Park leaders in Minneapolis have imposed new restrictions on boat traffic on city lakes, a drastic effort to prevent the spread of invasive species that surprised anglers and conservation leaders.

The Minneapolis Park and Recreation Board unanimously approved an emergency resolution Wednesday that will require boats entering its lakes to be inspected, chaining off boat launches during weekday afternoons and other times when inspectors aren't present.

The new rules go beyond state law -- which doesn't require boat checks unless an inspector is there -- making it the most stringent such measure by a Minnesota city.

"We're concerned about the loss of access and that we might end up with different restrictions across the state depending on who owns it," said Steve Hirsch, director of the Minnesota Department of Natural Resources' ecological and water resources division. "We need to be consistent."

He said the DNR hasn't determined if the city's steps are legal. "We wish that they would've consulted us before that action," he said.

The Park Board counters that to combat invasive species, they have to target boaters before they launch into lakes. By the DNR's count this week, 20 percent of boaters are violating invasive species laws this year-- up from 18 percent last year.

The Park Board was going to assemble a task force, but "we just felt it couldn't wait," said Debra Pilger, the board's director of environmental, equipment and volunteer services. "We needed to do something now."

Pilger said the new rules, which were approved by the board's attorney, are only in effect this year. A task force will decide actions for after this year.

"This is really a stopgap measure for us," she said. "The DNR can't do it alone."

It's part of ramped-up measures statewide to protect Minnesota's treasured lakes by the DNR, lake associations and cities. In Minneapolis, Lake Hiawatha and Minnehaha Creek already have zebra mussels, Pilger said -- three of the more than 40 lakes and rivers in Minnesota with the fingernail-sized nuisance.

"We're not White Bear Lake, we're not Lake Minnetonka," Pilger said. "We don't have the boat traffic. We're in a unique position that we might be able to protect our lakes longer."

Minneapolis is hiring seven inspectors to add to a staff of up to 20 at boat launches at Lake Calhoun, Lake Harriet and Lake Nokomis.

From July 13 to Sept. 30, they'll guard entrances from 6 to 10 a.m. and 5 to 9 p.m. Monday through Thursday as well as 6 a.m. to 9 p.m. Friday, Saturday and Sunday. Outside of those hours, boaters caught entering a launch could get a civil citation or fine.

Canoes or kayaks that don't need a boat launch can enter the lakes without inspection.

The new rules are disappointing to frequent anglers like Larry Peterson, 46, of Hopkins, who fishes Minneapolis lakes six days a week.

"I think it's a snap reaction to what's happening," he said about the spread of invasive species, pulling up his boat after fishing for muskies on Lake Calhoun on Thursday. "I hate to see restrictions. ... I'll have to make adjustments."

While anglers want to protect natural resources, he said they should have been consulted before the new rules.

Since 2010, the Park Board has increased its defense against invasive species, moving all harvesting of milfoil to city-owned equipment to ensure it was not contaminated by outside lakes and now, shutting down Theodore Wirth Lake's sole public boat launch. The extra inspections, additional staff time, education, new gates and signs this year will cost $100,000, taken from the Park Board's reserves.

"We're not closing these lakes down," Pilger said. "We are maintaining access. We just feel it's important to have boats inspected before then."

Kelly Smith • 612-673-4141 Twitter: @kellystrib