Coyote Valley Dam Reservoir Report

Last Updated: December 5, 2025

Coyote Valley Dam, also known as Lake Mendocino, is a federal-owned structure located in Mendocino, California.


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Summary

Completed in 1959, the dam stands at a height of 164 feet and serves multiple purposes including flood risk reduction, hydroelectric power generation, recreation, and water supply. With a storage capacity of 155,500 acre-feet, the dam is situated on the East Fork Russian River and covers a surface area of 1,740 acres.

A risk assessment conducted by the US Army Corps of Engineers in 2012 identified potential concerns such as erosion near the outlet pipe and embankment damage during earthquakes. Despite being categorized as having a moderate risk, the dam is subject to ongoing risk management measures including emergency preparation, enhanced monitoring, and surveillance protocols. The dam maintenance and operations staff continuously monitor its performance, while the emergency action plan ensures quick response and proactive warnings to evacuate downstream areas in case of an emergency.

Coyote Valley Dam plays a crucial role in reducing risk to the public downstream, with the US Army Corps of Engineers implementing measures to ensure its safe and reliable operation. Despite the identified risks, the dam's surveillance and emergency preparedness efforts aim to mitigate potential hazards and safeguard the surrounding community from the impacts of a dam breach.

Year Completed

1959

Dam Length

3525

Dam Height

164

River Or Stream

EAST FORK RUSSIAN RIVER

Primary Dam Type

Earth

Surface Area

1740

Hydraulic Height

161

Drainage Area

105

Nid Storage

155500

Structural Height

180

Outlet Gates

None - 0

Hazard Potential

High

Foundations

Soil

Nid Height

180
       
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.