Cochrane is a gravity dam located in Cascade County, Montana, built in 1957. It carries a High hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 105 ft105 ft tall and 856 ft long, taller than 98% of U.S. dams with a recorded height. Height is drawn to scale against a ten-story building, about 100 ft; the profile is a generic concrete gravity section and the water level is illustrative.
About Cochrane
The primary purpose of Cochrane 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 105 feet tall and stretches 856 feet across, creates a reservoir covering 249 acres, has a storage capacity of 8,464 acre-feet, and collects water from a drainage area of 23,270 square miles. Completed in 1957, the structure is well into its service life at over 50 years 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 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 08/12/2022.
At 105 feet, this dam is taller than 98% 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 | 47.55290, -111.14900 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 105 ft |
| Dam Height | 100 ft |
| Dam Length | 856 ft |
| Year Completed | 1957 (69 years old) |
Storage & Hydraulics
| NID Storage | 8,464 acre-ft |
| Normal Storage | 8,464 acre-ft |
| Surface Area | 249 acres |
| Drainage Area | 23,270 sq mi |
| Max Discharge | 140,000 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner | Northwestern Energy |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Fair |
| Last Inspection | 08/12/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MT00556 |
| Federal ID | MT00556 |
| More Info | State Dam Safety Program |