Eurasian watermilfoil discovered in Bad Axe Lake

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The Minnesota Department of Natural Resources has confirmed Hubbard County's first case of Eurasian watermilfoil, an invasive aquatic plant, in Bad Axe Lake.

DNR invasive species specialists confirmed Eurasian watermilfoil around the resort access to the lake. They reported it did not appear to be widespread into other areas of the lake.

"There is no public access on this lake and only one resort. The resort owner is extremely diligent about inspecting every boat that they launch and they also pressure-wash boats onsite," said Hubbard County AIS Program Coordinator Bill DonCarlos. "This is an example of an invasive species doing what they do best. They are invasive for a reason because they have evolved over thousands of years to be extremely good at spreading and inhabiting new waterbodies. Prevention is always important, but nothing is completely perfect. Even the best prevention practices cannot completely guarantee that a lake will not be infested. However, we still have to try, as we owe it to our resources to do our best to protect them."

Eurasian watermilfoil can limit recreational activities on water bodies by forming vast mats on the water's surface and thick, underwater strands of tangled stems. The plant's floating canopy can alter aquatic ecosystems by choking out native plants, according to a DNR press release.

It is typically spread when plant fragments have not been properly cleaned from trailered boats, personal watercraft, docks, boat lifts, anchors or other water-related equipment. Removing native vegetation also creates perfect habitat for invading Eurasian watermilfoil.

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," writes Minnesota Sea Grant, which is funded through the National Oceanic and Atmospheric Research and University of Minnesota.

It was first reported in Minnesota in 1987, when it was found in Lake Minnetonka. Today, it has colonized roughly 320 waterbodies throughout the state, reports Minnesota Sea Grant.

According to the Minnesota Pollution Control Agency, Eurasian watermilfoil "likes to live in lakes, ponds, shallow water reservoirs and slow-moving rivers and streams. It reproduces very fast and in many different ways. If a stem breaks off, it can start a new plant."

A single segment of stem and leaves can take root and form a new colony. It also spreads through underground runners.

It is also tolerant of cold water, so it can regrow quickly in cold Minnesota lakes in early spring.

Eurasian watermilfoil looks similar to Northern Milfoil, a native of Minnesota. The Eurasian variety has 12 to 21 feathery leaflet pairs, whereas Northern Milfoil only has five to 10 leaflet pairs. Eurasian watermilfoil is limp and soft, while the native species is stiff and bristly.

The DNR says treatment options include selective herbicides and mechanical removal to minimize the plant's impact while protecting native aquatic plant species. Treatment is unlikely to eradicate Eurasian watermilfoil from a lake. It may minimize impacts, but rarely prevents broader dispersion within a lake.

"The infestation is fairly confined to one general area on Bad Axe Lake. It is likely that the infestation will be treated to prevent it from spreading throughout the lake or to other lakes. There will likely be ongoing discussions about treatment options and details. At this time, I do not have more information on treatment details, we should know more later this fall," said DonCarlos.

The new infested waters confirmation is a reminder to boaters and anglers to follow Minnesota laws to prevent the spread of aquatic invasive species. Details about Eurasian watermilfoil and other aquatic invasive species are available at mndnr.gov/ais.