Little Grass Valley Reservoir Report

Last Updated: December 5, 2025

Little Grass Valley Reservoir is a lake located in Plumas County, California, USA.


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Summary

The reservoir was created by the construction of Little Grass Valley Dam, which was completed in 1961 by Pacific Gas and Electric Company. The dam is 105 feet high and 1,610 feet long. The reservoir has a capacity of 105,000 acre-feet and is part of the North Fork Feather River watershed. It is fed by the Little Grass Valley Creek and other small creeks, and provides water for irrigation, domestic, and industrial use. The reservoir is also used for recreational activities like fishing, boating, and swimming. The surrounding area has many campgrounds and hiking trails. Little Grass Valley is an important source of water for the region and is managed by the Plumas County Water Agency.

Reservoir Details

Storage 24hr Change -0.04%
Percent of Normal 179%
Minimum 36,493.0 acre-ft
2004-12-06
Maximum 94,390.0 acre-ft
2005-06-07
Average 47,809 acre-ft
Dam_Height 184
Hydraulic_Height 198
Drainage_Area 25.8
Year_Completed 1961
Nid_Storage 94660
Structural_Height 210
River_Or_Stream South Fork Feather River
Foundations Rock
Surface_Area 1630
Hazard_Potential High
Outlet_Gates Tainter (radial) - 2
Dam_Length 840
Primary_Dam_Type Earth
Nid_Height 210
       
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.