Province plots attack on zebra mussels

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This article was published 30/4/2014 (1204 days ago), so information in it may no longer be current.

Four Lake Winnipeg harbours will be off limits to boaters and commercial fishers this spring under a government plan to wipe out an infestation of zebra mussels in one fell swoop.

Gimli, Winnipeg Beach, Balsam Bay and Arnes will be the testing grounds until mid-June for the province to inject potassium-containing potash into the each harbour in a bid to choke out the aquatic pests and stop them from multiplying, Conservation and Water Stewardship Minister Gord Mackintosh said Wednesday. Each harbour outlet will be ringed by a special synthetic curtain to the lake bottom. Willow Point near Gimli will also be treated on limited basis.

"We were advised if this was done roughly mid-May it could be concluded mid-June, even staggering treatment in the different harbours," Mackintosh said. "The experience elsewhere has shown zebra mussels can really undermine the enjoyment of the lake with broken shells on the beach and the smell of dead zebra mussels. The one certainty we know of is if we do not take action, things will get worse."

The mussels were first found last fall on the hull of a private boat and a dock at Winnipeg Beach and on some fishing boats dry-docked at Gimli. The freshwater mollusk, native to southern Russia, arrived in North America decades ago and recently became established in the Red River watershed south of the border. 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.

Mackintosh said the government's plan is to attack the mussels as soon as the ice goes off the lake and when the water temperature allows for what is hoped will be a one-time treatment. It will cost $500,000.

"Because the density of zebra mussels is relatively low still, the action should be taken now and not postponed to later in the summer or even fall," he said. "The sooner, the more effective, given that female zebra mussels produce one million eggs a year. The Great Lakes were infested in less than five years."

Mackintosh and Water Stewardship assistant deputy minister Bruce Gray said the plan is still subject to provincial and federal approval.

Gray said the potash will be liquefied and injected throughout each harbour to reach a concentration of 100 parts per million.

"At that level, it's toxic to the zebra mussels but not toxic to fish," Gray said. Once the curtain is removed, the potassium will dissipate harmlessly into the lake. Potassium does not contribute to algae growth.

Mackintosh said the action is based on a successful experiment to eradicate the mussels at Millbrook Quarry in Virginia in 2006. The entire quarry was injected with 658,661 litres of a potassium chloride solution over a three-week period. The Lake Winnipeg effort will be the first time such a plan is executed in open water.

Mackintosh will be in Gimli today to begin a series of meetings on how fishers can be best accommodated if they do not have access to their home harbours, as the eradication plan will overlap with the commercial fishing season by about two weeks.

bruce.owen@freepress.mb.ca