Trial of new technologies to remove ‘lake snot’

Lake Wanaka. Pnoto: ODT files
Lake Wanaka. Pnoto: ODT files
Two water filtration technologies designed to remove the algae that causes lake snow will be trialled at the Lake Wakatipu and Lake Wanaka freshwater intakes over the next two months.

Queenstown Lakes District council chief engineer Ulrich Glasner said the Amiad/Arkal treatment and filtration system would be introduced at Queenstown’s Kelvin Heights and Wanaka’s Beacon Point intakes in mid-March. They would be used for three months.

The second trial would involve a membrane filtration plant and would be tested at Beacon Point only.

It would run for two months from mid April, he said.

In January 2016 the council conducted a three-month trial of a new treatment system, developed by Veolia, to remove the algae.

Mr Glasner said it had been widely used in Australia.

The Actiflo Mini pilot system required the use of chemicals "and the feedback we received all the time from the community was we don’t want to have chemicals [in our water]".

The two new filtration technologies did not use chemicals, he said.

Costs and results from the two trials were being shared with Central Otago District Council, which had experienced a similar algae (Lindavia intermedia) issue with its proposed water bore near Lake Dunstan.

Over the past six months both councils have worked closely on a Southern Lakes water treatment plant trial for Lake Wanaka, Lake Wakatipu and Lake Dunstan.

The floating mucous-like substance ("lake snot") caused by Lindavia intermedia first appeared in Lake Wanaka in 2004, when fishermen noticed it on their fishing lines and lures.

Since then it has caused problems for swimmers as well as in town water supplies, where it has clogged household water filters in particular.

kerrie.waterworth@odt.co.nz

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