Ravensdale Pit Reservoir Report

Last Updated: December 16, 2025

Ravensdale Pit is a privately owned dam located in Ravensdale, King County, Washington.


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Summary

Built in 1972, this Earth-type structure stands at a height of 18 feet and spans a length of 2950 feet, with a storage capacity of 165 acre-feet. Situated on the Tr-Green River, the dam serves a primary purpose other than flood control or water supply, and is regulated by the Washington Department of Ecology.

Despite its low hazard potential, Ravensdale Pit has not been rated for its condition since its last inspection in 1999. The dam's emergency action plan status, risk assessment, and inundation maps remain unprepared or updated. While the structure meets regulatory guidelines and is subject to regular inspections, its overall risk management measures and emergency preparedness are lacking in documentation.

For water resource and climate enthusiasts, Ravensdale Pit presents an intriguing case study in dam infrastructure management and emergency preparedness. With its unique characteristics and historical data, this site offers valuable insights into the challenges and opportunities of maintaining and regulating water storage structures in the Pacific Northwest region.

Year Completed

1972

Dam Length

2950

River Or Stream

Tr-Green River

Primary Dam Type

Earth

Surface Area

17

Hydraulic Height

18

Drainage Area

1.43

Nid Storage

165

Structural Height

18

Hazard Potential

Low

Foundations

Soil

Nid Height

18
       
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.