WATERTON, Alta. -- Parks Canada is banning motorized watercraft in Waterton Lakes National Park to try to prevent the spread of invasive mussels.

Canoes, kayaks and other hand-launched watercraft will still be allowed, although owners will have to inspect them for the acquatic species.

The agency says the move is necessary to protect the ecology of the park on the Alberta-Montana border.

It says mussel larvae were found last fall in the Tiber Reservoir in Montana -- less than a half-day's drive from Waterton Lakes.

A commercial boat tour will continue to operate on Upper and Middle Waterton Lake.

Parks Canada says it is working with the U.S. National Park Service and Alberta Environment and Parks to monitor for invasive mussels.