Buck Island Main Reservoir Report

Last Updated: December 4, 2025

Buck Island Main, located in El Dorado County, California, is a key infrastructure in the state's water resource management system.


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Summary

Owned by a public utility and regulated by the Department of Water Resources and Safety of Dams, this concrete gravity dam stands at a height of 22 feet and was completed in 1963. With a primary purpose of hydroelectric power generation, Buck Island Main also serves recreational purposes, offering a surface area of 78 acres for visitors to enjoy.

Managed by the Federal Energy Regulatory Commission, Buck Island Main has a storage capacity of 1,070 acre-feet and a maximum discharge of 15,000 cubic feet per second. The dam's spillway, at 130 feet wide, is uncontrolled, with a low hazard potential. Despite its moderate risk assessment score, the dam's condition assessment is currently not available, and its last inspection took place in August 2019. Emergency action plans have been prepared and revised periodically to ensure the safety and security of the surrounding area in case of any unforeseen events.

Located near Folsom and Rockbound Creek, Buck Island Main plays a vital role in water resource management and hydroelectric power generation in California. With its impressive engineering design by Bechtel, the dam continues to be a crucial asset in the state's efforts to harness renewable energy sources and provide recreational opportunities for the local community.

Year Completed

1963

Dam Length

233

Dam Height

22

River Or Stream

Rockbound Creek

Primary Dam Type

Concrete

Surface Area

78

Hydraulic Height

16

Drainage Area

6.1

Nid Storage

1070

Structural Height

22

Hazard Potential

Low

Nid Height

22
       
Seasonal Comparison

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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.