An invasive nuisance plant has found its way into the Sheyenne River in Ransom County, N.D., and a state biologist said it's probably already spread downstream.
Eurasian watermilfoil was found in September beneath the dam that forms Dead Colt Creek reservoir, south of Lisbon on the Sheyenne River.
The North Dakota Game and Fish Department announced the discovery of the watermilfoil in Dead Colt Creek reservoir in September, but did not say it was found in the Sheyenne River.
Game and Fish Department fisheries staff found the plant in Dead Colt Creek in late August while conducting a fish survey. The milfoil was widespread and well-established in the lake.
When a crew returned later, it found the plant in the stilling basin below the dam.
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"It's probably spread far downstream," said Gene Van Eeckhout, district fisheries supervisor in Jamestown. "We don't know how well milfoil does in flowing water, but we did find it below the dam."
Eurasian watermilfoil is a nuisance plant that forms thick mats in lakes and rivers, hampering boating, fishing and swimming. The plant reproduces through stem fragments, root runners and seeds, so it spreads easily. A single plant stem can create an infestation at a new location.
Van Eeckhout said a fisherman probably spread the plant to Dead Colt Creek by transporting a fragment on a boat or trailer, which is the most common way milfoil moves from one lake to another. It's also possible a migratory bird spread the plant.
Eurasian milfoil has been found in 37 states and three Canadian provinces. More than 160 lakes, rivers, streams and wetlands in Minnesota are infested, according to the state's Department of Natural Resources.
Like other states, Minnesota has discovered that eradicating the plant with herbicides is fruitless, said the DNR's Eurasian watermilfoil program coordinator, ChipWelling. Also, attempts to stop the spread of milfoil in an infested lake only slow its expansion.
The discovery of Eurasian watermilfoil in Dead Colt Creek is especially troublesome because the lake could serve as a "hub for dispersal" into Devils Lake, western Minnesota and western North Dakota, Van Eeckhout said.
"Our concern is that a lot of people who bring their boats to Dead Colt go to a lot of other lakes," Van Eeckhout said. "The plant could be transported to any number of places."
There also is concern Eurasian milfoil could spread to the Red River, Van Eeckhout said. The Sheyenne empties into the Red at West Fargo.
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In an attempt to kill the plants in Dead Colt Creek, the Game and Fish Department drew down the lake 10 feet this fall. The hope is to expose the milfoil and freeze it, but Van Eeckhout said seeping groundwater has already caused the lake to rise.
"It's unlikely we'll be able to keep that elevation all winter," Van Eeckhout said.
Game and Fish Department aquatic nuisance species specialist Lynn Schlueter has said using chemicals in the lake next spring for further eradication might be necessary, Van Eeckhout said.
Schlueter was on vacation and could not be reached for comment.
This is North Dakota's second reported bout with Eurasian watermilfoil. The plant was discovered in the Sheyenne River near Valley City a few years ago, but work on an upstream dam caused low river levels and the plant froze during the winter. It has not been found since.
Readers can reach Forum reporter Mike McFeely at (701) 241-5580
