Fanchers Dam Reservoir Report

Last Updated: December 16, 2025

Fanchers Dam, located in Tonasket, Washington, is a vital structure owned by the Tribal Government and regulated by the Washington Dept of Ecology.


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Summary

Completed in 1926, this Earth-type dam on Antoine Creek serves multiple purposes, including irrigation and recreation. With a height of 60 feet and a hydraulic height of 68 feet, the dam has a storage capacity of 600 acre-feet and covers a surface area of 28 acres.

Despite its historical significance, Fanchers Dam has a high hazard potential and poor condition assessment, with the last inspection date in August 2016. The dam poses a potential risk to the surrounding area, emphasizing the importance of regular inspections and maintenance. The emergency action plan (EAP) for the dam was last revised in July 2020, highlighting the need for ongoing risk assessment and management measures to ensure the safety of nearby communities.

As a key feature in the Okanogan region, Fanchers Dam plays a critical role in water resource management and climate resilience. With its proximity to Congressional District 04 and the Seattle District of the US Army Corps of Engineers, the dam serves as a vital infrastructure for both local residents and the environment. Ongoing efforts to improve the dam's condition and update its emergency preparedness plans are essential to safeguarding the surrounding area from potential risks and ensuring the sustainable use of water resources for future generations.

Year Completed

1926

Dam Length

450

River Or Stream

Antoine Creek

Primary Dam Type

Earth

Surface Area

28

Hydraulic Height

68

Drainage Area

34.3

Nid Storage

600

Structural Height

60

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

68
       
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.