The chairman of the Lake Waihola-Waipori Wetlands Society, David Vollweiler, told the District Development Board of the Clutha District Council this week it had awarded a weed control contract to Dunedin-based consultant Paul Pope.
Lake Waihola was a tidal lake which had rapidly been infested by weeds, especially crack and grey willows, which were clogging up the waterway and channels, Mr Vollweiler said.
"We believe that is a large reason for the silting of the lake ... if nothing was done, we predict in another 10-15 years the lake would be completely clogged."
The society had been given $280,030 from various funding bodies to clear about 200ha of weeds growing in the 2157 ha wetland.
Roundup would be applied by helicopter to the 200ha area in January, which Mr Vollweiler said would most likely be done in the early morning.
If the weather is right, the Roundup could be applied in one or two days, but might take up to two weeks, he said.
The water would be completely safe to use, and there was no danger to the public.
The cost of removing the dead plant life was prohibitive, and the wetland would look "pretty unsightly" until the dead willows eventually broke down.
"Once you knock the willows and other plants that shouldn't be there, the native plants start to regenerate."
Over the next couple of months the society would be working to inform stakeholders and the community about the long term goal for the wetlands and the work that was being done to achieve it, he said.
"We are looking at the bigger picture and preserving the use of the lake for generations to come."
