State conservation officials said Thursday a single zebra mussel was found in Minneapolis' Lake Harriet, one of the city's iconic lakes, but added that no more have been found and treatment isn't needed "at this time."
One was enough, however, to land the lake on Minnesota's infested waters list for zebra mussels.
The Minnesota Department of Natural Resources said it will carefully monitor the lake this year and next. Individual zebra mussels sometimes die after they are brought into a new lake, before they become established, DNR invasive species specialist Keegan Lund said in a statement.
The adult zebra mussel was found on a boat cover recovered from the bottom of the lake. No additional zebra mussels were found during 67 hours of diving, snorkeling and wading searches, the DNR added.
Zebra mussels are an invasive species that can push out native mussels. They can also cause more algae and weed growth — they filter the lake water, allowing sunlight to penetrate more deeply. They attach to boats, making it easy for them to travel and contaminate other waters.
Their shells are also razor-sharp, which could be a serious problem for a lake like Harriet, where thousands of people come in the warm weather months to wade and swim.
About 250 Minnesota lakes are now listed as infested with zebra mussels. DNR officials expressed hope that Lake Harriet may be removed from the list if future searches continue to show no zebra mussels.
Besides the Lake Harriet discovery, the DNR on Thursday said it's also confirmed zebra mussel infestations in Garfield Lake in Hubbard County and in Lakeville's Lake Marion, where five adult zebra mussels were found at the public access. "The city may apply for a pilot project treatment after a more thorough search of the lake is completed," the DNR said.
The agency again reminded people that state law requires boaters and anglers to clean boats of aquatic plants, drain all water by removing drain plugs and keeping them out during transport and disposing of unwanted bait in the trash.
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