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Area lakes battle invasive plants

The sight on the shores of Detroit Lake is all one needs to get a picture of the problem of aquatic invasive species in the region.

Besides being an eyesore, lake associations and lakeshore property owners have to cope with the problem of managing flowering rush and other problem plants.

The Becker County Coalition of Lake Associations sponsored a seminar on Friday at the Minnesota State Community and Technical College to get the word out that the problem won't just go away.

Minnesota Department of Natural Resources aquatic ecologist Dan Swanson said that once foreign aquatic species infiltrate new waters, it's not feasible get rid of them.

"Eradicate is not a word in our dictionary," Swanson said.

Fred Twominen, who lives on Big Toad Lake, said that his lake association is trying to be proactive about the problem.

"If the water quality is affected by aquatic invasive species, then it's going to affect property values," Twominen said.

Three species are already causing headaches for lake associations: curly-leaf pondweed, Eurasian watermilfoil and flowering rush.

Beachgoers and boaters on Detroit Lake know what flowering rush can do. It's a long, thick plant that has a fibrous root system.

Detroit Lakes is only one of 16 other bodies of water in the state that are affected by it.

"It was probably brought in by someone who didn't know what would happen if they planted it," Swanson said.

Since the mid-1970s, the city has tried to control it.

The problem at first was the mechanical methods of ripping up the plant instead helped spread flowering rush, Swanson said.

Curly-leaf pondweed seems to be the big battle to win right now, as it is the most widespread. Because it was introduced into the state in 1910, most people don't think of it as an invasive species, Swanson said.

He added that the plant should be dead now (the weed dies when lake temperatures reach 65 degrees), but because there is an absence of native plants in affected lakes, blue-green algae blooms sprout up.

The curly-leaf pondweed typically grows right before and right after the ice clears on a lake. Turions -- small pinecones -- form during the growing process and fall off the weed when the weed dies.

Embedding itself into sediment, the turions can survive several years before sprouting.

For small outbreaks, Swanson said that hand picking works and property owners do not need a DNR permit for that.

However, large outbreaks need to be controlled with herbicides.

Chemical treatments generally average about $300 per acre, Swanson said.

Some attendees at the seminar wondered if they could just do it themselves without having to hire a company to apply the chemicals.

Swanson said that there isn't much savings going that route because treatment companies can buy the chemical wholesale. Plus, the companies need to be licensed by the state, bonded and insured, so lake associations that try to control the problem on their own assume a lot of risk.

Eurasian watermilfoil is also spreading at a rapid pace. It was first discovered in Lake Minnetonka in 1987, and over 208 lakes in the state have it presently.

"It's thick and hard to navigate through," Swanson said.

There is one aquatic invasive species that hasn't reached the area yet, but is spreading in the state -- the zebra mussel.

The small creature spread from the Caspian Sea in Asia to Europe from a canal system. Ocean traffic spread the mussels into the Great Lakes system in 1988.

Zebra mussels cause problems for people, animals and objects alike.

They clog pumps and filters on boats, or attach themselves to a hull, and the zebra mussel can cut swimmer's feet in infested waters.

Swanson said that animals are being hurt since some birds eat the zebra mussel. Which accumulates toxins that can be spread to its predators.

Preventing additional aquatic invasive species infestation and working with local lake associations is the goal of the DNR, Swanson said.

He said that the DNR hopes to educate boaters to inspect their vessels after leaving a lake to throw away any plants or animals that may be hitchhiking. Washing and drying a boat before entering new waters also helps.

More information on the DNR's Invasive Species Program can be found at eco/invasives/index.html.