Eurasian Watermilfoil (Myriophyllum spicatum)

Eurasian watermilfoil (Myriophyllum spicatum) is a feathery submerged aquatic plant that can quickly form thick mats in shallow areas of lakes and rivers in North America. These mats can interfere with swimming and entangle propellers, which hinders boating, fishing, and waterfowl hunting. Heavy infestations may reduce property values. Matted milfoil can displace native aquatic plants, impacting fish and wildlife.

Since it was discovered in North America in the 1940s, Eurasian watermilfoil has invaded nearly every U.S. state and at least three Canadian provinces. Milfoil spreads when plant pieces break off and float on water currents. It can cross land to new waters by clinging to sailboats, personal watercraft, powerboats, motors, trailers, and fishing gear. Eradicating established infestations is nearly impossible. Your help detecting and reporting new infestations is vital for preventing their spread.

Identify Eurasian Watermilfoil

General Characteristics

  • Found in water less than 20 feet (6 meters) deep
  • May form mats in waters less than 15 feet (4.5 meters) deep
  • A native look-alike, northern watermilfoil, has fewer (5-10) leaflet pairs

What You Can Do

  • Learn to identify Eurasian watermilfoil
  • Inspect and remove aquatic plants and animals from boat, motor and tailer.
  • Drain lake or river water from livewell and bilge.
  • Dispose of unwanted live bait and worms in the trash
  • Spray/Wash boat, trailer, and equipment with high-pressure hot water (120° F), especially if more for more than a day, OR
  • Dry everything for at least 5 days before reuse.
  • Report new sightings - note exact location; wrap a plant fragment in a wet paper towel, place in a sealed plastic bag; and call Minnesota Sea Grant Program in Duluth, (218) 726-8712, or the Minnesota Department of Natural Resources in St. Paul, 1-888-MINNDNR or (651) 259-5100, or a local DNR fishery office.

Know the rules!

Specimens are needed to confirm sightings, but some jurisdictions prohibit or discourage possession and transport of Eurasian watermilfoil and other invasive aquatic plants and animals. Contact your local natural resource management agency for instructions. Unauthorized introduction of plants or fish into the wild is illegal. Protect your property and our waters.

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This page last modified on December 02, 2010     © 1996 – 2014 Regents of the University of Minnesota     The University of Minnesota is an equal opportunity educator and employer.
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