Youngs Lake New Inlet Dam Reservoir Report
Last Updated: December 15, 2025
Located in King County, Washington, the Youngs Lake New Inlet Dam serves as a vital water supply infrastructure built in 1926 along the Tr-Cedar River.
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Summary
Standing at a structural height of 20 feet with a hydraulic height of 18 feet, this earth dam plays a crucial role in storing water for public utility purposes. With a maximum storage capacity of 35,450 acre-feet and a normal storage capacity of 33,760 acre-feet, this dam covers a surface area of 690 acres and serves a drainage area of 2.19 square miles.
Managed by the Washington Department of Ecology, the Youngs Lake New Inlet Dam is classified as a high hazard potential structure but has been assessed to be in satisfactory condition as of June 2019. With state-regulated oversight and regular inspections, this dam is equipped to handle emergencies effectively, although its spillway type and discharge capabilities are not specified. Despite its age, the dam continues to meet water supply demands in the region and ensures the safety and reliability of the water source for the surrounding communities.
The Youngs Lake New Inlet Dam is a key piece of infrastructure in the region's water resource management efforts, providing a lifeline for residents in King County, Washington. With its stone core and soil foundation, the dam has stood the test of time and continues to be a crucial component in the state's water supply system. With its history dating back to the early 20th century, this dam represents a blend of tradition and modern engineering practices, ensuring the sustainable management of water resources in the area for years to come.
Year Completed |
1926 |
River Or Stream |
Tr-Cedar River |
Primary Dam Type |
Earth |
Surface Area |
690 |
Hydraulic Height |
18 |
Drainage Area |
2.19 |
Nid Storage |
35450 |
Structural Height |
20 |
Hazard Potential |
High |
Foundations |
Soil |
Nid Height |
20 |
Seasonal Comparison
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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.
Youngs Lake New Inlet Dam
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