It took an act of the Legislature, but now the annihilation of the cattails has begun at Loring Park pond in Minneapolis.

Workers using a backhoe with a 5-foot cutting blade on Tuesday began decapitating the invasive plants that have encircled the park's south pond and almost choked its north pond.

Normally, the Department of Natural Resources limits cattail clipping. But after the state and the Minneapolis Park and Recreation Board didn't see eye to eye on the rate of removal, local officials persuaded the Legislature to grant them authority to eradicate the invaders.

"We spent an extraordinary amount of time and energy," Brian Rice, the Park Board's longtime lobbyist, said in a report at the end of the legislative session.

Cattails are a relatively recent issue at Loring pond, which has been the target of several water quality interventions over the past 20 years. First, the fringes of the pond were planted in 1997 to discourage geese and to filter rain runoff to deal with an algae problem. Then a clay liner was installed in 2007 to try to keep the water level up.

But the pond in recent years has been enveloped by non-native narrow-leafed cattails and the hybrids they generated by crossing with the state's broad-leafed natives.

One park visitor said he fears some species (like the red-winged blackbird) might disappear with the destruction of the cattails.

"It's like they were on super steroids," Rice said.

The idea is to clip the unwelcome vegetation under the water line over the next four to six weeks, while trying to keep the water level high enough to discourage regrowth. Then a contractor will return next spring to follow up with additional cutting of what survived. Anything reappearing after that double-bladed attack will likely get a dose of herbicide, according to Deb Pilger, Park Board director of environmental management.

The work got off to a rocky start Tuesday when a cutting blade wielded by contractor Applied Ecological Services bent by midmorning. The removal will also use workers with brushcutter-like trimmers to attack the cattails. The cut cattails will be raked off and composted, which should reduce the amount of algae-feeding nutrients in the pond.

The Park Board has spent a lot of time and money trying to improve the ponds at the city's first park, sandwiched between downtown and Interstate 94. Spending to date has totaled about $300,000, and the current work will add $56,000. Some came from city money allocated to the Loring Park neighborhood association.

The cattails undid the planting of a variety of water-tolerant sedges, flowers and rushes in 1997 by crowding them out.

"It forms a monoculture," said park area resident Lee Frelich, who pressed legislators to allow the removal. More biodiversity in plants fosters the same in birds and other species.

The Park Board wanted the new measures, sponsored by Minneapolis DFLers Sen. Scott Dibble and Rep. Frank Hornstein, because the DNR limits on cutting were too tight.

"By following the DNR protocol, the cattails would be choking the lake," park spokeswoman Robin Smothers said. The agency said it allowed the rate of cutting it thought the Park Board wanted.

Hornstein said the new law gave him a chance to bond with rural legislators whose constituents are frequently at odds with the DNR. "It's probably the only time I'll have a provision in the game and fish bill," he said.

Steve Brandt • 612-673-4438

Twitter: @brandtstrib