Eurasian watermilfoil was accidently introduced to North America from Europe.
Spread westward into inland lakes primarily by boats and also by waterbirds,
it reached Midwestern states between the 1950s and 1980s.In nutrient-rich lakes it can form thick underwater stands of tangled stems and vast mats of vegetation at the water's surface. In shallow areas the plant can interfere with water recreation such as boating, fishing, and swimming. The plant's floating canopy can also crowd out important native water plants.
A key factor in the plant's success is its ability to reproduce through stem fragmentation and runners. A single segment of stem and leaves can take root and form a new colony. Fragments clinging to boats and trailers can spread the plant from lake to lake. The mechanical clearing of aquatic plants for beaches, docks, and landings creates thousands of new stem fragments. Removing native vegetation creates perfect habitat for invading Eurasian watermilfoil.
Eurasian watermilfoil has difficulty becoming established in lakes with well established populations of native plants. In some lakes the plant appears to coexist with native flora and has little impact on fish and other aquatic animals.
Likely means of spread: Milfoil may become entangled in boat propellers, or may attach to keels and rudders of sailboat. Stems can become lodged among any watercraft apparatus or sports equipment that moves through the water, especially boat trailers.
Eurasian watermilfoil typically has 12 to 21 pairs of leaflets.
The native northern watermilfoil, with which it is often confused,
usually has 5 to 9 pairs. Drawing courtesy Bell Museum of Natural History.Eurasian Water Milfoil (EWM) was discovered in Clearwater Lake in 1989.
Our Lake Association was one the first private groups to do its own Eurasian Watermilfoil treatment in the State of Minnesota. We treat about 116 acres of infested areas in our lake each year. The map BELOW shows the locations that have been treated. Our state permit only allows hs to treat 116 acres. We fund our project through a special assessment that is collected through the Clearwater River Watershed District and some money we get from the Minnesota DNR special fund. We have purchased a pontoon that has a electric broadcast spreader attached to the front. The state approved chemical for treatment is 2-4d, (navigate is the brand name). We apply 290 50-pound bags of chemicals. The labor to apply the chemicals is all volunteer and takes us about 3-nights, (if the weather is good). It is hard work to load all the bags of chemicals, but Marge Truman's meals and deserts brings the help back every year, (THANK YOU MARGE!!!!). We have assisted other Lake Owner Organizations on how to apply the chemicals and have loaned them some of our equipment to make their application easier.
