Provincial inspectors found two boats this summer that had harmful invasive zebra mussels on them, Alberta Environment says. 

The contaminated boats were discovered at the Dunmore vehicle inspection station southeast of Medicine Hat and the Vermilion station 200 kilometres east of Edmonton.

“One of the contaminated boat owners admitted he was very thankful for the inspection station, as he wouldn’t want to be responsible for bringing mussels into an Alberta lake,” the province said in a release.

Earlier this summer the province said it was deploying sniffer dogs at checkpoints near lakes and rivers around the province in a bid to prevent an infestation of zebra and quagga mussels in Alberta.

The fingernail-sized freshwater molluscs get attached to boats and can choke out native species and clog water intake pipes and machinery once they get established.

Quagga mussels arrived in Canada and the United States from Europe in the 1980s. Along with the closely-related zebra mussels, they cost governments in Eastern Canada and many U.S. states millions of dollars per year.

“Alberta is being very proactive in taking steps to stop invasive mussels from entering our lakes,” said Environment and Sustainable Resource Development Minister Robin Campbell in a release.

“Our success really depends on boaters taking advantage of inspection sites and always cleaning, draining and drying their boats. With only about half of boaters stopping to have their watercraft inspected this summer, stricter measures may be necessary to protect our waterways.”

An infestation in Alberta would cost an estimated $75 million annually, the province said.