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the University of Michigan and Michigan State
University. Funding: NOAA-National Sea Grant
College Program with matching funds from
the University of Michigan and Michigan State
University. Michigan State University and the
University of Michigan are equal opportunity/
affirmative action institutions.
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EURASIAN WATER-MILFOIL
What is Eurasian Water-milfoil (EWM)?
Invasive species disrupt the stability of lakes and
threaten native plants and animals. One invasive
species of special concern is Eurasian water-
milfoil (EWM). EWM was introduced into North
America and has spread to numerous water
bodies across the nation. During the 1960s, this
aggressive submersed plant found its way into
Michigan waters.
Eurasian water-milfoil forms thick underwater
beds of tangled stems and a vast canopy mat of
vegetation at the water’s surface. These dense
beds cause loss of native plants, degrade water
quality, and may reduce habitat for fish, inver-
tebrates and wildlife. They also hinder boating,
swimming and fishing. Many lake organizations
and local governments devote much of their man-
agement budgets to control this invasive plant.
EWM costs citizens of Michigan millions of dollars
in plant control and lost tourism revenue annually.
How does it spread?
This prolific plant spreads by shoots and runners
that creep along the beds of lakes and rivers.
EWM has become a successful invader primarily
by means of stem fragments transported from
one water body to another. A single fragment can
take root and form a new colony. Commonly it’s
transported by boats and trailers, but could also
be transported on SCUBA gear, water skis
or waterfowl.
EWM is most successful in lakes disturbed by
cultural activities such as shoreline construction,
watershed runoff, aquatic plant control projects,
heavy boat traffic, or stressed by pollution. It has
difficulty becoming established in waters with