Margaret Lake Dam
Margaret Lake Dam is an earth dam located in King County, Washington, built in 1933. It carries a High hazard potential classification and has a fair condition assessment.
About Margaret Lake Dam
The primary purpose of Margaret Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Lake Margaret Purposes Community Club (private). It impounds the Margaret Creek.
The dam stands 41 feet tall and stretches 480 feet across, creates a reservoir covering 52 acres, has a maximum storage capacity of 1,210 acre-feet, and collects water from a drainage area of 2 square miles. Completed in 1933, the structure is well-established, with more than 75 years of service.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. An emergency action plan is in place for this dam. The most recent inspection on record was 07/21/2020.
At 41 feet, this dam is taller than 88% of dams nationwide.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Washington dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Washington |
| County | King |
| River/Stream | Margaret Creek |
| Coordinates | 47.76698, -121.90143 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 41 ft |
| Dam Length | 480 ft |
| Year Completed | 1933 (93 years old) |
Storage & Hydraulics
| NID Storage | 1,210 acre-ft |
| Max Storage | 1,210 acre-ft |
| Normal Storage | 820 acre-ft |
| Surface Area | 52 acres |
| Drainage Area | 2 sq mi |
| Max Discharge | 750 cfs |
Ownership & Safety
| Purpose | Recreation |
| Owner | Lake Margaret Purposes Community Club |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Fair |
| Last Inspection | 07/21/2020 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | WA00236 |
| Federal ID | WA00236 |
| More Info | State Dam Safety Program |