Grant Lake Reservoir Report

Last Updated: December 5, 2025

Grant Lake is a man-made reservoir situated in Mono County, California.


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Summary

The lake was created in 1916 by the Los Angeles Department of Water and Power as a part of the Los Angeles Aqueduct system. The lake is fed by several sources, including Rush Creek and Lee Vining Creek, which are important surface flow providers, as well as snowpack melting during the spring and summer months. The water from the lake is used for irrigation of agricultural land in the surrounding area and also provides recreational activities such as fishing, boating, and camping. The lake is a vital hydrological resource in the area, and its water levels are closely monitored to ensure that it remains a sustainable source of water for the region.

Reservoir Details

Storage 24hr Change -0.14%
Percent of Normal 192%
Minimum 11,536.0 acre-ft
2022-04-04
Maximum 49,547.0 acre-ft
2023-06-19
Average 24,576 acre-ft
Nid_Height 87
Hydraulic_Height 72
Primary_Dam_Type Earth
Drainage_Area 60
Year_Completed 1940
Dam_Height 87
Surface_Area 1095
Nid_Storage 47525
River_Or_Stream Rush Creek
Dam_Length 700
Hazard_Potential High
       
Seasonal Comparison
Storage Levels
Pool Elevation Levels
Top Conserv Storage Levels
Inflow Levels

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.