Zebra mussels have been found in one of the northeast metro's premier boating and fishing lakes, the Minnesota Department of Natural Resources confirmed Friday.

Forest Lake, in northern Washington County, will be designated as a zebra mussel infested water to limit further spread of the invasive species, the DNR said. It's the latest on a growing list of high-use metro lakes, including Minnetonka and White Bear, that have the hated zebra mussels.

"These infestations are being moved by people and it's against Minnesota law," said Keegan Lund, a DNR invasive species specialist who called for even stronger vigilance against transporting them. "We can only do more, and I think what we probably need is more awareness at the individual level."

Statewide, about 125 lakes have confirmed infestations of the fingernail-sized zebra mussels, which cut swimmers' feet, clog water intakes, attach to boat motors and threaten ecological food chains in the water.

"As lakes become infested, it doesn't mean they are ruined, it just means that lake ecology and how we use these lakes change," Lund said. "It should be said that most of the high-use recreational lakes around the metro are infested with zebra mussels, but there are many outside of the metro that aren't."

At least 20 Washington County lakes have landed on the infested waters list, although mostly because of invasive plants. Both rivers bordering Washington County have infestations: The St. Croix has zebra mussels and a few isolated cases of carp, and the Mississippi has zebra mussels and bighead and silver carp.

The Forest Lake discovery began when a suspected zebra mussel was found on a rock on the eastern shore of the portion of the lake known as "Lake One," and was taken to the Comfort Lake Forest Lake Watershed District office. DNR biologists inspected the lake and found 11 more zebra mussels along the eastern shore. Private consultants later found mussels along the south shore as well.

The number and distribution of the zebra mussels indicate a population is likely established and natural reproduction is occurring and will spread, the DNR said. As a result, treatment would not be effective and is not planned, the agency said.

More details are available at www.mndnr.gov/ais.

Kevin Giles • 651-925-5037