Final report to - Sierra Forest Legacy

1018VOLUME II, CHAPTER 36FIGURE 36.2Schematic diagram of reservoirs in the San Joaquin River basin, plotted by elevation. Clifton Court forebay and four storagereservoirs in the Coast Ranges (San Luis, Little Panoche, O’Neil, and Los Banos) are included. Otherwise, all reservoirsshown are in the Sierra Nevada or its foothills. (Adapted from a plot prepared by the California State Water Resources ControlBoard, Graphic Unit.)with heavy grazing even in many high-elevation meadowsthat remain inaccessible to vehicles today (Dudley andEmbury 1995). As a result, channel incision and desiccationof meadow vegetation has been widespread in the SierraNevada. Grazing and its effects have been so pervasive andubiquitous throughout the American West that virtually nounaffected “control” conditions exist for comparison, andwhat most people would regard as “natural” conditions arein fact influenced by historical (if not current) grazing (Elmoreand Beschta 1987). Our best comparisons are derived fromstudies of vegetation and channel recovery when streams areexcluded from grazing, but channel conditions may be slowto recover from grazing effects (Kondolf 1993).Groundwater abstraction for municipal or agricultural usecan reduce alluvial water tables, stressing or killing riparianvegetation (Kondolf and Curry 1986; Wright and Berrie 1987).Groundwater pumping in the Owens Valley has had the greatestdocumented effects on vegetation known in the SierraNevada region (Perkins et al. 1984; Groeneveld and Or 1994).Recreation can affect riparian corridors through the concen-