Cushman No 1 Reservoir Report

Last Updated: December 13, 2025

Cushman No 1, also known as Upper Cushman Dam, is a public utility hydroelectric facility located in Mason County, Washington.


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Summary

Completed in 1926, this arch dam stands at a height of 235 feet and has a structural height of 271.5 feet, with a storage capacity of 482,757 acre-feet. Situated on the North Fork Skokomish River, the dam serves the primary purpose of hydroelectric power generation, while also offering recreational opportunities in the surrounding area.

Owned and operated by a public utility agency, Cushman No 1 is regulated by the Federal Energy Regulatory Commission (FERC) and has a high hazard potential due to its location and design. With a drainage area of 95 square miles and a surface area of 4,010 acres, the dam plays a crucial role in water resource management in the region. Despite its age, the dam's condition assessment is not available, indicating a need for further evaluation and potential risk management measures to ensure its safety and stability in the face of changing climate conditions.

As a key feature in the Skokomish River watershed, Cushman No 1 represents a significant piece of Washington's water infrastructure. Its presence underscores the importance of sustainable water resource management and climate resilience in the face of increasing environmental pressures. With its blend of historical significance and modern functionality, Cushman No 1 continues to be a noteworthy site for water resource and climate enthusiasts alike.

Year Completed

1926

Dam Length

1111

Dam Height

235

River Or Stream

North Fork Skokomish River

Primary Dam Type

Arch

Surface Area

4010

Hydraulic Height

250

Drainage Area

95

Nid Storage

482757

Structural Height

271.5

Hazard Potential

High

Foundations

Rock

Nid Height

272
       
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.