It's not a big surprise, but it is disappointing to Department of Natural Resource officials that invasive zebra mussels have been found in Cass Lake, a popular lake in the Bemidji area in northwestern Minnesota.
The agency announced Friday that a person who was collecting shells on a beach on the southeast corner of Cedar Island -- one of the lake's five islands -- found several dead zebra mussels, and reported the find to the DNR. A search of the lake near there found many other mussels of different sizes, meaning the animals are reproducing, the Star Tribune reports.
It's the first confirmed adult zebra mussel find in the Bemidji area, said the DNR.
“We were not dramatically surprised, but we are disappointed,” said Henry Drewes, DNR regional fisheries manager in Bemidji, according to the Star Tribune.
Cass Lake will now be designated as infested with zebra mussels, along with eight lakes that connect to it -- Buck, Andrusia, Wolf, Pug Hole, Kitchi, Little Rice and Big Rice lakes and Pike Bay. Although no zebra mussels have been found in those lakes, they are heavily used by boaters traveling from Cass Lake. This map shows the affected waterways outlined in red (click map for a larger view).
Zebra mussels have been filtering into Minnesota lakes and rivers at an alarming rate and have now claimed at least 200 state waterways, including Lake Minnetonka. Over the summer, a Detroit Lakes area lake became the first in that area to be found containing the invasive species.
The striped, fast-multiplying fingernail-sized mussels are a serious threat, officials say – they cut the feet of swimmers, muck up boat motors, crowd out native species and can alter a lake’s food chain.
The DNR says there is no way to get rid of zebra mussels once they establish a population in a given waterway. The only way to stop their spread is for boaters to inspect their craft before leaving a boat landing. State law requires boaters to remove aquatic plants from their boats, dispose of their bait and remove their drain plugs to drain water out of their boats.
However, a new product called Zequanox is being tested on a metro area lake -- Christmas Lake in Shorewood -- to see if it will eradicate zebra mussels.
The DNR has more information about aquatic invasive species in Minnesota and what state law requires of citizens.