Plans to increase water storage or manage demand in the Wellington region are on hold because use of drinking water has eased.
Greater Wellington Regional Council marketing water supply team leader Andrew Samuel said work during the past two years to extend the two storage lakes at Te Marua had increased total capacity by 12 per cent to 3.35 billion litres of usable water.
However, there had been a reduction in water use. Reasons for the drop include Capacity's work fixing supply leaks, more people living in city apartments and infill housing taking up garden areas, and more water-efficient appliances.
The council has begun negotiations with AgResearch to buy 200 hectares of land nearby for an additional lake, but more storage was not likely to be needed for at least 10 years and had not been budgeted for in the council's long-term community plan.
"If you look at water supply trends over the last few years since 2006, annual supply volume has been decreasing," Samuel said.
The potential new lake would be between the road to the Kaitoke reserve and Te Marua storage lakes.
However, the land purchase was to secure ownership in preparation for the additional storage when it was needed, he said.
Council staff were waiting to see population growth projections from the 2013 census and continuing to monitor water use.
If demand rose by 2 per cent additional supplies would need to be provided or there would need to be some form of demand management, he said.
The lakes project had been a success, Samuel said.
"We are pleased that project has finished on time and under budget."
A resource consent allowing the council to reduce flows in the Hutt River from the normal minimum flow of 600 litres a second at Kaitoke Weir to 400l/sec during the three years of construction was invoked once on March 12 this year and the increased take ended with the end of an outdoor watering ban on April 9.
The third contingency year was not required and the consent ended as soon as the upgrade work finished, he said.
The project had two goals, increasing capacity and reducing the chance that the lakes would leak after a major earthquake fault movement, he said.
Tough plastic liners were fitted to the lake beds.
- © Fairfax NZ News
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