources Symposium

., ii /""'-~ ~

CALL FOR PAPERS

wATER AND THE ENVIRONMENT

Abstracts due 31st March 199'5 21 - 24 May 1996 Wrest Point Hotel Casino Hobart , Tasmania, Australia

Author Genevieve Wataon is an Associate Lecturer in the Faculty of Business and Technology, Universi ty of Wes tern Sydney, Macarthur and was previously with the Urban Water Policy Centre of the University of New South Wales. She is currently researching in public sector micro-economic reform, particularly for water and airports.

Contact the Conference Manager at Dickensons Conference Department 111 Main Road, MOONAH , Tasmania 7009 Phone: (002) 28 1932

(Int) +6 1 02 28 1932

(002) 78 2956

(Int) + 61 02 78 2956

Fax:

CLASSIFIED - APPOINTMENTS

Great Organisation

G o ulburn Va ll ey Wa ter is a dy na mi c a nd s uccessful organi sati on marked by foresig ht and co mpe te nce. Recent amalgamations have seen Goulbum Valley Water assume regio nal responsibility for providing water services to residential, industrial and commercial customers in North Central Victoria - the Foodbowl of Victoria.

Great Lifestyle With these jobs, you will be living in the warm climate of the Go ulbum Valley, minutes from all water sports and renowned wineries and with easy access to the Victo ri an ski fi elds. You also have the convenience of a vibrant, progressive commercial centre with all the fac ilities of an established city. All this is in Shepparton which is j ust two ho urs from the Melbourne GPO .

Manager Industrial Wastewater Services The customer is the most important asset to a business, so this is a most important service role . You will manage industrial and commercial tradewaste, which represents 80 per cent of wastewater input. Your overall aim w ill be to optimise the quality and quantity of wastewater input, for system efficiency and environmental excellence. You are a progressive professional engineer, preferably chemical, with negotiation skills and a special expertise in tradewaste treatment/ acceptance and wastewater minimisation.

ManagerWastewater Treatment A quality operation is the backbone to a quality service. Reporting to the Director of Technical Services, you will manage 11 wastewater treatment plants, soon to increase by several more, and an .extensive land disposal operation. Yo u are a progressive professional engineer, a good manager and have substantial relevant experience and a special interest in land disposal of wastewater.

Gou/bum Valley Water is an Equal Opportunity Employer Negotiable remuneration inc ludes car and superannuation. Assistance will be provided with re location to Shepparton. Further information is available from Peter Poynting on (03) 418 3943. Resumes should be addressed in strictest confidence to PO Box 300 Fitzroy Vic 3065

WATER MARCH/APRIL 1995

TECHNOLOGY

TESTING AN EFFLUENT FOR TAINTING OF FISH - THE LATROBE VALLEY OCEAN OUTFALL PR L Masse, * J Kowarsky Keywords ocean outfall: industrial effluent: pulpmill effluent: petroleum effluent: fish tainting: Triangle test: olfactory evaluation

Summary Treated effluent, comprising a mixture of pulp and paper mill waste, domestic sewage and petroleum formation water, was tested for its ability to cause odour tainting in fish. Flathead (Platycephalus bassensis) were exposed for three days to seawater containing 2.5% and 1.3% of the effluent. A panel of 18 people conducted Triangle test evaluations on warmed samples of flesh according to Australian Standard AS 2542.2.2. There was no evidence that fish exposed to either concentration of effluent could be distinguished on the basis of odour from control fish exposed only to sea water. The minority of panellists who 'correctly' identified the effluent treated fish reported that the odour of these fish was slightly stronger than that of the controls, but these panellists did not indicate a clear preference for either the exposed or control samples.

Introduction Background. Construction of the Latrobe Valley Ocean Outfall generated considerable controversy in the Gippsland community (Donlon and Mosse 1994). One of the concerns, voiced by both commercial and recreational fishing interests, was the possibility that the effluent might cause tainting in fish. The secondary treated effluent discharged from the outfall consists of wastewaters from Australian Paper's pulp and paper mill at Maryvale, domestic and light industrial waste from the Latrobe Valley and formation water from the Esso-BHP operation at Longford (Mosse 1993). Effluents containing paper mill waste and oil industry waste have been shown previously to cause tainting in fish (Gordon et al 1980; Jardine 1992; and Koning and Hrudey 1992). An investigation of this possibility was deemed appropriate, and a fish taint test incorporated into the EPA licence conditions for the discharge. Experimental Rationale. While

sensory evaluations of tainting have traditionally used the sense of taste, the participation of the public in such assessments raises potential liability problems (Jardine 1992). These problems do not arise if tainting is assessed via the sense of smell. Studies where both taste and odour have been assessed independently (Heras et al 1992, Rasmussen et al 1992, Rounds et al 1992) found no difference in the evaluation of tainting between taste and odour. Poels et al (1988), in establishing a test guideline for the evaluation of fish tainting, found that evaluation by flavour or odour did not have a large or systematic effect on the evaluation. In another study where taste and odour were used separately in an analysis of drinking water affected by Bleach Kraft Mill Effluent run-off, both modes of sensory evaluation led to similar conclusions (Wong et al 1985). Tortora and Anagnostakos (1990) assert that much of what is thought of as taste is actually smell and that a given concentration of a substance will stimulate the olfactory system thousands of times more than it stimulates the gustatory system. It therefore seems reasonable to base Âˇan assessment of tainting on an evaluation procedure using odour rather than taste in circumstances such as these where fish are exposed to a complex effluent. The taint test reported here was therefore based solely on an assessment of the odour of the fish flesh. Earlier studies using odour alone include an investigation of tainting in fuel oil contaminated waters (Williams et al 1991) and in streams receiving pulp mill effluent (Jardine 1992). An exposure time of 72 hours was selected. This period of exposure of fish to effluent is consistent with the recommendations of McLeay et al (1986) and Anon (1987) both of which concluded that a 48 hour period was generally sufficient to elicit a tainting response to pulp mill effluent. Two dilutions of effluent were selected. A 1:75 (1.3%) dilution was chosen since this is the minimum design dilution of the outfall diffuser. A 1:40 (2.5%) dilution was chos~n as an extreme case, being roughly one half the design dilution

of the outfall diffuser. Australian Standard AS 2542 .2.2 (1982) (Sensory analysis of food: The Triangle test.) states that for statistical purposes at least 6 assessors are required for a Triangle test. Poels et al (1988) recommended a panel of 15-20 people representative of the general population of local consumers. Anon (1987) suggested a panel size between 10 and 50, with 20 being considered a reasonable number. Jardine (1992) used panel sizes of 8 and 17 in two separate tests . The power of the Triangle test (its ability to detect an existing difference) depends upon the individual abilities of the panellists to detect a difference between samples as well as on the number of panellists. Our calculations indicated that a minimum panel size of 15 would provide satisfactory power for the test (usually taken as 0.8) provided 50% of the panel had an ability to detect a difference. Our choice of 18 ptnellists (a multiple of 6) obviated the need to discard (as prescribed in the Australian Standard) any triplets of samples, thus avoiding any statistical problems which may be associated with such practice. The Australian Standard further recommends a number of selection criteria for panellists, these being motivation, availability and good health. Jardine (1992) adds the further requirements that the panellists must like fish, must be non-smokers, should not eat or drink at least 30 minutes prior to testing and should refrain from using perfume, aftershave or scented soaps on the day of the test. Jardine (1992) also suggests that there are advantages in using people from the general population rather than trained evaluators.

Materials and Methods Fish. Sand flathead (Platycephalus bassensis) were obtained from Port Phillip Bay, Victoria, using handlines with hooks with reduced barbs. On capture, the fish were transferred to covered 500L black polyethylene bins supplied with flowing seawater. On arrival at the aquarium facilities the fish were trans* Gippsland Water, P.O. Box 348, Traralgon, 3844. WATER MARCH/APRIL 1995

ferred to an outside, shaded, 5000L concrete holding tank supplied with flowthrough, clean, unfiltered seawater at a rate of 120 L/min. After a 20 hr acclimation period the fish were transferred into the laboratory into 90L treatment tanks which were at this stage supplied with fresh flowing seawater. Five fish in the size range 200 mm to 300 mm total length, and in apparently good condition, were allocated to eac h tank without known bias. These fish were then allowed to acclimate undisturbed for a further 50 hours. During this period no fish died or appeared sick or moribund . Effluent. Treated effluent was collected at the discharge point to the Latrobe Valley Ocean Outfall in cleaned 200 L drums which had been thoroughly rinsed with the effluent. The drums were road freighted to the aquarium facility and stored with caps on in an air conditioned room (18-19. 50 C). Exposure To Effluent .. The effluent dosing system was a modified version of the multi-channel gravity operated system describ ed by Connor and Wil son (1972). Sea water and efflu ent were mixed to the required dilution and stored in a l000L polyethylene reservoir from which it was pumped to a constant level header tank. Each treatment tank drew from a separate flow line through a glass flow meter connected to an adjustableheight flow control chamber. Fish were exposed to diluted effluent for a period of 72 hours. The 2 dilutions were 1:40 (2.5%) and 1:75 (1.3%). At the commencement of the exposure period there was a change in colour in the tanks which received the diluted effluent which sta bili se d over the fir st four hour s. There was no noticeable change in the behaviour of the fish over the exposure period. One fish died in one of the 1:40 exposure tanks. All tanks had similar ranges for water temperature, dissolved oxygen and pH (Table 1). Preparation Of Fillets. Fish were caught with a dip net and killed by a sharp blow to the head . The fish were then scaled and filleted and the fill ets from each fish sealed together in a labelled sterile whirl pack and fro zen. Details of the fish according to treatment are given in Table 2. The fi sh used in each treatment were of similar lengths and weights. The sex ratio was biased towards females in each case. Partially frozen fillets from each treatment were thoroughly minced in a blender. Five gram aliquots were weighed and immediately wrapped in aluminium foil packets. A random 3 digit identification code was marked on each foil packet and then sealed in a small plastic bag. Groups of three samples (triplets) were arranged in accordance with AS 2542.2.2 as follows, where A refers to control fish samples and B refer s to WATER MARCH/APRIL 1995

Table 1.Temperature, dissolved oxygen saturation and pH recorded during labora,tory acclimation and experimental exposure trials. Trial

Temperature °C Mean (a.d.)

DiMolved Oxygen % Mean (a.d.)

pH Mean(a.d.)

Control 1:75 1:40

16.6 (0.3) 16.8 (0.4) 16.8 (0.4)

87. 0 (4.1) 86.8 (4.2) 88.4 (3.2)

8.04 (0. 06) 8. 08 (0.02) 8.09 (0. 10)

Table 2.Summary offish data. Treatment

Number of fish sacrificed

Ratio female/male

20 9/1 6/3

14/6 252.7(17 .9) 264.8(24.3)

Total Length(mm)

Weight(g) me&J;l (s.d.)

mean(s.d.) Control 1:7510 1:409

256.5(16.1) 87.5(17 .8) 106.3(30.0)

92.9(19.5)

Table 3. Subjective assessments of the correctly identified exposed samples. Experimental fish sample

Trial

more pleasant 1:75 1:40

no difference

2 1

experimental fish samples: ABB BAA AAB BBA ABA BAB Three sets of the six triplets were prepared from fish exposed to the 1:75 diluted effluent, and from fish exposed to the 1:40 diluted effluent. The se were then stored frozen until the taint test. Assessment Of Tainting. Eighteen panellists were used in the sensory evaluation r ep orted here . Prospective panellists were screened to include only non-smokers and people who enjoyed eating fish. The panel consisted of 10 males and 8 females with an age range of 20 to 70 years and comprised five members of the Ninety Mil e Beach Environment Consultative Committee, five from the Ninety Mile Beach Observation Program, four Victoria University of Technology stud ents, three Victoria University of Technology staff and one Department of Conservation and Natural Resources staff. Panellists were in structed not to use aftershave or pe.rfume on the day of testing and to r efrain from eating or drinking (except for water) for at least 30 minutes prior to the evaluation. In each trial three responses were solicited from each panellist. The first two responses were forced choices while the third was optional. Response 1: Th e panellist was required to select the different sample from the three samples presented . (The so called triangle test). Response f: Th e pan elli st wa s required to nominate whether the different sample was more, equal, or less pleasant than the other two samples. Response 8: The panellist was invited to make any written comments about the sample.

less pleasant

no response

The sensory assessment was conducted in a well lit and well ventilated food technology laboratory. Each of the 18 panellists had a separate seat, set of instructions and record sheet. Samples of fish flesh were heated while in the sealed packs of triplets by immersion in a 60° C water bath for a minimum of 30 minutes. The heated samples were then randomly distributed to the panel. Each panellist was asked to promptly open and smell their allocated sample s in a specified order as.,,prescribed by AS 2542.2.2 and to make the required responses. Separate evaluation trials were conducted for the fi sh exposed to the 1:75 diluted effluent and then fish exposed to the 1:40 diluted effluent. A period of 30 minutes was allowed between these two evaluations. Data from the evaluation trials ·were collated manually and the number of 'correct' responses identified . 'Corre ct' responses were those which identified the different sampl e in each group of three.

Results and Discussion In the trial evaluations, for the fi sh exposed to the 1:75 diluted effluent there were 8 out of 18 'correct' responses while for the fish exposed to the 1:40 diluted effluent there were 3 out of 18 'correct' r esponses. Only one panellist correctly identified the different sample in both of the trials. The Triangle test is based on the assumption that, if there are no differences between the samples, the odd sample of the triplet' will be selected by chance one-third of the time. Reference to the significance table in AS 2542.2.2 showed that the minimum number of correct responses for a significant finding at the 5% level for a panel size of 18 was ten. As the number of correct responses 21

was less than ten in both trials, it was concluded that there was no evidence that the panel could detect a difference between the experimental and control samples for either trial. If there were a real, but largely undetectable difference, it might be reasonable to expect stronger tainting to take place with the more concentrated effluent treatment (i.e. 1:40 dilution), and as a consequence more 'correct' responses to occur in the sensory evaluation for that treatment. That this was not the case, and only one panellist gave a 'correct' response in both trials supports the view t ha t no di scernibl e tainting in fact occurred. The results of the subjective assessment of whether the correctly identified experimental sample was more or less pleasant are shown in Table 3. These results show that there was no cl ear agreement as to the nature of the difference. The correct panellists differentiated between the samples on the basis of the strength of the odour and reported that t he experim ental sample(s) had a stronger odour than the control samples. Had there been real tainting, we might have expected reports of a changed, 'off' or 'chemical' odour rather than simply a different strength odour. Two of the panellists noted that the fish samples cooled down during the evaluation procedure and that warmer samples were easier to smell. In future work it would be advisable to modify the method of presentation of the samples to ensure that all samples are assessed at the required temperature. In summary, the r esults provide no evidence of tainting in fish subjected to the experimental regime and assessment procedures applied here. This is in contrast to previous studie s which found both paper mill waste (Gordon et al 1980, Jardine 1992) and oil indu stry waste (Williams et al 1991; Koning and Hrudey 1992) caused tainting. Such differences in response could be due to the species used, or to the natur e of the waste streams and treatment processes used. They also highlight the risk of extrapolating from one tainting study to another.

Acknowledgement The authors acknowledge assistance provid ed by the Victorian Fisheries Research Institute, the Department of Food Technology, Victoria University of Technology a nd Mona sh Univ er sity Statistical Consulting Service. Mr Rob Niall of Kinhill Engineers Pty Ltd is also thanked for critically reviewing the manuscript.

References Anon (1987) ' Guidelines to method s for the analysis of the effects of effluent on the flavour of fish'. Technical Bulletin No. 513. National Council of the Paper Industry for Air and Strea m Improvem e nt. Madison Avenue, New York. Anon (1982) AS 2542.2.2 'Australian Standard

for the Sensory Analysis of Foods. Part 2 .. The Triangle Test'. Standards Association Of Australia. Connor P M, Wilson K W (1972) A continuous flow dosing apparatus for assessing the toxici ty of substances to marine animals. J. EXJ). Mar. Biol. Ecol. 9: 209-215. Donlon P , Mosse P R L ( 1994) Th e Latrobe Vall ey outfall, a co mmunity mediated solu tion. Water 21: 15-19. Gordon M R, Mueller J C, Walden C C ( 1980). Effect of biotreatment on fi sh tai n t ing propensity of bleached kraft whole mill efflu ent. Transactions of the Technical Section, Canadian Pulp and Paper Association. 6: TR 2-8. Heras H, Ackman R G, Macpherson E J (1992) Tain t in g of Atl antic salmon by petroleum hydrocarbons during a short term exposure. Mar. Poll. Bu ll. 24: 310-315. Jardine C G (1992) Public evaluation of fish taint ing from pulp and paper mill discharges. Wat. Sci Tech. 25(2): 57-64. Koning C W, Hrudey S E (1992) Sensory and chemical characterisation of fish tainted by exposure to oil sand wastewaters. Wat. Sci. Tech. 25: 27-34. McLeay D J, McKague A B, Walden C C (1986) 'Aq uatic toxicity of pu lp mill effluent: a review'. D. McLeay and Associates Ltd. 3001497 Marine Drive. West Vancouver, B.C. V7T 1B8. Report prepared for: Environment Canada, Fisheries a nd Oceans Ca nada, Canadian Pulp and Paper Association and Ontario Ministry of the Environment. Masse P R L (1993) Dilution factors at the Latrobe Valley Outfall. Water. 20: 10-12. Poels C L M, Fischer R, Fukawa K, Howgate P, Maddock B G , Persoone G, Stephenson R R, Bontinck W J (1988) Establishment of a test guideline for the evaluation of fish taint ing. Chemosphere 17: 751-765. Rasmussen T, Skar a T, Aabel JP (1992) Oil tainting of cod. In: 'Quality assurance in the fish industry'. Denmark Ministry of Fisheries. pp359-367. Rounds R C, Gl enn C L, Bush A O (1992) Co nsumer acceptance of brown trout as an alternative species to rainbow trout. J Food. Sci. 67: 572-574. Tortor a G J , Anagnostakos N P (1990) ' Principles of anatomy and physiology'. 6th ed. Harper and Row, London. Williams U P, Kiceniuk J W, Fancey L L, Botta JR (1991) Tainting and depuration of taint by lobsters exposed to water contaminated with a No.2 oil: Relationship with aromatic hydro carbon content in tissue. J Food Sci. 64: 240243. Wong A., Voss RH, Kovacs T G., Dorica JG (1985) Drinking water organoleptic quality as influenced by biologically treated bleached kraft mil efflu ent. J Pulp Pap. Sci. 11: 161166 .

Authors Dr. Peter MoBBe graduated in Bio chemis try and Zoology from Melbourne in 1981 and then worked as a Medical Research Fellow in Melbourne and then as a L ecturer at Monash University, Gippsland. He joined Gippsland Water in 1987 in charge of the Water Science L aboratory. Amongst other responsibilities he supervises the licence requirements and monitoring of the Latrobe Valley Ocean Outfall. Dr. John Kowarski is an environmental scientist with a background of biological research, lecturing, environmental impact assessment and policy developm ent. He has worked in the Victorian Division of Fisheri es and in the Environment Protection Authority. Recently he has established his own consultancy.

Urban Runoff - Review of Data The Cooperative Research Centre for Catchment Hydrology is collating a list of data useful for estimating: • Urban runoff water quantity • Urban runoff water quality • Pollution control pond perfor mance • The impact of changes in physi cal habitat on aquatic flora and fauna in urban areas If you are aware of any data which fit one of the following 8 categories we would very much like to hear from you . A list of these data sets and a discussion of the overall data availability is being compiled and will b e made available to water r esource manager s and scienti sts. Such a list will provide a valuable resource for Australia's urban water industry so please help us make sure it is comprehensive.

• Water Quantity (1) Streamflow in urban areas

(2)Continuou s pluvio grap h d ata (only if collected for more than one year) (3) runoff coefficients determined for urban areas (4) Percent impervious surface area information for an urban area • Water Quality (5) Grab sampling of water quality at sites in urban areas (only if sam piing takes place over a period of greater than one year and at least 12 samples have been taken) (6) Event sampling of water quality at sites in urban areas (only if more than four sampl es were taken during at least one event and an estimate of the discharge over the storm is available)

• Pollution Control Performance

Pond

(7) Data with which it is possible to estimate the load into and load out of a pond receiving sewage or stormwater in an urban or rural area.

• Aquatic flora or fauna (8) Any sampling of aquatic flora or fauna in urban areas. If you have data t hat may fit into one of these 8 categories please contact: Michael Stewardson, Dept Civil and Environmental Engineering, Uni of Melbourne, Parkville, Vic 3052. Tel (03) 344 4709 fax (03) 344 6215 WATER MARCH/APR IL 1995

TECHNOLOGY

STOCHASTIC DATA GENERATION: YIELD ASSESSMENT OF MT BENNET DAM, N.T. JN Paiva* Keywords Stochastic data generation, rainfallrunoff (tropical conditions), streamflows, dam yield estimates

Abstract To assess yields of the proposed Mt Bennet dam for the Darwin Water Supply in the Northern Territory Top End, synthetic annual streamflows at the Mt Bennet dam site were generated from stochastic annual rainfalls in conjunction with a rainfall runoff relationship. The statistics, flow duration curve and dam yields obtained from the generated streamflows were compared with those of annual streamflows, generated stochastically, directly from estimated streamflow records. Generating streamflows via stochastic rainfall was found to be better than those generated directly from streamflow data.

analysis method helps overcome the problem of the dependence of the yield estimate on the starting condition of the reservoir (McMahon and Mein 1986). This paper examines the application of stochastic data generation for the estimation of yields of the proposed Mt Bennet dam, for Darwin Water Supply, in the Top End of the Northern Territory.

Mt Bennet Dam

To meet the increasing water demand of Darwin and its environs, preliminary engineering and environmental investigations were carried out on potential water sources within the Darwin Region (S.M.E.C. 1971). On the basis of these investigations and after evaluation of planning factors of cost, social impact and development potential, three preferred dam sites, namely, Marakkai and Warrai on the Adelaide River and Mt Bennet on Introduction the Finnis River (Figure 1) were selected for detailed investigations (Power and The design and operation of a water resource system depends on the predic- Water Authority 1988). The proposed Mt Bennet Dam is sitution of the future inflows over the economic life of the system. Reliance on his- ated on the Finnis River, 6 kilometres torical streamflow records has several downstream of the Finnis River gauging station at Gitchams (G8150180) . The inherent deficiencies. The historic record dam site drains a catchment area of 1155 is not likely to be repeated in the future. square kilometres. It provides only one sample of possible S.M.E.C., in their reconnaissance surfuture inflow sequences and is insufficient to measure the uncertainty in sys- vey of 1971, estimated the safe yield of tem response that is assignable to hydro- Âˇ Mt Bennet dam by means of storage logic variability. Also, existing records behaviour analysis of 37 years (1941 1977) of streamflow record. The safe may be of insufficient length to provide even one reasonable sample over the eco- yield was reviewed by Stewart and Baker (1987) using estimated monthly inflows nomic life of the system. Stochastic' data generation provides from 1900 to 1984, derived from daily designers with alternative sequences of rainfall records (1900 - 1984) and recorded streamflows (1960 -1976). streamflow for a longer period having the same statistical properties as the historic record. It is then possible to determine Earlier Studies of Stochastic Data Generation in the the design parameter (eg. the dam yield Northern Territory Top End for a given storage) for each sequence, and thus arrive at a distribution for the In a study undertaken to comprehendesign parameter. This process gives an sively analyse timing requirements for idea of the confidence which can be source augmentation of Darwin Water placed on the adopted design value. Supply, Gibb Australia (1984) stochastically generated monthly streamflows for Moreover, in dam yield estimation, Darwin River at Darwin Dam, and in the use of very long sequences of generat- turn, for Manton River at Manton Dam. ed data with the reservoir behaviour The Matalas three parameter logarithmic monthly generating model (McMahon and ' The word 'stochastic' means, according to its Mein 1986) was used to generate stochasGreek origin, to contemplate or to conjecture. In tic monthly streamflow sequences, from hydrology it has been used in a special way to monthly streamflow records at Darwin refer to a time series which is partially random (Linsley et al 1982) Âˇ Dam and Manton Dam, respectively. WATER MARCH/APRIL 1995

Stewart (1986) used Matalas' mome residual approach (McMahon and Me 1986) with, a 3 parameter log normal d tribution (to generate annual flow VI umes) together with the method of fr~ ments, to generate 100 year and 10 ye sequences of monthly flow volumes a1 monthly loss unit data. The generat, monthly data were used to obtain yie estimates of Darwin River Dam and predict the range of possible future mil mum storage levels over periods fro one to ten years. Baker (1988a, 1988 also used the moment residual approa, to generate annual flow volumes in h studies to predict Darwin River Da water levels. To estimate dam yields of the pr posed Warrai and Marrakai dams (Figu. 1), Paiva (1991a, 1991b) used a lag 01 Markov model incorporating a 3 paran: ter log normal distribution, together wi the method of fragments, to generate 5( year sequences of stochastic month streamflows. In all the above studies, streamflo sequences were stochastically generau either from streamflow records, or fro an estimated long term streamflo record (derived from a rainfall runo regression relationship or rainfall rune model). Paiva (1992) reassessed the yields Mt Bennet dam and its associated prot bilities of failure, with increased strea1 flow and rainfall records using stochast rainfall generation techniques, and this the subject of this paper.

Variability and Period of Stream Flow Data

Due to the high temporal variabili of North Australian streams (McMah< 1977, 1979), the period of the availab flow records is too short to define tl long term mean annual runoff at the da sites with any precision. Still longer pe1 ods of streamflow are required for tl definition of statistics such as coefficie; of variation, skew and serial correlation. There are two options for deriving long period of inflow: * by calibration ,of a suitable determini tic rainfall-runoff model with the ava able streamflow and rainfall record, ar then obtaining streamflows from tl model for the period of available rainfall

*NT Power and Water Authority, GPO B, 1096, Darwin NT 0801

* by statistical regression, if satisfactory statistical correlation exists between rainfall and streamflow for the period of common record. Âˇ For the Mt Bennet dam site, attempts to satisfactorily calibrate the USDA rainfall runoff model (USDA 1963) with the available monthly flow records and daily rainfall records were unsuccessful. This was probably due to the highly variable nature of the rainfall, both spatially and temporally, within the catchment. Much of the rainfall is produced by local thunderstorms which do not occur uniformly over the study area at any given time. Therefore, it is possible for a large rainfall to be recorded with no runoff, and conversely, a significant runoff may occur with apparently little rain. This effect increases with distance between the rainfall station and the stream gauging station. Willing and Partners (1989) used the Monash Model (Porter and McMahon 1971) in the Northern Territory Top End. The Monash Model is also a deterministic rainfall runoff model, but unlike the USDA Model it is a conceptual model. It models the rainfall runoff process by simulating the distribution of moisture in the soil subject to several governing parameters and requires extensive calibration. The Sacramento Model (Burnash et al 1973) is another conceptual rainfall runoff model that has been used in Australia. The number of parameters in the model are several and it requires extensive calibration. With the very scanty rainfall data available and the highly variable nature of the rainfall both spatially and temporally within the catchment, it was considered unlikely that the Monash or the Sacramento model would produce results any better than the USDA model, and therefore were not tried. Good statistical correlation was, however, found in the logarithmic domain between Darwin annual rainfalls and annual streamflows at Mt Bennet dam site, for the period of availab le rainfall and streamflow record (Figure 2). The annual streamflow record at Gitchams gauging station was estimated for 100 years (1889 - 1988) from 100 years (1889 - 1988) of annual rainfall records at Darwin using the statistical correlation relationship obtained. The statistics of the estimated annual streamflow record are shown in Table 1. That the estimated mean annual runoff was less than the recorded mean annual runoff was consistent with the results obtained in previous studies for streams in the Top End (Paiva 1991a, 1991b and Stewart 1991a, 1991b). The values of coefficient of variation obtained agreed with those obtained by McMahon (1977) for streams in the Northern Territory Top End. The estimated annual streamflow record (1889 - 1988) was therefore considered representative of the long term variability of flow at the Gitchams gauging station. 24

Stochastic Data Generation To generate stochastic data it is necessary to select an appropriate model, depending on the nature of the hydrologic time series. Stochastic data generation techniques use a set of parameters estimated from historical records as input, and therefore, errors due to insufficient samp le sizes are also reproduced. Rainfall records are generally longer than streamflow records. Moreover, for a given length of historical record, rainfall data display less persistence than streamflow data and consequently each additional observation of rainfall adds more new information about the process than each new item of streamflow. The statistical characteristics of rainfall data are defined more closely than those of streamflow. Therefore, the parameters estimated from rainfall records are generally more reliable than those obtained from streamflow records. Streamflow sequences generated from stochastic rainfall sequences via a rainfall-runoff model would therefore be expected to be more reliable than those generated using streamflow data directly. This is valid only if a good correlation exists between annual streamflow and annual rainfall. Also, obtaining streamflow via generated rainfall does not explicitly preserve the serial correlation in the annual streamflow series and this is a serious limitation for streams with significant serial correlation.

From studies carried out on 15 rainfall stations including Darwin) to cover a range of rainfall conditions across Australia, Srikanthan and McMahon (1985) recommended a lag one auto regressive model (or AR(l), also called a lag one Markov model) incorporating the Wilson-Hilferty (WH) transformation, to stochastically generate annual rainfall values. This model degenerates into a White Noise (or purely random) model when skewness and serial correlation are close to zero. They found that 30 years of data allow the parameters of the model to be defined adequately. StudieÂˇs carried out by Paiva (1991a,1991b) to estimate yields of the proposed Warrai and Marrakai dams in the Northern Territory Top End showed that a streamflow sequence of at least 400 years is required to minimise the effect of the initial starting condition of the reservoir on the yield . A 500 year long stochastic annual rainfall sequence was therefore generated using a lag one Markov model incorporating the WH transformation. The statistics of the generated and historical annual rainfall sequences are shown in Table 2. Using the rainfall-runoff regression relationship, a 500 year inflow sequence for Gitchams gauging station was derived from the 500 year stochastic rainfall sequence. For comparison purposes, a 500 year annual streamflow sequence was stochas-

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Figure 1 Location Map

WATER MARCH/APRIL 1995

generate the 500 year annual streamflow sequence from the estimated annual streamflow record. The statistics of the streamflow sequences obtained from stochastically generated rainfall (500 years) and those of the annual streamflow sequence (500 years) derived by stochastic streamflow generation, have been compared with those from the estimated 100 years (1889 - 1988) annual streamflow record in Table 3. The respective annual flow duration curves are shown in Figure 3. The two sets of generated annual streamflows were disaggregated into monthly flows by the method of fra gments. Using storage behaviour analysis, 5% probability of failure yields were obtained, for different dam full supply

tically generated from the estimated annual streamflow record. Srikanthan et al (1983) studied 156 Australian streams and concluded that 73% of the streams could be modelled using a white-noise model but because most streams exhibited mild positive serial correlation recommended a first order autoregressive model. Also, from a study of 16 rivers (which represented the ranges of streamflow across Australia) to determine suitable distributions for use in the lag one Markov model for generating annual streamflows, Srikanthan and McMahon (1978) showed that the 3 parameter log normal distribution was suitable for an annual coefficient of variation lying between 0.2 and 1.0. A lag one Markov model incorporating a 3 parameter log normal distribution was therefore used to

Table 1. Finnis River at Gidtchams G 8150180 Annual Streamflow statistics

Period

Mean Annual

Runoff MAR

Coefficient of Variation

Coefficient of Skew

Serial Hurst Correlation Coefficient H R1

(ML)

Historical 19601989

340,000

0.58

0.78

0.18

0.74

Estimated 18891988

272,100

0.51

0.71

0.12

0.72

Table 2 Statistic of Darwin Annual Rainfall

Mean Annual Rainfall

Coefficient of Variation

Coefficient of Skewness

(mm)

Serial Correlation R1

Historical (1889-1988)

1579

0.21

0.07

0.09

Generated (500 years)

1575

0.20

0.03

0.08

Table 3. F'innis River at Gitchams GS 8150180 Statistics of Generated Annual Stream flow

Period

Mean Annual Runoff MAR

Coefficient of Variation

Coefficient of Skew

Serial Correlation R1

(ML)

Q90* (ML)

100 years estimated 1889 - 1988

272,100

0.51

0.71

0.12

109,100

500 years via stochastic rainfall

268,600

0.51

0.93

0.10

107,900

500 years stochastically generated from 100 years of streamflow

266,000

0.52

0.95

0.16

114,700

*Q90 values have been taken from the annual flow duration curves, and are commonly used as low-flow indices WATER MARCH/APRIL 1995

leve ls and t h e results are shown in Figure 4.

Discussion and Conclusion It can be seen in Table 3 that the statistics of the 500 year streamflow sequence and the flow duration curve obtained from stochastically generated rainfalls compare better with those of the estimated 100 year annual streamflow record (1889 - 1988), than those of the 500 year streamflow sequence obtained by stochastic generation directly from the estimated streamflow record. Moreover, the yields obtained from streamflows derived via stochastically generated rainfall were up to 15 % higher than those obtained from stochastically generated streamflows, depending on the full supply level of the dam. It is therefore concluded that for the assessment of yields of the Mt Bennet Dam, using streamflows derived from stochastic rainfall data is better than using stochastic streamflows generated directly from streamflow data.

Acknowledgements The author thanks Fred Barlow, the Principal Engineer Surface Water of the Northern Territory Power and Water Authority, for his support and appraisal of the paper, and Lynton Fritz, the Manager GIS of the Water Resources Division, for assisting with drafting. The author also thanks the Water Resources Division of the Northern Territory Power and Water Authority for providing the time fo f preparation of the paper.

References Baker, A., (1988a). 'Darwin River Dam Water Level Predictions for twelve months March 1988 to March 1989'. Water Resources Divi sion. Power and Water Authority, Darwin . Baker, A., (1988b). 'Darwin River Dam Water Level Predictions for the next ten years com mencing 30 November 1988'. Water Resources Division. Power and Water Authority, Darwin. Burnash, R.J .C., Ferra! , R.L. , and McGuire, R.M., (1973). 'A Generalised Streamflow Simulation System - Conceptual Modelling for Digital Computers'. Joint Federal Rivers Forecast Centre, U.S . Nationa l Weather Service and California Department of Water Resources, Sacramento, California. Gibb Australia, (1984). Darwin Water Supply Risk Management Study. Department of Transport and Works, Darwin. Linsley, R.K., Kohler, M.A., and Paulhus, J.L.H., (1982). 'Hydrology for Engineers'. McGraw Hill International Book Company. McMahon, T.A., (1977). 'Some statistical charac teristics of annual streamflows of Northern Australia'. Hydrology Sympos ium, The Institution of Engineers, Australia, Nat. Conf. Pub. No. 77/5, 131-135. McMahon, T.A., (1979). 'Hydrologic characteris tics of Australian streams' . Civil Engineering Research Report, Monash University (Australia), Report No. 3/1979. McMahon, T.A., and Mein, R.G., (1986). River and Reservoir Yield . Water Resources Publications, Colorado.

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Derived from stocMstically generated rainfall 1500 years)

Derived from stochastically generated streamf lo w (500 years)

Derived from estimated stre amflow record (100 years)

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Âˇ Figure 3 Âź TIME ANNUAL FLOW VO LUME EXCEEDED . ANNUAL FLOW-DURATION CURVE AT GITCHAMS G8150180

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FULL SUPPLY LEVEL (m AHD)

MT. BENNET DAM Figure 4

5% YIELD VERSUS FULL SUPPLY LEVEL

Paiva, J., (199\a). 'Warrai Dam Yield Reappraisal' . 'Water Resources Division Report No .53/91, Power and Water Authority, Darwin. Paiva, J., (1991b). 'Marrakai Dam Yield Study'. Water Resources Division Report No.54/91, Power and Water Authority, Darwin. Paiva, J., (1992). ' Mt.Bennet Dam Yield Reassessment'. Water Resources Division Report No.32/92, Power and Water Authority, Darwin. Porter, J.W., and McMahon, T.A., (1971). 'A model for the Simulation of Streamflow from Climatic Records'. Journal of Hydrology, Volume 13: 297-324. Power and Water Authority, (1988). 'Darwin Regiona l Water Supply and Land Management St'rategy 1988 - Consolidated Report'. Power and Water Authority, Darwin . S M E C., (1971). 'Darwin Water Supply Future Source - Appraisal Study'. Northern Territory of Au stralia Department of Transport and Works, Darwin. Srikanthan, R., and McMahon, T.A., (1978). 'A review of lag one Markov models for genera tion of annual flows'. Journal of Hydrology, 66: 1-12. Srikanthan, R., McMahon, T.A., and Irish, J.L., (1983). 'Time series analysis of annual flows of Australian streams'. Journal of Hydrology, 66: 213-226. Srikanthan, R., and McMahon, T.A., (1985). Stochastic Generation of Rainfall and Evaporation Data AWRC Technical Paper No.84. Department of Resource s and Energy, Canberra. Stewart, T.R., (1991a). 'Pine Creek Water Supp ly Dam Site 15' . Water Resource s Division Report No. 27 / 1991, Power and Water Authority, Darwin. Stewart, T.R., (1991li). 'Katherine Water Supply Dams Yield Study' . Water Reso urc es Division Report No . 28/1991 , Power and Water Authority, Darwin. Stewart, B., ., (1986). 'Darwin River Dam Safe Yield Analysis and Minimum Storage Predictive Model'. Water Resources Division Report No.30/1986, Department of Mines and Energy, Darwin. Stewart, B.J., and Baker, A., (1987). 'Mt. Bennet Dam Safe Yield Studies' Internal Fil e Records, Water Resources Division, Power and Water Authority, Darwin. Thomas, H.A., and Fiering, M.B ., (1962 ). 'Mathematical synthesis of streamflow sequences for the analysis of river basins by simulation' . Chap. 12 in Design of Water Resources Systems (A.Maass et al. ), Harvard University, Massachusetts. United States Department of Agriculture, (1963). 'So il Conservation Service: National Engineering Handbook '. Section 4, Supplement A, 'Hydrology', United States Department of Agriculture. Willing and Partners, (1989). 'Pine Creek Region Surface Water Resourc es Assessment'. Northern Territory Power and Water Authority, Darwin

Author J81'0'TM Paiva graduated B.Sc (Civil Engineering) from the Univ ersity of Ceylon in 1969 and in 1977 M.Sc (Water Resources) from Nev,;castle-on-Tyne in 1977. He has worked in Sri Lanka, Nigeria and Singapore on water supply, irrigation and drainage projects, and since 1989 on flood and surface water resources assessment in the Northern Territory. WATER MARCH/APRIL 1995

TECHNICAL NOTE

A NORWEGIAN SUSPENDED-CARRIER BIOFILM PROCESS SM H Jones* Abstract This article introduces the Norwegian-developed KMT process. It has recently been adopted for new WWTP projects in Wellington, N.Z., and Shoalhaven, N.S.W.

Introduction The KMT Suspended Carrier process for biological treatment of waste water has been developed since 1987 by Kaldnes Milj0teknologi (KMT) of Norway in co-operation with the Norwegian research institute SINTEF. Based on biofilm retained in suspended lightweight plastic elements, it has proven to be more effective and stable than traditional technologies. The Anglian Water Processes (Purac) Group of UK and Scandinavia has recently launched the KMT Suspended Carrier (Moving Bed) biological process on the world market. Purac Pacific Pty Ltd, the Australian subsidiary of the Anglian Water Processes Group and sister company to KMT has recently been awarded the major turnkey wastewater projects for Wellington, NZ (municipal sewage) and Australian Paper, Shoalhaven (paper mill effluent).

Description of Process The KMT technology is based on a development of the fixed biofilm principle. The process concept provides a continuously operating, non cloggable biofilm reactor with low head-loss and with a high specific biofilm surface. This is achieved by growing the biofilm (or biomass) on small carrier elements which are not stationary but which circulate with the waste water in the reactor. (Odegaard et al, 1994) The biofilm carrier elements are made from polyethylene with a density slightly below that of water. They are cylindrical in shape with internal and external fins, about 8mm long and 10mm in diameter, and are designed to provide a large protected surface for the biofilm and optimal conditions for the bacteria culture (figure 1). The reactors are filled to a maximum of 70% by volume with biofilm carrier elements, the actual volume occupied by the plastic then being about 11 %. The degree of filling depends on the duty and biological loading requirements. The specific

surface area for growth is effectively 350 to 400 m 2/m 3 at maximum filling levels The biofilm carrier elements are kept in suspension by aeration from diffusers in aerobic reactors or by means of a mixer in anoxic/anaerobic reactors. A screen installed at the outlet of the reactor retains the biomedia elements within each reactor, but the suspension can be . pumped if necessary. The KMT suspended carrier process has been used for both anaerobic, anoxic and aerobic treatment. Because of the retention of the active biofilm within the carriers there is no necessity to recirculate sludge for the simple BOD removal process. For nutrient removal processes, of course, liquor is recirculated from aerobic to anoxic zones, etc. The process was originally developed in Norway in response to the eutrophication, by nitrogen, of the North and Baltic seas and was aimed at enhancing nitrification even in the cold environment of Scandinavia. Figure 2 is a schematic of the nitrogen removal system. Subsequently it has been proven to be more widely applicable, and is effective and trouble-free for waste water ranging from very low pollutant concentrations (COD 100-200 mg/!) up to concentrated industrial waste waters with COD content up to 40 000 mg/I.

Features of the Suspended Carrier Process • Compact - HRT often only 20% of conventional processes. • Easily controllable due to process stability and simplicity

Figure 1 WATER MARCH/APRIL 1995

• Robust biofilm process - stable under large load variations • No sludge return - no sludge bulking • No clogging of reactors • Low loading on the excess sludge separation stage downstream of the biological stage • Flexible reactor design - normally it is possible to use existing reactors/aeration tanks • Easy upgrading of existing activated sludge plants to higher capacity, or for nitrogen removal without additional tankage volume • Low sensitivity to wide temperature extremes

Wellington Sewerage Scheme, New Zealand For all of this century, Wellington NZ has had no effective sewage treatment, increasingly discharging screened sewage directly fnto Cook Strait and fouling Wellington's southern beaches as the city has developed. In 1993, Wellington City Council determined to call bids from prequalified international Water Companies for a Design Build and Operate (DBO) contract to provide sewage treatment and disposal facilities, the preferred concept being the design and construction of new infrastructure, comprising:1. Moa Point Sewage Treatment Works (200,000 EP). 2. Western Sewage Treatment Works (11,000 EP). 3. Sludge Dewatering Plant and Pipeline. 4. Sea Outfall (1.8 km). The operating contract is 21 years from completion of the construction phase. Anglian Water/Purac Pacific was the contractor selected for the scheme, to a capital value of around $A125 Million, their bid for the treatment plants being based on the KMT Suspended Carrier process. The Moa Point STW will utilise a hybrid system, comprising Suspended Carrier first stage followed by Solids Contact Aeration and Return Sludge ·Reaeration. The Wes tern STW will also utilise a hybrid sy~tem, comprising Suspended Carrier first stage followed by an Activated Sludge second stage to complete the BOD rectduion. Average treated effluent standards required are *Purac Pacific, 678 Bridge Rd Hornsby NSW 2077

20 BOD, 30 SS. Both designs proved optimum for these restricted sites, being lowest in land area and capital cost, and more efficient in overall power consumption requirements than the alternative conventional processes considered.

Shoalhaven Wastewater Treatment Purac Pacific has recently been awarded the contract for the turnkey design and construction of the new wastewater treatment facilities for Australia Paper Pty Ltd. at the Shoalhaven Mill, south of Sydney. The plant design is a hybrid KMT Suspended Carrier process and will treat the whole of the mill wastewater, which presently discharges with only primary treatment to the Shoalhaven River. The new EPA licence requires the mill to discharge to full tertiary discharge standards by late 1995. The principal process units comprise:• Balance Tank • Suspended Carrier Aeration Tank (first stage) • Activated Sludge Aeration Tank (second stage) • Secondary Clarifier • Tertiary DAF (for phosphorus removal) • All ancillary plant The plant design capacity is 13 ML/d, influent quality BOD 555 mg/1 and NFR 120 mg/1, and the required treated effluent quality is: • BOD (average) less than 30 mg/1 • NFR (average) less than 50 mg/I • TKN (90%ile) less than 4 mg/1 • P (90%ile) less than 0.25 mg/I Senior technical representatives of Australian Paper visited the KMT installations in Scandinavia, plus other competing processes from Europe and USA (ie. IDAL's and Activated Sludge Selector processes) and ultimately selected the KMT Suspended Carrier process based on lowest capital cost, low operating costs, and greatest process stability and flexibility.

Conclusion The KMT Suspended Carrier process is the latest, most advanced, stable and cost effective process to enter the world market for Biological Wastewater Treatment. Apart from its cost effectiveness on new plant installations, it is ideal for simple upgradings of existing overloaded WWTPs or for conversion to nutrient removal processes. This may be achieved simply by compartmentalising existing tankage, adding the suspended biomedia and retaining screens, and upgrading the aeration capacity.

AE = Aerobe reactors organic+ nitrification NH4-N -> N03-N AN = Anoxic reactors organic+ denitrification NO3-N -> N2

KMT combination process for nitrogen removal Figure 2

Author Stephen M H Jona, BE (Chemical),

Sydney University, is Managing Director, Purac Pacific Pty Ltd. and a Director, Anglian Water International

Pty Ltd. He has been in the Water and Wastewater Treatment industry for over 20 years, specialising in process contracting, design and construction and management.

Have you registered? to attend the AWWA 16TH FEDERAL CONVENTION 2 - 6 April 1995 Over 350 technical papers will be presented in 6 parallel streams: • • • • • •

Wastewater Collection and Treatment Water Supply and Treatment Water Resources and Catchment Management Operations and Management of Water Infrastructure Environmental Quality and Ecosystem Stability Water Industry Policy Management and Financing

TECHNOLOGY

TREATMENT OF PRIMARY TANK SKIMMINGS IN PERTH K Cadee *, M Domurad, G Munns Introduction Primary tank skimmings (skimmings) are one of the most objectionable by-products of conventional wastewater treatment. Skimmings normally only constitute no more than a few percent of the solids removed by wastewater treatment, but treating and disposing of skimmings without nuisance can result in disproportionately high costs. Several different methods of treating and disposing of skimmings have been used in Perth; these are reviewed and recent developments in Perth are described.

Methods of Treatment Anaerobic Digestion. The most common method of dealing with skimmings is to mix dilute skimmings with raw sludge and to treat the mixture by anaerobic digestion. Disposal is then via the same route as the digested sludge. Skimmings are generally highly biodegradable and very amenable to anaerobic digestion and produce a useful byproduct in the form of digester gas. Anaerobic digestion of skimmings has been used at the Subiaco WWTP in Perth since the early 1960's without any major problems for digestion, dewatering or disposal. Subiaco WWTP is located in the western suburbs of Perth and is a conventional secondary treatment plant with a design capacity of 71.5 ML/d. The treatment process at the Subiaco WWTP consists of screening, grit removal, primary sedimentation and secondary treatment by activated sludge. Sludge treatment consists of waste activated sludge thickening by dissolved air flotation, two stage, mesophilic, heated digestion and sludge dewatering by filter belt presses prior to off-site disposal of sludge cake. Dilute skimmings are collected from the four circular primary settling tanks by rotating scum collectors and conveyed hydraulically to two (both duty) Nash pneumatic ejectors which inject into the raw sludge rising main, downstream of the raw sludge pumps. The mixture of raw sludge and skimmings is fed to the primary digesters which operate with a nominal detention time of 14 days at 35Â°C. Some ragging of recirculation pumps and blockages of heat exchangers (mainlywi th plastics) have occurred in the digestion process but these problems have beengenerally manageable. The major adverse impact with this approach WATER MARCH/APRIL 1995

has been that skimmings contribute approximately 15% of the hydraulic load on the sludge digestion and dewatering facility and this represents a substantial capital cost. Incineration. Incineration is attractive in principle as it is a clean and sanitary disposal method with very little residual solids for final disposal (since the volatile content of skimmings is greater than 95% by weight). In practice, incineration is often expensive to construct and operate, messy and has the potential to create air pollution problems unless substantial counter measures are taken. Dewatered skimmings were disposed of at the Beenyup WWTP in Perth in a multi-hearth incinerator prior to 1990, along with dewatered raw and waste activatedsludges. This process was very unstable and led to smoky and odorous emissions. A small dedicated incinerator has been used at the Woodman Point WWTP in Perth since 1983 to burn dewatered skimmings. The flowsheet for this process is shown in Figure 1 and the plant is shown in Figure 2. . Woodman Point WWTP is located south of Fremantle and is a primary treatment plant with a design capacity of 125 ML/d. The process consists of screening, grit removal and primary settling. Sludge treatment consists of two stage, mesophillic, heated digestion with sludge dewatering by centrifuge and sand drying beds prior to off-site disposal of the sludge cake. Dilute skimmings from the four rectangular primary settling tanks are passed through a Franklin/Miller Inc . Model No. 8000 multi-cutter macerator then conveyed by two, (both duty) Comeng Industrial Equipment pneumatic ejectors to an Envirotech-ESP skimmings concentrator. Dewatered skimmings are stored in the concentrator prior to disposal in a small, dedicated Stevenson-Ward incinerator which operates on a batch basis. Performance of the Woodman Point skimmings disposal system has been adequate but it has been expensive to operate and maintain due to a high incidence of blockages and failure of the dewatered skimmings pumps. The installation of the macerator improved the reliability of the system and reduced maintenance costs by $14,000 pa but annual operating and maintenance costs have still been $60,000 pa. Other Methods. Skimmings may

be dewatered and disposed of offsite by either incineration or landfill. This was employed at the 1 ML/d Canning Vale WWTP in Perth prior to its closure in 1987. Skimmings from the 4.8 ML/d Point Peron WWTP are currently bagged and transported to Woodman Point WWTP for incineration. Where lagoons are employed as part of the sludge treatment process, untreated skimmings may be mixed with digested sludge and lagooned. This gives rise to few, if any, adverse impacts in the lagoons. This has been proposed for the 2.1 ML/d Kwinana WWTP as an alternative to the current practice of pumping the skimmings into the anaerobic digesters. Dewatered and dilute skimmings may be tankered off-site for co-disposal with septage or grease trap waste. This method has been employed from time to time in Perth. Dewaterec;I skimmings may create a problem unless the processing is very simple such as lagooning. Dilute skimmings have created less problems but the tankering costs are high. A small trial was conducted some years ago with an animal byproducts processor to blend dewatered skimmings into their existing operations. This trial was hastily ended due to the foul odours emitted from dewatered skimmings.

Recent Developments a, Beenyup WWTP Responding to the difficulties encountered with the incinerator at the Beenyup WWTP, and incineration in general, skimmings treatment and disposal was re-examined with the aim of simplifying and reducing the costs of skimmings disposal. Beenyup WWTP is located north of Perth and is a conventional secondary treatment plant with a design capacity of 75 ML/d. The treatment process consists of screening, grit removal, primary sedimentation and secondary treatment by activated sludge. Sludge treatment consists of gravity thickening of raw sludge and waste activated sludge thickening by dissolved air flotation, two stage, mesophilic, heated, digestion and sludge dewatering by filter belt presses prior to off-site disposal of sludge cake. Anaerobic digestion of skimmings at the Subiaco WWTP has been virtually trouble free for more than three decades *Water Authority of Western Australia 29

PRIMARY SEDIMENTATION PRETREATMENT

SECONDARY SEDIMENTATION

Retum Acttveted Sludge SKIMMINGS EJECTORS

GntOn~te Bunal

Effluent to DISSOLVED AIR FLOTATION THICKENER

SKIMMINGS MACERATOR

SCREENINGS INCINERATOR

Q-ÂˇQT c:=:--i

AshOnsite Bunal

GRAVITY THICKENER

Ocean Outfall Waste Activated Sludge

PRIMARY DIGESTER

c:=:--i

BELT

PRESS FILTER

SECONDARY

DIGEST~

Off-site Dtsprua/

Figure 1. Flowsheet of Skimmings Treatment System at Woodman Point WWTP

and as new digesters had been constructed at the Beenyup WWTP, methods of introducing skimmings into the digester at low cost and without reducing digester capacity were investigated. As waste activated sludge is thickened at Beenyup by dissolved air flotation prior to digestion, it was considered likely that skimmings could be co-thickened with the waste activated sludge. Skimmings were injected into the waste activated sludge main, but to avoid blockages the skimmings were first passed through a multi-c utter mac e rater machine. Two different macerators were trialled with a .fine tooth Mono Muncher found to be the most effective in dealing with "cotton buds" which present the greatest problems with skimmings. The Flowsheet of the skimmings treatment system installed at Beenyup is shown in Figure 4. The modified skimmings treatment system was commissioned in November 1992 and operation has been trouble free and odour-free ever since. There have been no discernible impacts on the flotation thickeners, anaerobic digesters or filter belt presses and for all practical purposes the treatment system has cost nothing to operate. Consideration is currently being given to modifying the skimmings system at the Subiaco WWTP to the same system as employed at Beenyup WWTP.

Summary Primary tank skimmings are a very objectionable by-product of conventional wastewater treatment and are often difficult an.d expensive to treat without causing a nuisance. A variety of different treatment methods have been installed in Perth in the past but none of these methods were without problems. Mixing skimmings with waste activated sludge and co-thickening by dissolved air flotation followed by anaerobic digestion at Beenyup WWTP has been shown to be a cheap and virtually trouble free method of skimmings treatment.

Figure 2. Skimmings Treatment System at Woodman Point WWTP PRI MARY SEDI MENTATION

Acknowledgments The Authors thank the staff of the Wastewater Treatment Section for their kind assistance in implementing the changes to the skimmings systems and the Regional Manager, Headworks and Treatment of the Water Authority of Western Australia for his support.

Authors

Ash On-site Bunal

AshOnSIIB Bum,/

Off-s11e0tsposa/

Figure 3. Flowsheet of Skimmings Treatment System at Beenyup WWTP 30

All the authors are employed by the Water Authority of Western Australia. Keith Cadu is a Supervising Engineer, previously responsible for the Beenyup and Subiaco WWTPs, and currently responsible for surface water sources supplying Perth. Gary Munns is an Engineer, responsible for engineering input and Margaret Domurad is a Senior Engineer with extensive experience in design and commissioning. Both are involved in operation, maintenance and optimisation of the WWTPs. WATER MARCH/APRIL 1995

INDUSTRY NEWS

Yan Yean Water Treatment Plant This, the first Build, Own, Operate (BOO) water project in Australia, was formally opened in December 1994 by the Premier of Victoria, the Hon Jeff Kennet. The opening was attended by a number of notables including Sir Desmond Pitcher, Chairman of the North West Water Group PLC, of UK, the parent company of North West Water Australia, who partnered Transfield Construction in this project. The photograph demonstrates the degree of mutual cooperation and congratulation between Graham Joyce and Peter Horvath, the project managers in Melbourne Water, Dr David Iverach, Executive General Manager - Development, of Transfield, and Graham Dooley Managing Director of North West Water Australia. As outlined in our front cover story, the plant was constructed remarkably rapidly for an infrastructure project in the water field. Yan Yean Water, a joint company of North West Water Australia and Transfield financed, built and will operate the plant under a 25 year contract to take water from Melbourne Water's oldest reservoir, treat it to agreed standards and to agreed supply patterns in the summer season only. The project capital cost was $25M. The maximum treated throughput is 155 ML/d but filter bypass allows up to 210 ML/d. Ten filters of 67 m' each, with 1500mm of filter coal and 200 mm of sand, are used, at a rate of 10.3 m/h . They are backwashed by North West Waters' air/air and water/water system. Alum, polymer, lime, fluoride and chlorine are used to attain the specified quality.

Murray-Darling News Goulburn Valley Salinity. The Commonwealth has handed over $1 million for salinity control work to help ensure the international competitiveness of products from the area around WATER MARCH/APRIL 199!':> â&#x20AC;˘

Shepparton, Victoria. This is the first instalment of $6 million allocated over three years to accelerate construction of stages 5 to 10 of a 31 kilometre surface drainage project in the MurchisonEchuca Drainage Basin at Mosquito Depression. Stages 1 to 4 (about 19 kilometres) were completed in December 1994. The project has been designed to yield the greatest agricultural and environmental benefits for the least cost. It will be linked to natural watercourses in the Depression to recreate the drainage conditions that prevailed before intensive agriculture upset the region's ecological balance. Unless this work is carried out, it has been estimated that rising water tables would cost the region around $50 million a year in agricultural losses by 2000 and $120 million a year by 2020. Landcare Cost Sharing. A feasibility study is to be carried out into the likelihood of financial support being provided for landholders who carry out specific landcare projects in the Murray-Darling Basin. The Commission's Community Advisory Council has suggested that the cost to landholders of landcare projects could be partially offset through government contributions linked to the overall public benefit derived from the project. Computer Mod6l for Irrigation. The Bureau of Resource Sciences is working with the Institute of Sustainable Irrigated Agriculture and the Rural Water Corporation from Victoria, the CSIRO Division of Water Resources, the New South Wales Department of Water Resources and the Murray-Darling Basin Commission to develop a computer package which will allow policy groups and irrigation managers to evaluate various options. , The project is titled Biophysical agricultural production and socioeconomic futures in irrigation regions: a 20 year profile and is expected to be ready for use by 1997. The computer package will use detailed information on groundwater conditions, soil characteristics, climate, landuse, production and financial information collected from the Barr Creek, Harston and Mokanger-Warragoon districts on the Riverine Plains of the River Murray. Using the studies of irrigation activity in these districts, communities will be able to test the impact of changing environmental, production and market conditions on different options being considered for the development of their own areas. Groundwater Maps. A series of maps

has been prepared detailing the flow of underground water in the MurrayDarling hydrological basin, embracing an area extending from near Broken Hill to east of Narrandera and south of Wangaratta to Bendigo and Ballarat and west to Hamilton and Naracoorte in South Australia to Lake Alexandrina. They also include the Darling River drainage basin, which takes in the Darling River from the source of the Condamine River near Toowoomba in Queensland to the Darling's confluence with the Murray on the New South Wales-Victorian border near Wentworth. The maps mark the culmination of a six-year cooperative project between the Australian Geological Survey Organisation (AGSO) in cooperation with the Murray Darling Basi n Commission (MDBC) and State water agencies in Victoria, NSW, South Au stralia and Queensland. They highlight the problems associated with rising groundwater tables and provide an invaluable tool for planners and instrumentalities responsible for the long term future of natural resources in the Murray-Darling Basin. The Murray-Darling Basin Commission estima~s that 500,000 hectares of the Basin is affected by dryland salinisation and another 1-million hectares is at risk because of rising water tables. In additio , it's estimated that by the year 2040 about 1.3 million hectares of irrigated land will be salinised or waterlogged. The 26 map sheets of the Murray Basin Hydrogeological Map Series at 1:250,000 scale, and the Darling River Drainage Basin Hydrogeological Map at 1:1,000,000 scale were produced at a total cost of around $9m. Information: Alan Reid, MDBC tel (06) 179 0189 fax (06) WJ 8058.

WAWA Water Restrictions The Class One water restrictions introduced in Metropolitan Perth, Mandurah and Kalgoorlie on 1 November 1994 had (at 20 December 94) achieved a 9% reduction in water consumption compared to last summer (the target being 10%). Negligible rainfall in November and so far in December is however not helping with the achievement of the target. An extensive marketing and communication strategy appears to be having the desired effect with ,77% of people knowing that WAWA wants them to achieve a significant water saving, and also being able to quote that the target saving is 10%. The next phase of the campaign will concentrate on savings to be made by watering lawns and gardens effectively 31