Doug Catherwood, chair of CPWL, in announcing the agreement said he was unaware of any other storage facility offering to release contracted water on demand in New Zealand.
“We have to book the volume a year in advance but TrustPower will release it with about a day’s notice,” he said.
The agreement follows months of discussion and has been made possible by the Government’s decision to alter the Conservation Order covering the river and lake.
“This is another big step forward for us. Lake Coleridge is an existing reservoir, and at this early stage the Coleridge Storage will support Stage 1 at least of the CPW Scheme, which involves water supply to 20,000 hectares of farming land,” Catherwood said.
TrustPower would provide 95% reliability for the scheme for Stage 1, he said. Before the agreement was signed, CPW was able to offer only 70% reliability with the run of river supply.
“This is good news for us. Ninety-five per cent reliability is virtually water every day for farmers. This is a real alternative to our own water storage reservoir.”
There is potential for more stored water to be available for future stages of the CPWL Scheme.
“Research will need to be conducted before we can be assured on the reliability of the next tranche of water. We now know the reliability will be considerable and well worth pursuing. This will constitute the next phase of our discussions.”
Catherwood said having reliable alpine water was key for the viability of CPWL.
The positive impact meant that current ground water users who are pumping from up to 200m wouldswitch to surface water, releasing the pressure on the over allocated ground water usage, enabling the aquifers to be replenished and increase the environmental flows in the lowland streams.
“As our construction proceeds over the next couple of years, we will provide equal reliability for the coming stages of the CPW, without compromising environmental concerns for the river and the lake.”
The first stage of the irrigation scheme will run from near the Rakaia River bridge to near the Hororata River. It will be worth approximately $144 million.
A high percentage of reliability is the key to success for irrigation.
Without it water takes are reduced or cut altogether when farms need them most.
We were in North Canterbury in March visiting farms which had had their water take cut. That was having a significant impact on grass growth and milk production.
The North Otago Irrigation scheme has 99.9% reliability thanks to minimum flow requirements on the Waitaki River and the seven dams above the supply ponding area which can store water until it’s needed.