The cost of eliminating algal contamination from Wanaka's drinking water supplies could cost $28 million, Queenstown Lakes District Council capital works manager Ken Gousmett said yesterday.
"The range of options [to address the problem] range from zero to $14 million. That's per treatment plant. We are looking at two intakes," Mr Gousmett said at a Wanaka Community Board meeting.
One of two reports the board received on the algae issue which has plagued many householders for several years was by MHW Ltd and Otago University (at a cost of $38,000) that included a comparison of various remedial options open to the council.
Mr Gousmett's report instead recommended several new maintenance steps, including cleaning and repairing intake screens, changing back wash and pumping cycles, undertaking more regular intake inspections, and installing light shields on intakes next summer.
It would cost $200,000 and Mr Gousmett conceded the programme, designed to keep intakes clean, would probably not satisfy most people.
The maintenance programme was criticised by Wanaka Residents Association chairman Graham Dickson, who said in the public forum the council was not doing enough to reduce harm caused by clogged domestic filters.
Mr Dickson had little patience with some conclusions in the reports, such as the algae did not pose a health risk.
"Health problems were never the issue. The issue has been clogged filters." Mr Gousmett's report did not contain a strategy to solve the problem, Mr Dickson said.
Wanaka resident Jan Burdon said she had spent $2000 to get her water toby rectified and filters cleaned and had to get her washing machine and dishwasher replaced.
The board questioned Mr Gousmett, QLDC Wanaka project manager Rob Darby and the council's 3 Waters manager Gerry Essenberg for about 30 minutes.
There had been exploratory drilling for bankside bores at four sites (the most affordable and realistic option outlined by MWH at $1 million) but Mr Gousmett said the results were "quite bad".
Only one bore, at the Roys Bay intake near the yacht club, was "promising" and although more test bores would be drilled, the results might never be positive.
Microstrainers were the next best option (about $3 million-$4 million) and a supplier had offered to take part in a free trial, although there could be set-up costs, Mr Gousmett said.
He promised to "move fast".
"We want to stop algae growing on the intake. That's the issue," he said.
