Preventing Spread of Invasive Water
By DJ Slater
Wisconsin State Journal
Published June 15, 2006
It hovers on the surface of the water, creating a green,
weed-like canopy near the lake's shore. Small fish may
swim beneath it, but they go unnoticed.
A boater unloads his craft into the water, and as the
trailer leaves the park, the green substance hangs onto
the frame. The driver is oblivious to its presence.
The substance is Eurasian water milfoil, and it's one
of the invasive species that has called Madison lakes
home over the past 30 years. Now, the Wisconsin Department
of Natural Resources and the Dane County Lakes and Watershed
Commission seek to inform Madison residents about these
invasive species and ways to prevent their spread to other
A boat-cleaning demonstration, held Wednesday at Wingra
Park, was part of Yahara Lakes Week, a celebration highlighting
grass-roots efforts that improve Madison's lakes. The
tutorial showed techniques to prevent the spread of invasive
"In the southern part of Wisconsin, Eurasian water
milfoil and curlyleaf pondweed are pretty common,"
said Donna Sefton, the Lakes Monitoring and Aquatic Invasives
Specialist for the DNR. "One of the concerns is boats
coming from down here and taking that up to the northern
lakes . . . and then causing problems on the lakes. We
want to particularly bring the message to boaters to be
aware of cleaning their boats before (and after) they
go into those lakes."
Milfoil is an aquatic plant that originated in Asia and
Europe, according to the DNR. Ships traveling from overseas
to the United States empty excess water from the ocean
into the Great Lakes, Sefton said. That water carries
exotic species like the milfoil and zebra mussels. Once
exotic species spread in the Great Lakes, local users
pick up the organisms on their boats and then transport
them to other Wisconsin lakes.
"Our lakes form so much of the basis of our economy
and our way of life in Wisconsin," Sefton said. "If
you have an invasive species that affects the use of the
water bodies . . . then it is really a threat."
Milfoil easily becomes a nuisance to a lake's ecosystem
and users. Sue Jones, a Lakes and Watershed management
coordinator, said the plant grows from the lake bottom
and spreads over the surface water, preventing sunlight
from reaching other plants.
"It shades other plants out and makes conditions
better for its growth instead of the native plants we
would like to see," Jones said.
Sefton said the plant can break into fragments, which
then grow new milfoil plants. With a growth rate of 2
inches per day, she said it doesn't take long for the
plant to create problems for recreational lake users.
It also can carry with it other invasive species like
zebra mussels, a hard-shelled organism that attaches itself
to anything, according to the DNR.
Few lakes in Wisconsin remain free exotic species. Sefton
said Black Hawk Lake in Iowa County is one of the only
lakes left in the state that the DNR is trying to preserve.
As for methods to combat the existing problem, Sefton
said the DNR has tried removing some nutrients from the
lakes and chemical treatments, which Sefton calls a Band-Aid
"There's just no magic bullet to deal with it,"
she said. "It didn't get here just overnight, and
you're not going to solve it overnight."
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