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Proposed Dam in 1968 for Chowilla, north of Renmark
Listen to a Podcast transcript by Dr. Jennifer Hamilton-McKenzie regarding the Chowilla Dam project
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This content has been reproduced from a South Australian Government supplement to the Riverlander, July 1968 promoting the 'benefits' of a dam at Chowilla.
1. Where is Chowilla?
The site of the Dam is in South Australia, 37.5 river miles (60 km) above Renmark. The bulk of the water body would lie equally in Victoria and New South Wales.
2. How big would it be?
That Chowilla Reservoir is designed to be 55 miles long (88 km), up to 20 miles wide (32 km) and to cover an area of 530 square miles (1,372 sq km). The Dam wall would be 18,000 feet long (5.5 km) and water depth up to 55 feet (16.7m). This represents 5.06 million acre feet.
3. Who would benefit by it?
In addition to South Australia, New South Wales and Victoria would gain considerably from the yield benefits of the storage by an estimated amount of 589,000 acre feet per year. South Australia cannot further develop without Murray water. Indeed, without a guaranteed supplied it could not support the people and industries depending on over 9,000 miles of pipelines reticulating Murray water.
4. Is it practical?
Yes. Investigations carried out over seven years support its feasibility.
5. Five who says so?
- The Snowy Mountains Authority says so.
- Soil Mechanics Ltd of London says so.
- The U.S. Army Corps of Engineers says so.
- The Engineering and Water Supply Department of South Australia says so.
The Governments of the Commonwealth, New South Wales and Victoria have always, and still do except the practicality of the storage at Chowilla but have subsequently requested examination of the competitive benefits of Chowilla against other storages.
6. Would there be much evaporation loss?
Examinations of the annual evaporation losses from Chowilla storage indicate whilst it could reach 25% of maximum capacity you could also be as low as 5% of maximum capacity it is considered that this would not contribute to a significant increase in salinity levels even in the Dam or downstream of it.
Evaporation losses occur in Lake Alexandria and Lake Albert but, even in years of minimum flow or no flow at all the water in these lakes is still useful for irrigation purposes.
7. What about salinity?
When higher flow rates enter and fill the reservoir this will generally be of a low salinity level. Even under high evaporation conditions the quality of the water will still be satisfactory for domestic and irrigation purposes. Chowilla Dam will provide the security of a regular annual flow at least equal to South Australia's entitlement under the River Murray Waters Agreement. It will also provide flushing water downstream when salinity levels demand it.
8. Why is Chowilla the best site?
Because it is downstream from ALL the Murray River tributaries. These include the Darling, Murrumbidgee, Loddon, Campaspe, Goulburn, Ovens, Kiewa and Mitta Rivers. Over the past 20 years an average of 9 million acre feet (3.6 hectare) per year has flowed into South Australia from the tributaries of the River Murray proper. The Hume Reservoir is filled from the upper arm of the Murray River and the Mitta, and of the two the Mitta is the smaller contributor under normal circumstances.
The alternative site of Dartmouth is some 1,200 river miles (1,903 km) from the metropolitan pipelines and some some 1,000 river miles (1,609 km) from South Australian irrigation settlements. The water would take some six weeks to reach South Australia.
9. What would Chowilla cost?
The total cost of the project was $68 million, which included (a) the tender price, (B) the amount already spent on the investigations and designs, (c) land acquisition, (d) supervision costs. The elimination of the lock from the original design has reduced the total cost by $6 million, and as $6 million has already been spent on investigations, land acquisition and designs, there is a balance of $56 million yet to be expended. This is not an unreasonable sum in view of Commonwealth support already given to other States for water supply. Some of the schemes are quite localised, but Chowilla will support a whole State with a population in excess of a million. And the $6 million already spent must be added to the cost of work at an alternative site.
10. Has Chowilla been agreed to?
Yes. It was accepted by the River Murray Commission in September 1961 and an agreement between the four Governments was ratified by their respective Parliaments in 1963.
11. What, now, is the difficulty with Chowilla?
The representatives of the Commonwealth, New South Wales and Victoria on the River Murray Commission have asked for an examination of an alternative storage to Chowilla to provide an answer to the relative cost yield benefits to be gained.
12 Is South Australia still committed to Chowilla?
Yes, most definitely. The Government of South Australia believes firmly that Chowilla should proceed.
13. What next?
The South Australian Commissioner at the last River Murray Commission meeting accepted the move by the other parties for comparison between Chowilla and an alternative site rather than create a dispute which would have unduly delayed the project. We are determined to have this comparison made on the basis that South Australia must receive all the advantages fro any alternative that it would obtain from Chowilla.
14. The reasons for this pamphlet?
This information is supplied because:
- The South Australian Government still believes the Chowilla scheme is the best proposal.
- In South Australia it is not just another irrigation scheme but is a lifeline for future development.
- Any comparison of an alternative must use Chowilla as a yardstick.
This is only a very brief summary of the facts.
Issued by the South Australian Government, July 1968
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Lake Victoria in western New South Wales was eventually negotiated as the water storage site for the security of South Australia's water supply and Chowilla Reserve was protected for future generations.
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