Zebra mussels found on sailboat from Bde Maka Ska

Bde Maka Ska is the latest Minnesota waterway with a confirmed zebra mussel infestation, officials said Monday.

A Minneapolis Park and Recreation Board watercraft inspector contacted the state Department of Natural Resources (DNR) after finding two juvenile zebra mussels on a sailboat as it was being removed from the lake for the season after being moored there for quite some time.

Park Board, DNR and other inspectors have been working on the lake "to determine the extent and distribution of the zebra mussel population," read a statement from park officials.

Zebra mussels were confirmed in September 2017 in Lake Harriet, immediately downstream of Bde Maka Ska, formerly named Lake Calhoun.

The Park Board is in the midst of inspecting all boats as they are taken off the lake — the deadline for removal was Monday — and there have been no additional zebra mussel findings.

Also, DNR invasive species staff conducted a dive search in the buoy field and at the access of the lake and came up empty as well.

Zebra mussels can drastically change a lake's plant community and food supply. The tiny mussels multiply into the millions and sometimes billions, filtering out nutrients until the water becomes "gin clear." Their sharp shells cut the feet of swimmers, foul boat motors and damage water pipes.

The other side of the Twin Cities got the same bad news from the DNR in August, when zebra mussels were found in Bald Eagle Lake north of White Bear Lake, Lake Johanna in Arden Hills and Lake Isabelle near Hastings.

"To help prevent further infestations, we need people to do a thorough job of checking for zebra mussels and other invasive species when removing their boats, docks and lifts on all bodies of water at this time of year," said Heidi Wolf, DNR invasive species unit supervisor.

State law requires boaters and anglers to clean their watercraft and trailers of aquatic plants and prohibited invasive species, drain all water by removing plugs and keeping them out during transport, and dispose of unwanted bait.

In addition, when moving from one waterway to another, the state wants boaters to spray their vessels with high-pressure water and then let dry for at least five days.

Through late July, according to the DNR, 16 percent of boats checked at Minnesota aquatic invasive species stations were in violation of state requirements in the battle against zebra mussels and other invasive species.

The thumbnail-sized mollusk traveled to the U.S. from the Caspian Sea region in far eastern Europe, hiding in the ballast water of ocean freighters. They first took hold in water connected to Lake Erie in 1988, multiplying and spreading rapidly across Michigan, Illinois and other Great Lakes states.

The first Minnesota zebra mussels, besides those plucked from a buoy in Lake Superior in 1989, arrived in the Mississippi and Lake Pepin in 1992.

Paul Walsh • 612-673-4482