Last update: July 13, 2004 at 6:54 AM

Curly-leaf pondweed turning lakes green

Associated Press
July 13, 2004 CURLY0714

RICE, Minn. -- Little Rock Lake is no longer the Mecca of fishing and water sports that Jeff Soderholm remembers.

For the past two years, heavy mats of weeds have floated along the surface of the lake in June. By midsummer, the plants died off and were replaced by a scum of green algae on the water's surface.

``By the Fourth of July, it was like pea soup,'' Soderholm said.

The culprit is curly-leaf pondweed.

``It's becoming probably one of the most invasive aquatic species we have in Minnesota right now,'' said Paula West, executive director of the Minnesota Lakes Association.

Like Eurasian milfoil, curly-leaf pondweed can be transported from lake to lake by boaters who don't clean weeds off their motors. Once it's in a lake, it spreads quickly and is costly to control.

The nuisance plant is causing headaches for the state Department of Natural Resources, lake associations and concerned lakeshore owners like Soderholm.

Soderholm helped create the Little Rock Lake Clean Water Committee, which he hopes will find a solution. If nothing is done, Soderholm fears the lake's quality will continue to deteriorate.

Curly-leaf pondweed has spread to more than 500 lakes in Minnesota.

``It's in almost every county in the state,'' said Neil Vanderbosch, DNR aquatic plant management specialist.

Curly-leaf's unusual life cycle gives it a competitive edge over other aquatic plants. It sprouts from seed-like pods in the fall and continues to grow under the ice during the winter. Typically it's the first plant to bloom in the spring and dies off by late June or early July.

While in bloom, curly-leaf pondweed grows quickly and can create a mat of vegetation near the surface. It clogs up boat motors and makes the lake unappealing for swimming and other water sports.

``It's a problem that is getting really bad,'' said Don Zieglmeier, president of the Little Rock Lake Association. ``People are getting really uptight. It's so bad now, in some places you can't go 40 feet without cleaning off your (propeller).''

Recent winters marked by late freezes, minimal snow cover and early melts have been ideal for curly-leaf, said Steve McComas of Blue Water Science, a St. Paul-based consulting firm that helps lakes battle the plant.

``The last few years have been perfect growing years, so that's why it's become more noticeable,'' McComas said.

Officials say there is no cheap or easy way to control curly-leaf pondweed. In Sauk Lake near Sauk Centre, a weed harvester has been battling the plants for nearly 15 years, but ``that's more like mowing the lawn than actually taking care of the problem,'' said Julie Klocker, administrator of the Sauk River Watershed District.

Officials are looking into other potential solutions, such as drawing down a lake's water level in the winter or chemically treating the plants with an herbicide.

The DNR strictly regulates who can apply such chemicals and in what amounts, typically limiting application to small areas. And such chemical treatments are costly - as much as $300 an acre, West said. And because curly-leaf pondweed can keep coming back, several years of treatment are needed.

For a lake such as Little Rock, which spans 1,270 acres, that's a hefty price tag. And while the DNR offers some funding for treating lakes with Eurasian milfoil, there is no money available for controlling curly-leaf pondweed.

``In our opinion, the DNR needs to take a more aggressive approach to curly-leaf management,'' West said.

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Information from: St. Cloud Times, http://www.sctimes.com

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