North Canterbury could be transformed by dairy conversions worth up to $2 billion under a massive irrigation plan.
The Hurunui Water Project (HWP) plans to build a 75-metre high dam in the south branch of the Hurunui River, creating a 7km-long lake, papers filed with Environment Canterbury show.
Together with a weir that would raise Lake Sumner's level by up to 3.2m, an extra 138 million cubic metres of water would be stored for irrigation.
More than 200 farmers have a stake in the project, which aims to irrigate 42,180 hectares between the Pahau River in the north and the Waipara River in the south.
Water storage and distribution infrastructure will cost $160 million, while "on-farm" costs for irrigation and associated capital work for dairy conversions range from $200m to $2b.
Dairying now occupies 9 per cent of HWP's irrigable area, but 45 per cent of the land is expected to convert to dairy if the irrigation plan is approved.
Environmentalists are outraged, especially because of a proposed water-conservation order for the Hurunui River.
Green Party co-leader Russel Norman said the project "will effectively privatise what is a public resource, which is a wild river, and using the water to carry out a huge dairy conversion in Canterbury".
"The implications are that we will lose one of the last wild rivers," he said.
Forest & Bird South Island conservation manager Chris Todd called the plan "outrageous".
The Department of Conservation (DOC) is almost certain to oppose it. In May, it supported an application for a water-conservation order for the Hurunui River sought by Fish & Game and the New Zealand Recreational Canoeing Association. A tribunal has yet to make a decision.
Canterbury conservator Mike Cuddihy said yesterday the proposal ran "completely counter" to a conservation order.
HWP is owned by the Hurunui Irrigation and Power Trust, Ngai Tahu Property, Mainpower and Eskhead Station.
Hawarden farmer Mark Zino, who heads a Hurunui Irrigation and Power Trust working group into the project, said it " was not about making huge profits it's about making sure the community is stable and strong."
Drought had destroyed dryland farming in the area and irrigation could easily double or triple production. If water was able to be delivered as cheaply as possible then farmers would have a wider range of options.
Under the plan, up to 32 cubic metres per second of water will be diverted from the Hurunui River into an intake and canal system for irrigation and hydro-power generation.
A control gate about 80m downstream of Lake Sumner's outlet could raise the lake level 3.2m.
The project's economic assessment says the best-case economic benefits to the area are $312m, based on the entire area converting to dairy. This could create 1190 more jobs.
HWP documents say potential environmental impacts include degrading water quality and the development of algae in the Hurunui River.
About 525ha in the Hurunui's south branch will be inundated, including nesting areas for the endangered black fronted tern, the papers say.
About 40 per cent of kowhai trees on the edge of Lake Sumner could be lost.
Public submissions on the plan close on September 11.
- © Fairfax NZ News
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