Minnesota's long tradition of carefree boating is coming to an end.

As zebra mussels, Asian carp and other invasive species invade our waters, the state is ramping up its defenses, posting more inspectors at lake accesses, stopping drivers at first-ever mandatory roadside checks, doubling fines and increasing a fleet of boat decontamination units. "People have to get used to this new way of life," said Steve Gunther, president of Lake Minnewashta Preservation Association. "It's a culture clash. There's this sense of entitlement that has to be overcome."

Some lakeshore homeowners are taking matters into their own hands, paying for electronic gates restricting public access outside of certain hours and hiring private inspectors to watch lake entries. Boaters in Shorewood who skip inspection could soon face a misdemeanor, with jail time and fines.

It's a new reality for the state's lakes and the estimated 2.3 million Minnesotans who boat on them.

"In the next generation, the landscape of our lakes is going to be very different,'' said Dick Osgood, executive director of the Lake Minnetonka Association and a national expert on lakes management.

Roadside checks

The most visible change starts this month, when motorists towing boats will encounter signs ordering them to pull over at checkpoints near infected waters and high-use areas around the state.

Department of Natural Resources inspectors will see if drain plugs have been removed from boats and if they're transporting water or invasive species. Conservation officers will be on hand to write citations for violations. And boats with invasive species will be sent to nearby decontamination stations.

The DNR's random roadside checks for game and fish violations ended in the mid-1990s, after the state Supreme Court ruled that random State Patrol sobriety checkpoints set up to nab drunken drivers without probable cause violated the state Constitution. But the DNR says a law passed by the Legislature in 2011 gives it legal ground to start up this summer's roadside checks for invasive species.

That law made compliance with the inspections an "express condition'' of operating or transporting boats and other water-related equipment.

Outside of the roadside check stations, however, conservation officers can't stop boaters or motorists towing boats to check for invasive species violations without probable cause, said the DNR's Maj. Phil Meier. But the law says they can inspect boats or water-related equipment at both public and private sites if "there is reason to believe'' they're violating the law.

DNR officials haven't decided when or where the checks will begin.

Inevitable spread?

About 40 Minnesota rivers and lakes now have zebra mussels, a fingernail-size nuisance that can change the aesthetics of lakes, clutter beaches with razor-sharp shells, clog motors and lakeshore homes' sprinkler systems, and alter the ecosystem.

Yet, some question if state invasive species laws -- and the intensifying enforcement efforts this season -- will be effective.

Last year, conservation officers reported 18 percent of the boaters they made contact with were breaking the law by leaving boat drain plugs in or transporting water or invasive species, most often in their bilges, live wells or bait buckets. So far this spring, noncompliance is running 10 percent to 12 percent.

Professional fishing guide Bob Turgeon, who spends nearly every day on Lake Minnetonka, expresses the concern of many: "The spread is inevitable; it will change fishing and it will change recreation."

Avid angler Kirk Brum of Minnetonka admits the ramped- up inspections will keep him off targeted lakes. "I'm all for inspections, but a lot of the time I don't want to deal with the hassle," he said as his boat was inspected at Lake Minnetonka's Grays Bay.

Want to boat? Get a code

Changes are rippling across the region and state. At Green Lake in Spicer, Minn., residents are paying for their own lobbyist and coordinating with the DNR to power wash every boat that enters for fishing tournaments -- that's up to 600 boats just on July 4th weekend.

And in June, Lake Bavaria residents are pushing Carver County leaders to approve an electronic gate at their access. The lake association there and three others are looking to band together to create a centralized inspection next spring where boaters would check in at one -- such as Lake Minnewashta, where inspectors work full-time now -- before getting a digital code like car wash's that would allow them to have one-time access at other lakes.

"It's an inconvenience for the boater ... but it's a tragedy and disaster when it infiltrates the lake," Gunther said.

When Sen. Al Franken, D-Minn., toured "ground zero" for invasive species, boating around Lake Minnetonka on Thursday, local leaders all stressed the need for partnership between lakes associations, conservation and watershed districts, cities, counties and the state.

The stakes are high for Minnesota's 800,000 boat owners, $11 billion a year tourism industry and 800 resorts.

"We've got huge economic impacts that can severely damage our state's economy," said Barb Halbakken Fischburg of the Lake Detroiters Association. "We can't go from lake to lake any more."

Biologists and other experts say the infestation could leave a lasting impact on Minnesota's lakes -- increasing water clarity, weeds and other vegetation and decreasing coveted fish populations. Yet, Peter Sorensen, a University of Minnesota professor and director of its new state-funded invasive species center, said the fight isn't futile.

"They sky isn't going to fall, but I think the lakes are going to change; they'll be different than the lakes your father and your grandfather knew," he said.

A gated lake

At Christmas Lake in Shorewood, gates automatically close at 10 p.m. and open at 6 a.m. Signs with red letters warn that inspection is required. And each day, private inspectors check incoming boats. Lake association members forked over most of the $30,000 to install the gates and $46,000 to hire inspectors, who receive DNR training. As a result, homeowners now pay $350 a year.

At 6 a.m. last week, University of St. Thomas student Erik Noonan, 21, set up a folding chair on the dock, guarding the launch most of the day. The job is more than a summer paycheck.

"It's my hope it will prevent [invasive species] long enough for a solution to be found," said Noonan, a lifelong resident of the lake.

The tight-knit community around the lake, known for its cleanliness and clarity, has long vocalized frustration with the DNR for preventing their attempts at regulating boat traffic.

"It flies in the face of free and unfettered access to the lakes," said Joe Shneider, president of its lake association. "But it's the only answer we have."

Staff writer Tom Meersman contributed to this report.

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doug.smith@startribune.com • 612-673-7667 • Twitter: @dougsmithstrib