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Since the supply of phosphorE.is usually governs the amount of algae in a lake, if the amount of <br />phosphorus in the iake can be controlled, then algal growth can be controlled. The suitability of <br />the lake to support recreational and other uses can thereby be maintainecE/improved. This is a <br />principal objective of many lake water quality protcction/improveznent efforts. <br />Finding ways ta protecVimprove the q�ality of t�e lake environment for Lan�ton and Bennctt <br />Lakes was a prirnary objective of thzs project. Of particular concern is the control and reduction <br />of the amount of pollutants that reach these lakes, especially from developed areas in the lake's <br />watershed. EIevated pollutant loadings from devejoped areas are in-part a consequence of rnore <br />runoff volut�e as a result of coverage by impervious surfaces such as roads, parking lots, <br />roofto�s, and driveways. They are also a consequence of higher concentrations of pollutants in <br />runoff from urbanized areas. For example, major sources of the pollutant phosphorus in urban <br />runoff include: <br />■ irnproperly applied fertiiizers containing phosphorus, <br />■ ve�etative material ]eft on hard surfaces, <br />• soil and dust particles, and animal waste. <br />Municipal storm drainage systems installed to prevent flooding provide an ef�cient vehicle far <br />delivery of these pollutants from their pIaces of ori�in to the receiving water. <br />OVERVIE�V QF CURRENT LAKE WATER QUALITY <br />A lake water quality report card has been developed by staff from the Met Council to grade <br />water quality in lakes in the Metro area based on summertimc (May-September) values for <br />several key parameters, including total phosphorus. The grades and total phosphorus ranges to <br />which they apply are shown in Table 5.2. <br />Ciry of Roseville 34 <br />Parks Natrrral Resoirrce Maliagenteitt <br />