Upper Gorge Reservoir Report

Last Updated: December 5, 2025

Upper Gorge is a gravity dam located in Bishop, California, along the Owens River.


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Summary

Completed in 1953, this structure stands at a height of 44 feet and has a hydraulic height of 35 feet. With a storage capacity of 26 acre-feet and serving the primary purpose of flood risk reduction, Upper Gorge plays a crucial role in managing water resources in the region. The dam is under the jurisdiction of the California Department of Water Resources and is regulated, permitted, inspected, and enforced by state agencies to ensure its safety and functionality.

Despite its age, Upper Gorge has been assessed to be in satisfactory condition with a low hazard potential. The last inspection was conducted in September 2019, with a regular inspection frequency of once a year. In case of emergencies, such as potential inundation events, the dam's emergency action plan (EAP) status and preparedness remain unclear, indicating a potential area for improvement. Overall, Upper Gorge serves as a vital infrastructure for flood risk reduction and hydroelectric purposes, contributing to the water management efforts in the Mono County region.

With its location in the picturesque Mono County, Upper Gorge not only provides flood protection but also adds to the scenic beauty of the area. Managed by local government authorities, this dam stands as a testament to human ingenuity in harnessing water resources while also highlighting the need for ongoing maintenance and preparedness for any potential risks. For water resource and climate enthusiasts, Upper Gorge presents a fascinating case study of dam infrastructure in California and the importance of effective regulation and inspection to ensure public safety and water security.

Year Completed

1953

Dam Length

37

Dam Height

44

River Or Stream

Owens River

Primary Dam Type

Gravity

Surface Area

2

Hydraulic Height

35

Drainage Area

457

Nid Storage

26

Hazard Potential

Low

Nid Height

44
       
Seasonal Comparison

Weather Forecast

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.