The next weapon is being wheeled out in the battle for improved water quality for Alexandra.
The Central Otago District Council has been investigating options for improving the town's water supply for more than four years, after fielding numerous complaints about lime scale, hardness, taste and odour.
Last year, the Vincent Community Board decided against further development at the existing bore site and heard that trials on reducing the lime scale in the water failed to impress users.
Council water service manager Russell Bond said yesterday investigations were under way into a new source for the water supply. The Ngapara pools site, near the Clutha river bank on the northern outskirts of the town, was being tested to assess water quality and volume.
Redevelopment of the current borefield, on the true left of the Clutha River, near Eclipse St, would not solve the problems with the water supply, the board was told last year.
"We'll see if the Ngapara pools site is an improvement on that, and if the water quality and volume results stack up, then we'd consider a test bore," Mr Bond said.
"The aim is to do the cheapest option [for investigation] first, to see if the site is ruled in or out, before you'd proceed to more expensive work," he said.
A study done by the council in 2007 into supply alternatives identified solutions ranging in costs from $1.77 million to $13.62 million. Removing the hardness from the water and meeting the health department's drinking water standards could cost residents an extra $420 a year on their rates bills, the board was told last year.
Mr Bond said low river flows were thought to play a factor in the water quality problems.
"Historically, the existing bores have generated complaints in terms of the water's hardness, taste and occasional odour. These issues tend to increase when river flow is low and are thought to be the result of changes in the underlying hydrology," he said.
During times of low flow, water flow into the bores appeared to change, and was more affected by "underlying influences" such as the old coal workings in the Boundary Rd area.
There was no evidence of a health risk from those changes, or of infiltration from the closed landfill, but there could be changes in water taste and odour, Mr Bond said.
Any physical works to improve the town's water supply would be timed to coincide with meeting the drinking water standards.
"It's been difficult to find the solution for Alexandra water; a good cost-effective, quality system."
