DNR tries to keep up with recent spree of lakes infested with zebra mussels

It's become a weekly alert in the Twin Cities: Another lake infested with zebra mussels.

This week, it's Lake Independence in the west metro. Last week, it was Lake Waconia and White Bear Lake. Earlier last month, it was Christmas Lake and Lake Virginia, smaller lakes in the west metro.

Despite new efforts by the Department of Natural Resources, the recent spree of lake infestations have left some critics feeling like the state is losing the battle against the proliferating pests that threaten to forever alter Minnesota's lakes.

"I just don't think they get it; they're just too slow," Mike McLaughlin, president of the Lake Independence Citizens Association, said of the DNR. "They're in charge of protecting our lakes and whatever they're doing isn't working."

DNR staff counter that they're responding to lake infestations as quickly as they can with limited resources and funding. Keegan Lund is the agency's only aquatic invasive species (AIS) specialist overseeing responses to all four metro lakes in the past month. He's one of eight in the state.

In the past two years, Lund said there were no metro-area lakes that were infested with zebra mussels.

"It's definitely been a busy fall," he said. "The lakes that have seen infestations are some of the most heavily used lakes in the metro. One would have thought they'd have been infested long ago. I'd say we're winning the battle and preventing the spread."

Zebra mussels, one of numerous, aquatic invasive species in Minnesota, have infested nearly 200 waterways like popular Lake Minnetonka, Lake Mille Lacs and lower St. Croix River. But experts have long said the effort to eradicate them is far from futile given the many more of the state's nearly 12,000 lakes that aren't infested.

"I think they've done the very best with the resources they have," said Peter Sorensen, head of the Minnesota Aquatic Invasive Species Research Center at the University of Minnesota. "I don't blame the boat builders, the anglers, the politicians, the DNR — it's all of us."

The DNR has started some innovative new measures, such as adding zebra mussel-sniffing dogs to the increased boat inspections statewide. Last month, crews used Zequanox, a biopesticide, on Christmas Lake to kill off zebra mussels — the first time in the country that the product was used on a lake, not for experimental purposes. And now, the DNR is seeking federal approval for potash on Christmas, the first in Minnesota.

Heidi Wolf, the DNR's Invasive Species Program supervisor, said the number of DNR watercraft inspectors has remained flat the past two years — 146 statewide — as has funding.

"It's a challenging situation," she said. "We're doing what we can with what we have."

But while progress is being made, the list of infested lakes keeps getting longer.

Last Friday, the DNR declared White Bear Lake infested with the fingernail-sized pests, and the mussels are widespread in four spots, so no treatment will work like Christmas Lake's. Then on Tuesday, Three Rivers Park District, which operates one of two landings on Lake Independence, announced that zebra mussels were discovered at the Baker Park Reserve boat launch.

On Monday, Lund inspected the lake and found thousands of mussels that are two times larger than Christmas Lake's. However, he said, mussels haven't been found elsewhere so far.

The water is too cold for Zequanox to be effective. So instead, Rich Brasch, Three Rivers' senior manager of water resources, said the area will be curtained off Wednesday and copper sulfate, which kills all invertebrates, may be applied as soon as Friday.

"I was really disappointed," said Brasch, who discovered the mussels. "We worked hard to educate the public and we have a vigorous watercraft inspection program."

McLaughlin and Brasch point to Lake Minnetonka, which had a first-ever no-wake restriction on the entire lake for nearly two months this summer, diverting boaters to lakes like Independence. An effort to get a no-wake rule on Independence to slow traffic didn't work, McLaughlin said, "so here we are."

"There's a lot of boat traffic in and out of there. They just can't respond very quickly," he said of the agencies' reaction and the boat launch remaining open Tuesday. "A lot of people feel it's inevitable. But the longer you keep a lake from being infested, the longer you can wait until someone finds a solution."

Three Rivers increased boat inspections two years ago, but they're only on weekends. Brasch said the district is looking to boost funding for inspections next year since it's often cheaper than responding afterward. The lake's treatment is expected to cost $6,500 to $8,000.

"It's a tough battle," he said. "It's a difficult public policy issue you have to try to balance … people's right to recreate and preventing AIS."

Kelly Smith • 612-673-4141

Twitter: @kellystrib