Warning of extreme flood
THE debate over whether to raise the wall of Tweed's Clarrie Hall Dam is back on the agenda after Tweed Shire Council officers warned a decision must be made on upgrading the spillway to avoid a disaster in an "extreme flood".
Councillors voted in October not to raise the wall of the dam, south-west of Murwillumbah, and not to build another dam at Byrrill Creek, further west, with any decision likely to be left to the next council after the election in September 2012.
But council officers want them to vote next week on a $6.3 million upgrade to the spillway of the Clarrie Hall Dam, warning "the do-nothing option presents an unacceptable risk to the people and property located downstream".
The move raises the prospect of the council voting to upgrade the spillway with a future council later deciding to raise the wall.
However, Mayor Barry Longland yesterday said he was confident construction work would not begin before a new council reconsidered raising the wall, saying preparations for the spillway could be "integrated into that".
He said raising the wall of the Clarrie Hall Dam - which has been fiercely opposed by affected farmers - was the best option for Tweed's future water supply.
Cr Longland said an upgrade of the spillway was a requirement of the Dams Safety Committee of NSW, which reviewed all dams in the State in the light of new standards relating to "probable maximum floods".
"To integrate the spillway upgrade with the raising of the dam wall was going to be the most cost-efficient option," he said.
"It's unfortunate that was overturned. We don't have an option not to proceed with the spillway upgrade.
"Our future water security would be more than adequately met through raising of the Clarrie Hall Dam."
Cr Longland said that option had fewer environmental consequences than others and would be the least costly.
He hoped councillors would vote to proceed with the spillway upgrade but said it would take years before earthworks began, giving the next council plenty of time to vote on raising the wall as part of the project.
Council staff say the spillway work would take about six months and warned the dam's water level might have to be temporarily reduced during construction.