Weed levels in Lake Dunstan are an "environmental disaster'', a group trying to tackle the problem says.
At an Otago Regional Council draft annual plan submissions hearing in Cromwell this week, Guardians of Lake Dunstan chairman Andrew Burton said action needed to be taken on lagarosiphon levels in the lake.
"This is now a money issue, due to its vast spread, but action must be taken for its effective control.''
The regional council contributed $100,000 a year to the problem in Lake Dunstan, but this needed to be increased as it was an "environmental disaster'', he said.
The group favoured "environmentally friendly'' methods of killing the weeds, rather the present extensive use of herbicide, he said.
These strategies could be employed year-round, whereas herbicide spraying was weather-dependent, he said.
He did not specify what the alternative methods were.
The regional council, Central Otago District Council and Government should work together to create a plan for areas where the weeds grew, he said.
Submitter John Wilson said the situation was "not going to go away'' without action.
"This is serious, guys. At Bendigo, you can practically walk across it.''
If the lake level was dropped by 8m for about 30 hours in summer, the Central Otago sun would kill the exposed weed, he said
However, he acknowledged Contact Energy, which controlled the lake's levels, was not allowed to do this, because of rules in its resource consent.
