Water Journal March 1984

ISSN 0310-0367

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Official Journal of the

" M•~ii;M•M:lf.!Mi=l;E1:l•J W4-i i :f.Wi i=I ;E--J.i•It) Mi [I]~ 1 Registered b A Y ustralia Post -

publicat1·0 n no. VBP 1394

IVol. 11 , No. 1, March 1984 .

$2.50

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FEDERAL PRESIDENT F. Bishop , Scott & Furphy , 390 St. Kilda Rd ., Albert Park , 3004

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FEDERAL SECRET ARY F. J. Carter, Bo x A232 P.O. Sydney South , 2001.

Official Journal of the - ~A~u~s=T=RA ~L ~l~ A~ N WATER AND WASTE WATER ASSOCIATION

Vol. 11, No. 1 March, 1984

FEDERAL TREASURER J. H. Greer, C/- M.M.B.W. 625 Lt. Collins St. , Melbourne, 3000.

BRANCH SECRETARIES Canberra, A .C.T .

J. E. Dymke , 4 Story St. , Curtin , 2605.

Office 062 (54 1222)

New South Wales D. Rus sell , Camp Scott & Furphy , · 781 Pacific Highway , Chatswood 2067. (02 412 2688)

Victoria J. Park , S.R.W.S.C. Operator Training Centre, P.O . Bo x 409, Werribee, 3030. (741 5844)

Queensland D. Mackay, P.O . Bo x 412, West End 4101. (07 44 3766)

CONTENTS Viewpoint ................................ . .. . ...... .

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Association News, Views and Comment ................ .

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New South Wales State Water Plan and Water Use Efficiency -M. Lindner and C. Creevey ............... . ...... .

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Storage and Salinity Works for New South Wa les in the 1980s -M.A. Watts . . .. .... ...... ...... . .... ........ .. .

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Keeping the Murray Clean - The Role of the River Murray Commission -K. E. John son . . . .... .. ..... . . ... . ............. .

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Calendar and Book Reviews .......... . ... . .... ... . . .. .

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Technical Interests .. . . .. ..................... . . . .... .

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Plant and Equipment

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South Australia A. Glatz, State Water Laboratories , E. & W.S. Private Mail Bag, Sal isbury, 5108. (259 0319)

Western Australia

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R. Loo , 455 Beach Rd ., Carine, 6020. (09 447 6550)

Tasmania G. Nolan, 21 Browne St. , W. Hobart , 7000. (002 28 0234)

Northern Territory G. Sleeman , P.O . Bo x 37283 Winnellie, N.T. 5789. (089 81 5772)

EDITORIAL & SUBSCRIPTION CORRESPONDENCE G. R. Goffin , 7 Mossman Dr., Eag lemont 3084 03 459 4346

COVER Glennies Creek Dam on Glennies Creek in the Hunter Valley is the latest multi-purpose storage to be completed by the Water Resources Commission of New South Wales. With a Storage capacity of 283 000 megalitres, this dam will supply the water needs associated with the planned development of the extensive coal resources of the Hunter Valley and for further irrigation.

The dam was opened by the Premier, Mr Wran, on the 9th December, 1983. At the time of this photograph, Glennies Creek Dam had filled to only 3 per cent of its capacity.

The photograph shows the unusual curved formation of the dam's concrete faced earth and rockfill embankment. The intake tower, on the right, will allow selective withdrawal of water from the storage enabling greater control over the temperature and quality of releases.

ADVERTISING Miss Ann Sykes , Appita, 191 Royal Parade, Parkville 3052.

03 347 2377

The statements made or opinions expressed in 'Water' do not necessarily reflect the views of the Australian Water and Wastewater Association, its Council or committees .

New South Wales State Water Plan and Water Use Efficiency M. Lindner and C. Creevey 1. INTRODUCTION

In New South Wales a number of State and local authorities share responsibility for water-related services such as the provision of water for urban and rural uses and the protection of water quality and natura l aquatic environ ments . In 1976 the Water Resources Commi ssion Act made the Water Resources Commission responsible for coordinating the management and development of the State's surface and groundwater resources. The Commission retained the responsibility of its predecessor, the Water Conservation and Irrigat ion Commi ssion , for rural water supply but also assumed new responsib ilities including flood mitigation in the the non-tidal reaches of rivers and the monitoring of water quality.

State-wide water planning began in 1982 when it became apparent that the valley and project-based planning undertaken until that time would no longer meet the needs of either the community or the Government. Conditions were changing. Intensifying competition for .water and funds and more concern with the preservation of natural env ironments were part of this change.

For example, in the Hunter Valley competition for water became particularly acute during the 1979-83 drought when irrigation, industry and other urban uses competed for limited water supplies. Embargoes on the issue of irrigation licences on the State's regulated strea ms and the number of frozen applications for such licences reflect the importance of water to irrigators and would-be irrigators. The water needs of the Macquarie Marshes, which emerged as a matter of public concern in 1979 when the Commission proposed water regulatory works, illustrated another conflict, that between the interests of irrigators and the maintenance of natural aquatic environm en ts. These interests are not necessarily in conflict but the 'best' deci sion when an Australian ecosystem is affected is often difficult beca use not enough is known about how our ecosystems work or about how water diversion for consumptive uses might affect them.

Funds for the Government to provide the goods and serv ices society need s and expects are always limited and today are spread over a wider range than 50 years ago: welfare, education, hospitals , public transport, the a rts . The spreading - thick here, thin there - reflects society' s values and perceived needs as expressed through its government.

While so me government authorities are self-fu nding, others are not, and if responsible for the provision of serv ices they mu st compete for the limited funds available. Within the water industry itself, the supply of water to rural areas and country towns, flood mitigation work, salinity co ntrol and other functions is each important; the difficult task for a government is to determine priorities and to ensure that its funding reflects these .

The Commission is preparing a State Water Pla n to help the Government resolve questions about the allocation of water and of funds within the water industry. To do this the Plan must: • recognise all interests in water • review the serv ices now provided by water authorities and the problems associated with each • examine options to overcome these problems and to meet or modify needs • formulate alternative programmes that would suit a range of likely future demands for water, budgets and conditions - such as technological innovations and changes in the markets for agricultural products - most of which are beyond the water planner' s co ntrol.

The Water Utilisation Council, and advisory body to the Commissio n representing 11 government bodies with significa nt interests in the water industry and the Treasury, is assisting the Commission with the State Water Plan . Its members originally helped define the scope of the Plan and the issues that they believed it should address. They also contributed information, for example, on the natural resources of Michael Lindner, Manager, State Water Plan and Coralie Creevey, Scientific Officer, Water Resources Commission of New South Wales.

the State and their significance to water use and quality. The Council is reviewing Plan documents as they become available.

The Government recently initiated a water management audit to review organisational effectiveness and efficiency in the water industry. This a udit will complement the State Water Plan.

This article defines the Plan's functions and identifies the important iss ues associated with water that studies to date have indicated face water authorities and the community generally in the 1980s. It then focuses upon studies , initiated for the Plan, that look at the opportunities to make better use of already available water supplies. In particular the paper discusses an area that is now receiving a lot of attention , not only from water authorities in New South Wales and other States but around the increas ingly urban world: urban demand management.

2. FUNCTIONS OF THE ST A TE WATER PLAN

To provide a sound basis for public comment on proposed priorities in the allocation of funds and water and for Government decision on these priorities, the State Water Plan will: • summarise data on the sources, volume, quality and reliability of surface and groundwater • review the historical, economic, social, environmental, legal and institutional context within which the Plan must work in order to establish an understanding of the present state of water management, development and use, and to help formulate effective strategies for the future • identify factors likely to affect future water demands, such as population growth, markets for rural output, pricing policies, technical innovations a nd public attitudes, and, using this information , make alternative forecasts of what these future demands may be • identify key issues and emerging problems associated with water; explore their sig nificance and consider their importance from a State-wide perspective • identify alternative strategies by which problems may be overcome and the alternative forecasts met; evaluate their likely impacts in terms of State goals of efficiency, effectiveness and equity in the management of natural resources • present recommended alternative strategtes for public comment.

3. KEY ISSUES IN THE 1980s

The functions listed above were formulated to ensure a comprehensive review of the important issues identified by the Commission during the early work on the Plan. The identification of these issues was assisted by contributions from other government authorities and environmental and water-user organisations.

The significance of the issues identified below springs from their frequent interaction and relationships with each other, and from the broad environmental and development and management to date which has sometimes ignored , and sometimes been unaware of, these complex interactions and relationships. It stems also from the importance of water in all aspects of our lives - from earning a living on the land to industry, in the disposal of wastes, to our recreation and health, and in both natural and man-made environments.

Hence these issues, which were categorised by Mr Allan Mclachlan of the Water Resources Commission in his address to the Australian Water and Wastewater Association Summer School in Canberra on 9th February thi s year, relate to the equitable distribution of the right to use water, to maintaining its quality for consumptive and natural purposes, to recognising the land-water nexus, and to the need for research and monitoring of water related problems.

3.1 Financial Issues

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The key financial issues relate to : the problems associated with a squeeze on public funds generally while working expenses continue to increase in real terms WATER March, 1984

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th e problems associated with historical cost accounting such th a t prices charged for se rvices do not refl ect tru e costs revenues do no t ma ke a sufficient co nt ributi o n to new cap ita l wo rks excessive reli a nce o n loan funds results in high in teres t repayments inadequa te fund s a re ava ila ble for replacements a nd renewa ls of structures and work s.

3.2 Pricing and Allocation Policies

Incentives mu st be provid ed to users to conserve wa ter and in crease effi ciency. A pro blem here is tha t ma ny past inves tments were justified o n social a nd not economic grounds (as will ma ny fu ture in vestments no do ubt) a nd cannot pay th eir way witho ut major a nd un acceptable impacts on bo th the user community a nd society generall y. However , a distin ctio n mu st be made between pay- for -use pricing regimes whi ch may not recover fu ll costs but th a t still pro vide in centives fo r efficiency, a nd user-pays regimes which attem pt to reco ver full costs fro m users .

3.3 Increased Customer Attention and Invol vement

Public interest in the water industry will continue to increase a nd mu st be accommodated .

3.4 Co-ordinated Land and Water Resource Management

The ma nagement of la nd a nd the management of water resources a re increas ingly in conflict alth o ugh very cl osely rela ted in na ture.

3.5 Increased Efficiency in Water Use

As supply becomes limited, tec hnologica l, a nd perha ps orga ni sati o na l, ad va nces are needed to imp rove effi ciency. T his may in cl ude the re-use o f water.

3.6 Adequate Provision for In-stream Uses and the Protection of Water Quality

These will become more impo rta nt as conflicts a bo ut water use increase .

3. 7 Data Collection and Research A major impedim ent to proper ma nagement o f a ' ma ture' water in du stry will be th e lac k of inform a tion a bout a vaila ble water , the cost of providing wa ter (parti cula rly groundwater) a nd a bout t he dema nd s for water use. Research fund s will be ava ila ble to study o nly the major issues fac ing wate r ma nagers.

3.8 Commonwealth Government Involvement

The Commonwealth 's role will be of signi fica nce to t he future of the indu stry. Its finan cia l co ntribu tio n to project develop ment , resource ma nage ment , data collection , etc. ca n influ ence th e directi o n the industry tak es over th e nex t 10 yea rs . In additi o n , ma ny of the above issues have inter-State d imensio ns which mi ght need Common wealth co-ordi nati o n fo r their reso luti o n .

T wo furth er issues o f major significa nce, rela ted to the o ther iss ues by competition fo r publi c fund s, res ult from Australia ' s hi ghl y vari a ble rainfall.

stab ilisati o n , the preparati o n o f fl oodpla in maps, a nd th e da ta co llectio n a nd pla nnin g necessa ry to avo id da mage.

4. WATER USE EFFICIE CY

Three stud ies have bee n don e in thi s a rea, th e fifth o f th e key issues identi fie d above. Th ey have conce ntra ted upon th e opportuniti es to use water mo re effi cientl y a nd effectivel y in three a reas: • urba n : home, in d ust ry, park s a nd gardens • the conveya nce of water fro m da ms to rural users • ir ri gation .

The fir st a rea is most full y discussed here because o f its releva nce to the readers of Water. Brief reference onl y is made to con veyance a nd irri ga ti o n efficiency.

U rban Demand Management

Th e Urban dema nd ma nagement st udy sought to assess opportunities fo r in creasing effi ciency in urba n wa ter reticula tio n a nd use. It did thi s by assessing d ocum ented overseas a nd A ust rali a n ex per ience throu gh di scuss ion with wa ter a uth o riti es in New South Wales.

Doc um ented Australian ex perience was limited : it rela ted mostl y to a pplyi ng restricti o ns durin g d roughts to ma ke the avail a ble suppli es go fu rther.

Greater effi ciency in urba n water use ca n be ac hi eved pa rtl y by ma king people con scious o f t he cost of wa ter so tha t t hey ca n va lu e it a nd ma ke informed decisio ns a bou t t heir use of it. Mo re reali sti c water prices or pricin g stru ct ures will not prevent peo ple using water fo r essenti al a nd hig hl y-va lu ed purposes (such as personal indoor uses) but it may alter con sumptio n for o th er purposes such as hosing paths, car was hin g a nd garden wa terin g. It may a lso pro mote the ado ptio n of o th er meas ures such as more wa ter-efficient appli a nces, native gardens a nd du al fl ush to ilets.

When sho uld a water suppl y a uth o rity seek to a lter th e prevailing dema nd ? In simple terms, thi s should be necessary onl y when cha nges in consumption occ ur fa ster t ha n the suppl y system ca n res pond . In a n expanding system , thi s problem ca n occur fro m ti me to time for a variety o f reasons - fro m pla nning a nd co nstru cti on lags a nd lead times , to lack of fund s to con struct work s. In ge neral, two situa ti o ns can a ri se: insuffi cient source capacity or insuffi cient trea tm ent a nd/or ret icul atio n capacity.

The potenti al benefit s of urba n dema nd ma nage ment include lo wer wa ter treat ment a nd suppl y costs a nd t he deferral of ex pensive new capital works . A ll o f these could contribute to lower ; ate increases for most co nsumers. Such ma nagement also postpon es th e social a nd environm ental di sturba nce often associated with new constructi o n.

T he urba n dema nd ma nagement stud y emphasises th a t a water co nservati on strategy needs to suit the ph ys ical"a nd social conditi ons of each community. Exa mpl es of dema nd ma nagement are now disc ussed .

T he Hunter District Water Boa rd faces problems simila r to ma ny Australia n urba n water supply a ut horities . Infla ti o n a nd th e cos t of bo rrow ing capital have coin cided with a growing popula tion a nd in-

3.9 Drought Management

From th e 19th to the mid-20th century wa ter ma nagement aimed to drought-proof the country. Economic pragma ti sm suggests th a t drought-proofing is a n unreali stic, even a n una ttaina ble, goal.

Econo mic stud ies have show n that irrigation da ms become uneconomic wh en operated to provide protectio n aga in st drgught by carryin g la rge volumes of water o ver from one season to a noth er . The benefit s gained in drought years a re fa r o ut we ighed by th e benefi ts fo regone in norm al years . This is because th e da ms can supply mu ch more water on average when operated to re- regul a te water within a season . Droughts will undoubtedly occur in th e 1980s a nd low-cost ma nagement strategies will be needed to deal with them .

3.10 Floodplain Management

On ce again the cha llenge will be to find a nd commit fin a ncia l and oth er res ources to the protecti on of li fe a nd property, ri verba nk 14

W A TER March, 1984

Fig. l. Dethridge outlets constructed to measure a water supply from the Coleamball y Irrigation Area to a group of landholders.

creased industrial demand. The communit y ex pects high quality, reli ab le water but resists rate increases . The Board is therefore attempting to co ntain the demand for water and co ncurrently increase the efficiency of the existi ng supply system through pay-for-use and leak . reduction.

Equ ity was a major cons ideration in the Hunter Board' s introducti on of pay-for-use. It had found that under the land value rating sys tem: • 5,500 hou seholds in low valued properties who used water carefully paid $ 1.00 per kilolitre for their water , wh ile • 500 households a lso in low valued properties who squandered water (using four times as much as the typica l consumer) paid $0.30 per kilolitre, and • 1,000 hou seholds in high valued properties who used water ca refully paid $2.30 per kilolitre while • 230 households in high va lued properties who sq uandered water (using five times as much as the typical consumer) paid $0.30 per kilolitre.

Under the land va lue rating system from which such inequities flowed, th e consumer's water bill was not related to water use and there Fig . 2. Use of treated sewage effluent on golfcourse greens and fair-· was no way consumers could decide whether they valued some uses as -ways. much as their consumpt ion indicated. For example, many people may The actions of these three major supply authorities show that water . not think that hos ing down dri veways is a waste of water until they are authorities and water use rs can respond sensibly to the financial , in a position to decide that sweeping the driveway wou ld save them ph ysical and other constraints which are unlik ely to diminish in the money. A water bill based on pay-for-use puts them in this position.

1980s.

The new system has two parts: a fixed charge to cover each user's share of the yearly cost of owning the Board's assets - its plant and Whi le it can be seen that the introduction of more realistic water charges has a significant effect on water demands, it may not be possi-. equipment. Such cos ts are incurred independent of use. The fixed ble or practical in every situation to rely on water price to a lter the charge remains based on land value - 1.33 cents in the dollar of land prevailing levels of demand. Therefore, consideration of other poss ivalue - but the Board intends to change thi s to a flat dollar charge. ble mechanisms for water managem ent is of major importance to the The fixed charge for non-residential users will be based on capacity to State Water Plan, as they may expand the range of means avai lable to obtain water, that is, on pipe size, so that big users will pay a higher achieve better use of existing water supplies. Therefore the urban defixed charge than small users. mand management study examined demand and supply management The seco nd component is a volume-related or variable charge to .options including: cover the Board 's management , maintena nce and operating costs.

Stopping Leaks. A significant proportion of water supplied can be This is presently $0.45 per kilolitre. lost in the supply system , much of it through leaks. The Hunter Pay-for-use pricing provides an incentive to consumers to use water District Water Board found that over 30 per cent of water supplied out efficiently. The Hunter Board hopes to iss ue water bills quarterly so that people ca n clearly see how much water they are using and how of its main water sources goes 'unaccounted for' . About half of this much it costs them . Metering is essential. was due to leakage . Therefore, maintenance of the supply system is ' vital.

The introduction of pay-for-use pricing, combined with the effects of the economic recession and th e recent drought , reduced water conPressure Reduction may a lso help reduce leaks. This appears an opsumption among the Board' s consumers 28 per cent in the first year. tion for the larger towns of New South Wales where variations in terrain cause excessive pressure or where long trunk mains are used and The Board expects this to level out at about 15 per cent. This will defer water is held in these under pressure. ,headworks augmentation for at least five years, probably more.

Garden Watering . Residential garden watering is responsible for Since 1978 the Perth Metropolitan Water Authority has also about 50 per cent of the yearly residential water consumption and adopted pay-for-use water charging for residential properties . The price structure comprises a uniform service charge to cover a small more than 80 per cent of peak day summer demand . In the 1970s, it ' free' all owance of 150 kilo li tres and a volume charge per ki lolitre of generated the highest growth in water consumption but is has proved, water consumed above that. T he volume charge is now $0.36 per at least during drought, to be the area where major reduction in use kilolitre. Non-residential services continue to pay under the previous can be achieved. land -value system . However, it is intended to progressively change thi s The Melbourne and Metropolitan Board of Works has popularised to a pay-for-service/ use charging system . The introduction of pay-fordrip watering of suburban garden s to promote more effective and effiuse caused a dramatic drop in water consumption - about 30 per cient garden watering. This confines the app lication of water to the cent. Some customers made adjustments of a permanent nature, parplant' s root zone rather than deluging the foliage of a ll plants in the sprinkler's circumferences rega rdless of their need for water. ticularl y in relation to methods of garden watering and the introducIn the long-term, a reduction in ga rden watering may require a tion of native species. However, others sunk wells for garden irrigachange in the type of plants grown . Trial low-water-usi ng gardens tion so the overall reduction in water consumption may not be so have been planted in the Pilbara by the Forests Department of dramatic.

The Melbourne and Metropolitan Board of Works also recently Western Australi a and water use data from this may be instru ctive. considered options in demand management. The Board is in a situaThere is some doubt as to the acceptability of native gardens to the tion where Melbo urne's demand is growing at about 3 per cent per public: a public information program might be necessary to encourage year, finance for new works is limited and the best sites are already a change in attitude. Of course, it should be remembered that not all dammed. It has concluded that water gained through increased effi-' natives need little water, and not a ll exotics are forever thirsty.

Toilet Flushing. Of domesti c in-house water uses, toilet flu shing. ciency is the cheapest source of extra water and is progressively implementing a series of demand management measures. For example, seems to offer the greatest opportunity for conservation at the least cost and inconvenience to consumers. It has been demonstrated in the more efficient garden watering techniques are being promoted .

The Board recognises that an effective strategy may take years to United States that free hand-outs of water cistern dams to co nsumers paid for itself within a year. Although the greater flushing volumes in achieve: changing commun ity attitudes, introducing more efficient appliances, a new pricing structure and town planning strategies are the United States present greater opportunities for sav ing water, it is not accomplished overnight. However such a strategy can help avoid considered that the installation of low-flush volume or dual-flu sh toilets should be encouraged and may be expected to save up to 15 per another water crisis: since the I 981 -82 drought the Board's slogan has been 'You will never be able to take water for granted again'. cent of in-house water use. Victoria is now considering making dual WATER March, 1984

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flush units compulsory for all new and replacement toilets. The possibility of reducing flu shing volumes is also being considered.

Water Using Appliances such as washing machines a nd dishwashers offer the second greatest opportunity for domestic conservation with. least inconvenience to consumers . Savings of up to 12 per cent of inhouse use are possible by re-designing appliancs so that they use less water. Similar savings in industry and commerce could also apply.

Melbourne authorities are considering putting water efficiency tags on appliances. These would be similar to the energy efficiency ratings now used.

Demand reduction ach ievable from other domestic in-house uses appears to depend on consumer attitudes as much as on the use of any particular technique . For instance, flo w control devices on shower heads will reduce consumption but a greater savin g could result from people spending less time under the shower . This is, however, a matter of individual decision and prefere nce.

Water Re-use. Recycling domestic grey water - bath water, dishwater etc. - while being worthwhile in particular circumstances, is not considered generally applicable or acceptable in New South Wales at present.

Industry already achieves a significant saving in consumption by using reclaimed water, particularly in recycling processes . For example, the iron and steel industry re-u ses water 20 to 30 times. In contrast, because of organic material in their waste water, the paper and brewing industries re-use only once. But economics and consideration · of discharge standards are encouraging re-use. Re-use by rural indu stry is also widespread.

The use of treated sewage effluent shou ld be encouraged. Many towns throughout New South Wales already use such effluent to irrigate golf courses, gardens and parks. The Task Force on the Use of Reclaimed Water suggested that many more could. Extended use of irrigation and the recharge of water aquifers appears worthwhile, particularly in areas (which rely significantly on groundwater. In Victoria a pilot scheme to \eticulate reclaimed water to vegetab le growers is under consideration.

Dual supply systems, provided for potable and non-potable water to be provided through two separate pipe networks . While generally considered to be uneconomic at present, such sys tems are becoming more acceptable in other countries. Countries like Hong Kong and Gibra ltar can point to a history of dual supplies with no adverse effects. For new developments, pa rticularly in industrial areas where water of lower quality may be acceptable, the benefits of installing dual supplies should be assessed at the design stage. This would greatly increase the use a nd acceptability of this type of system. However the potential health hazard of dua l supplies must be examined.

Public Information Programs are most effective if designed to inform people of local conditions and how specifically their behaviour interacts with these. But the best advertisements will be undermined if people see public authorities splashing water about or continuing to plant exotic gardens. The Melbourne and Metropolitan Board of Works considered public information so important that it established a unit to inform people of water saving measures.

Conveyance Efficiency

Becau se water is conveyed from 15 major rural dams to users along 12 500 km of rivers and through 8000 km of mostly open channels and bore drains, one must expect losses of water to occur. The study of conveyance efficien cy identified where and how these losses occurred and what cou ld be done about them. The best opportunities to save water were considered to be : • telemetering streamflows so dam releases can be more accurately matched to needs • debiting irrigators' annual allocations by the amount of water they order from storage rather than by the volume of water they actually divert . This would assist in reducin g water losses caused by over

16

WATER March, 1984

ordering. However, the suitability of this method to part icular river vall eys as well as its acceptability to water ~ers needs assessment • more re-regulation weirs and lakes at key sites could save much water but more detailed engineering, economic and environmental studies are req uired • metering of sur face and groundwater di vers ions to provide information esse ntial to managing the use of th e State's water.

Irrigation Efficiency

First, an explanation of terms will help .

The term irrigation efficiency referes to the performance achieved by irri gators in minimizing water losses during on-farm distribution and application, matc hing water applications to crop needs, and combining water and other inputs (including fa rm management expertise) in ways which maximise biological output. Irrigation efficiency, therefore , is a composite of several concepts of efficien cy relating to various stages of the process of agric ul tural productio n.

Engineering efficiency relates to phys ical aspects of the irrigation system; it can be meas ured as the ratio of wate r diverted to the water ultimately used by the plant.

Biological efficiency is measured (for individual crop types) as the ratio of actual output (tonnes per hectare or per megalitre) co mpared with the yields th at could be obtained under optimal irrigation practices on th e basis of 'best farmer' and experimental yields.

The concept of irrigation efficiency ca n be extended also to incorporate an economic aspect wh ich takes into account the level and value of irrigated output and the costs incurred in producing it.

Case study ev idence coll ected for the State Water Plan investigation of irrigation effi ciency in New South Wales shows that there are marked differences between the ' most ' and 'least' effi cie nt irrigators, both within regions and across the State. This suggests that there is real potential for average efficien cy levels to be li fted, thereby perm itting a significant expansion of agricultural output from the water now available for irrigation. Strategies through which th ese potential improvements may be realized include: • improved farm layout • on-farm water harvesting and drainage re-use • further research on biological aspects of irrigated agriculture • extension services to improve water and crop management.

Such options will be investigated and evaluated as part of the ongoing process of water planning in New South Wales.

5. CONCLUSION

Some of the State Water Plan's recomlijendations may be controversial and opposed by so me groups. We therefore cannot ex pect everyone to welcome changes which, althou gh just and reasonable, might mean less water and press ures to use it more efficiently in some sectors. Water is money, a nd if there was no conflict and controversy over it we would not need a State Water Pla n.

The Plan will help the government to resolve these conflicts rationa ll y, with a view to the long-term prosperity and health of the community and its human and natural environm ents, by providing a sound and comprehensive information base. This article's identification of key issues and survey of the studi es in water use efficiency which have been undertaken for th e Plan wi ll , it is hoped, indicate to readers that the Plan is relevant and practical for N .S. W. in the 1980s and beyond .

6. ACKNOWLEDGEMENTS

Contributions to thi s paper by Andrew Amos, Jan Eberha rdt and Des Cleary of the State Water Plan Task Force are gratefull y acknowledged.

STORAGE AND SALINITY WORKS FOR NEW SOUTH WALES IN THE 1980s M.A. Watts 1. INTRODUCTION

The Water Co nservation and Irrigation Comm iss ion of New South Wales was established early thi s century to develop the state' s water resources for irri gation and other rural uses. In 1976 the Commission's charter was broadened to encompass overall responsibi li ty for the management and development of water for all purposes and to include the review and co-ordination of the storage proposa ls of other authoriti es, statewide water planning , flood plain and catchment man agement and the assessment and contro l of water quality.

Conseq uent ly it was reconstituted as the Water Reso urces Commission.

Since 1913 the Commission has built 15 major water storages within New South Wales, and has been party to three on its border river system s, to improve the reliability of rural water supplies. Most of these storages were completed during the 1960s and 70s to provide for the requirements of an expanding irrigation industry.

At the start of this decade, faced with a continuing downturn in the economy, it might have been expected that major water storage construction would be seve rely curta iled . However the State Government 's $200 million water resources program has enabled the Commission to finish one major multi-purpose water storage - Glennies Creek Dam at a cost of nearly $47 million; almost complete another - Windamere Dam at a n estimated cost of $56 million and begin construct ion of a further two important water conservation works to meet the new and changing water needs of this decade enlargement of Glenbawn Dam ($45 million) and Split Rock Dam ($47 million).

In addition State and Commonwealth funds have been provided to enable the Comm ission to begin construction of the WakoolTullakool Sub-surface Drainage Scheme ($27 million) and the Berriquin Surface Drainage Scheme ($40 million) to control salinity and drainage problems in the Murray Valley. The location of these major storages and the areas in which the salinity works are being carried out are shown on Figure I and their sco pe, purpose and so me of their more interesting technical detail s are now described.

2. WATER STORAGE CONSTRUCTION 2.1 Glennies Creek Dam

This dam, the first project to be comp leted under the government' s $200 million water resources program, was officially opened by the

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I I Legend

A Dam •

Irriga t ion Area 01s t

cJ lmgat 1on

Figure 1

LOCALITY

PLAN

M. A. Watts, Senior Engineer Planning Branch, Water Resources Commission of New South Wales.

Premier on 9th December 1983. Construction work began on this dam in August 1980.

In February 1979 the Comm iss ion published its 'Prelimin ary Plan for Development of Water Resources in the Hunter River Basin' which assessed that the planned expansion of coal mining and power generation, and the attendant population growth in the valley, could result in a more than doublin g of water demands by the end of the century and could require a se ries of new water storages. Glennies Creek Dam, the fir st in this series of new storages, is the second major storage in the upper Hunter Valley. Glennies Creek Dam will add to the wate r reso urces available from Glenbawn Dam whi ch was compl eted in 1958 to provide water for mainly irrigators and towns along the Hunter River .

Although Glennies Creek Dam is a multi-purpose storage and will supply water for power generation, coal mining, town s, stock and irrigators, more than half of the addit ional water available to the upper Hunter system will be used by power stations and coa l mines . Building a dam as a large indu stria l water source was a relatively new direction for the Commission and required different operational strategies.

Unlike irrigation, water for industrial purposes needs to be provided at a high reliability. For thi s reason, the water availab le from the dam had to be estimated in term s of its sa fe yield. The Commission has assessed that Glennies Creek Dam, once fully operational, wi ll be capable of suppl ying an additional 65 000 megalitres per yea r during severe drought cond itions.

Glennies Creek Dam is a concrete faced rock fill dam with a storage capacity of 283 000 megalitres. This is the largest storage that cou ld economically be built at the site and of interest is the fact that, because of the topographical conditions, it was less expensive than construction of a smaller storage.

The geology of the dam site also proved to be a major factor in the design of Glenn ies Creek Dam and led to it s unu sual 535 metre long curved wall. This curved formation, seen clearly in the photograph of the dam on the front cover, was necessa ry to avoid a 10 metre thick bed of non-welded tuff and so provide a sound fo rmation for the upstream face of the dam which is concrete faced. Non-welded tuff is a volcan ic rock whi ch is highl y susceptible to weather in g.

Similarl y the spillway excavat ion , which provided all the rockfill for the dam embankment, was located and oifentated to ensure that the harder welded tuff wou ld be obtained and that the cutting would not encroach upon the underlying zo ne of non-welded tuff.

The co ncrete face of the dam was laid in just seven weeks. The 12 metre wide slabs were constructed using . a sophisticated slip form travelling on rails and electricall y winched from the top of the embankment. The concrete was delivered by way of a chute arrangement from the embankment crest to a conveyor belt on the slip form. Reinforcement mats were placed by a trave lling gantry. Work was carried out around the clock, seve n days a week, with only every 14th day off.

The completion of the dam on sc hedule in just three years was a major achievement. The dam began storing wa ter in August 1982 , but because of contin uing dry cond iti ons, it had filled to only 6 per cent of its full capac ity by February I984.

Glennies Creek was one of the fir st dams to be subjected to a forma l Environmental Im pact Statement. It was assessed that the dam would have little adverse impact on the existing natural environment. The land had a lready been significantly altered by the long-estab lished farming activit ies and no rare native fauna or flora species still existed in the area. The only animal of note , althou gh not rare, identified during the fauna survey was a native Tiger Cat. It was considered that little of the habitat of this species wou ld be destroyed by the storage and that suitable habitat existed nearby . . Water in the lower layers of large reservoirs can be very cold and problems of deoxygenation and nutrient enrichment can occur .

Safeguards developed to maintain water quality and to protect the downstream aq uatic environm ent were the inclusion of destratification equ ipment and a control tower with vari.ab le level outlets. This allows the better water, in terms of quality and temperature, to be WATER March , 1984

17

selected and released from the dam . The outlet tower can be seen on th e cover photograph.

Glennies Creek Dam will provide an important recreation al amenity. When full , the storage will have a surface area of over 1500 hectares with conditions varying from sheltered inlets to areas with reac hes up to five ki lometres lon g. The lake will provide opportunities for sw imming, fi shing and boating.

Glenn ies Creek Dam was completed at a cost of nearly $47 mi ll ion and emp loyed up to 200 peop le during its construct ion . At its open ing last December, the Premier commented that the dam will play an importan t ro le over the next decade in ensuring that industry in the Hunter Region wi ll be ab le to re-assert its industr ia l muscle and maintain its economic leadership of N.S.W. 2.2 Glenbawn Dam

The government' s $200 million water resource program has allowed the Commission to make an immediate start on the next project in the Hunter Valley to follow Glennies Creek Dam - the enlargement of Glenbawn Dam .

A start on the en largement of the dam by the end of 1983 was essential to ensure that there would be no shortfall in supplies to water users during the latter part of this decade. The Commission's studies have shown, that although Glennies Creek Dam has only just been completed, the projected water requirements assoc iated with the ind ustrial development of the Hunter Valley, cou ld exceed the combined yield from the Glennies Creek Dam and the existing Glenbawn Dam before the end of the 1980s. Detailed in vestigation s identified the raising of Glenbawn Dam as the most cost-effective and environmentall y acceptable means of providing additional water in the upper Hunter Valley.

TABLE 1: GLENNIES CREEK DAM TECHNICAL DETAILS General Infor mation Location Catchment Area Average Annua l Inflow

Glennies Creek, 25 km north of Singleton 233 sq km 62 000 ML

Reservoir Storage Capacity

283 000 ML

Ma in Embankment Type Height Crest Length Crest Width Fill Volume Concrete Volume

840 000 m 3 13 000 m 3

Spillway Type Crest Lengt h Volume of Excavation

Uncontrolled, unlined rock cutting 37 m 790 000 m3

Ou tlet Wo rks Type

Outlet Capacity

Concrete faced rockfill 67 m 535 m

6m

Reinforced concrete intake tower , steel main conduit a nd steel bypass in concrete tunnel, and fixed dispersion cone valves in dissipater at downstream end of tunnel.

4700 ML/d at Full Supply Level 3850 ML/d at 30% storage.

The ex tstmg Glenbawn Dam on the Hunter River was one of Australia's fir st major earth and rockfi ll dam s when comp leted by the Commission in 1958. It is 76.5 metres high wit h a conservation storage of 228 000 mega litres and a flood mitigation storage of 132 000 mega litres . Apart from Burrendong Dam on the Macq uar ie River, G lenbawn is the only other Commiss ion storage that has a flood mit igation component. Glenbawn Dam is now approaching full commitment in meeting the existing town, domestic, stock, irrigation and industrial need s along the upper Hunter River.

The Commission intends to raise the embankment height to 100 metres by the mean s of an earth and rockfi ll cap . This is feasible beca use the ex isting embankment was made quite broad in crosssection , about 500 metres at its widest point, to accommodate both a zone of weak rock uncovered during the foundation investigation and 18

WATER March, 1984

GLENBAWN

" ,. ~ ., 10 DAM ENLARGEMENT 1 Figure 2 -.,,,,._..,,,..._.,,,, """'

the use of a high proportion of cheap earth and gravel fi lls. A crosssection of the ex isting and proposed en larged embankment is shown on Figure 2. The raising will more than treble the dam' s conservation capacity, bringing it to 75 000 megalitres . At the sa me time the dam 's flood mitigat ion function will be retained by providing an ai r space of 120 000 megalitres.

Enlarging the dam is expected to cost about $45 mi ll ion. Bes ides raisin g the embankment crest level, the project will invo lve construction of a new spi ll way, enlargement of the di scharge works, modification of the out let works and new access road s.

The current spi ll way will be blocked by a 35 metre high earth and rockfi ll saddle dam and the new spillway will have an uncontrolled ogee crest located on the floor of the original rock fi ll quarry.

The design of the outlet works for a dam en largement is an engineering chall enge. T he existing low level outlet works wi ll be retained with some renewal. The existing bypass in the diversion tunnel will be upgraded and a new auxi liary outlet in the tunn el connected to the storage by an inclined shaft . As the existing dam does not allow for selective withdrawal of water, a full height intake tower will also be constructed over the new auxiliary out let. The Commission will then be able to re lease water from either outlet or take a mix of water from both the old tower and new higher level intakes resulting in an improvement in the quality of releases from the dam.

Raising the storage level will also require 1.5 kil ometres of the public road fro m Scone to the dam to be relocated and construction of a new access road to the spi llway area, T he ex isting recreatio n amenities on the foreshores of the storage wi ll also be partially submerged by the new lake and will need to be relocated or replaced.

Major objectives during the raising of the dam are to ensure that the dam operates uninterrupted allowing present demartds to be met, flood s to be mitigated and recreational use of the storage to continue.

Th e existing out let will therefore continue to operate as a regulating and flood control outlet until the embankments are at sa fe levels, the new spillway is operative and there is am(Jle water in storage to operate the new auxiliary outlet. The existing outlet will then be closed and remedia l work, involving strengthening and replacing of some parts, wi ll be carried out.

Pre liminary site work began in September 1983 and the contract for the ma in wall was awarded in Febru ary 1984 . T he project is expected to be completed in 1986, An important side benefit of the dam is that it wi ll directly emp loy up to 280 peop le over the two years of peak construction act ivity and will generate a furt her 500 jobs in support industries . In addition G lenbawn Dam is already a popular touri st and recreational area and the larger storage will enhance its attraction.

Because of the extent of the land acquired for the existing dam, very little additional land is needed and so the enlargement will not have a major impact on land use. The additional capacity can also be ready for sto rage much sooner and with far less impact on the environment than a new dam at another site. An indicator of its public acceptance is the Environmental Impact Statement which was pub licly displayed early in 1982 and drew no objections.

Of course the most important benefit of the en largement is that it will prov ide an addi ti onal 60 000 megali tres of water per year to the Hunter system. T hi s wi ll bring the total sys tem safe yield by the end of this decade to 280 000 mega li tres per year as shown below: Combination of Dams Glenbawn Da m + Glennies Creek Dam + Glenbawn Da m Enlargement

System Yield (ML/yr)

Increment (ML/yr)

155 000 220 000 280 000

65 000 60 000

...

l

Bes ides a high sec uri ty of supply, the q uali ty o f the water provided is a n im po rta nt factor for users . T he Co mmi ssion has been mo nitoring water q uality in the H unter Valley since 1968 and co llecting data from over 100 locat ions. From this data .a nd the deve lopment of watec q uality models the Commission has been ab le to assess t he likely quality of water in its storages .

Bo th Gle nnies C ree k a nd Gle nbawn Da ms are in that part of t he Hun ter Va lley whi ch contains the best qu ality water - ranging from 25 0 to 500 mi crosemi ens per centim etre (uS/ cm) . T he qua lity of wa ter is dependent on th e sur face geology o f th e vall ey. W hi le most waters a re less tha n 1000 uS/cm, in t he a reas associ ated with P ermian ma rine st ra ta base fl ows may be as hi gh as 20 000 uS/ cm . Gro undwater entering th e Hunter River a ppea rs to be the maj o r cause of sa linity in creases a lo ng the ri ver .

Releases fro m G lenbaw n Dam a lready decrease t he sa li nity of river fl ows. G len nies C reek Da m will also co ntrib ute lower salinity water and therefore have a significa nt effect o n decreasi ng the sa linities along the ri ver and consequently will improve water supplies. Increased releases fro m th e enl a rged G len baw n Da m are also expected to suppress sa line gro und water flows to t he river a nd prov ide increased dilu tion .

Bo th da ms will be a ble to provi de wa ter fro m vari o us levels and will have dest ra tifi cati on equipment . Destrat ifi cati o n will be achi eved with co mpressed a ir a t a rate of up to 180 li tres per seco nd delivered thr o ugh recovera bl e fi xed ae ra t io n hea ds . At p rese nt wate r tempera tures below G lenb aw n Da m a re depressed by mo re th a n 2°C T A BLE 2: GLEN BA WN DAM EN LARGEMENT TECH NICA L D ET A ILS Ge nera l Information Location Catc hment Area Average Annual Inflow

H unter River, 14 km east of Scone 1300 sq km 175 000 ML

Reservoir Conservat io n Storage Flood Storage Co nserva tio n Sto rage Flood Storage

228 132 750 120

Main Embankment Type Height : Ex ist ing Raising Total Crest Length Crest Width Fi ll Volu me: Existing Ra ising Total Concrete Vo lume

Zoned Earth and Rock fill 76.5 23.5 m 100 m 1130 m 6m 7 648 000 m3 3 085 000 m3 IO 733 000 m3 1314 m3

Spillway Sadd le Dam Type Height Lengt h Crest Width Fi ll Volume

Zoned Eart h a nd Rockfi ll 35 m 585 m 6m 379 000 m3

Spi llway Type Crest Length Volume o f Excavation Volume o f Concrete

Concrete Side Chan nel 191 m 4 1 600 m3 29 600 m3

Auxiliary Outlet T ype

Out let Capac ity

Existing Low Level Outlet Out let Capacity

000 ML 000 ML

Ex isting Dam

OOO ML

Enlarged Da m

000 ML

for up to 50 kilometres . Thi s tem pera tu re defi cit will be removed o nce the enl a rged da m becomes opera ti o nal.

Although t he most d ra matic growt h in water req ui rements has occurred a nd wi ll occur in the H unter Va lley, in the inla nd regio ns of the State there is also strong press ure for furt her water storages to expand rura l production.

2 .3 Windamere Dam

Co nstru ction of Wi nda mere Da m o n th e Cudgegong Ri ver , 140 kilo met res upstream of th e wa ll of Bu rre nd o ng Da m , was a uth orised

by P a rli a ment in I 970, but work o n the proj ect was delayed unti l recentl y beca use of lack o f fund s.

Acq uisiti o n of la nd began in 1973. T hi s was fo llowed by some site wor k between 1974 a nd 1976 which was carri ed o ut by day la bour supervised by Co mmission staff. Durin g this same period , local co un ci ls a lso started work fo r the Com m issio n o n the di version of a sect ion of a main road which is to be in unda ted by t he da m.

However it was no t unt il 198 1 that the State Go ernment was ab le to commit su ffic ient fu nds towards the project to allow contracts to be awa rded for the river diversion works a nd the ma in em ba nkment . T he mai n em bankment, a conventiona l ea rth a nd rockfi ll structure 67 metres hi gh with a ce nt ral clay core, was substanti all y comp leted by Dece mber 1983 . Wo rk is now progress ing on th e in stalla ti o n of t he o utlet valve wo rk s a nd th e co nstru ction of a n eight span co ncrete access bridge across th e spi ll way excavati o n . All work , includ ing site resto ra tion , is plan ned to be completed by the end of 1984. Th e fin a l cost o f t he da m is estim a ted a t aro und $56 milli o n .

Win da mere Da m was scheduled to commence sto rin g water by mid Septe mber 1983 but the storage was de layed by th e need for more intensive grou ting of fa ul ts a nd shears in the fl oor of t he river valley. A second deep grout curtai n o ne metre upstream of t he original had to be provided across t he 140 metre wide river bed. The a mount of cement inj ec ted in to the fo undation , some 95 000 bags, far exceeded expectations a nd req uired a two shift operatio n by the co ntractor.

Because of poss ible seepage through th e grou t curta in , a bla nket fil ter was placed on t he 40 met res of fo und a ti o n under the rock fill immed iately dow nstream of t he clay core to prevent was h o f fin e fo unda ti o n ma teria l int o roc kfi ll voi ds . Th e da m commenced storing water in Fe brua ry 1984 .

Ano th er major pa rt of the work in vo lved in t he Winda mere proj ect was the re locati o n of a sect io n of Trunk Road 55. T he 15.5 kil ometres of new ro ute generally traverses the hills to the west o f the storage area but crosses an arm of t he storage at Li mestone Cre~k. T he road co nstruction in vo lved major earthwo rks incl ud ing cu ts up to 23 metres TABLE 3: WIN DAMERE DAM TECH NICAL D ETA ILS General Informati on Location Catchm ent Area Ave rage A nnu al In flow

Cudgegong Ri ver, 23 km sout h east of Mudgee 1067 sq km 54 000 M L

Rese rvoir Storage Capacity

353 000 ML

Main Embankm ent Type Height Crest Length Crest Widt h Fill Vo lume

Eart h and rockfill 67 m 825 m 8m I 640 000 m3

Spillway Type Crest Length Vo lum e of Excava ti on

Rein forced concrete intake tower, steel main penstoc k in inclined shaft leading to fixed dispersion cone valve.

2200 ML/d at Full Su pply Level

7400 ML/d max .

5000 ML/d operating.

Outlet Works Type

Outie! Capacity

Uncont ro lled, un lin ed roc k cutt in g 130 m I 060 000 m3

Re in fo rced concrete intake towe r, steel main conduit and steel bypass in concrete tu nnel, and fixed dispe rsion cone valves in dissipator at downstrea m end of tun nel.

2100 ML/ d at Fu ll Supply Level 1800 ML/d at 30% storage.

WATER March, 1984

19

deep and an embankment at Limestone Creek 28 metres high. The Department of Main Roads and the Commission jointly designed and funded the deviation . The new section of road is half a kilometre shorter than the old route and includes 6.8 kilometres of slow vehicle lanes. The road was opened to the public in December 1982 and the deviat ion is considered a major improvement in the road network.

Five kilometres of secondary road between Cudgegong and Rylstone were also relocated.

Windamere Dam wi ll be ab le to store 353 000 megalitres and provide an average of about 30 000 megalitres per yea r of regulated flow in the Cudgegong River to provide for the need s of a variety of users .

It will enable the expansion of irrigation in the highly fertile Cudgegong Valley , provide water for riparian landholders a long the river and improve water supplies to the towns of Mudgee and Gulgong which often face summer water restri ctions and water quality problems. Additionally the storage capacity of the dam has been sized so as to allow releases from Windamere Dam to Burrendong Dam to maintain the security of supply to users along the Macquarie River .

As a t the majority of the Comm ission 's dam s, a recreation area along the foreshores of Windamere Dam is likely to be developed. A st udy by consultants has estimated that over I 38 000 peop le a year would visit Windamere Dam if it were developed as a State Recreation Area.

There is a great demand for additional regulated flow in the Namoi Valley . Keepit Dam on the Namoi River was completed in 1960 and irrigation development was so rapid that just seven years later irrigators in the va lley agreed to a vo luntary a ll ocation scheme - a sys tem of sharing the limited water available.

2.4 Split Rock Dam

This dam on the Manilla River, an upper tributary of the Namoi River , was authorised by Parliament in October 1974 but lack of ongoing funding delayed progress on the project.

Spli t Rock Dam will now be completed under the State Government 's water resources program. In December last year the Premier, Mr Wran, set off the first explosive charges at the site. This multipurpose 66 metre high concrete-faced rockfill dam is expected to take five years to complete at a cost of around $47 million. The dam wi ll have a storage capacity of 372 000 megalitres and will provide an add itional 66 000 megalitres per year to the Namoi Valley.

Cotton is the main crop irrigated in the valley and, wh ile cotton growing in the Namoi has been one of the state' s most successful rural indust ries, its development has reached the lim it which can be supported from the presently deve loped surface and groundwater resources of the Valley. In the main cotton growing areas, the water table has been significantly lowered by groundwater pumping and a Restricted Sub-surface Water Area has had to be declared to contro l . . gro undwater use.

The demand for irrigation water alone is such that the entire yield from Split Rock Dam could be used immediately. In addition, augmentation of supplies to Manilla, Barraba and Tamworth is a poss ibility. Extensive coal deposits have been found in the va lley and the development of coal mines and power stations will no doubt follow.

While the dam is being constructed the Commission will be undertaking st udies to determine the most efficient allocation of water from Split Rock Dam . Options identified include combinations of: • giving more secure irrigation supplies for the estab li shed cotton in du st ry in the Namoi Valley ; • a llowing the development of additional areas of intensive cropping in the Mani ll a and Namoi Valleys; • . providing a reserve of water for the augmentation of supplies for Manilla, Barraba and Tamworth and for town s along the Namoi River; • supplying possible future industrial development.

Sp lit Rock Dam will be operated in conjuction wit h Keepit Dam to maximise the flow availab le in the Namoi Valley. Releases wi ll be made co ntinuou sly from Split Rock Dam to sati sfy requirements along the Manilla River and Namoi River to Keepit Dam. However, Keepit Dam, being the most down stream storage, wi ll be drawn on fir st to meet demands along the Namoi River. This will minimise spillage from the storages . Keepit Dam wi ll sat isfy all downstream demands until the storage is depleted to about a quarter of its conservation capac ity. At this point the water surface area of the lake will be reduced to abo ut 40 per cent and releases from Split Rock will be in20

WATER March , / 984

TABLE 4: SPLIT ROCK DAM TECHNICAL DETAILS General Information Location Ca1chment Area Average Annual Inflow

Manilla Ri ver, 28 km upstream of Manilla .

1660 sq km 120 000 ML

Reservoir Storage Capacity

372 000 ML

Main Embankm ent T ype H eight C rest Length C rest Width Fill Volume Concrete Volume

Concrete faced rockfill 66 m 480 m 6m 1 000 000 m 3 12 150 m3

Saddle Darn T ype Height Lengt h Crest Width Volume of Fill

Zoned earth, weathered rock a nd gravel 20 m 2800 m 4. 7 m 789 000 m3

Spillway T ype C rest Length Volume of Excavation Volume of Co ncrete Outlet Works Type

Outlet Capacity

Ungated ogee crest with partially lined chute

96.5 m 1 072 000 m3 6280 m3

Reinforced concrete inta ke tower, steel main conduit and steel bypass in concrete tunnel, and fixed dispersion cone valves in dissipator at downstream end of tunnel.

6400 M L/d at Fu ll Supply Level 5000 ML/ d at 30% storage.

creased to supplement regulated flow s downstream of Keepit. The new operational procedures, besides being the most efficient, will also all ow longer recreational use of the storages in dry years.

Split Rock Dam was proposed in the early 1970s a's an earth and rockfill dam. However, since that time, concrete faced rockfill dams have proved to be a more economical method of construction when the foundations are sound. The dam has now been designed for this method of co nstruction. " To date work has begun on th·ree ki lometres of access road and bridge works and work is shortly to commence on the construction of a saddle da m. The saddle dam will, when completed, form a significant embankment in itself. It will be over 2.8 kilometres long, fill three natural saddles and reach a maximum height of 20 metres . Two of the three natural saddles, whi ch occur about 3.5 kilometres north-west of the site of the main wall, will be filled fir st. These two sections of the saddle dam will be used to retain only flood surcharges, while the third wi ll hold part of the dam's storage when full. The main dam contract, including filling of the last of the saddles, is expected to begin in July this year.

Split Rock Dam will play an important part in easing unemployment in the still economically depressed rural sector . Direct employment on the project will build up to an average of 230 over the two and a half years of peak construction activity. During that period effects generated by the project can be expected to maintain a further 450 jo~ . .

As with all new Commiss ion storages, Split Rock and Wmdamere Dams will be provided with multi-level offtake and destratification equipment to assist in maintaining water quality and protecting the downstream aquatic environment. It has been assessed that nutrient concentrations in the stored waters should be generall y low and that algal blooms should be uncommon. The Commission has water quality monitoring programmes for each of its new water storages .

3. SALINITY WORKS 3 .1 General

The Commission also has a role in detecting and monitoring diffuse

or non-point sources of pollution. The most signifi cant problem to occur to date, and one that has required immediate remedial measures, is that of rising watertables and consequent waterlogging and land sa lini sation in some of the Irrigation Ar_eas and Dist ricts of the Mur-. ray Valley.

High water tables now occur in the Berriquin a nd Wakool Irrigation Distri cts and the Tullakool Irri gation Area which are located on the riverine plains of the Murray Valley. These plains are characteristi cally flat, have poor na tural drainage and overlay groundwaters that are inherently saline.

These irrigation projects were estab li shed as early as 1933 to stabili se the existing wool and wh eat production by allowing a small part of each holding to be irri gated . Because of the low intensity of irrigation proposed, they did not incorporate provision for drainage.

However, over the years, with the subdivision of the la rger holdings, the emphasis shifted from wool growing and basically dryland agricu lture to fat lamb production on irrigated pastures and crops such as rice and winter cereals. The Southern Ri verina Irrigat ion Districts now use a major portion of N .S. W" s share of the water of the Murray River.

Waterlogging occurs if the watertable ri ses into the plant root zone and is usuall y associated with intensive irrigation and heavy rainfall.

This not only reduces crop yield s, but can also lead to pla nt death.

Land salini sation occurs when salts accumulate at th e surface or in the main root zo ne. With high watertab les saline water is drawn into ¡ the root zone by capillary action and after evapotranspiration processes a residue of sa lt is left behind. Sa linisation, in the form of a sa lt crust on the surface, can be found in low lying irri gated areas, however, it is most prevalent on dry land within irri gation areas as irrigation app lications help to leach out th e sa lt.

Two methods are available to counter the deve lopment of high watertab les - gro undwater pumping as a reclamation measu re, a nd sur face drainage as a preventative measure . The Commission is using the fir st method to combat salinity problems in the Wa kool Irrigation District and Tulla kool Irrigation Area and the second in t he Berriquin Irrigation District. Both schemes will protect the qua lit y of the Murray River by preventing saline waters from these areas entering the system.

3.2 Wakool-Tullakool Sub-surface Drainage Sc hem e

Waterlogging and soil salinisation appeared in the early 1950s in the low lyin g areas of Wakool and spread at a n alarming rate. The Wakool-Tullakool Sub-s urface Drainage Scheme was devised to reclaim and protect a total of about 47 000 ha in the Tullakool Irrigation Area and th e surrounding Wakool Irriga tion District. It involves lowering the water table by pumping groundwater from underlying sandbed s by means of a series of 42 tube wells with electrically driven pumps . The saline effluent is piped for di sposal to evaporation areas, which consist of concentrating bas ins and smaller crystalli sing ponds for salt production .

In Stage I of the Wakool -Tullakool Scheme, the saline effluent enters the evaporation basin from a pipeline under the road and flow s by gravity through one pond to the next becoming in creasingl y saline as more of the water is evaporated. The sa lt is to be harvested from the crystalli sation ponds at the cent re rear of the basin.

Work began on Stage I of the Scheme in 1979. Comprising 23 tube well installations, it has been operating since January 1982 and Stage II is now under con struction. The area of influence of Stage I alone is about 13 800 hectares, within which a fa ll in the water ta ble has occurred in about 8000 hectares and further lateral sp read has been arrested.

In the last 12 months about 8 100 megalitres of water containing 155 000 tonnes of salt have been pumped from beneath irrigated farm s within t he scheme. It is expected that commercial salt harvesting from the crystallising pond s by a priva te contractor wi ll commence next summer .

The Stage I pipelines, which vary from 200 to 900 millim et res in diamete r and ex tend over 48 ki lometres, were speciticall y designed to resist saliniti es of up to 50 000 parts per million (ppm) which is 1.5 times that of seawater.

Stage I has been completed at a cost of some $9 million and to date $5 million has been spent on Stage I I. A further $ 13 million wi ll be required to compl ete the schem e over th e next three yea rs.

3 .3 Berriquin Surface Drainage Scheme

The Berriquin Irrigation District , which covers an a rea of 325 000 hectares, did not become a ffected by hi gh watertab les until around 1970. Groundwater ridges have now developed under the two main pr ior st reams deri ving their water from direct percolation through the light tex tured soil s. Under na tural condit ions gro und water levels were some 30-40 metre below the surface a nd input by rainfall was counterba la nced by na tural groundwa te r dissipation. Irrigation has increased water inputs to such a n ex tent as to destroy the equilibrium conditions a nd estab li sh a new d ynami c set of ri sin g ground wa ter conditions .

To reduce water logging, surface drainage works are to be const ructed for a ll 1316 farms in the Berriquin Irri gation District. Th e Berriquin Surface Drainage Scheme in volves excavation of a network of drains along th e natural depress ion s throughout the Dist ri ct. The drainage system will run parallel to the present suppl y chan nel sys tem which follows genera ll y the areas of hi gher relief. In thi s way suppl y a nd drainage waters will gravitate t hrough the Distri ct wit h the minimum of disturbance.

Work on th e drainage sc heme began in 1980 and is bein g implemented progress ive ly, concentrating first on those a reas worst affected by surface wate rloggin g. The overall sc heme is estimated to cos t in excess of $40 million . To date some $5 million have been spent on drainage works.

An important sid e benefit of the sc heme is that th e co llection of drainage water will mak e more usable water available in the Murray Ri ver system . The Commission monitor s the flow s emanating from the drainage sc heme from both quali ty a nd quantity aspects. Water quali ty data obtained so far show typical drainage waters to have a salinit y of about 200 ppm wit h much lower va lues during periods of heavy rainfall runoff. No water qua lit y problems a re therefore ex pected from th e introduction of drainage waters to the Murray River system .

The Commonwea lth Government is co ntributing 5°0 per cent of the capital cost of th e Berriquin and the Wakool-Tulla kool Schemes, while the schemes will be operated and maintained as part of the District works.

4. THE FUTURE

The State Government's $200 million water resources program has enabled the Commission to fini sh one major multi -purpose storage and to accelera te the construction of anot her three important works.

Th ese storages will be operated in conjunction with the Commission's ear li er works in each va lley to maximi se yields and to supply a range of users, including irrigators a nd riparian la ndholders as well as towns and indu stries.

Some $65 million will be spent this decade on the construction of two salinity control schemes . Th ese salinit y schemes will not only protect a nd reclaim valuable agricultural la nd in the Murray Valley from waterlogging and land salini sation , but also protect th e qualit y of th e Murray River water by preventing salt from entering the river system.

The sto rage a nd salinity work s described in this pa per are examples of the new era of multi-p urpose water resource developments. Th e Commission is now preparin g a State Wa ter Plan which will indicate li kely direction s for the future developm ent of the state's irri gation industry and water resources.

WATER March, 1984 21

KEEPING THE MURRAY CLEAN The Role of The River Murray Commission K. E. Johnson A n edited version of the address to Th e A nnual General Meeting of Th e NS W Branch, A ugust 1983.

1.

INTROD UCTION

Th e centra l issue of water qua lit y ma nagement of the Ri ver Murray was bro ught into sharp fo cus by a pro posa l of th e Victo rian E nviro nment Protect io n Authori ty to lice nse a woo l sco uring plant to discharge waste int o the ri ve r. After carefull y consider ing the proposa l, the Ri ver Murray Commission ca me to the view th at there were feas ibl e alternati ve mean s of waste di sposal av ailable to the Company con cern ed whi ch would not in volve di scharge of was te to the Ri ve r, a nd so th e Commi ss io n prepared to appeal aga inst the E. P. A 's decision to grant thi s licence. In th e event , the Victoria n E. P .A. dec ided th at it di d not have the right to issue a licence to disc harge waste to a New South Wales strea m, and the Co mpa ny decided to look elsewhere fo r a site for its proposed woo l scourin g pl ant.

The most import ant outcome o f thi s incid ent was th at it led the Ri ver Murray Commi ssion to consider its water quality poli cy . At its meeting in Ma rch 1983, the Commi ssio n noted th at th e impact o f th e wool scour proposal o n th e water quality of the Ri ver Murray was not of major signifi ca nce in itself . It wo uld o nl y add abo ut 200 tonnes of salt per a nnum to a sectio n o f the river where salini ty was already very low. However, recogni sing the possible lo ng-ter m impli cation of allow in g a large number of small in crement s o f pollutants to be added to the ri ver and particularly in view of th e la rge amo unts of expenditure being in vested by governm ents and oth ers in projects to reduce salt entering the Ri ver furth er downst ream , th e Co mmissio n agreed that it must o ppose thi s proposa l.

T he Commmiss ion's view was that governments sho uld consider very critica lly any proposals to locate new industries nea r the river or its tributari es which could add polluta nt s to the Ri ver Murray. In any case, th e policy o f ' best practical mean s' of was te treatment and di sposa l sho uld be ado pted. In thi s in stance, the Co mmi ssion con sidered that ' best practica l means' required the disposal of all effluent by evaporatio n.

T he Co mmiss ion acco rdingly agreed th at pending the determinat ion o f firm o bj ecti ves fo r water qua li ty alo ng th e river, its policy would be as follo ws : • In the case of those para meters such as salinit y a nd nutrients which a re alread y recognised as causin g problems in certain sectio ns of the river , the Commi ssion deci ded th at it would endeavour to ensure that ex isting quality would be improved • In th e case of oth er pa ra meters whi ch may at the mo ment be well belo w recognised limits, the Commission' s policy is to endeavour to ensure tha t ex isting quality is not allowed to deteriora te .

There is a widespread impress io n that in ri ver management we ca n 'h ave our cake and eat it too '; that rivers can accommodate every hum an need includin g th e need fo r waste disposal. It has been th e comm o n fate of ri vers througho ut th e indu stri alised world that their use as d ra ins for industrial , agricultural a nd urba n waste has been in direct conflict with th e other uses we make of rivers; drinking, irrigati o n , recreation and so on . Many important rivers in Europe and Ameri ca a re now so severely polluted th at they ca n no longer support th ese benefici a l uses . In Au stralia, we also have severe water polluti on in .st rea ms and rive rs adj acent to major cities, indust rial and min ing centres. Ho wever, the River Murray is not yet in this category, and although th ere a re real water quality problems, it is quite obviou s th at we a re in a ve ry fo rtun ate position by world standard s.

Is the Ri ver Murra y to be used as a d ra in , or should we endeavour by every practi ca l means to maintain and , wh ere necessa ry, improve the ex isting water qu ality of our most important inland stream?

The Murray, is after a ll , Austra li a's most important river. From the geographi c, political a nd resource viewpoints, th e basin of th e Mu rray and its majo r tributa ry, the Da rlin g, occupies prid e of place amongst all the ca tchments o f the dri es t, th e fl attest and th e lowest continent of the world.

K. E. Johnson, Chief Executive, River Murray Commission.

22

WATE R M arch, 1984

The Ri ver M ur ray a nd its tribut aries d rain one milli on squa re kil ometres or one-seve nth o f th e a rea o f Australi a. The MurrayDarling bas in produces a bout half o f Au strali a's to ta l gross va lue o f primary producti on in ag riculture . It is the most important agri cultural region in Australi a. Within the one-seventh of contin ent al area occ upi ed by th e basin is co nt ain ed approxim ately o ne q uarter of th e nati on's cattle herd , o ne half o f the nation 's sheep fl ock , one half o f the nat ion 's crop la nd , and three qua rters o f the nation 's irrigati on area. It s natura l resources support bot h di rectl y and indirectly so me tw o million peo ple with a total of its primary and seconda ry produ ction currentl y es tim ated to be in excess of $ 10 000 million per annum .

With one million hectares o f land under irri ga ti on , water resources play a major part in th e overall va lu e o f produ ctio n .

2. ADMI NISTRATIV E ROLE OF TH E RIV ER MURRAY COMMISSIO N In som e ways , the admini stration of th e River Murray over the last century has bee n in ha rmony with the ri ver itself. As you know , the Ri ver Mu rray is very murk y; it normally flow s very slowly, a nd in deed, m some places, it has been known on occas io ns to fl ow back ward s.

The Ri ver Murray Co mmission has o perated since 191 7 under an Agreement betwee n th e States of New So'uth Wales, Victoria, and South Austra lia and the Common wealth as the bod y responsible for the economi ca l use o f the wa ters o f the River Murray and its tributaries for irri gati on and nav igation .

For the last IO years, negoti ati ons have bee n proceeding on th e develo pment of a new Ri ver Murray Wa ters Agreement to broaden th e Ri ver Murray Commission 's role and in parti cular , to ' protect a nd where necessary improve the q ua lity of the Ri ver Murray waters' .

Altho ugh ratifi cation of the new Agreement still awa its action by the New South Wa les a nd Co mm onwealth Governments in fact the River Murray Commi ssion has bee n operatin g as if th e Ag; eement was in fo rce.

The new powe rs cover the abilit y to consid er wa ter qu ality in the o perat io n and in vest igation o f ex isting or future wo rk s, the o bligati on to monitor water qu ali ty, the co-ordination of qu ality and quantity management, th e power to ma ke representations to governm ents and authorities on water qu alit y issues and th e abili ty to recomm end water qu ali ty obj ecti ves to th e states . It has bee n claim ed that even with these new powers, th e Ri ver Murray Commi ssion will be a 'toothless tiger' and ineffecti ve because it will lack spec ific enfo rcement powers .

In parti cula r, Clau se 29 o f the new Agreement has been strongly criti cised by Pro fessor Sa ndford Clark from Melb ourne University.

This Clau se requires th e participa ting states to inform the River Murray Commission of a ny developm ents within their states which may significantly a ffect th e flo w, use, control a nd qu ali ty of a ny wa ter und er th e control of the River Mur ray Commission so as to enable the Commiss ion to assess the possi ble effect o f the proposal on that water and to ma ke representations to that governm ent or th e authorit y concern ed. It has been argued by Professor Clark that the wording o f Clause 29(2) definin g th e types of proposa ls which will be referred to th e Commiss ion , may enable th e states to avoid th e intent of this Clause.

However , the effecti veness of th e new Agreement , a nd indeed any Ag ree ment for tha t matter , depend s in large meas ure o n th e wil lingness of th e parti cipating parties to co-operate rath er th an on th e legal interpreta tion of the fin e print used to describe the Agreement.

Certainly, th e intent of Clau se 29 is quite clear , and to date, all of the states have parti cipated in providin g details o f waste di scharges to the River and its tributari es.

Clause 25 o f the new Agreement enables the Commission to carry o ut surveys , investigati ons a nd studies and to inititate proposals fo r the protection and improvement of water qu ality. In thi s regard , co nsultants, Maun sell and Partn ers, together with Binnie & Partners and Dwyer Les lie a re now completing a $500 000 Water Quality Management Study fo r th e Commiss ion which will develop a model o f the

movement of sa lt a nd water a lo ng the Ri ver and use thi s model to evaluate different sa lt mitigation schemes a nd alternative management strategies for preservation of the river' s quality.

Clau se 26 requires the Commiss ion to monitor water quality in the river and the downstream reaches of its tr ibutaries. The Commission's water quality monitoring programme was initiated five years ago and we now have a comprehensive programme which monitors water chem istry, bacteria, phytoplankton an d stream biota in the river.

Summary statis tics from this programme are produced in the Commiss ion's Annual Reports and a detailed review of the data coll ected so far is now in progress.

Clause 27 enab les the Commission to formulate water quality objectives and standards for any part of the River and to make representations with respect to such objectives a nd standards to the contract in g governments. It is intended that the present Water Quality Management St udy will produce such objectives in relation to sa linity .

Cla use 28 enables the Commission to make recommendation s to the contracting gove rnm ents on a ny matter whi ch may in any way affect the quality or quantity of the waters of the River Murray.

Clause 97 empowers the Comm ission to adjust the upst ream states' shares of wa ter to take accou nt of the quality of each state' s tributary and drainage inputs to the r iver.

3. PRESENT WATER QUALITY

.,

The River Murray as yet receives very little indu st rial or dom est ic waste and our major water quality problems are sa linit y, turbidity an d nutrients. The o nl y large industrial plant on the river is a recently constructed thermo-mechanical paper mill at Albu ry which discharges effluent of 'drinkab le' quality to the river after efficient secondary treatment.

Along the 2700 kilometre length of the Ri ver Murray, t here are 35 sewage treatment works, most of whi ch serve quite small population centres . About 80 per cent of these sewage plants currently practise land di sposal of seco ndary treated effluent. Of those towns whi ch are still disposing treated effluent to the river, several now have plans to upgrade sewage treatment and convert to land disposal of effluent by irrigation or evapo ration.

We have none of the massive industrial and domestic point source discharges which have caused so much damage to rivers in Europe and North America, and by wo rld standards the present quality of the water of the Ri ver Murray is good.

The results of our monitoring programme and the longer water quality records avai la ble from state a uthoriti es sho w t hat the river is well oxygenated, a nd that concentrations of toxic materials such as heavy metals a nd pesticides are genera lly near the detection limi ts for these parameters in the river water. There is some ev id ence that pesticides and metals may accumu late to significant levels in fish and water fow l a nd this is an a rea which requires further in ves tigat ion. By and large, however, the water quality problems of the river are limit ed to problems related to the hydrology a nd geomorphology of the river basin whi ch have been exacerbated by agricu ltu ra l land use (or abuse) and river regulation.

As mighty as it may be, t he River Murray in its lower reaches is, a nd always has been, a slow-flowing, muddy a nd periodically salty st ream.

The first explorers of our inla nd river sys tem reported high sa linit y in the lower Murray a nd fou nd the mid-Darling too salty to drink. Prior to dam const ruction a nd river regulation, the River became extremely saline in periods of prolonged drought. In the drought of 1914/ I 5, for example, when the river was reduced to a series of waterholes, salinity at Morgan rose to 10 000 E.C. units (approximately 6000 mg/ L T.D.S.). With the present regul ation of the river ensuring a continuous flow to Sout h Australia, saliniti es at Morgan rarely now exceed 1500 E.C. units a nd are usually well below 1000 E.C . unit s .

Long before fert ili sers were being used and was hed off into the river, algal blooms were a periodic problem in its lower reaches. In 1878, a bloom of the blue-green alga, Nodu laria, in Lake Alexandrina caused extensive stock losses due to the toxin produced by thi s alga.

The effects of the river regulation on water quality are complex.

One clear effect has been to reduce the variability in flow a nd flo wrelated water quality para meters . We will never again experience t he salinity extremes of the magnitude recorded in 1914. On the ot her ha nd , the conservation and usage of wa ter by the upstream sta tes has effect ively halved the average ann ual flow of the Murray to South Australia.

What then has been the effect of hum an activities in t he catchment on the water qual ity of the River?

This question is of obvious imp ortance, but the facl'"ls that we have . no accurate means of quantifying the extent to which water quality has deteriorated. Thi s is not entirely because we lack sufficient data; we have records of sa linity and turbidity covering about four decades for certain locations on the river. But because of the inherent variabi li ty in flow and flow-related water quality parameters, it is not poss ible to derive accurate estimates of long-term trend s in water q uality.

As late as 1979, the report by Maun sell a nd Partners on Murray Valley Sa linity and Drainage found there was no clear evidence of a significant trend in River Murray salinity.

Over the last year, C unnin gham and Morton of the Australian National Universit y have used a more sophisticated statistical modelling technique to analyse the trend in salinity at Morgan over 43 years of record. Their conclus ion is that there is a positive trend; sa linity has increased at a rate of 1.4 per cent per annum. Due to the variability of the data, however, the co nfidence limits of this estim ate are from 0.04 per cent per annum to 2.84 per cent per annum. In other words, the estimated increase in ri ver sa linity over the 43 years of record is 84 per cent with confidence limits of 2 per cent and 233 per cent. Of course, even an increase of the magnitude of 84 per cent over such a short period is a cause for real co ncern; if such a rate of increase were allowed to continue, we would be faced with a doubling of present salini ty leve ls withi n the next 50 years, wh ich is obviously unacceptable.

Another prob lem associated with River Murray sa linity is hardness.

This hardness causes significant financ ial disbenefits to the industrial and domestic users of river water in South Austral ia . Here , the differences between Murray and Darling wa ters become important. the Darling has much higher proportions of calcium and magnesium ions t han the Murray and when Darling flows dominate, the hard ness of the water flowing to South Austra lia increases substantially.

Like salini ty, turbidity is highly var iable in the River Murray. The turbidity of the river is obv iou sly affected by runoff of soi l from th e catchment whic h is in turn increased by overgrazing and other poor land-use practices. We have turbidity records from the ri ver in Sout h Austral ia spanning nearly 40 yea rs and these records show that turbidity is related to flow a nd that when a fl ood occurs in the Darling fo llowing a prolonged dry spell or drought, t he turbidity of the river is very high indeed. Under low flow conditions and with low flow in the Darling Ri ver , turbidity at Morgan is typically less than 100 N.T.U. When floodwaters from the Darling pass through the River Murray in So uth Austra li a, turbidities in excess of 400 N.T.U. have been recorded. This is the highest turbidity recorded for Morgan si nce August 1947, when a turbidity equivalent to 900 N.T.U. was recorded.

Statisticia ns have yet to analyse the turbidfiy record, but it is very doubtful t hat even they co uld estab li sh a trend in such variable data.

The Comm issio n is current ly in vestigating th e relationship between algal grow th and nutrient concentrations. as part of it s monitoring work on the river, but is is already quite clear t hat t he more nutrients allowed into the river, the more frequent and intense will algal blooms be. The major sources of nutrients are agricu ltu ra l runoff and sewage effluent. The point-source discharges from sewage effluents are amenable to contro l and there are very few sewage plants now di scharging effluent to the river. There is no threshold concentrat ion of nutrients above whi ch co nd it ions wi ll sudden ly and permanently deteriorate . Rather, there will be an increasing frequency of alga l blooms as more nutrients are discharged to th e river. We should thus seek to prevent a ny further discharge of nutrients and where possible, reduce the ex isting inputs of nutrients to the river. The fact that pointsource d ischarges may be relatively minor compared with diffuse inputs from agricultural runoff is not an adequate reason to a ll ow or enco urage further point-source discharges. Rath er, we should be investigating ways of minimi sing the diffuse inputs as well as contro lling t he point-s ources.

There is a lso the problem of water-borne pathogens a nd the health risks associated with the use of River Murray water for drinking and for recreation. Faecal coliform bacteria can originate from a ny warm blooded a nima ls, and in t he River Murray there is no doubt that the major source of contamination is from the grazing a nima ls whi ch by and large have free access to the river along its length. There have been regular counts of faeca l co li form cells over many years at a number of locat ion s alo ng the river, and as might be expected, the number of WATER March, 1984

23

these bacteria in the water is hi ghly variable and is influenced by rain fall and river flow.

The health ri sk from animal waste is less tha n th at from human faeca l contamination and obviously every possible measure should be taken to minimise th e contamination of the river by human exc rement. Short of fencin g off most of the river from grazing li vestock, it is difficult to see how contamin ation from an im als co uld be reduced , but human waste is certain ly amenable to co ntrol. There is no untreated sewage entering the ri ver but a source of concern in the past has been the hou seboats and commercial passenger vessels operating along the middle and lower reaches of th e Murray. Over the las t few yea rs , pump-ashore stations have been provided along thi s part of the river to receive waste from commercial vessels and pleas ure craft such as hou seboats. Th ere are, however, still a few commercial tourist vesse ls operatin g on the river which are continuing to dump untreated toilet was te into the river. Des pite strong representat ions from our Commission, there has not yet been any firm action by the respon sible state authorities to prevent this pollution .

4. OVERSEAS EXPER IENCE

Water qualit y managem ent in the United States has undergone some profound cha nges over the last decade or so and there are lessons to be learnt from their experience .

Growing publi c awareness of the appa lling condition of many im portant rivers in the United States led to the pass in g, in 1965, of the Federal Water Quality Act which was to be th e legal basis for a mass ive cleanup of surface waters. By 1970, the fee ling was tha t too little was being ac hieved and in 1972, Congress passed a Clean Waters Act which required adequate treatment of a ll waste before di sc harge to stream s, irrespecti ve of whether such treat ment was needed to meet the water quality standards which mi ght have been set for the stream .

Many billions of dolla rs were provided and the stated aim of govern ment policy was to restore ' fi shab le/ swimmable ' waters wherever possible a nd ' zero di scharge' of pollutants . Now, a decade later, the political pendulum has swung bac k the other way. River Basin Commi ssion s have been abol ished and Federal funding for treatment work s and water quality projects has been slashed.

With hindsight , it now appears that the original goals of the U.S. water quality manage ment programme may have been unobtainable, given the deplorable sta te of many rivers and the fact that major industrial shutdowns or relocations wou ld have been required to meet the 'zero-di sc harge' requirement.

At least a share of the respon sibility for the ineffectiveness of the U.S. approach must be shouldered by the scientists and engineers involved. Large amounts of resea rch fund s went into developing the idea that quantitati ve water quality objecti ves could be defined for each of the man y beneficial uses of surface waters . This invol ved an enormous scientific effort to develop quantitative water quality criteria as the basis for manage ment objectives. As Professor Clark has pointed out , in relation to the Ri ver Murray, 'expenditure on research provides a rationally defen sible and politi call y positi ve substitute for action '.

This approach seems to ignore the inherent variabi lity which occurs in all flow-related water quality parameters in rivers and the vastly different nature of surface waters to whi ch such criteria and objectives are required to app ly. For polluted rivers being used for domesti c supply and irrigated agricu lture , there is no doubt a need for clear quantitative guidelines on tolerable levels of pollutants. But even for these clear cut uses, there are no clear cut criteria, as is shown for example by the differences between World Health Organi sation a nd Australian sta ndards for drinking water, or the dose/ response relationships for sa lini ty and crop yield on the River Murray . For uses such as the protection of aquatic ecosystems, where the biology and ecology of such ecosystems are ve ry poorly understood , the idea of quantitative criteria to cover a ll surface waters seems quite unreali stic .

As the effects of the current eco nomic crisis continue to be felt in Australia, we cou ld well follow th e same sort of pendulum swing that has occurred in the United States where environmental iss ues such as water quality seem to have now been relegated to a lower position in their list of priorities for govern mental fund s and actio n .

In fairness, it should be said that we have already made considerable progress with controlling the sa linity problem. Our ac-

24

WATER March , 1984

tion/ talk ratio compares very favourab ly with that of the United States. On the River Murra y, 11 schemes costing over $32 million have bee n completed since l 968. The nett result is that an overall total of about 300 000 tonnes of sa lt mi xed with 30 gigalitres of water has been kept out of the river each year and is di sposed of by evaporation. This is in sharp contrast to the Co lorado River of the U.S.A. where in spite of a programme which goes back some 10 to 15 years and an expenditure of the order of $30 million on planning and investigation s, so far little sa lt has actuall y been kept out of the river . The institutional and managemen t arrangements for the River Murray are far simpler than those app lying in relation to the Co lorado where the problem is exacerbated by an over-comm itm ent of the water resource and a reluctance of any state to give up water to assist in reducing salinity in the down stream reaches .

S. FUTURE MANAGEMENT OPTIONS

There is no doubt that we do have real water qualit y problems with the River Murray and that ha rd decision s will have to be made in the very nea r future, decisions which will have long-term effects on water quality and ultima tely on the viability of developm ents which have already occurred along th e river.

As a n example , consider the current problems of one important irrigation area, th e Shepparton District o n th e Goulburn Ri ver in north western Victoria. Here , ri sin g groundwater is causing quite severe problems of orchard lo sses and pasture degeneration. Since 1975, a system of groundwater pumps has been installed to reduce groundwater levels und er the horticultural areas of this irrigation di st rict.

Plans are now in progress to extend this system of groundwater pumping to adjacent pasture areas . Althou gh a large proportion of the pumped water wi ll be recirculated in the distribution system, the scheme, when full y developed , wi ll generate a large volum e of sa lin e water which must be di sposed of. One proposal is that this water should be allowed to drain to the River Murray. This cou ld involve the discharge of some l 00 000 tonnes of sa lt to the river in 40 giga litres of water each year when the drainage scheme is fully developed.

Given the Commission's stated policy of seeking to reduce river salinity, what should the Commission do in regard to this proposa l?

To see k to prevent the entry of this drainage to the river co uld clearly have serious repercussions on the success of this scheme and thus could a ffect the viabi li ty of thi s important agricultural district. On the oth er hand, should other water users further downstream be asked to suffer? What about 'the polluter pays' principle? Should an ' offset poli cy' be accepted? • Perhaps the im pact of this relativel y straightforward engineeri ng ' fi x' can be reduced by the adoption of other measures such as more efficient irrigat ion practices, treeplant ing, canal lining, and better .,_ overa ll water management.

In thi s same context of better management, over the last year or so, there has been active discussion about poss ible future in stitutional arrangements for the Murray/ Darling bas in . Ideas such as a MurrayDarling Authority, a Freshwater Research Institute, an expanded role for the C.S. l.R.O . and a Water Researc h Council have been proposed. For the foreseeab le future, however, the River Murray Commi ss ion is lik ely to be seen as the body respon sible for the water quali ty of the river. The effectiveness of the Commission in this role will depend on th e contin ued co-operat ion of all parties concerned. Coercion would not be possible or effective.

6. CONCLUSION

We have a go od chance of meeting our policy goals of maintaining and where necessary improvin g the water quality of th e River Murray, provided that we recogni se and ex ploit our distinct advantages co mpared with overseas countries .

As well as administrative advantages, we have the physical advantages of avai lab le land and suitable climate to ass ist with off-r iver treatment and di sposal of waste. We have a very different sta rting base in the River Murray and therefore, while learning from overseas experience, we must not blindly fo ll ow their policies and methods.

With adequate support from a ll the gove rnments involved, the River Murray Commi ss ion can develop and implement co-ordi nated manage ment plans which are essent ia l if the river is to be cleaned up a nd kept that way.