The search is on to find a filtration solution for the Lake Dunstan Water Supply that will counteract the discovery of Lindavia intermedia algae in the lake.
A different filtration system will now be needed from the previously proposed simple cartridge system which wouldn’t combat the algae.
Trials at Clyde and Wanaka between January and April 2020, in partnership with Queenstown Lakes District Council, will work towards finding the best filtration solution.
The findings will inform the design of the Lake Dunstan Water Supply Treatment Plant and assist with project planning for a Cromwell water upgrade scheduled in our Long-Term Plan.
Lindavia intermedia algae are a microscopic species responsible for causing lake snow, a glue-like slime that blocks water inlets and filters. The algae aren’t toxic and pose no known human health risk.
The algae were first discovered in 2018 in Lake Dunstan by CODC during filter trials for the new water supply. It’s been in Lake Wanaka and Lake Wakatipu for some time and blocks domestic filters in Wanaka.
An interim water treatment plant may be established to provide safe drinking water to Alexandra and Clyde when the Lake Dunstan Water Supply becomes operational in mid-2020. This is because more time may now be needed to install a permanent filtration solution that addresses Lindavia intermedia.
While CODC’s share of the cost of filtration trials is expected to be $450,000, the cost of implementing a new filter system and how this will impact overall project costs can’t be confirmed until the best filtration system is identified.