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<br />,_,,-_1-__~_______ ~,-"____,_,__,_"____-------'_~,_ <br /> <br />I <br /> <br />I <br /> <br />These concentrations of phosphorus indicate a general <br />EPA eutrophication classification. The upper boun- <br />dary between eutrophication and hypereutrophication <br />is in the range of 0.5 mg/l or 604# for Silver Lake. <br />What all this indicates is that the lake is already <br />eutrophied with 40# to 128# of phosphorus and the <br />addition of, at worst, another 5.55# will not make <br />conditions significantly worse. <br /> <br />I <br />I <br />I <br />II <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />In summary, as the project affects Silver Lake, the <br />lake could experience slight increased water level <br />and nutrient loading as a result of the proposed <br />action. These impacts are on the order of <br /> <br />1. 1/2 inch additional rise (maximum) of the <br />lake level following 4" of rainfall. <br /> <br />2. An increased nutrient loading which will not <br />significantly increase eutrophication of the <br />lake. <br /> <br />I <br /> <br />Because there is the potential for degradation of <br />Silver Lake, an alternative plan for part of the <br />drainage should be evaluated by the proposer. This <br />involves collecting and treating, by ponding, storm <br />'water from roughly the eastern 1/3 of the site and <br />discharging, after treatment, into the 15" stub and <br />ultimately to Long Lake and Rice Creek. <br /> <br />I <br /> <br />It is not advisable to put a lot of water into this <br />system, but dispersion of the treatment and dis- <br />charge is very likely to decrease the overall pollu- <br />tion and high water conditions. If perhaps 1 cfs <br />could be discharged into this pipe after having <br />been ponded for a period of time and having passed <br /> <br />I <br />I <br /> <br />I <br /> <br />II <br /> <br />V-7 <br /> <br />_ ~~__..___ .__~__~..___..____._. J <br />