Zebra mussels found to have infested harbours in the south basin of Lake Winnipeg now have a date with death.
A treatment plan to eradicate the parasite begins next at Winnipeg Beach and ends June 12 at Balsam Bay Harbour on the other side of the lake.
Much of what the province has planned is dependent on the weather and the breakup of ice on the lake, although the lake does not have to be totally ice free for the eradication plan to begin, the province said Tuesday.
The province plans to blast the four affected harbours with liquid potash (potassium) in a bid to choke out the aquatic pests and stop them from spreading.
Conservation and Water Stewardship Minister Gord Mackintosh said the province will spend an extra $100,000 above the $500,000 already planned to accommodate commercial fishers.
Mackintosh said to lessen the impact fishers will still be allowed to use harbours as they are being treated. Rather than using a stationary curtain across the mouth of the harbour as originally planned, the province will now install a gated silt curtain that will keep the liquid potash in the harbour, but can be opened to allow fishers to get in and out of the harbour.
The gated curtain will also allow the Coast Guard and search and rescue boats out onto the lake. They will have clear signage and be supervised and operated by staff according to operational guidelines provided to the Harbour Authority.
The only exception is Balsam Bay Harbour, which is too shallow to accommodate a movable curtain so a full containment curtain will be installed.
As soon as boats passed through more liquid potash will be injected into the harbour to keep the treatment level at a concentration of 100 parts per million 24 hours a day during the treatment period.
The province’s project coordinator Rob Nedotiafko said use of the gated silt curtain will allow fishers quick exit and access to the harbour.
He said the province wants to install the first curtain at Winnipeg Beach as soon as the ice threat passes.
"We’re watching and reducing the potential for any ice moving into the harbours," Nedotiafko said. "The timing of the season is working out well as the ice is moving off the lake at a time when we’re wanting to implement the treatment. Right now, it’s sort of perfect conditions."
Mackintosh said the province believes the liquid potash treatment will work as it’s has been proven effective against zebra mussels in other jurisdictions. It does not impact fish or discolour water. The application will be undertaken by the ASI Group Inc.
"There’s only one guarantee, and that’s if nothing is done the lake will certainly get worse," he said, adding the province may repeat the process next spring depending on the effectiveness of this year’s treatment.
"We will continue to be nimble on this given our ongoing monitoring," he said.
The zebra mussel infestation was identified in the four harbours in the south basin of Lake Winnipeg last fall. Additional inspection this spring has confirmed the zebra mussels survived the winter. If left to thrive, the mussels could contribute to the growth of green-algae blooms on the lake, curb production of certain fish species and foul beaches. Because of their ability to attach to solid objects such as boats and docks, they can also clog water-treatment-plant intake pipes and effluent-discharge pipes.