Boeing Creek M1 Detention Dam Reservoir Report

Last Updated: December 15, 2025

Boeing Creek M1 Detention Dam, located within Seattle's city limits, serves as a vital flood risk reduction structure along Boeing Creek.


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Summary

Built in 1983, this earth dam stands at a hydraulic height of 40 feet and a structural height of 27 feet, with a length of 160 feet. The dam's primary purpose is flood risk reduction, contributing to the protection of the surrounding area from potential flooding events.

Managed by the Washington Department of Ecology, the dam is state-regulated and inspected regularly to ensure its satisfactory condition and high hazard potential. With a storage capacity of 12.5 acre-feet and a maximum discharge capability of 1200 cubic feet per second, the dam plays a crucial role in managing water levels and reducing flood risks in the region. Despite its solid structural assessment, emergency action plans are in place to address any unforeseen events and ensure the safety of the community.

Boeing Creek M1 Detention Dam stands as a testament to effective water resource management and climate resilience efforts in King County, Washington. With its strategic location and robust design, the dam continues to provide essential flood protection to the area, highlighting the importance of proactive infrastructure investments in mitigating the impacts of changing climate patterns on water resources and communities.

Year Completed

1983

Dam Length

160

River Or Stream

Boeing Creek

Primary Dam Type

Earth

Hydraulic Height

40

Drainage Area

1.08

Nid Storage

12.5

Structural Height

27

Hazard Potential

High

Foundations

Soil

Nid Height

40
       
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.