Glacier National Park will allow non-trailered, non-water cooled boats with electric motors on Bowman, Two Medicine and St. Mary lakes this summer.
Last year, in response to the discovery of non-native mussels in two reservoirs east of the Park, Glacier closed all but Lake McDonald to boats with motors.
A 10 horsepower limitation applies to motors on Bowman and Two Medicine Lakes.
The boats will still be required to undergo a mandatory inspection.
Motor boats with trailers will be allowed on Lake McDonald, provided they’ve been inspected, sealed and undergone a 30-day quarantine.
This year, the park will honor Montana State, Whitefish Lake, and Blackfeet Tribal motorized watercraft inspections and seals with verified 30-day dry time before launch on Lake McDonald.
Inspection stations will open on May 12 for west side waters, and June 1 for east side waters.
Park waters were surveyed for the presence of the invasive mussels and tests using environmental DNA as well as more standard juvenile mussel sampling all indicate park waters remain free of these species.
Environmental DNA sampling is a relatively new method for early detection of aquatic invaders and uses water samples collected from a lake or stream to look for the DNA of invasive mussels whereas other sampling methods generally rely on capturing the ”veligers,” or juvenile planktonic stage of the invasive mussels to confirm their presence in a lake or stream. The latter approach can only be used in the park in summer and fall when water temperatures are suitable for mussel spawning. Environmental DNA sampling can occur at any time of the year because DNA is continually being shed into the environment. Both approaches have their pros and cons, Park biologists say, but by using them in combination, the Park intends to maximize its early detection ability which is critical to managing the potential spread of any infestation.
In 2018, in cooperation with the Glacier National Park Conservancy and the Flathead Lake Biological Station, the park plans to expand the environmental DNA monitoring beyond invasive mussels to include invasive aquatic weeds such as Eurasian watermilfoil and others. These plant invaders can also degrade the park’s aquatic environment, impacting the natural resources and public recreation. Visitors may see park boats out on lakes in the spring, summer, and fall collecting water samples as part of the park’s aquatic invasive species early detection and monitoring program.