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• ^ ^ <br />ro,%ect Synopsis <br />A Use AttainabilityAnalysis (UAA) is a scientific assessment of a water body's physical, chemical, and biological <br />conditions. Ruses anoutcome-based evaluation and planning process in order to obtain or maintain optimal water <br />quality conditions and achieve beneficial uses, such as swimming, fishing, orwildlife habitat. <br />During 2001-2003, the Black Dog Watershed Management Organization {BDWMO) conducted a UAA for <br />Crystal LakeJKeller Lake to address current water quality issues. The UAA includes a water quality analysis and <br />prescription ofprotective measures for Crystal Lake/Keller Lake and the watershed, based on historical. water <br />quality data, the results of intensive lake water quality monitoring, and computer simulations of land use impacts on <br />water quality. <br />Typical ran Lake ater uality Problems <br />The primary problem in urban lakes is "cultural eutrophication," which is defined as the accelerated increase in <br />concentrations ofnutrients,primarily phosphorus and nitrogen, in a lake as a result ofhuman activities in the <br />watershed. Eutrophication is often indicated by increased algal growth, <br />decreased water clarity, and loss of dissolved oxygen in the bottom <br />waters ofthe lake, which leads to a shift in fish species from desirable <br />game fish tonon-game species such as carp and bullhead. <br />"The OJsual Suspects <br />These problems typically occur because of watershed urbanization and <br />nonpoint source pollution. Increased urbanization in a watershed leads <br />to more streets, driveways, and rooftops (impervious surfaces). This <br />increased imperviousness results in more stomlwater runoff traveling <br />quickly through storm sewers, diminishing the runoffpollutant retention <br />capacity of watershed ponds and wetlands. The increased stormwater <br />nznoffcarries excess nutrients into lakes and streams as nonpoint <br />source pollution. Increased concentrations ofphosphorus in lake <br />waters is the leading cause of algal blooms and decreased water clarity. <br /> <br /> <br />Source: Monson (1992) <br />Before development (top <br />image), stormwater travels <br />slowly through a watershed. <br />After development (bottom <br />image), impervious surfaces are <br />increased, resulting in more <br />stormwater runoff and less <br />frltration of nutrients. <br />Nuisance algae in lakes results from the <br />excess phosphorus that reaches lakes due to <br />increased stormwater runoff `.' <br />f~ ~, <br />tip- ~°--_~'. <br />~,~, a:..~~`~ <br />ff <br />A lake's clarity (transparency) is <br />measured by submerging a black <br />and white patterned disc (a Secchi <br />disc) into the lake. The depth at <br />which the Secchi disc disappears <br />determines the lake's transparency. <br />Watershed Mana ement Organlzatfon I <br />