SFPUC 2001 Alameda Watershed Management Plan

III. ENVIRONMENTAL SETTING AND IMPACTSD. HYDROLOGY AND WATER QUALITYpotential water quality impacts associated with expansion of golf course use by requiring firehazard reduction activities for new lessees and providing fire suppression equipment needs.Watershed Activities Policies WA24 and WA25 require a grading plan and require all lesseesand permittees to comply with the Integrated Pesticide Management Plan and ChemicalApplication Management Program. In addition, Actions env1 through env5 ensure that anyproposal for expansion of the existing golf course must comply with the CaliforniaEnvironmental Quality Act. Actions lea3, lea4, and lea5 would ensure that land use leasesinclude water quality protection measures and monitoring plan. Actions des1 and des2 require areview process for all proposed plans and projects. Action fic2 authorizes or prohibits specificlease or permit activities based partially on impacts to water quality. Action inf3 records andupdates water quality data.Implementation of these policies and management actions, as described above and in Section IV.D,could reduce potential water quality impacts associated with expansion of golf course uses to a lessthan significant level, at a program-level. Nevertheless, more detailed project-specificenvironmental review would be required at the time of project proposal for expansion of the golfcourse. Project-level environmental review would be required to determine any additional,project-specific potential water quality impacts and mitigation measures.Build-Up of SedimentsOn a program-level, implementation of the Management Plan is not anticipated to substantiallyalter drainage patterns or cause flooding conditions. The major hydrologic flow patterns in theWatershed, as described above under Section 1.0, Setting, would essentially remain unalteredunder the Management Plan (with the possible exception of the new water storage reservoirs,discussed above). Natural drainage patterns have been modified over the past century toaccommodate water diversion, storage, treatment, and conveyance facilities. Both natural andhuman activities in the Watershed have resulted in sedimentation to reservoirs and streams,which has indirectly affected both water quality and hydrology. During the rainy season, runoffin the Watershed transports sediments to streams, and some of the sediments eventually reach thereservoirs, resulting in increased turbidity in both the streams and reservoirs. Gradually,sediments settle at the bottom of the streams and reservoirs, and over time, the accumulatedsediments have altered stream channels, modified stream flow and capacity, and reduced thewater storage capacity of reservoirs.As described above under the heading “Impaired Water Quality,” numerous Watershed activities,such as new trails, increased public access and use, unauthorized off-trail use in areas nearreservoirs and creeks, construction activities, any grading activities, wildland fires, and manyoperations and maintenance activities, could result in erosion and sedimentation. These activitiescould exacerbate natural sedimentation processes, alter stream channels, and result in cumulativebuild-up of sediments, gradually reducing the water storage capacity of reservoirs. In addition, inthe event of a large fire on the Watershed followed by rainfall, there would be a substantialincrease in sedimentation, particularly on steeper slopes denuded of ground vegetation, whichcould lead to blocked or partially blocked stream channels, altered stream flows, and increaseddeposition of sediments to reservoirs. Unless appropriate control measuresNOP 96.223E: Alameda Watershed Management Plan III.D-34 ESA / 930385January 2001