Alternative proposed to Waimea Dam construction

December 5th, 2014

The "pipe dream" of piping water from Lake Rotoroa to feed the Waimea River, rather than building an expensive dam, is being advocated by Gary Watson, a candidate for Tasman District Mayor last year.

Gary says with the huge opposition from ratepayers to the dam being built and the estimated costs continuing to escalate, "the question is, is there an alternative solution to address the region's long term water supply?"

He says that over 10 years ago the TDC looked at piping water from Nelson Lakes, but at the time they didn't consider using the existing railway reserve corridor from Brightwater to the Gowan River to avoid land purchase costs.

Gary says Lake Rotoroa (pictured right) is approximately 22km long by 2km wide and 145 metres deep max, and it is a potentially huge natural water reservoir for the Nelson and Tasman region for the foreseeable future.

"Lake Rotoroa is in a larger catchment area with higher rain fall than Lee Valley, the water is flowing down the Gowan River into the sea now in huge volumes, the small amount of water required would be barely detectable in the river and the collection facility could be totally concealed.

"Using pure lake water means no major environmental damage, no risk to life of a dam breaking and is a very simple, low cost and reliable solution.

"Past studies are believed to have included the costs of purchasing land and all the legal costs involved but this is not a major issue now as pipe line costs are low and the land is mostly available at no cost.

"The existing railway reserve corridor from Brightwater to the Gowan River is still in place including tunnels and it is an ideal gental slopping path way for an above ground low cost pipeline so almost no land purchase is required and little earthworks.

"An above-ground large pipe is low cost to maintain and repair if required and it would provide an over 300 metre head at Brightwater where the surplus water could be discharged into the Appleby river and thus generate about $20 million in electricity every year whilst also maintaining the current Waimea aquifers.

"The electricity revenue could pay the interest and the principle on the loan with little or no ratepayer funding required. A pipeline could provide Nelson and Tasman with an almost endless supply of quality water that would require little treatment.

"Existing water users could keep using their current systems with no water restrictions and their current water consents could even be increased.

"Auckland pipes its water from the polluted Waikato River with pumps and filters but in our case it's gravity feed so there are no pump running costs.

"Piping water long distances is done all over the world. Low cost PVC pipes can be used in the upper sections where the pressure is lower and steel pipes used in the high pressure lower sections.

"Laying the pipeline above ground is low cost and the whole project could be done within 2 years so the benefits are enjoyed earlier. This idea removes all the negative arguments of building a dam. Water rights and consents are required no matter which option is decided but a pipeline is a very simple solution.

"Despite what the experts say there are dams in NZ and all over the World that break, kill people and destroy property that are said to be 100% safe. Pipelines have next to no risk as they have shut off valves and limited flow.

"The Lee Valley / Waimea Community dam would flood a huge area, adversely effect a lot of people and could only generate a very small amount of electricity compared to what a pipeline from the lake could generate.

"The question - is would the TDC and Engineers consider this alternative or oppose it, as who can make big consultancy fees from just a pipeline and hydro compared the complexities of a dam and all its issues and costs. pipe?

"Using lake water would not require a region wide, huge rate increase because of the electricity generation revenue component. Maybe it's a case of a Pipe dream actually being the alternative solution."

Comment by John Lee:
[Posted 9 December 2014]

Very interesting idea, but will the author please provide documented evidence as to the benefits, before he gets my vote?

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