2004 – Environmental Release from Awoonga Dam

Russell Paton, Clancie Saverin

The Awoonga Dam Raising Project, completed in July 2002, consisted of raising the full supply level by 10 metres. As part of the project the discharge capability of the dam was increased to a maximum of 3210ML/day (37.2m3/s) to meet the environmental release requirements of the Boyne River Basin Resource Operations Plan. The final design incorporated the use of an existing intake tower and outlet works supplemented by an auxiliary inlet to meet this release.

Between January and February 2004 rainfall within the dam’s catchment resulted in inflows to the storage raising it to within 5m of the new spillway crest, historically its highest level. Subsequently, two environmental releases, which required full utilization of the dam’s discharge capacity, were made. These regulated releases created a precedent for the Boyne River, and were the first time flow passed through Awoonga’s auxiliary intake.

Throughout the releases, water levels and water quality downstream were monitored to determine the effect of the release on the stream and to ensure the community was not inconvenienced due to flooding. The MIKE11 model created for the recently completed Boyne River Flood Study was used to estimate water levels. Inspections were continuously carried out to ensure the intakes, pipework and discharge valves operated without incident and to monitor bank stability and fish movement during and after the releases.

The paper discusses the requirement to make the environmental release, and the infrastructure together with the operation and monitoring undertaken to facilitate it.

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