Trossachs Detention Pond Pc-2
Trossachs Detention Pond Pc-2 is an earth dam located in King County, Washington, built in 2002. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Trossachs Detention Pond Pc-2
The primary purpose of Trossachs Detention Pond Pc-2 is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by Sammamish City Public Works (local government). It impounds the Patterson Creek - Offstream near Carnation.
The dam stands 21 feet tall and stretches 1,100 feet across, creates a reservoir covering 4 acres, has a maximum storage capacity of 76 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 2002, the structure is relatively new.
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 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 07/12/2022.
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 |
| Nearest City | Carnation |
| River/Stream | Patterson Creek - Offstream |
| Coordinates | 47.59487, -121.97115 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 21 ft |
| Dam Length | 1,100 ft |
| Year Completed | 2002 (24 years old) |
Storage & Hydraulics
| NID Storage | 76 acre-ft |
| Max Storage | 76 acre-ft |
| Normal Storage | 54 acre-ft |
| Surface Area | 4 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 85 cfs |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | Sammamish City Public Works |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 07/12/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | WA01833 |
| Federal ID | WA01833 |
| More Info | State Dam Safety Program |