The San Francisco Public Utilities Commission (SFPUC) owns and operates Hetch Hetchy Water and Power Project (Hetch Hetchy Project). This system, located in the upper Tuolumne River watershed, includes dams and flow diversions on the Tuolumne River, Cherry Creek (a tributary to the Tuolumne River), Eleanor Creek (a tributary to Cherry Creek), and Moccasin Creek (tributary to New Don Pedro Reservoir). As part of establishing a common foundation of environmental information for the river and stream reaches affected by the Hetch Hetchy Project, the SFPUC Natural Resources and Hetch Hetchy Water and Power Divisions funded a one-year effort to describe current ecological and geomorphic conditions in the Tuolumne River from O’Shaughnessy Dam to New Don Pedro Reservoir, Cherry Creek downstream of Cherry Valley Dam, and Eleanor Creek downstream of Eleanor Dam. Study plans and reports were reviewed by the Tuolumne River Stakeholder Group, which includes representatives from federal, state, and local agencies; local water districts; environmental organizations; and the whitewater rafting community. In particular, the Yosemite National Park Service and U.S. Fish and Wildlife Service have provided valuable technical expertise to this study.

This one-year effort included four tasks:

1. Identify and compile existing information, identify key information gaps, and develop a reconnaissance-level field plan to begin gathering additional information in 2006 (completed in October 2006);
   
2. Implement the 2006 field plan (completed from January 2006 to September 2006);
   
3. Summarize and synthesize available information and information collected in 2006 in an initial report that describes current ecologic and geomorphic conditions in key reaches below the Hetch Hetchy Project (completed in October 2006); and
   
4. Identify short- and long-term future monitoring activities necessary to build on this foundation (purpose of this report).

Tasks 1-3 were completed by October 2006, and are summarized in the “Upper Tuolumne River: Available Data Sources, Field Work Plan, and Initial Hydrology Analysis” report. This report summarizes information in Tasks 1-3 to describe current ecologic and geomorphic conditions in each reach, and recommends short- and long-term monitoring needed to improve understanding of the effects of the Hetch Hetchy Project on river and riparian ecosystem function, and identify measures to reduce these effects (Task 4). The objectives of this report are to:

1. Begin informing existing Hetch Hetchy Project operations to promote opportunities to protect ecologic and geomorphic values within the context of meeting current water supply, power generation, and water quality objectives, and minimum flow requirements;
   
2. Describe key flow-related river ecosystem processes and how these processes are affected by historical and current Hetch Hetchy Project operations;
   
3. Guide future work to better understand the relationship between the Tuolumne River ecosystem and Hetch Hetchy Project operations; and
   
4. Identify short- and long-term annual monitoring activities necessary to support this work.

An additional product of this effort includes a database of available information compiled during the development of these two reports. This database and other supporting information compiled or generated by this effort will be made available to the Tuolumne River Stakeholder Group and other interested parties.

Attachments: 

Upper Tuolumne River: Description of River Ecosystem and Recommended Monitoring Actions