Madsen Creek West Basin Dam Reservoir Report
Last Updated: December 14, 2025
Madsen Creek West Basin Dam, located in King County, Washington, is a crucial piece of infrastructure owned by the local government to reduce flood risks in the area.
°F
°F
mph
Wind
%
Humidity
Summary
Designed by King County and completed in 2008, this earth dam stands at a hydraulic height of 13 feet and spans 800 feet in length. With a storage capacity of 27 acre-feet and a drainage area of 0.11 square miles, this dam plays a vital role in managing water resources in the region.
The dam has a high hazard potential but is currently assessed to be in satisfactory condition, with the last inspection conducted in August 2018. The emergency action plan (EAP) for the dam was last revised in December 2019, ensuring that appropriate measures are in place to address any potential risks or emergencies. The dam's primary purpose is flood risk reduction, with a normal storage capacity of 16.1 acre-feet and a maximum discharge of 50 cubic feet per second, highlighting its importance in protecting the surrounding communities from flooding events.
Despite its critical role in water resource management, Madsen Creek West Basin Dam does not fall under the jurisdiction of federal agencies and is regulated by the Washington Department of Ecology. With its strategic location and efficient design, this dam serves as a vital asset in safeguarding the local area against flood risks and underscores the importance of sustainable water resource management in the face of changing climatic conditions.
Year Completed |
2008 |
Dam Length |
800 |
Primary Dam Type |
Earth |
Surface Area |
4 |
Hydraulic Height |
13 |
Drainage Area |
0.11 |
Nid Storage |
27 |
Structural Height |
13 |
Hazard Potential |
High |
Foundations |
Soil |
Nid Height |
13 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Madsen Creek West Basin Dam
Shady Lake Boat Ramp