Easton Diversion Reservoir Report

Last Updated: January 11, 2026

Easton Diversion, located in Kittitas, Washington, is a concrete gravity dam on the Yakima River built in 1929 by the Bureau of Reclamation for irrigation purposes.


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Summary

Standing at 66 feet in height and 248 feet in length, the dam has a storage capacity of 5000 acre-feet, with a maximum discharge of 15000 cubic feet per second. The spillway, controlled and 64 feet wide, ensures the safe release of excess water.

Despite its age, Easton Diversion remains a critical piece of infrastructure for water management in the region, with a high hazard potential due to its very high risk assessment rating. While the condition assessment is currently listed as not available, regular inspections by the Bureau of Reclamation help ensure the dam's integrity and safety. In the event of an emergency, an Emergency Action Plan (EAP) is in place, last revised in June 2020, although details on its guidelines and effectiveness are not provided.

Easton Diversion serves as a testament to the enduring legacy of water resource management in the Pacific Northwest, under the stewardship of the Bureau of Reclamation. Its strategic location and design play a crucial role in providing irrigation water to agricultural lands in the area. While the dam's age and hazard potential pose challenges, ongoing monitoring and risk management measures by the Bureau of Reclamation help ensure the safety and reliability of this vital infrastructure for the community.

Year Completed

1929

Dam Length

248

Dam Height

66

River Or Stream

YAKIMA RIVER

Primary Dam Type

Concrete

Surface Area

275

Hydraulic Height

43

Drainage Area

185

Nid Storage

5000

Structural Height

66

Hazard Potential

High

Foundations

Rock

Nid Height

66
       
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.