04/30/2014 06:14 EDT | Updated 06/30/2014 05:59 EDT

Manitoba zebra mussel concerns close 4 Lake Winnipeg harbours

The Manitoba government plans to close four major harbours on Lake Winnipeg in an attempt to eradicate invasive zebra mussels.

The small filter-feeding mussels reproduce aggressively and were first spotted in Lake Winnipeg's algae-ridden waters in October 2013.

Conservation Minister Gord Mackintosh said the province still needs approval from Ottawa, but it wants to dump tonnes of potash into the harbours at Gimli, Winnipeg Beach, Balsam Bay and Arnes, shutting the harbours down from mid-May to mid-June.

Mackintosh said the process could take a month, which means no fishing boats or leisure watercraft will be able to use those harbours.

Certain aquatic areas will be roped off with a silt curtain, and boats will be sent out to inject liquid potash into the lake

The potash treatment is allegedly not harmful to humans and any other aquatic life, but the closure will directly impact Lake Winnipeg’s tourism and fishing industries, forcing commercial fisherman ashore for an entire month.

There is no plan in place yet to compensate those impacted, but the province said it's short term pain for long term gain. 

Potash treatment uncertain

The province is investing $500-thousand in the potash treatment, despite the fact that it isn't certain to cure Lake Winnipeg's zebra mussel woes.

But Mackintosh said the province has no choice.

"While it can't be certain, the only certainty that we do have at hand here is if nothing is done," said Mackintosh. "And if this isn't, if we don't make this application, the situation will certainly get worse​."

Mackintosh said the province is relying on one U.S. study which said potash is effective in eradicating zebra mussels.

"This can be a really rapidly developing threat to the health of Lake Winnipeg and the economy, and the families that rely on Lake Winnipeg for incomes," Mackintosh said.

Zebra mussels can have a significantly negative impact on fresh water ecosystems.