Rubicon Main Reservoir Report

Last Updated: December 4, 2025

Rubicon Main is a hydroelectric dam located in El Dorado County, California, along the Feather River.


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Summary

Built in 1963, this concrete gravity dam stands at 35 feet tall and spans 644 feet in length, with a storage capacity of 1439 acre-feet. Managed by a public utility, the dam's primary purpose is hydroelectric power generation, with additional recreational benefits for the surrounding area.

The dam is regulated by the Federal Energy Regulatory Commission and the California Department of Water Resources, ensuring regular inspections and enforcement of safety measures. Despite its low hazard potential, a moderate risk assessment has been assigned to the dam, indicating a level 3 risk. Emergency action plans are in place, with the last revision in December 2020, to mitigate any potential risks associated with the dam's operation.

With a maximum discharge capacity of 39,000 cubic feet per second and an uncontrolled spillway, Rubicon Main plays a crucial role in water resource management and renewable energy production in the region. Its location in Folsom, California, and its proximity to San Francisco District of the US Army Corps of Engineers make it a vital piece of infrastructure for water supply and climate adaptation efforts in the area.

Year Completed

1963

Dam Length

644

Dam Height

35

River Or Stream

Feather River

Primary Dam Type

Concrete

Surface Area

108

Hydraulic Height

32

Drainage Area

27.3

Nid Storage

1439

Structural Height

40

Hazard Potential

Low

Nid Height

40
       
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.