Winnipeg's drinking water is vulnerable to zebra mussels, experts say

Some zebra mussel experts say Shoal Lake is ripe for an infestation of the invasive water pest. And they applaud the city for being proactive with plans to keep the mussels out of Winnipeg's drinking water.
Shoal Lake, where Winnipeg gets its drinking water, has no zebra mussels, but some experts say it's ripe for an infestation of the invasive water pest. (Roxanne K. Greene)

Some zebra mussel experts say Shoal Lake is ripe for an infestation of the invasive water pest, even though they applaud the city for being proactive with plans to keep the mussels out of Winnipeg's drinking water. 

Experimental Lakes Area research scientist Scott Higgins says a number of factors govern the potential for a zebra mussel infestation.

"One of them is zebra mussels require a calcium concentrate of about 12 milligrams per litre. So if you're anywhere above that, you're at a fairly high risk," said Higgins.

On Tuesday, the City of Winnipeg web site reported test results from Shoal Lake water between Jan. 1 and June 30, 2015 for calcium levels between 17.7 and 22.9 parts per million.
Zebra mussels have infested Lake Winnipeg but so far there's no evidence they're in Shoal Lake, the source of Winnipeg's drinking water. But experts say that could change. (CBC)

"So that would mean if zebra mussels were to make it to Shoal Lake via a boat (or other means) there is the potential for a large population to become established. i.e. high risk," Higgins said Tuesday.

He says the fact Shoal Lake is currently remote, with no road access, helps to protect Winnipeg's drinking water.

Higgins likes the city's plan to consider treating the water from Shoal Lake with copper which would kill the zebra mussels and have no effect on the taste or smell of the water.

The city has called for proposals to build a copper-ion generating station at the Shoal Lake intake facility.
Bids for the project close this Friday, Nov. 20.

"What they're doing is creating copper ions that are toxic to any mussel. But they don't create some of the other hazardous byproducts that chlorine and other chemicals can produce. Typically you do this before you treat the water. And you do it in a confined location, so within a pipe or within a confined water reservoir. You create these copper ions. They kill the zebra mussels," Higgins said.

'All it takes is a single boat'

As far as he knows Shoal Lake has no zebra mussels now.

"And I would be quite surprised if they did," said Higgins. "I would have heard about it. All it takes is a single boat. It's possible there could be a zebra mussel in there that we don't know about. They could be invaded next year. It could be ten years. It's hard to say."

Meanwhile, Manitoba Hydro has ramped up its fight against zebra mussels after finding the invasive water pests at its Selkirk generating station.

Hydro spokesperson Scott Powell said they found two mussels at the Selkirk generating station six weeks ago. 

"We've only found the two. We haven't found any others since. They were on an intake screen at one of our cooling water pumps on the Red River. That's the only two we found."

Powell says the mussels can't cling to Hydro's giant turbines, but they can cause serious problems to the supporting facilities.

More than a dozen Manitoba Hydro sites vulnerable

Zebra mussel consultant and biologist Renata Claudi of RNT Consulting in Picton, Ont. is working with Manitoba Hydro to come up with eradication plans for 14 sites across the province which are considered vulnerable to damage from the mussels.

Claudi is also keeping a close eye on the city of Winnipeg's strategy for Shoal Lake.

"There is no doubt that the mussels will survive in that lake. And then the second issue is how likely is it that they are going to get there," said Claudi. "Usually the risk to a lake is dependent on how many boats [there are] and where do they come from. So if most of the boats in this lake come from Lake of the Woods, you're good. Because Lake of the Woods doesn't support a mussel population. But if the boats come from somewhere else, like Lake Winnipeg, you're not so great."

"You really can't ignore zebra mussels, Claudi said. "Well, you can ignore it for a little while. And then you have no flow. And it's really expensive to get it back."

No one could say how much it will cost the city of Winnipeg or Manitoba Hydro to prevent zebra mussel from infesting untouched waters.

Scott Higgins says funding to fight the water pest will have to be a constant in the future.

"We're not going back. Zebra mussels are here to stay," said Higgins. "I think the big wake-up call came this September/October when boats started being pulled out of Lake Winnipeg and they saw just how dense the zebra mussels were on them. Before that it wasn't just, 'Oh, zebra mussels are here. Oh well'. Once people see how much they've increased over one year, from a dozen mussels on a boat last year to tens of thousands or millions of zebra mussels now."

Manitoba will host the next International Aquatic Species Conference in April 2016. Experts from around the world will be in Winnipeg comparing their experiences eradicating zebra mussels and other water pests.


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