Cowlitz Falls Reservoir Report

Last Updated: December 12, 2025

Cowlitz Falls is a captivating hydroelectric dam located on the Cowlitz River in Lewis, Washington.


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Summary

This concrete gravity dam, completed in 1994, stands at a height of 120 feet and has a structural height of 145 feet. With a storage capacity of 11,000 acre-feet and a maximum discharge of 360,000 cubic feet per second, Cowlitz Falls plays a crucial role in providing renewable energy to the region.

The dam serves multiple purposes, including hydroelectric power generation, recreation, and fish and wildlife conservation. Operated by a public utility, Cowlitz Falls is regulated by the Federal Energy Regulatory Commission. The dam's spillway type is controlled, with a width of 224 feet, ensuring the safe management of water flow. Despite its significant hazard potential, the dam is regularly inspected to ensure its structural integrity and safety.

Overall, Cowlitz Falls is a vital piece of infrastructure that not only generates clean energy but also contributes to the conservation of the local ecosystem. Its strategic location on the Cowlitz River makes it a key player in water resource management and climate resilience efforts in the region. With a commitment to safety and environmental stewardship, Cowlitz Falls stands as a symbol of sustainable energy production in Washington state.

Year Completed

1994

Dam Length

700

Dam Height

120

River Or Stream

Cowlitz River

Primary Dam Type

Concrete

Surface Area

700

Hydraulic Height

120

Drainage Area

1000

Nid Storage

11000

Structural Height

145

Outlet Gates

Tainter (radial) - 4

Hazard Potential

Significant

Foundations

Rock

Nid Height

145
       
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.