Copperopolis Reservoir Report

Last Updated: December 5, 2025

Copperopolis, located in Calaveras County, California, is home to an essential water supply dam known as the Copperopolis Dam on Penney Creek.


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Summary

This private dam, completed in 1905, stands at a height of 33 feet and has a hydraulic height of 29.2 feet, providing a storage capacity of 225 acre-feet for irrigation and water supply purposes. The dam, classified as an earth type structure, covers a surface area of 24 acres and serves a drainage area of 1.4 square miles.

This dam in Copperopolis plays a crucial role in water resource management, as it is regulated, permitted, inspected, and enforced by the California Department of Water Resources (DWR) under the Safety of Dams program. With a high hazard potential but a satisfactory condition assessment as of September 2017, the Copperopolis Dam ensures the safety and reliability of water supply operations in the region. Despite not having associated structures or locks, the dam's primary purpose is to provide water for agricultural irrigation and local water supply needs.

Furthermore, situated within the San Francisco District of the US Army Corps of Engineers, Copperopolis Dam underscores the importance of infrastructure maintenance and risk management in safeguarding water resources in the face of changing climate conditions. As climate enthusiasts and water resource stakeholders continue to monitor and assess the resilience of such critical structures, the Copperopolis Dam stands as a testament to the ongoing efforts to balance water supply needs with environmental stewardship and public safety in California's diverse landscape.

Year Completed

1905

Dam Length

600

Dam Height

33

River Or Stream

Penney Creek

Primary Dam Type

Earth

Surface Area

24

Hydraulic Height

29.2

Drainage Area

1.4

Nid Storage

225

Hazard Potential

High

Nid Height

33
       
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.