A Canterbury irrigation scheme's chief executive says the Government's move to allow electricity supplier TrustPower to release water from Lake Coleridge into irrigation schemes when rivers are running low will benefit farmers and the environment.
Derek Crombie, who heads the Central Plains Water Trust, says the change to the Rakaia Water Conservation Order, announced on Monday, will greatly improve the reliability of water in the region.
He says reliability is fundamental to irrigation and if there are more than about 14 days without water, crop growth stops and in some cases growers can lose crops entirely.
Mr Crombie says people will use less water when there is reliable supply because they don't have to put a lot on when it is available to cover for the times that it isn't.
He says water reliability will increase from 70% to 95%.
The Central Plains Water Trust has consents to take water from the Rakaia and Waimakariri Rivers, and irrigate up to 60,000ha of farm land.
Mr Crombie says the way in which TrustPower releases the stored water will change over time.
Initially TrustPower will store water during the winter and early spring and then during summer discharge it through the existing pennstocks on the hydro station at Coleridge.
Central Plains will pick that water up from its intake lower down the river.
Eventually TrustPower plans to build a canal down the north side of the river and discharge directly into the trust's head race.
Mr Crombie says three irrigation schemes will be able to access the stored water.
One is an existing group already irrigating in the lower Rakaia, Barrhill-Chertsey Irrigation which is on the south bank, and Central Plains on the north bank.