About
The UTREP works to advance stewardship of the Upper Tuolumne River ecosystem
Background
The San Francisco Public Utilities Commission (SFPUC), a department of the City and County of San Francisco (CCSF), owns and operates the Hetch Hetchy Water and Power Project, located in the upper Tuolumne River watershed in California's Sierra Nevada. The Hetch Hetchy Project is a system of major dams, diversion structures, and hydropower facilities on the Tuolumne River, Cherry Creek (a tributary to the Tuolumne River), and Eleanor Creek (a tributary to Cherry Creek). The system supplies water to 2.6 million people in the San Francisco Bay Area and provides hydropower for Turlock and Modesto irrigation districts and San Francisco municipal uses.
In June 2006, the SFPUC adopted the Water Enterprise Environmental Stewardship Policy, which requires the protection and rehabilitation of ecosystems affected by SFPUC water system operations, within the context of water supply, power generation, water quality, and existing agreements. The policy broadens the scope of SFPUC instream flow releases by requiring that they mimic, to the extent feasible, "…the variation of the seasonal hydrology (e.g., magnitude, timing, duration, and frequency) of their corresponding watersheds in order to sustain the aquatic and riparian ecosystems upon which native fish and wildlife species depend."
Mission
The Upper Tuolumne River Ecosystem Program (UTREP) develops data, analyses, and recommendations for improving ecosystem conditions downstream of Hetch Hetchy Project facilities consistent with the Stewardship Policy. The UTREP is a program of the SFPUC, with numerous scientific collaborators, including the National Park Service (NPS) at Yosemite National Park, the U.S. Fish and Wildlife Service (USFWS), the U.S. Forest Service (USFS) at Stanislaus National Forest, consultants, researchers, and academics. Valuable input is also provided by the members of the Upper Tuolumne River Workgroup.
Goals
- Describe historical and present day upper Tuolumne River ecosystem conditions
- Assess the relationship of historical and present day conditions to Hetch Hetchy Project operations
- Develop recommendations for improving ecosystem conditions on a long-term, adaptively managed basis
Where We Work
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The UTREP study area includes portions of the upper Tuolumne River mainstem and major tributaries regulated by the Hetch Hetchy Project, and has been delineated into seven reaches based on present-day operations and major tributary locations.
Hetch Hetchy Reach
Tuolumne River from O'Shaughnessy Dam (RM 117.5) to Kirkwood Powerhouse (RM 105.7). This reach is bypassed by Canyon Power Tunnel. Flows in this reach are affected by instream flow and reservoir management releases from O'Shaughnessy Dam and accretions from small tributaries. Roughly, the upper half of the Hetch Hetchy Reach is located within Yosemite National Park, the lower half within the Stanislaus National Forest. All other reaches within the study area are located within the Stanislaus National Forest.
Kirkwood Reach
Tuolumne River from Kirkwood Powerhouse to the Cherry Creek confluence (RM 103.8). Flows in this reach are affected by releases from O'Shaughnessy Dam, hydropower operations at Kirkwood Powerhouse, and small tributary accretions. Maintenance operations at Early Intake Diversion Dam occasionally affect flows in the reach; however, the diversion dam is typically operated as run of the river with no diversions.
Lumsden Reach
Tuolumne River from Cherry Creek confluence (RM 103.8) to Don Pedro Reservoir (RM 78.5). Flows in this reach are affected by the sum of Hetch Hetchy Project operations and accretions from several major unimpaired tributaries.
Upper Cherry Reach
Cherry Creek from Cherry Valley Dam to the Eleanor Creek confluence. Flows in this reach are primarily affected by instream flow and reservoir management releases from Cherry Valley Dam. The reach is bypassed by the Cherry Power Tunnel.
Eleanor Reach
Eleanor Creek from Eleanor Dam to the confluence with Cherry Creek. Flows in this reach are affected by instream flow and reservoir management releases from Eleanor Dam and tributaries.
Lower Cherry Reach
Cherry Creek from Eleanor Creek confluence to Holm Powerhouse. This reach is partially bypassed by the Cherry Power Tunnel. Flows in this reach are primarily affected by instream flow and reservoir management releases from Cherry Valley Dam and Eleanor Dam. Maintenance operations associated with the Cherry Creek Diversion Dam and Cherry Aqueduct occasionally affect flows in this reach; however, the Cherry Creek Diversion is typically operated as run of the river with no regular operational diversions.
Holm Reach
Cherry Creek from Holm Powerhouse to the confluence with the Tuolumne River. Flows in this reach are affected by releases from Cherry and Eleanor dams, and hydropower operations at Holm Powerhouse.