SEIS - Eagle Lake Property Owner's Inc.

THE NEED FOR MILFOIL CONTROLMuch has been \vritten on the need for management of invading non-native species (Miller,1994; Cunningham and Saigo, 1999), and specifically on the need for control of Eurasian\vatern1ilfoil (Newroth, 1979; Shireman et aI., 1982; Hoyer and Canfield, 1997). Still morediscussion has been held at a wide variety of symposia and workshops devoted to environmentalmanagement in general or aquatic plant management specifically (e.g., those of the NorthAmerican Lake Management Society and Aquatic Plant Management Society). There are bothecological and economic reasons for controlling milfoiI. Ecologically, this plant displaces nativespecies and decreases biodiversity. It also provides limited habitat value when dominant,negatively affecting aquatic fauna. Economically, milfoil creates nuisance conditions whichimpair recreational use and reduce property value. Milfoil impacts should be considered on threescales: localized impacts, lakewide impacts, and regional impacts.Localized ImpactsAt the scale of the individual plant, milfoil is just one more species in a large assemblage in mostlakes where it has just been introduced. If the native community persists and maintainsdominance, scattered individual milfoil plants are not a major threat. They do not appear to addany appreciable structure to the community beyond that which most native plant speciesassemblages already possess, but an individual milfoil plant is only a problem for chancerecreational encounters, due to entanglement. The problem is that rarely does the nativecommunity withstand milfoil invasion indefinitely, or even for more than a few years. Eurasianmilfoil has become the dominant plant in the vast majority of lakes in which it has beenintroduced in less than 10 years (Carpenter, 1980; Wagner, pers. obs.). If not attackedaggressively in the early stages of establishment, the likelihood of expanded milfoil coverage isvery high, with concurrent loss of native assemblages and associated habitat value.The ecology of the species involves reproduction primarily by vegetative means, usually byfragmentation of plant tips or by root crown expansion. Root crown expansion appears to be thedominant means of local expansion, while fragments are the primary means of more distantdissemination and colonization (Madsen and Smith 1997). Both are highly effective means ofpropagation. Adventitious roots form on the plant tips, allowing rapid re-rooting and growth ofnew plants. Viable fragments may be produced by motorboat propellers, but fragmentation isnaturally most prevalent in the autumn when assemblages of annual species dependent upon seedgermination have died back, providing ample open substrate for the milfoil to colonize.Fragments persist through the northern winter, can grow with low light availability, and initiaterapid growth (as much as 1 ft per week) in the spring before many seeds have germinated.Likewise, established plants with expanded root crowns can send up new stems earlier in thespring than most other species in northern lakes. Rapid dominance is thereby ensured in mostcases.At the scale of the bed, milfoil is predominantly a recreational problem by virtue of its-location.Occurrence of beds in shallow water in swimming or docking areas creates an impediment tohuman access and use which is usually evident by the start of more intensive spring use (post­Memorial Day). \Vhile other species can create nuisance conditions, the early appearance andDSEIS for Eagle Lake 8 ENSR