Work on the ACT's new $363 million Cotter dam will begin next month after the Federal Government approved the project yesterday on the proviso more water is sent downstream to protect the environment.
The new 78 gigalitre dam will be built slightly downstream of the existing 4GL Cotter Dam, increasing Canberra's water storage by about 35 per cent.
Canberra households will have to pay about $100 more a year in water bills to fund the expansion of the dam. The cost of the project has blown out to more than double the estimate two years ago of about $150million, and significantly higher than last year's estimate of about $250million.
Federal Environment Minister Peter Garrett said yesterday his department had assessed the proposal and determined the impacts on nationally protected matters would be effectively managed.
Actew would fund and implement a fish management plan to ensure any impacts on Macquarie perch were acceptable. Road crossings upstream would be modified to allow access to additional spawning habitat.
Conditions of the approval also included increasing minimum flows downstream of the dam to 34 megalitres a day, more than double the current requirement.
Mr Garrett said, ''This increased environmental flow will support the health of the downstream environment, and in particular will ensure the protection of the Murray cod that live below the dam.''
Actew managing director Mark Sullivan said the requirement for increased environmental flows was not a concern. It would have been met in all but four weeks over the past four years.
From next year, environmental flow would be provided by pumping water from the Murrumbidgee to the dam wall.
The water would then flow downstream back to the Murrumbidgee.
Mr Sullivan said documents would be lodged on Monday in compliance with the ACT development application conditions. All sorts of licences were going through the process.
Up to 1000 pages of information on the cost increase and a compact disc would be supplied to each ACT Legislative Assembly member.
Meanwhile, Actew was preparing its response to the ACT and NSW governments to comments on its environmental impact statement for the proposed pipeline to transfer water from the Murrumbidgee River to Googong Dam.
It was hoped that project would be approved in the first quarter of next year. Subject to approval, the pipeline would also be completed by late 2011.
After average spring rain, water was spilling from the existing Cotter Dam. Mr Sullivan said this was a clear indication the new dam would fill.
ACT Minister for Environment, Climate Change and Water Simon Corbell said despite the cost increase, this project would give good value for money. ACT Treasury had estimated the annual cost of Stage 4 restrictions, under which all outdoor use of potable water would be banned, would be equivalent to the cost of building the dam.
He did not believe the Government had unnecessarily delayed construction of the dam.
In 2005, Actew had recommended no new dam was required. He did not believe that advice had been incorrect.
Mr Corbell said, ''At that time we believed we had already experienced the worst case scenario.'' But 2006 had been the worst year on record and the CSIRO had to reconfigure its projections.
Greens water spokesman Shane Rattenbury welcomed the requirement for increased environmental flows downstream of the new dam.
He said it was hoped similar standards would apply to the proposed pipeline.
Liberal water spokeswoman Vicki Dunne had not returned a call from The Canberra Times at the time of writing.