Folsom Dike 4 Reservoir Report

Last Updated: December 5, 2025

Folsom Dike 4 is a crucial federal structure located in Folsom, California, along the American River.


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Summary

Built in 1956 by the Bureau of Reclamation, this earth dam stands at 30 feet in height and spans a length of 1450 feet. Its primary purpose is flood risk reduction, with additional functions including hydroelectric power generation, irrigation, recreation, and water supply.

With a storage capacity of 1,120,000 acre-feet and a surface area of 11,180 acres, Folsom Dike 4 plays a significant role in managing water resources in the region. Despite its high hazard potential, the dam has not undergone a recent condition assessment, raising concerns about its long-term safety and maintenance requirements. However, the Bureau of Reclamation remains responsible for the regulatory oversight, inspections, and operations of the structure.

As a critical component of the water infrastructure in Placer County, Folsom Dike 4 requires continued monitoring and risk management measures to ensure its effectiveness in flood control and water supply management. Given its location in a high-risk area and the absence of recent inspections, stakeholders and climate enthusiasts must advocate for regular assessments and maintenance to safeguard the surrounding communities and ecosystems from potential disasters.

Year Completed

1956

Dam Length

1450

Dam Height

30

River Or Stream

AMERICAN RIVER

Primary Dam Type

Earth

Surface Area

11180

Hydraulic Height

25

Drainage Area

1570

Nid Storage

1120000

Structural Height

30

Hazard Potential

High

Foundations

Rock

Nid Height

30
       
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.
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Area Campgrounds

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