Environmental risk of Tillegra Dam exposed in new report

The internationally listed Hunter Estuary Wetlands, under threat from the Tillegra Dam proposal. Photo: Vanessa Culliford

A new report has been released by the University of New South Wales and the Australian Wetlands and Rivers Centre that presents powerful new evidence for the NSW and Australian Governments to reject the proposed Tillegra Dam.

The report, 'The impact of the Tillegra Dam', exposes the real ecological risk that would be seen from the construction of the dam, proposed to be the largest built in Australia for 20 years. It is due to be constructed on the Williams River, the Hunter catchment's most intact and ecologically important river.

Professor Richard Kingsford's study demonstrates that the proposed Tillegra Dam would significantly reduce flows to the Hunter Estuary and its Ramsar-listed wetland, Kooragong Island. By reducing flows to downstream ecosystems, the dam is likely to increase salinity with a 'salinity wedge' intruding further up the Hunter and Peterson Rivers, affecting fish and shorebird populations and potentially resulting in the collapse of food webs.

The Wilderness Society is concerned by serious flaws in Hunter Water's Environmental Assessment of Tillegra Dam which are highlighted in the UNSW report.

Read the report online

Hunter Water's assessment relied on annual flow figures and concluded that water flow would only be reduced by 0.3%. However, in the report Professor Kingsford based his assessment on daily flow and concluded that flows could be reduced by as much as 40% in some months.

There is concern that the Hunter catchment cannot withstand that reduction in flow, and that it would eventually lead to ecological collapse of the system.

There has been an alarming decline in shorebirds in the Hunter River estuary since the 1970s: from 15-20,000 in the 1970s to approximately 3.000 in 2000-2007. By reducing the frequency of flooding, the proposed Tillegra Dam would further reduce shorebirds and aquatic food webs.

The report also warns of desynchronised environmental cycles and disrupted reproductive cycles for fish species including the sea mullet, freshwater mullet, striped gudgeon, freshwater herring and Australian bass.

The proposal to build Tillegra Dam is currently being assessed by the Planning Department in NSW. The final determination of the proposal will be made by Federal Environment Minister Peter Garrett.

In light of this new evidence showing serious flaws in the Environmental Assessment, we call for Premier Keneally to immediately reject Tillegra Dam. 

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