Summary

The reservoir was constructed in the early 1900s to provide water and hydroelectricity to San Francisco. The lake is fed by the Tuolumne River and is surrounded by the Sierra Nevada mountains. The hydrology of the area is influenced by the snowmelt from the surrounding mountains. The lake provides surface water for San Francisco, Modesto, and Turlock, and also supports hydropower generation. The area around the lake is not used for agriculture, but is popular for recreational activities such as camping, hiking, and fishing. The lake has a capacity of 28,000 acre-feet and is managed by the San Francisco Public Utilities Commission. The surrounding area is protected by the Yosemite National Park.

Regional Streamflow Levels

Lk Eleanor Div To Cherry Lake Nr Hetch Hetchy Ca 1.00cfs	1cfs
Eleanor C Nr Hetch Hetchy Ca 533.0cfs	533cfs
Cherry C Bl Valley Dam Nr Hetch Hetchy Ca 50.2cfs	50cfs
Tuolumne R Nr Hetch Hetchy Ca 480.0cfs	480cfs
Cherry C Nr Early Intake Ca 596.0cfs	596cfs
Tuolumne R Ab Early Intake Nr Mather Ca 565.0cfs	565cfs

15-Day Long Term Forecast

Reservoir Details

Lake Or Reservoir Water Surface Elevation Above Ngvd 1929, Ft 24hr Change	0.0%
Percent of Normal	100%
Minimum	4,614.07 ft 2015-10-03
Maximum	4,662.66 ft 2017-01-09
Average	4,658 ft

Seasonal Comparison

Reservoir Storage, Acre-Ft Levels

Lake Or Reservoir Water Surface Elevation Above Ngvd 1929, Ft Levels

5-Day Hourly Forecast Detail

Dam Data Reference

Condition Assessment

Satisfactory
No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.