Despite an accelerated effort this summer to fight the spread of aquatic invasive species in Minnesota lakes -- including stiffer fines, more boat inspections and widespread publicity -- many boaters continue to violate the law.

So far this summer, about 16 percent of the 12,000 boaters checked by Department of Natural Resources conservation officers have been cited for not passing inspections.

That's a slight improvement from mid-June, when noncompliance was about 20 percent -- a figure officials then called unacceptable.

But the violation rate at DNR random roadside check stations, begun midsummer, is more than 35 percent, said Phil Meier, DNR enforcement division operations manager.

"We don't really have an understanding of why there's that big of a difference," he said. Noncompliance at some stops has exceeded 50 percent, he said.

"Obviously 1 percent is too high," Meier said.

So far, the DNR has issued 1,977 citations and warnings, more than double the 850 issued all of last year.

"We're going to keep doing what we can do to stop the spread," Meier said. "Hopefully our actions are making a difference."

But critics of the state's efforts say the noncompliance figures -- and the continued spread of species such as zebra mussels to ever more lakes -- show that it's too little, too late.

In 2009, there were 16 lakes and four rivers infested with zebra mussels. Today, those numbers are up to 29 lakes and nine rivers, including Gilbert Pit, a mine pit lake on the Iron Range that officials announced Tuesday was infested.

"That tells me their program isn't working," said Terry Kalil, vice president of the Becker County Coalition of Lake Associations.

"Yeah, I'm frustrated," she said. "This is an epidemic."

Kalil said the DNR's 23 decontamination units -- which use high-pressure, hot-water washers -- have cleaned only 774 boats thus far. "That's just 33 per unit, over a 60-day period -- one boat every other day," she said.

But, said Jim Japs of the DNR, "Low numbers are good because that shows a high level of compliance." Only boats with invasive species on them are being decontaminated, he said.

Meanwhile, Kalil said some have wrongly pitted anglers against lakeshore owners.

"It's Minnesota's problem, and we need to fix it," she said.

Doug Smith •