lake access home empact metro project
lake access header
lake data understanding lakes current issues land use/GIS history lawn fertilizer study
 Eurasian Watermilfoil

Eurasian Watermilfoil (Myriophyllum spicatum) is an invasive, submersed aquatic plant that was first introduced to North America from Europe. Spreading primarily by overland boat transport to over 45 U.S. states, it began occurring in midwestern lakes between the 1950s and 1980s. In 1987, the first discovery of Eurasian Watermilfoil in Minnesota was found in Lake Minnetonka. Since then, it has spread to over 112 water bodies statewide.

Why can it be a problem?

Eurasian Watermilfoil can form thick underwater stands of tangled stems and vast mats of vegetation at the water's surface, especially in nutrient-rich lakes.

Potential Problems

  • Interferes with recreational water activities such as boating, fishing, and swimming
  • Crowds out important native aquatic plants which decreases important habitat and diversity in the lake

(compiled and presented by Larry Space and Joanna Wright on the Impact of Small Lakes of Vermont by the Invasion of Eurasian Watermilfoil: A Property Owners Perspective)

Eurasian Watermilfoil may…

  • Increase boat repair and maintenance costs (One boat owner in Vermont spent $800 repairing his boat when the motor intake became clogged with milfoil)
  • Cause a decline in native plant diversity (Madsen, et, al. 1991; Trebitz 1993)
  • Depress real estate values (Bates et. al 1985)
  • Inhibit water circulation (Smart and Doyle 1995)
  • Reduce the levels of dissolved oxygen, cause the release or build up of nutrients…which may provide unfavorable conditions for both macroinvertebrates and fish (Lille & Budd 1992)
  • Reduce the number of invertebrates (fish food) per square meter by ½ as compared to native plants (Keast 1984)
  • Have three to four times less fish versus native plant beds (Keast 1984)
  • Cause significant increases in permanent pool mosquitoes (Bates et. al 1985)

To see what species make up the aquatic plant community in Lake Independence and other MCWD metro lakes click here.


How does it spread?
Stem or leaf fragments spread by watercraft to new lakes or rivers or areas in the same water body can take root and grow into new plants
Underground runners also generate new plants in the same water body

Stop the spread

  • Eurasian Watermilfoil may become entangled in boat propellers, and may wrap around other external parts of your boat. Stems can also become lodged among any watercraft apparatus or sports equipment that moves through the water, including boat trailers.
  • The actions YOU take as a responsible boater are critical in preventing the spread of Eurasian Watermilfoil to new Minnesota water bodies. Clean your boat.
  • Please remember to remove all aquatic plants from your boat, motor, and trailer before you enter and after you leave any lake or river.

Is it in my lake?
Find out from the Minnesota Department of Natural Resources EXOTICS IN MINNESOTA WATERS

Be on the Lookout!

  • Eurasian Watermilfoil may be present in your lake or river, but has not yet been discovered.
  • Learning to recognize Eurasian Watermilfoil and reporting new sightings are critical in stopping the spread of this invasive plant. (Link to Report New Sightings on Exotic page)
  • Think you might have found a new infestation of Eurasian Watermilfoil? Contact the MN Department of Natural Resources at (651) 296-2835 or (888) 646-6367 or Mail them a sample of a suspected milfoil plant in a sealed, plastic bag

Mail samples to:
Eurasian Watermilfoil Program
Minnesota DNR
Ecological Services Section, Box 25
500 Lafayette Rd.
St. Paul, MN 55155-4025

What does it look like?

  • Submersed aquatic plant
  • Long stems with soft, feathery leaves
  • Leaves usually attached in whorls of four
  • Each leaf has 12-20 pairs of leaflets
  • Leaves limp out of water

Don't Mistake!

Eurasian Watermilfoil is only one of six aquatic plants in the Watermilfoil family found in Minnesota.

Most commonly mistaken for native Northern Watermilfoil

  • 5-12 leaflets
  • Leaves rigid out of water

  • Can Eurasian Watermilfoil be eradicated from my lake?

    Once Eurasian Watermilfoil is established in a lake, it is almost impossible to eradicate. It does not cause problems in every water body it infests, but for those that it does, three of the most common control measures for managing nuisance growths are listed below.

    What's controlling Eurasian Watermilfoil in your lake?

  • Mechanical Harvesting
  • UMN Biological Control Research
  • UFL Biological Control
  • Chemical Treatment
  • Control of Eurasian Watermilfoil in Lake Minnetonka

    The Lake Minnetonka Conservation District and Hennepin Parks currently control nuisance growth of Eurasian Watermilfoil in Lake Minnetonka in cooperation with Department of Natural Resources and lake homeowner associations. They primarily use mechanical harvesting to control nuisance Eurasian Watermilfoil, but also use chemical treatments in small areas around boat launches and fishing piers where the harvester can't operate.

    Eurasian Watermilfoil grows mostly around the shoreline, especially in channels and shallow areas with high boater traffic and in areas where past harvesting has occurred. Problem areas vary from year to year so the Lake Minnetonka Conservation District flies over the lake to determine which areas need to be harvested.

    What are the costs of Eurasian Watermilfoil Control?
    The Department of Natural Resources spent approximately $119,000 for maintenance management of Eurasian Watermilfoil in 1999!

    Lake Minnetonka Conservation District 1999 Eurasian Watermilfoil Final Harvesting Report

    1999 Department of Natural Resources Exotic Species Annual Report

    Help Managing Eurasian Watermilfoil in Minnesota

    Email us to share the status of Eurasian Watermilfoil in your lake.

    More Exotic Species

    home what's new about us contact us
    faq's site map links