Eureka Reservoir Report

Last Updated: December 5, 2025

Eureka, also known as Eureka Lake, is a state-owned dam located in Johnsville, California, within Plumas County.


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Summary

Built in 1866, this earth dam stands at 29 feet high and spans 410 feet in length, with a storage capacity of 220 acre-feet. Operated by the California Department of Water Resources (DWR), Eureka serves primarily as a water supply source while also offering recreational opportunities for visitors.

Managed and regulated by the DWR's Safety of Dams program, Eureka is classified as a significant hazard dam with a satisfactory condition assessment as of September 2017. The dam overlooks Eureka Creek and plays a crucial role in maintaining the water supply for the surrounding area. Despite being under state jurisdiction, Eureka is not associated with any federal agencies and has not undergone any major modifications in recent years.

With a notable presence in the beautiful landscape of Plumas County, Eureka dam stands as a testament to California's commitment to water resource management and safety. From its historical significance to its ongoing role in providing essential water supply, Eureka remains a vital infrastructure for the region's water needs and a destination for recreational enjoyment.

Year Completed

1866

Dam Length

410

Dam Height

29

River Or Stream

Eureka Creek

Primary Dam Type

Earth

Surface Area

22

Hydraulic Height

14.5

Drainage Area

0.52

Nid Storage

220

Hazard Potential

Significant

Nid Height

29
       
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.