Eurasian Watermilfoil (Myriophyllum spicatum) was accidently introduced to North America from Europe. Its spread westward into inland lakes and streams is primarily attributed to boats, with some spreading caused by waterbirds. It reached the Midwestern states between the 1950's and the 1980's.  It was established in Iowa in 1992, in Hancock County's Crystal Lake. By 1993, the 260-acre lake was taken over by the plant, and was rendered virtually unusable from mid-July until fall.  It has since been reported in St. Benedict pond, Walnut Creek Marsh, Kounty Pond, Wilson Grove Pond, and Snyder Bend Lake (see map below). To date, all infestations in interior waterbodies have been successfully eradicated with the exception of Wilson Grove Pond and Synder Bend, which are scheduled for eradication in the spring of 1997, and the Mississippi River.

In nutrient-rich lakes, it can form thick underwater stands of tangled stems and vast mats of vegetation at the water's surface. In shallow areas, the plant can interfere with water recreation such as boating, fishing, and swimming. The plant's floating canopy can also crowd out important native water plants.

A key factor in the plant's success is its ability to reproduce through stem fragmentation and underground runners. A single segment of stem and leaves can take root and form a new colony.  Fragments clinging to boats and trailers can spread the plant from lake to lake. The mechanical clearing of weed beds for beaches, docks, and landings creates thousands of new stem fragments that can drift with the wind and current. Removing native vegetation creates perfect habitat for invading Eurasian watermilfoil.

Eurasian has difficulty becoming established in lakes with healthy populations of native plants. In some lakes the plant appears to coexist with native flora and has little impact on fish and other aquatic animals.

Eurasian watermilfoil typically has 12-21 pairs of feathery leaflets. The native northern milfoil, with which it is often confused, usually has 5 to 9 pairs.

The invasive plant has extended its range to include most of the continental United States.

Currently it is illegal in Iowa to 1) transport Eurasian watermilfoil on a public road, 2) place a trailer or launch a watercraft with Eurasian watermilfoil attached in public waters, and 3) operate a watercraft in aa marked Eurasian watermilfoil area. The penalty for violating this law is a $100 fine. The law requires the DNR to identify bodies of water with infestations and post signs alerting boaters. According to the law, the DNR may prohibit boating, fishing, swimming, and trapping in infested bodies of water. This law was a result of the Iowa Eurasian watermilfoil Program, which began on July 1, 1996.

You can help effectively manage and control the spread of this aquatic invader by:

• Cleaning all aquatic vegetation from your boat and trailer before leaving any boat ramp.
• Removing all plants and other debris from boats, motors, trailers, and other equipment before launching--especially if you have been in an infested area.
• Disposing of any plant debris away from the lake.
• Reporting any aquatic vegetation you suspect is Eurasian watermilfoil to DNR fisheries personnel.
• Passing the word about Eurasian watermilfoil to your friends and neighbors.