Scheme's cost to rise without high dam

11:07, Apr 20 2009

A massive scheme to irrigate 60,000 hectares of Canterbury farmland is likely to cost more now that plans to build a 55-metre high dam have been effectively rejected.

The $409 million Central Plains Water irrigation scheme was dealt a blow last week when hearing commissioners signalled their likely rejection of plans to build a dam in the Waianiwaniwa Valley, near Coalgate, holding 290 million cubic metres of water.

When pressed about the cost of alternative storage, Central Plains Water chairman Pat Morrison admitted the project cost could rise.

The Central Plains Water website said using "turkey-nest" storage many small storage sites instead of a single reservoir would at least double the total cost of the project.

Morrison said without storage, farmers would not get reliable production from the scheme.

"(The scheme) won't be as reliable as it could have been," he said. "There are options, and that's what we've got to look at in the future."

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The most important short-term goal was to get water takes from the Waimakariri and Rakaia rivers granted, he said.

"Once we get the water, we can look at other options for storage," Morrison said.

He said CPW's legal and engineering advisers were preparing information for the hearing's resumption on May 11.

At that time, commissioners will decide whether to issue a final decision on the project proposal or allow further evidence.

Malvern Hills Protection Society secretary Liz Weir said the whole scheme was premised on water storage. "I fail to see how they can get enough storage from a run-of-river scheme to supply their shareholders."

The group was in favour of on-farm storage, she said.

Morrison said possibly using Lake Coleridge for storage, as identified in the Canterbury strategic water study, "was for the future".

The upper part of the Rakaia River was subject to a water conservation order, which could prove an obstacle to any irrigation scheme for Coleridge.

Central Plains Water's website said a $20 million canal would have to be built to bring water out in sufficient volume.

The Press