Longley Reservoir Report

Last Updated: December 5, 2025

Longley, also known as McGee Lake, is a privately owned dam located in Bishop, California.


°F

°F

mph

Wind

%

Humidity

Summary

Built in 1910, this earth dam stands at a height of 27 feet and serves primarily for hydroelectric power generation and recreation purposes. It has a storage capacity of 178 acre-feet and covers a surface area of 11 acres, with a maximum discharge capacity of 300 cubic feet per second.

Managed by the Federal Energy Regulatory Commission, Longley is regulated and inspected to ensure its safety and compliance with state standards. Despite being classified as having a low hazard potential, the dam is subject to regular inspections and emergency action plans to mitigate any risks. With a moderate risk assessment rating, Longley plays a crucial role in water resource management and climate resilience efforts in the region.

The dam's location on McGee Creek in Inyo County, California, highlights its importance in providing water resources and recreational opportunities for the local community. With a history dating back over a century, Longley stands as a testament to the ingenuity of early hydroelectric infrastructure projects and continues to play a vital role in supporting sustainable water management practices in the area.

Year Completed

1910

Dam Length

120

Dam Height

27

River Or Stream

McGee Creek

Primary Dam Type

Earth

Surface Area

11

Nid Storage

178

Structural Height

27

Hazard Potential

Low

Foundations

Rock, Soil

Nid Height

27
       
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.