Ryan
Ryan is a gravity dam located in Cascade County, Montana, built in 1915. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Ryan
The primary purpose of Ryan 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 Northwestern Energy (private). It impounds the Missouri River near Fort Benton.
The dam stands 82 feet tall and stretches 1,465 feet across, creates a reservoir covering 168 acres, has a maximum storage capacity of 3,613 acre-feet, and collects water from a drainage area of 23,080 square miles. Completed in 1915, 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 07/18/2022.
At 82 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 Montana 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 | Montana |
| County | Cascade |
| Nearest City | Fort Benton |
| River/Stream | Missouri River |
| Coordinates | 47.56880, -111.12510 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 82 ft |
| Dam Height | 61 ft |
| Dam Length | 1,465 ft |
| Year Completed | 1915 (111 years old) |
Storage & Hydraulics
| NID Storage | 3,653 acre-ft |
| Max Storage | 3,613 acre-ft |
| Normal Storage | 3,653 acre-ft |
| Surface Area | 168 acres |
| Drainage Area | 23,080 sq mi |
| Max Discharge | 188,000 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner | NorthWestern Energy |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 07/18/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MT00555 |
| Federal ID | MT00555 |
| More Info | State Dam Safety Program |