As zebra mussels spread faster than expected in Lake Minnetonka, residents from Maple Grove to Chanhassen are pleading for more protection for surrounding lakes by closing public access when there's no one around to inspect boats.

Hoping to persuade governments to take stronger stands, residents on Fish Lake, Christmas Lake, Lotus Lake, Lake Minnewashta and Medicine Lake are working to limit ramp use to times when an inspector can look over boats for evidence of the tiny, razor sharp shells that cluster on rocks, docks, boats and beaches.

Closing a public lake access would contradict a long-standing Minnesota tradition of open lakes. The Department of Natural Resources, despite its concerns about spreading invasive species, has opposed it.

But the Minnehaha Creek Watershed District, which includes Lake Minnetonka, sides with residents in contending that closing boat ramps when inspectors are not present should be tested.

"It is extremely likely that zebra mussels will be introduced into Christmas, Minnewashta and other lakes surrounding Lake Minnetonka unless something is done to inspect boats and manage access at these lakes," said Eric Evenson, director of the watershed district.

The district staff has found that "the spread of zebra mussels in Lake Minnetonka is happening much faster than they anticipated and that mussels have now spread throughout most of the lake," Evenson said. Zebra mussels were discovered in the lake in 2010.

Evenson joined several environmental groups in urging Gov. Mark Dayton to close public accesses at all state lakes and rivers infested with aquatic invasive species during a government shutdown.

Support for restricted access

At the Christmas Lake boat ramp in Shorewood, which is just a stone's throw from Lake Minnetonka, the watershed district wants to test an electronic access gate that boaters would lift by punching in an access code provided at an inspection site.

Last week, the city of Shorewood endorsed the idea and provided up to $1,000 to install the electrical service for the gate, post signs and stripe the parking lot.

The aim is to provide a common inspection site for Lake Minnewashta, Lotus Lake and Christmas Lake at nearby Lake Minnewashta Regional Park by August, said Joe Shneider, president of the Christmas Lake Homeowners Association. Individual inspections at each lake would be too expensive, he said.

Approvals are still needed from the city of Chanhassen, Carver County parks and the DNR, which is closely watching the proposal, Shneider said.

Could Medicine Lake be next?

On the north side of Lake Minnetonka, Terrie Christian is on a similar mission to persuade Three Rivers Park District to limit use of the public boat ramp on Medicine Lake at French Regional Park to times when inspectors are present.

"We want them to close the ramp when inspections are not happening," said Christian, president of the Association of Medicine Lake Area Citizens. "We want 100 percent coverage, either inspections or closure."

Taking its cue from the DNR, Three Rivers staff has already refused her.

"From our perspective, having the gate closed at Medicine Lake forces a potentially contaminated boat into another lake and that really doesn't achieve our objective of slowing the spread of invasive species," said John Barten, director of natural resources for Three Rivers.

The park district has 14 boat ramps and favors a regional and statewide approach to the problem. "It really is counter-productive to close one lake. We need to treat all lakes the same," Barten said.

Christian called the response "very unsatisfactory" and plans to continue the discussion with park board members at a meeting on July 7.

"I do not give up and I do not go away," Christian said. "This is not personal. This is only about doing what is best for the lake and that is what we have always done."

Highways track the problem

In April, Christian wrote Three Rivers that "Medicine Lake was infected with Eurasian water milfoil two years after it was first found in the state in Lake Minnetonka. We are the second-largest lake in Hennepin County with many boats coming from Minnetonka and Mille Lac which are now considered to be super spreaders of zebra mussels. We know we are at very high risk of infection through your ramp."

Maps charting the spread of aquatic invasive species show that they are spread "exactly along the lines of highways where the lakes are most accessible," Christian said.

To address concern about the spread of zebra mussels, Three Rivers has added 1,000 more hours of inspections this summer at Medicine Lake, Fish Lake and Lake Independence.

At Medicine Lake, inspectors are on duty from 8:30 a.m. to 9 p.m. Monday through Friday and from 9 a.m. to 9 p.m. on weekends, he said.

Three Rivers invited volunteers to help beef up its inspections and 14 people took training to do inspections. So far, only three have claimed spots on the inspection schedule.

Laurie Blake • 612-673-1711