Farmer’s pipe dream for lake
Waipara farmer John McCaskey believes the current design for the Hurunui irrigation scheme is ‘‘an expensive piddle in a very big bucket’’.
The $400 million Hurunui Water Project (HWP) is the creation of the Waitohi Irrigation Scheme, a proposed water storage pond planned to sit along the length of the upper Waitohi River and provide irrigation to more than 58,000 hectares around the Hawarden area.
McCaskey believes the future prosperity of the Hurunui District can only be assured with reliable sources of water to irrigate and support an increasing proportion of its productive farmland – not just the Hawarden area.
He is convinced there is only one long-term solution to the Hurunui’s water woes: Lake Sumner. McCaskey believes it would service not only the Hawarden area but it has the potential to hydrate the entire Hurunui, both agriculturally and domestically.
On his farm in Glenmark are the remnants of 1980s government project to irrigate the area, a scheme which now services several vineyards with no detriment to water tables or river flows. A weir placed at the top block of the farm extended what was already a natural water storage point in the Weka Creek. From there it was funnelled off, with the minimal flow of the river maintained and the excess water gravity fed along a channel to a larger man-made dam which in turn is siphoned off to three separate schemes. McCaskey views it as a small, yet highly successful model. One which could be implemented on a much grander scale across the district, with Lake Sumner as the starting point.
McCaskey’s plan starts by raising the lake by three meters to establish a reservoir of water that ‘‘other areas can only dream about, capable of supplying all domestic, stock and irrigation for generations to come.’’ With the modern technology and machinery he has seen in action building the schemes in Mid Canterbury and Selwyn, McCaskey is convinced it would make placing a pipe system to Amberley and Cheviot ‘‘a simple operation.’’ He points to the Los Angeles aqueduct, which stretches some 389km.
Utilising an 1883 railway survey, McCaskey ascertained that to pipe water from Lake Sumner to Amberley and Cheviot is roughly 70km. Once the weir is in place at Lake Sumner, the pipes would divert the excess to the gravity fed pipelines Being gravity fed, it would not be a drain on the electricity network. In fact, it could be fitted with miniature turbines to produce power, one of the ecological benefits of the scheme, with the major impact being the flushing effect on the groundwater aquifers. He said the economic benefits would also be major, creating jobs in the short term to construct the scheme with the long-term benefits to farmers in the region - a steady supply of water and the flow on effects that has in the local economy.
Resource Management Act legal processes, which have twice made Lake Sumner off limits to development, have restricted the progress of the HWP and the ability for dams and storage systems to be built elsewhere in the region. McCaskey’s scheme would see the rivers maintain at least a minimum flow and the access water collected. Then through the series of pipes and ponds, distributed throughout the district.
The only problem is the changing of course, from the Waitohi Irrigation Scheme to McCaskey’s Lake Sumner Scheme. This would restart the multi-million dollar process that has already had the Waitohi scheme delayed on several occasions.
While McCaskey’s suggested plan has so far fallen on deaf ears, the HWP has been hampered by ongoing delays since it first applied for consents to take, store and use water in the Hurunui catchment in 2009. ’’As many farmers in the district will attest, a reliable supply of irrigation water, in combination with our good soils, will open a diversified and wonderful array of agricultural opportunities, if we have vision and courage’’