Agenda - 11-19-1997 - 10a - Laserfiche WebLink

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21 EXECUTWE SUMMARY (4) Management Options No single management option can meet all six of the water quality and non-water quality objectives. OWASA and the community must therefore consider scenarios that combine multiple forms of management(Chapter 3 and Appendix F). • Watershed Management. Achieving water quality objectives in Cane Creek Reservoir is best addressed through management actions in the watershed and tributary arms of the lake. Four alternative management approaches or scenarios, reviewed and refined by the Advisory Committee, are proposed for further review and evaluation by the OWASA Board and community(See Table E-1). The scenarios include different combinations of zoning; open-space preservation; buffer requirements; residential, agricultural, and forestry best management practices,land acquisition, and in-lake management options which are detailed in Exhibit E-1 at the end of the Executive Summary. Although each scenario is projected to,meet water quality objectives, they differ in key areas for consideration, including political feasibility,certainty of effectiveness,potential for unintended adverse consequences, and ability to develop additional or retrofit solutions when unotpected conditions occur. Further input on community preferences and concerns should therefore be gathered and considered before deciding on a specific alternative (Chapter 4). Table E-1. Preferred Management Scenarios for Further Review Auaitia..l Bat OWA" Oraage Co. Opt:,Pow mmafemaot AcgaWdon In-Labe maoftenent Somario Zowng Prtsoervatioa IhAers Pracd= (airs) Optim Currat Derider 36 4 tributary 2. Tributary Detention Ponds 2-aae voltu tart' detention 4a. Open space 2-sae Voluntary` Current Raidential,forestry, 632 1 tributary Preservation and BMPs 5R Nearshore S. Lute Lot Zoning and 5/2 voluntary current Fares",sgricultum 1265 None BMPs I I dairies 6. Mandatory Gloater 2•scm Mandatory Cornet Real,dairies 1377 2 tributary Development detention • In-lake Management. Several m-lake management options were evaluated for addressing key risks, but were rejected because of high cast and uncertainty in effectiveness. These options included mechanical destratftation,hypolimnedc aeration, alum and copper sulfate applications, and biomampul=On(changing biological community structure). Further evaluation of constructing impoundments(large detention ponds) in one or more of the tributary alms of the lake to enhance removal of sediments and contaminants prior to reaching the intake area is recommended, however, as part of the four watershed management scenarios (Chapter 4 and Appendix F). • Water Supply Treatment. Attempting to address degradation of the raw water supply solely through enhanced processes at the treatment plant will not provide the desired level of assurance for providing high quality drinking water. Certain problems in raw water supply quality (e.g., periodic low levels of dissolved oxygen,high levels of iron and manganese, and high levels of total organic carbon) are, however, expected to continue even with the most restrictive watershed management options under E-6