Underwater curtain at Clear Lake dislodged days after completion, zebra mussels still not contained

A curtain placed below the surface of Clear Lake in August as part of an effort to slow the spread of zebra mussels was only in place for two days before it was dislodged by high winds.

Parks Canada says it's still trying to complete the containment effort in Riding Mountain's largest body of water, though some cottagers along the lake fear the federal agency missed an opportunity to contain and possibly eradicate the invasive molluscs, which have already colonized Lake Winnipeg and other Manitoba waterways.

On July 27, a contractor employed by Parks Canada began assembling an 1,800-metre-long curtain that was supposed to isolate the Boat Cove area of Clear Lake, said Dameon Wall, external relations manager for Riding Mountain National Park. The curtain is a waterproof membrane secured with weights to the bottom of the lake.

That curtain was nearly completed by Aug. 6 but was dislodged by winds two days later, Wall said.

"We found that just before it was completely deployed, wind was pushing it in. So by the eighth of August, that curtain had moved out of where it was supposed to stay in the lake and was no longer containing the water in an area where we were trying to keep it contained," Wall said Tuesday in a telephone interview from Brandon.

"Since that time we've been, we've been working with the the company that did the installation to find solutions on that."

Wall said if the isolation is successful, Parks Canada still plans to apply potash to the affected waters in effort to kill any zebra mussel larvae and adults in the area.

A clump of adult zebra mussels was first detected in Clear Lake in the Boat Cove area, just west of Wasagaming's beachfront, in November 2023.  Another live adult mussel was found in the same area on July 17.

Cottagers in the Wasagaming area say they're disappointed Parks Canada was unable to hive off the Boat Cove area this summer, especially considering zebra mussels were first found in the area more than nine months ago.

"I don't know why they wouldn't put that curtain up immediately to try and isolate the area," said Kyle Bazylo, who has owned a cottage at Clear Lake for 20 years and sits on the board of the Clear Lake Cabin Owners' Association.

He said he does not believe the contractor that installed the curtain weighted the structure down sufficiently.

"Sure enough, within a week the curtain blew in," Bazylo said in Winnipeg. "We're talking over a month ago now and that curtain is still wide open areas."

Bazylo said Parks Canada has effectively missed an entire year to slow or stop the spread of zebra mussels in Clear Lake because mussels reproduce more quickly in the summer, when the water is the warmest.

His cottage association is also disappointed in what they describe as poor communication about the mussel eradication effort from Parks Canada, noting cabin owners have complied with regulations intended to contain invasive species, have helped educate visitors about those rules and have reported violations.