Huge Rakaia irrigation scheme for 100,000 ha

Press, 22 June 1984, Page 1

Huge Rakaia irrigation scheme for 100,000 ha

Plans for New Zealand’s biggest irrigation scheme were announced yesterday at the annual meeting of the Central Plains Irrigation Association at Darfield.

Under the four-stage scheme, about 100,000 ha between the Rakaia River and the Waimakariri River will be irrigated at an estimated cost of $lOO million. The Minister of National Development, Mr Birch, told the meeting that storage in Lake Coleridge could be used to boost low flows in the Rakaia River, making it possible to irrigate all the area sought by the association.

Under low-flow limits set by the Draft Conservation Order on the river, only 70,000 ha could be irrigated if water stored in Lake Coleridge was not spilled into the river.

Farmers at yesterday’s meeting regarded Mr Birch’s announcement as an important step forward for the scheme, which was outlined by an irrigation engineer with the Ministry of Works and Development, Mr Brin Williman.

The first stage to be developed would be 30,000 ha bounded in the north by the Waimakariri River, in the east by the North Canterbury Catchment Board’s proposed groundwater line, in the south by the Selwyn River, and in the west by the 220 m contour, he said. The scheme would be gravity-fed by the Rakaia River and only spray irrigation used. Mr Williman said that although the cost of taking

water from the Rakaia into the area would be high, the benefits of irrigating that stage first would outweigh the disadvantages.

Spray irrigation would be used only to minimise the impact of any run through of surplus water to the lower plains. Drainage difficulties, water-quality problems, and the eutrophication of Lake Ellesmere could be caused by too much water reaching the lower plains, he said.

The scheme’s second stage, in the south, would be bounded by the Selwyn River and Wrights Road, State highway 1, the Rakaia River, and the 225 m contour.

The area of 25,000 ha, would be gravity-fed by the Rakaia River and spray and border application would be used.

Two, smaller, pumped stages were also included in the scheme. One was a northern area of 7000 ha surrounded by the Waimakariri River, the 220 m contour, and the foothills, where water would be pumped from either the Rakaia River or Waimakariri River and only spray irrigation used. The other southern area would be bounded by the Rakaia River, the 225 m contour and the foothills. Spray irrigation with water pumped from the Rakaia would be used on its 4000 ha. Mr Williman said the

boundaries of each stage were subject to change, pending detailed investigations.

If further investigations, Government approvals and water right application hearings went smoothly, work on the first stage could begin in late 1988 and stage two about two years later.

Small hydro-electric power stations might be built to use surplus water diverted for irrigation, he said.

The irrigation ’ association’s chairman, Mr David Watson, said the plans did not pre-empt the Draft Conservation Order, although a decision on the hearing date for the order was not expected until 1985. “All we are saying is that if there is a share of water available for irrigation from the Rakaia, then we have a use for it,” he said. The association wanted to push ahead with the plans rather than wait for the decision. If the decision was appealed and went before the High Court, it could be another two years before a final decision was reached. Mr Birch said the Natonal Development Act could be used to help implement the scheme if people used the legal system just to continue the public debate “ad nauseam.” He did not think the act would have to be used.

“I would hope that once a

decision is released from the hearing, the community will accept it,” said Mr Birch.

Using the act now would be of no benefit. “You can’t do away with the public debate, just see how you can get it over with quickly,” he said.

If the decision on the order did not reduce the water level available for irrigation, later applications for water rights should go smoothly. “You have my guarantee that a National government would treat the scheme with priority,” said Mr Birch. “Any project that can deliver increased production, enhanced employment, and greater foreign exchange earnings would be approved by the Government, and quickly,” he said. The association has said that irrigating the central plains would double farm production. It would add $3O million a year to farm output, $6O million a year to secondary output through the community, and $ll million a year to household income in Christchurch and surrounding communities. It said that 750 jobs on and off farms would be created. Mr Watson said the release of the plans was “a milestone” for the association. Yesterday’s meeting was its most important. “It is a turning point in planning for the central plains,” he said.