Kachess Reservoir Report

Last Updated: December 15, 2025

Kachess is a federal-owned dam located in Easton, Washington, along the Kachess River.


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Summary

Built in 1912 by the Bureau of Reclamation, the primary purpose of this earth dam is flood risk reduction, with additional benefits for irrigation and recreation. With a height of 63 feet and a hydraulic height of 59 feet, Kachess has a storage capacity of 245,000 acre-feet and a surface area of 4,535 acres. The dam plays a crucial role in managing water resources in the region, with a maximum discharge capacity of 5,516 cubic feet per second.

Despite its age, Kachess remains a vital infrastructure for water management in Kittitas County, Washington. With a hazard potential classified as high, regular inspections by the Bureau of Reclamation ensure the dam's structural integrity and safety. While the exact condition assessment is not currently available, the dam has an emergency action plan in place, last revised in June 2020, to mitigate any potential risks or hazards. Kachess serves as a key component in the region's water resource management, highlighting the importance of maintaining and monitoring aging infrastructure in the face of changing climate conditions.

Year Completed

1912

Dam Length

1400

Dam Height

63

River Or Stream

KACHESS RIVER

Primary Dam Type

Earth

Surface Area

4535

Hydraulic Height

59

Drainage Area

64

Nid Storage

245000

Structural Height

115

Hazard Potential

High

Foundations

Soil

Nid Height

115
       
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.