SFPUC 2001 Alameda Watershed Management Plan

III. ENVIRONMENTAL SETTING AND IMPACTSD. HYDROLOGY AND WATER QUALITYProject water system, which the City may purchase during a drought). There are also facilities topump groundwater from the Sunol Infiltration Galleries (discussed below) to San AntonioReservoir. Below the diversion dam, Alameda Creek receives local waters only, including runofffrom the lower watershed and groundwater accretion.Water quality testing of Alameda Watershed source waters was conducted as part of the HetchHetchy Water Quality Planning Study (Camp Dresser & McKee, 1995). Monitoring of Calaverasand San Antonio Reservoirs indicated good overall water quality. Turbidity levels in bothreservoirs are typically low in the summer and higher in the winter. Giardia, Cryptosporidium,and total coliform levels were very low during monitoring. Water in San Antonio Reservoir hasexhibited higher levels of sodium as well as other salts compared to Calaveras Reservoir, whichis most likely due to the addition of water from the South Bay Aqueduct. Since San AntonioReservoir has no aeration system, seasonal stratification results in oxygen depletion in the lowerdepths. Increased pH levels in the reservoirs are usually a direct result of algae blooms thattypically occur during the warmer summer months. All water from both reservoirs is treated atthe Sunol Valley WTP before it enters the SFPUC water system for distribution to customers.Alameda Creek water quality was tested as part of the Alameda Creek Water Resources Study(Bookman-Edmonston Engineering, Inc., 1995). Water quality testing indicated that the qualityof Alameda Creek water is acceptable for establishing a trout population. Water temperature,dissolved oxygen, pH, hydrogen sulfide, copper, iron, and manganese in Alameda Creek surfacewater were all within water quality criteria established by the U.S. Environmental ProtectionAgency for the protection of aquatic life.As part of the development of the Management Plan, characterization of existing conditionsincluded identifying Water Quality Vulnerability Zones (WQVZs). These zones are areas whereactivities or disturbance would have the greatest potential to affect the water quality of surfacerunoff and water stored in the reservoirs. The WQVZs were classified as high, moderate, or lowvulnerability based on criteria that assessed proximity to water, intensity of rainfall, wildlifeconcentration, vegetation as a protective layer, slope, and soil. Disturbance to areas of thehighest vulnerability would result in the greatest risk to water quality. The Management Planidentified some areas of high vulnerability within the Watershed, large areas of moderatevulnerability, and almost no areas of low vulnerability (see Figure 2-3 of the Management Planfor a map of WQVZs). The Management Plan map implies that activities in most locations onWatershed lands would likely affect water quality.1.5 GROUNDWATERGroundwater investigations were conducted in the Sunol Valley as part of the Alameda CreekWater Resources Planning Study (Luhdorff and Scalmanini Consulting Engineers, 1993). Theinformation on groundwater presented below is based on that study.In the Sunol Valley, the potential water-bearing geologic units consist primarily of alluvium andLivermore Gravels. The alluvium contains relatively large volumes of groundwater compared toNOP 96.223E: Alameda Watershed Management Plan III.D-5 ESA / 930385January 2001