Reservoir plan as dam alternative
A new water scheme has been unveiled as a much cheaper alternative to the proposed $82.5 million Waimea dam in the Lee Valley.
Proposed by a group of irrigators from Waimea Irrigators and Waters Users Inc, the scheme involves a series of clay-lined, inground reservoirs to be filled during winter months.
Spokesman for the group, consultant Brian Halstead, said preliminary costings had come in at $25m for the proposed scheme’s three reservoirs – one each side of the Wairoa River just below the Waimea East Irrigation Scheme intake off Clover Road East and the third along the Waimea River at Challies Island.
There would also be the cost of land purchases for the sites near Clover Road East; Challies Island was already owned by the council. It was proposed the scheme would cover about 75ha over the three blocks. The reservoirs would be about 7m deep. ‘‘Preliminary estimates suggest a storage capacity of 5 million to 6 million cubic metres,’’ Halstead said.
While that was less than half of the storage tipped for the proposed Waimea dam, it would ‘‘better serve the community and irrigators as a shorter-term measure at a fraction of the cost’’.
‘‘In conjunction with strategically placed weirs in both the Wairoa and Waimea rivers, Richmond and the irrigators would have a much more reliable buffer against normal dry spells.’’
Halstead said the third reservoir at Challies Island would not be used for irrigation. Its stored water would only be released into the Waimea River to counter any salt intrusion ‘‘to protect the well fields at the end of Lower Queen St’’.
The price estimate of $5 a cubic metre was based on the costs for the Rooney Group water scheme in Canterbury. A surveyor had drawn up initial plans for the Waimea scheme but Halstead was calling for a proper investigation of the proposal by Tasman District Council.
‘‘I’d like them to reconsider their proposal and consider this,’’ he said.
It was proposed the reservoir scheme would be owned by the council, which would later sell shares to irrigators or charge for the water to help service the debt. Halstead estimated it would provide the council with enough water for the expanding urban areas of Richmond and Mapua for at least 40 years.
Water for the Waimea East Irrigation Scheme could be drawn from the reservoirs instead of directly from the river. There would also be opportunities for the Waimea East scheme to expand west. That water not drawn from the river for irrigation would allow a greater flow, helping to recharge the aquifers.
Waimea East would be a priority user. Halstead said his rough calculations indicated it would be cheaper by about 10c a cubic metre for Waimea East scheme irrigators to buy water from the proposed council-owned reservoir system than via the Waimea dam.
Halstead said the council had already earmarked $25m in its Long Term Plan for the dam. ‘‘This could be diverted to this muchmore affordable and realistic proposal,’’ he said.
The Waimea dam had gone ‘‘beyond the boundaries of common sense’’. It was too large, it had support from irrigators for less than half of the 5850ha capable of irrigation and faced obstacles for funding.
The reservoir proposal would create an opportunity to build a stopbank to help protect Brightwater from flooding. There would also be the chance to sell gravel that was removed.
Tasman mayor Richard Kempthorne said the council would welcome the chance to have a look at the concept while mayoral candidate Maxwell Clark said it sounded like an ‘‘excellent scheme’’ that was worth investigation.
However, the third mayoral aspirant, Kit Maling, said it did not sound as if the reservoir plan would provide enough water. He said he would look at any proposal but did not want to delay the process for the proposed dam. Securing a financial contribution from the Government was key and the government could change next year.
‘‘We’ve got one chance to build this dam,’’ he said.