About 40 people attended a water quality meeting jointly held by the Otago Regional and Queenstown Lakes District councils at the Lake Wanaka Centre yesterday
Another meeting was held in Queenstown last night. .
Most of the Wanaka meeting was taken up with the lake snow issue.
Lake snow is a mucus produced by the algae Cyclotella bodanica. It has been present in Lake Wanaka since at least 2008 and was discovered in both Lake Hawea and Lake Wakatipu this year.
Regional council resource science manager Dean Olsen said at the meeting the council was still trying to determine where the algae had come from and why it was producing the mucus known as lake snow.
The same or very similar type of algae had been found in other lakes but they did not produce lake snow, Mr Olsen said.
There was little overseas evidence which could be used to create a management plan to control lake snow, he said.
It was very likely lake snow was present in the Clutha River and Lake Dunstan but it had not been confirmed, he said.
A study of the algae's DNA would give scientists are clearer idea of its origins.
''To be able to manage lake snow in the long term we need to know if it's an invasive species or not,'' Mr Olsen said.
A number of different causes for lake snow had been identified by the council. One possible cause was a higher level of nutrient runoff from urban and rural developments.
Preliminary studies by a Phd student at the University of Otago showed the algae produced more slime when nutrient levels were higher.
Other possible causes included climate change and the emergence of a non-native water flea which had replaced the native species.
District council chief engineer Ulrich Glasner said complaints of water systems being affected by the mucus in Wanaka were becoming more common.
The council had mapped where the complaints were coming from, which showed the issue was not isolated to one specific area of the town, Mr Glasner said.
A trial of a Actiflo Mini pilot system earlier this year was very successful, with about 95% of the lake snow removed from raw water.
The council would now investigate the feasibility of purchasing the system but it would cost ''big money'' Mr Glasner said.
Other filtration systems were also being looked at.
A second meeting last evening at the Queenstown Events Centre attracted a relatively small turnout, with QLDC and ORC representatives outnumbering the half-dozen members of the public who attended.
Queenstown Mayor Jim Boult said the low turnout probably reflected the fact that lake snow had only recently been noticed in Lake Wakatipu.
-Additionally reported by Guy Williams
