DNR confirms Eurasian milfoil

The Minnesota Department of Natural Resources has confirmed the presence of Eurasian watermilfoil in Union Lake near Erskine, Minn.

The finding marks the farthest northwest the aquatic invasive plant - characterized by thick mats that choke out native aquatic vegetation - has been found in Minnesota.

Eliminating the plant is "not a realistic goal," a DNR official said.

According to Chip Welling, head of the DNR's Eurasian Watermilfoil Program in St. Paul, an area resident reported the possible presence of the plant on Union Lake earlier this month, and a site visit last week confirmed it.

The invasive plant was thickest on the southeast side of the 734-acre lake, Welling said, but last week's DNR survey also documented lesser amounts in the central and western basins.

That suggests the plant has been in Union Lake for quite some time, he said.

"Obviously, it's abundant in Union Lake," Welling said Monday. "It's overwintered and grown quite abundantly. I'd say multiple years. I can't say for sure, but to be that widespread, it's been there for some time."

There haven't been any reports that Eurasian watermilfoil has spread to adjacent Lake Sarah, Welling said, but the DNR hasn't checked for the invasive plant in the smaller neighboring lake.

Before the recent confirmation on Union Lake, Eurasian milfoil reports in the DNR's northwest region were limited to Leech Lake near Walker, Minn., and Lake Oscar near Glenwood, Minn.

Now what?

With the invasive plant now confirmed in Union Lake, Welling said the next step will be to educate boaters and other recreational users about the need to remove aquatic vegetation from trailers and other equipment. That will include placing signs at public water accesses and also at private sites, if the owners agree.

Next summer, Welling said, the DNR will have watercraft inspectors on-site at Union Lake.

Managing the Eurasian watermilfoil also will be an objective, Welling said.

"Unfortunately, eradication of this plant is not a realistic goal, based on our experience in Minnesota and elsewhere," he said. "We tried early on and found in no case was that achieved.

"Where the plant becomes abundant and interferes with use (of the lake), control can reduce those problems."

Local perspectiveBryan Paradis of Erskine, president of the Union Lake Sarah Improvement District, said confirmation of the milfoil came as a surprise. The group initially sent a sample to DNR staff in Detroit Lakes, Minn., who suspected northern milfoil, a common native vegetation.

"We're doing everything we can to take care of it before it spreads any further," Paradis said.

Short term, that includes sending letters to all of the group's 370 members on Union and Sarah, informing them about the Eurasian watermilfoil discovery and keeping them abreast of plans to control the outbreak.

DNR staff also will attend the group's regular meeting Oct. 10, he said.

"Hopefully, a lot of (the members) will come to the meeting," Paradis said. "It will be key to identify it, point out the locations and then do something about it."

Recreational impactThe DNR's Welling said boaters and swimmers typically feel the biggest impact of Eurasian watermilfoil because of the thick mats it forms on the surface. The mats also can displace native aquatic vegetation.

In the case of Union Lake, Welling said many areas, especially on the western side of the lake, are too deep to support Eurasian watermilfoil. He said he would be surprised to see the plant in 15 feet of water, if it even can grow that deep.

Most of the milfoil sampled to date has been found in 9 feet of water or less, he said. As a result, the impact on fish habitat should be minimal.

"I doubt that invasion by watermilfoil is going to dramatically change habitat for fish," Welling said. "There are lakes with milfoil that have very popular game fisheries, not the least of which would be Minnetonka."

Welling said Eurasian watermilfoil first was discovered in Minnesota in 1987 on Lake Minnetonka near the Twin Cities. The plant since has spread to about 200 lakes across the state.

In North Dakota, aquatic biologist Lynn Schlueter of the Game and Fish Department said Eurasian watermilfoil has been found in Dead Colt Creek and Dead Colt Reservoir south of Lisbon, N.D., and in the Sheyenne River in Valley City, N.D.

In both cases, winter drawdowns have minimized the spread of the plant, Schlueter said.

Reach Dokken at 780-1148; (800) 477-6572, ext. 148; or bdokken@gfherald.com .