Chicago Park Forebay Reservoir Report

Last Updated: December 5, 2025

Chicago Park Forebay, located in Nevada County, California, is a vital water resource infrastructure managed by a public utility.


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Summary

Constructed in 1966 by Ebasco Services, Inc., this earth dam serves multiple purposes including irrigation, hydroelectric power generation, and water supply. With a dam height of 60 feet and a maximum storage capacity of 103 acre-feet, the forebay plays a crucial role in water management in the region.

The dam's spillway, with a width of 427 feet, is designed as uncontrolled, and the hazard potential is classified as low. Despite its age, the structure has a moderate risk assessment rating and is under the regulatory oversight of the Federal Energy Regulatory Commission. The forebay's primary function of irrigation highlights its importance in supporting agricultural activities in the area. With regular inspections and emergency preparedness measures in place, Chicago Park Forebay stands as a key component of the regional water infrastructure.

Overall, Chicago Park Forebay is a significant water management facility that contributes to the sustainable use of water resources in California. As a multipurpose structure with a history of reliable operation, it serves as a critical asset for irrigation, hydroelectric power generation, and water supply. The low hazard potential and moderate risk assessment underscore the importance of ongoing maintenance and regulatory oversight to ensure the continued functionality and safety of this essential infrastructure.

Year Completed

1966

Dam Length

2000

Dam Height

60

River Or Stream

Chicago Park Conduit

Primary Dam Type

Earth

Surface Area

1

Hydraulic Height

56

Nid Storage

103

Structural Height

60

Hazard Potential

Low

Foundations

Rock

Nid Height

60
       
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.