Mccarty Reservoir Report

Last Updated: December 5, 2025

Mccarty is a privately owned dam located in Copperopolis, California, along the Tr Johnny Creek.


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Summary

Built in 1938, this earth dam stands at 19 feet high and stretches 670 feet in length, with a storage capacity of 93 acre-feet for water supply purposes, including irrigation. The dam is regulated and inspected by the California Department of Water Resources (DWR) under the Safety of Dams program, ensuring its safe operation and compliance with state regulations.

Despite its age, Mccarty has a low hazard potential and is deemed to be in a satisfactory condition following a recent assessment in September 2017. The dam undergoes regular inspections, with the most recent one conducted in March 2021, ensuring its continued safety and reliability. In the event of an emergency, there are established protocols in place, although specific details about an Emergency Action Plan (EAP) are not provided in the data. Overall, Mccarty serves as a crucial water resource infrastructure in the region, contributing to water supply and agricultural needs while being closely monitored for its safety and regulatory compliance.

Year Completed

1938

Dam Length

670

Dam Height

19

River Or Stream

Tr Johnny Creek

Primary Dam Type

Earth

Surface Area

17

Hydraulic Height

14

Drainage Area

0.57

Nid Storage

93

Hazard Potential

Low

Nid Height

19
       
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.