Agenda Packet Cc - regular meeting 10/24/1988

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Eurasian water M11foll What is the problem? Most aquatic plants are an important part of the ecology of our lakes and streams. They provide food and habitat for many organisms. They also help to stabilize the bottom and aerate the water. But when weeds are too abundant, they can upset the natural ecology and Interfere with our aesthetic and recreational en;oyment. This usually happens when the weeds are over - fertilized by nutrients provided naturally or by human activities In the watershed. Sometimes, however, weed problems result from the Introduction of an "outsider," a plant for which there are no established natural controls. Eurasian water milfoil is such a plant. First observed in North America in the early 1940s. Eurasian water milfoil has spread rapidly across the continent In Minnesota, It was officially identified in Lake Minnetonka In 1987 and Its spread to other Minnesota lakes has already begun. a1 1 J'1'I does it grow and spread? Eurasian water mllfoll Is a perennial herb, growing on the bottom of lakes and streams from a fibrous root system. During the spring and summer months, rapid growth from the root crowr• area produces reddish shoots that may reach the surface and flower In water from the shoreline out to a depth of about 10 to 15 feet. Dense populations may occur on a varlet"r of bottom types, Including silt, sand and even gravels and broken rock, making most Minnesota lakes susceptible to nuisance growth of this plant. Waves and human disturbances such as boats, boating equipment and water sk;!ng produce plant fragments which are spread rapidly by water currents, making the plant difficult to contain. New plants grow when the fragments form roots. Though It roots best in protected areas, the weed can also thrive in river channels. weed fragments can hitchhike on boats, trailers, weed harvesting equipment and other vehicles and be transported from one take to another. Thorough cleaning of all aquatic equipment Is the best way to help control the spread of Eurasian water milfoil. Eurasian water milfoil causes many problems: • Swimming, boating, water skiing and fishing .j; o all adversely affected by dense growths. • Exisr,ng co;onies of more desir4-,e plants are Ovaded arc replaced. • Plant ', dgments which wash up on shore make beach areas unappealing. • LUXuriant growth can affect flood control, irnga,*Ion, drainage, water treatment facilities and fish spawning areas. • Eurasian water milfoil is costly, particularly in areas reliant on recreation and tourism. • Mats cf vegetatfen formeo by the weed are ideal breeding areas for mosquitoes.