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that are proposed within the drainage area, restrictions on the use of phosphorus -containing fertilizers, and limited harvesting of aquatic macrophytes. Large reductions in phosphorus could only be achieved by constructing basins upstream from Silver View Pond to treat storm water already flowing into the pond or by applying chemicals which cause phosphorus to precipitate and settle out. The application of herbicides would create too drastic a change in the ecology of the pond and would most likely lead to further problems with excessive macrophyte growth. Although it may be desirable to remove some macrophytes, herbicides leave organic matter and nutrients such as phosphorus in the pond; macrophyte harvesting does not leave behind these residues. VII. RECOMMENDED MANAGEMENT MEASURES A. Water Quality Measures 1. Ponding Pre -ponding of storm -water runoff from new commercial developments should be undertaken where practical to minimize additional phosphorus loading to Silver View Pond. Potential locations for such ponding are wet meadow wetlands between County Road I and the old County Road I corridor at the north end of the drainage area and similar wetlands east and west of Silver Lake Road on the west edge of the drainage area. Additional ponding for storm water already flowing via storm sewers to the pond is not recommended. 2. Limitation of Phosphorus Containing Fertilizers It is recommended that the City consider an ordinance to eliminate the use of phosphorus -containing lawn fertilizers within the drainage area of the pond. Nitrogen and potassium -containing fertilizers are sufficient for lawn maintenance and will minimize both aquatic macrophyte and blue-green algae problems. 3. Limited Harvest of ASLUatic Macrophytes It is recommended that the City undertake limited harvesting of aquatic macrophytes within portions of Silver View Pond. The portions where macrophytes are presently a problem and where harvesting would not promote blue-green algae problems are shown in Figure 9 and summarized as follows: - southern portion of the south arm (approximately 1 acre) - shallow eastern portion of the east arm (approximately 1.5 acre) 89