Success stories exist in the fight against invasive species

Water quality managers report headway against invasive grasses, milfoil and carp.

A sign in Detroit Lakes reads, "Help stop aquatic hitchhikers!" The sign urges lake goers to remove aquatic species, drain their watercrafts and dispose of unwanted bait in the trash. (Meagan Pittelko/Tribune)
A sign in Detroit Lakes reads, "Help stop aquatic hitchhikers!" The sign urges lake goers to remove aquatic species, drain their watercrafts and dispose of unwanted bait in the trash. (Meagan Pittelko/Tribune)

Zebra mussels, Eurasian milfoil and other aquatic invasive species are so prevalent and damaging in Minnesota that a whole industry has sprung up around fighting them.

There's a whole research center at the University of Minnesota. Private industries help locate them and treat or remove them. Boat inspectors stand guard at entry points to vulnerable lakes. Billboards remind boaters to "Stop Aquatic Hitchhikers!"

But do these efforts work?

At a three-day conference Sept. 22-24, the Minnesota Aquatic Invasive Species Research Center saved the good news for last, bringing out three Minnesota water managers who told their stories of making headway against invasives.

"We're well on our way to eradication here," said Justine Dauphinais, a water quality coordinator for the Coon Creek Watershed District near the Twin Cities. Her particular battle is against invasive phragmites, a tall, aggressive grass that can invade wetlands and shorelines. It is often confused with native phragmites, but it has been verified throughout Minnesota, although not yet in Douglas County.


She flashed slides of the grass clogging a shoreline.

"If this was your lakeshore, it would certainly impede your view and your access," she said.

Dauphinais credited the research center for finding a strategy to get rid of the grass. It involved a step-by-step method of mowing and spraying, and after it was done, her crew has reduced its presence in their district from about 2.5 acres to about 0.14 acres, or 6% of the original area.

Lake Minnetonka, a popular boating destination in the Twin Cities, has also seen success in getting rid of Eurasian watermilfoil, particularly an aggressive, hard-to-treat hybrid variety.

After treating it for years, only to see it bounce back, the company hired to take care of it changed its strategy, and treated the whole bay with low levels of an herbicide called fluridone over 90 days, said Patrick Selter, vice president of Midwest operations at PLM Lake and Land Management.

This year, his company has found just one plant in the entire bay, he said.

Another watershed district near the Twin Cities was able to reduce the number of invasive carp by penning them up with bluegill, which are known to eat carp eggs, and also capturing them in nets.

Josh Maxwell, the water resources coordinator of the Riley-Purgatory-Bluff Creek Watershed District, said the carp had turned one lake they were in, Staring Lake, into a "mudhole lake." After they knocked back the population, the lake became clearer, phosphorus levels dropped by 35%, and native plants began thriving.


The three managers said it was sometimes challenging to convince local authorities to spend the money going after invasive species.

But Meg Duhr, outreach specialist for the research center, said there's a lot of common ground for people who care about lakes even if they do so for different reasons.

For instance, she cares passionately about native species while an angler going after walleye might not. However, the angler cares about whether the walleye is full of mercury and whether there are enough of them for a satisfying day on the lake, both aspects of which could be worsened by invasive species.

Aside from cost, local authorities might be leery about spraying chemicals into a lake.

Selter said risks have to be balanced with benefits, and that managers have to present the risks to those making the decisions.

"It's all about managing those fears and uncertainties," he said. "It's going to look ugly before it gets better. People understand that."

Non-native Phragmites reaches a height of 15 feet. It has a ridged, hollow stem with a rough texture. The blue-green leaves are 15-20 inches long by one inch wide and remain on the stem through the winter. Minnesota Department of Agriculture

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