Accidentally introduced from Europe in the 1940s, Eurasian watermilfoil (Myriophyllum spicatum L.) has become one of the most troublesome submersed aquatic plants in North America. It has spread to at least 45 U.S. states and three Canadian provinces. Although most frequently found in quiet bodies of water (1 - 10 m. deep), it has shown an ability to grow in rapidly flowing water. The plant has been known to degrade shoreline quality, clog propellers, restrict boat access, impair swimming, increase water temperature, and crowd out important native water plants. In some lakes, however, the plant appears to coexist with native flora and has little impact on fish and other aquatic animals. A variety of physical, chemical, and biological control methods have been used in attempts to manage infestations of Eurasian watermilfoil. Unfortunately, complete eradication is rare.