Lake Sumner the solution to water woes
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 wier 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.
‘‘I’ve had this dream longer than many North Canterbury residents have lived,’’ he said.
‘‘The answer to that dream has been, and always will be, water stored in a mountain lake.’’
He said a reliance on bore water was idiotic in terms of geophysics when the ‘‘world’s best water’’ was only 50 km away.
Continually pumping groundwater to the surface means the water not captured by plants percolates back to the underground reservoir so ‘‘every season another load of surface pollutant is regurgitated, leading to increased concentration’’.
He compared it to drinking your own urine time and time again, slowly increasing the toxicity.
‘‘Bringing fresh mountain water to irrigate has a different effect,’’ he said.
‘‘The loading of soil with this water allows underground water to be replenished by natural forces and its eventual exit to the sea, flushing the system.
‘‘Allowing the aquifers to keep full prevents salt water ingress and maintains the springs that bubble up to keep our local creeks flowing. And an end to the boil water notices.’’
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 HWPand the ability for dams and storage systems to be built elsewhere in the region.
As the drought continues on this side of the main divide, orthographic rainfall has kept the West Coast green and rain in the alps has meant desperate farmers watch the rivers flood with precious water flowing by unabated to sea.
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 multimillion 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 HWPhas been hampered by ongoing delays since it first applied for consents to take, store and use water in the Hurunui catchment in 2009.
McCaskey isn’t alone in his skepticism of the HWP, set for a construction start date in 2018.
In a Federated Farmers submission to the Hurunui District Council’s annual plan earlier this year, concerns were voiced over a lack of financial support from the council and the current plan’s viability.
‘‘It is possible that only part of the originally proposed scheme will be developed leaving some of the district’s best soils for primary production vulnerable to drought.’’
It also stated that the scheme has never included the Cheviot area, which was one of the areas most affected by drought.
‘‘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’’
McCaskey’s vision would be substantially larger in size and coverage and come with a heftier price tag but as he quipped, you can’t put a price tag on the future.
‘‘Without water, there won’t be a future,’’ McCaskey said.