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Since the supply of phosphorus usually governs the amount of algae in a lake, if the amount of <br />phosphorus in the lake can be controlled, then algal growth can be controlled. The suitability of <br />the lake to support recreational and other uses can thereby be maintained /improved. This is a <br />principal objective of many lake water quality protection/improvement efforts. <br />Finding ways to protect /improve the quality of the lake environment for Langton and Bennett <br />Lakes was a primary objective of this 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. Elevated pollutant loadings from developed areas are in -part a consequence of more <br />runoff volume as a result of coverage by impervious surfaces such as roads, parking lots, <br />rooftops, 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 />■ improperly applied fertilizers containing phosphorus, <br />■ vegetative material left on hard surfaces, <br />■ soil and dust particles, and animal waste. <br />Municipal storm drainage systems installed to prevent flooding provide an efficient vehicle for <br />delivery of these pollutants from their places of origin to the receiving water. <br />OVERVIEW OF 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 summertime (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 />City of Roseville 36 <br />Parks Natural Resource Management <br />