The DNR is gearing up to fight zebra mussels and other invasives.
There’s still a hefty layer of ice on area lakes, but park and natural resource crews are ramping up for another year of boat inspections and washdowns to prevent the spread of zebra mussels and other aquatic invaders.
City councils, county boards and park systems are allocating money and hiring seasonal inspectors. State natural resource experts are training them. Boat manufacturers are developing filters to keep invaders out of ballast water. All are aware that it’s only a few weeks before Minnesota’s 800,000 registered boaters begin to head onto open waters to fish, cruise, paddle and sail.
Last year, roadside inspections of boats and trailers showed a 19 percent violation rate of invasive species laws, said Ann Pierce, invasive species program supervisor at the state Department of Natural Resources. Those rules require boaters to pull plugs and drain bilge water that can carry invasives into uninfested lakes. Bait buckets and live wells also need to be emptied, and weeds and other debris must be removed from all boats, trailers and equipment.
“We need to get to a point where people understand what the laws are,” Pierce said. “It’s not so much focusing on the violation rate as realizing that getting to zero [violations] means protecting our lakes.”
The DNR will launch a marketing campaign with TV and radio public service announcements and billboards to raise awareness about aquatic invasives, she said.
Zebra mussels have infested about 40 state lakes and rivers, Pierce said, and are suspected of being in another 100 connected to them. The nonnative mussels have been confirmed in some of the state’s most popular lakes, including Mille Lacs, the lower St. Croix River and Lake Minnetonka.
They attach themselves to boats, docks, rocks, native clams, and other solid surfaces, and proliferate by the millions. They grow only to fingernail size, but clutter beaches with razor-sharp shells, clog motors, change habitat for fish and insects, and jam intake pipes for water and power plants.
Pierce said the DNR will certify about 300 inspectors to work for city, county and park systems to check boats entering clean lakes and leaving infested lakes. About 150 DNR inspectors will be assigned to high-risk sites with lots of boat traffic, and will operate 23 portable decontamination units to disinfect boats and trailers with high-pressure hot water.
John Barten, natural resources manager for the Three Rivers Park District, said inspectors will also be stationed during park hours at premier park lakes in the west and south metro, including Fish, Bryant, Medicine, Independence, Minnetonka and Hyland, and that at least one roving inspector will cover less heavily trafficked lakes. Barten said most parks have staff at entry gates who will do the inspections. The program cost the district $50,000 last year.
Money drain or well spent?
Critics call such expenditures a waste of money because zebra mussels and plants such as Eurasian watermilfoil and curly-leaf pondweed are likely to spread everywhere. But Barten said inspections have slowed the spread. “Compared to the actions we’d have to take once they’re in the lakes, the amount we spend to keep them out is well justified,” he said.
Another reason to check boats is to forestall the arrival of new species, he said, such as the hydrilla plant, the New Zealand mudsnail, the rusty crayfish, and the spiny water flea, all of them listed on the “least wanted” list by the Minnehaha Creek Watershed District.
Buying time to prevent the introduction of such species is critical, said district spokeswoman Telly Mamayek, as researchers push for solutions.
The U.S. Geological Survey will test a new biopesticide called Zequanox this year in one part of Lake Minnetonka. The product has killed zebra mussels in lab tests and industrial settings and may have potential to control the pests in localized nearshore areas such as marinas, docks, and beaches.
Scientists are also just getting started at the University of Minnesota’s new aquatic invasive species research center, created after legislators appropriated funds for it in 2012.
Stirrings in industry
Boat manufacturers are also showing interest.