Nine Mile
Nine Mile is a gravity dam located in Spokane County, Washington, built in 1908. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Nine Mile
The primary purpose of Nine Mile is hydroelectric. The dam generates hydroelectric power by channeling water through turbines, converting the energy of flowing water into electricity. The dam is owned by Avista Corporation (private). It impounds the Spokane River near Suncrest Development.
The dam stands 87 feet tall and stretches 466 feet across, creates a reservoir covering 440 acres, has a storage capacity of 4,600 acre-feet, and collects water from a drainage area of 4,998 square miles. Completed in 1908, the structure is over a century old.
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 08/16/2022.
At 87 feet, this dam is taller than 97% of all dams in the United States.
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 | Spokane |
| Nearest City | Suncrest Development |
| River/Stream | Spokane River |
| Coordinates | 47.77478, -117.54467 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 87 ft |
| Dam Height | 58 ft |
| Dam Length | 466 ft |
| Year Completed | 1908 (118 years old) |
Storage & Hydraulics
| NID Storage | 4,600 acre-ft |
| Normal Storage | 4,600 acre-ft |
| Surface Area | 440 acres |
| Drainage Area | 4,998 sq mi |
| Max Discharge | 60,000 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner | Avista Corporation |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 08/16/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | WA00068 |
| Federal ID | WA00068 |
| More Info | State Dam Safety Program |