Youngs Lake Cascades Dam
Youngs Lake Cascades Dam is an earth dam located in King County, Washington, built in 1950. It carries a Significant hazard potential classification and has a satisfactory condition assessment.
About Youngs Lake Cascades Dam
The primary purpose of Youngs Lake Cascades Dam is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by Seattle Public Utilities (local government). It impounds the Tr-cedar River.
The dam stands 16 feet tall and stretches 1,425 feet across, creates a reservoir covering 690 acres, has a maximum storage capacity of 35,450 acre-feet, and collects water from a drainage area of 2 square miles. Completed in 1950, the structure is well-established, with more than 75 years of service.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 06/02/2024.
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Location
| State | Washington |
| County | King |
| River/Stream | Tr-cedar River |
| Coordinates | 47.41957, -122.10876 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 16 ft |
| Dam Length | 1,425 ft |
| Year Completed | 1950 (76 years old) |
Storage & Hydraulics
| NID Storage | 35,450 acre-ft |
| Max Storage | 35,450 acre-ft |
| Normal Storage | 33,760 acre-ft |
| Surface Area | 690 acres |
| Drainage Area | 2 sq mi |
Ownership & Safety
| Purpose | Water Supply |
| Owner | Seattle Public Utilities |
| Owner Type | Local Government |
| Hazard Classification | Significant |
| Condition Assessment | Satisfactory |
| Last Inspection | 06/02/2024 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | WA00209 |
| Federal ID | WA00209 |
| More Info | State Dam Safety Program |