Deadmans Basin Dam
Deadmans Basin Dam is an earth dam located in Wheatland County, Montana, built in 1941. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Deadmans Basin Dam
The primary purpose of Deadmans Basin Dam is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by State Water Projects (state). It impounds the Tr-musselshell River near Ryegate.
The dam stands 60 feet tall and stretches 1,490 feet across, creates a reservoir covering 2,120 acres, has a maximum storage capacity of 100,000 acre-feet, and collects water from a drainage area of 7 square miles. Completed in 1941, 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 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 04/01/2024.
At 60 feet, this dam is taller than 95% 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 | Wheatland |
| Nearest City | Ryegate |
| River/Stream | Tr-musselshell River |
| Coordinates | 46.33960, -109.40850 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 60 ft |
| Dam Height | 60 ft |
| Dam Length | 1,490 ft |
| Year Completed | 1941 (85 years old) |
Storage & Hydraulics
| NID Storage | 100,000 acre-ft |
| Max Storage | 100,000 acre-ft |
| Normal Storage | 72,218 acre-ft |
| Surface Area | 2,120 acres |
| Drainage Area | 7 sq mi |
| Max Discharge | 1,080 cfs |
Ownership & Safety
| Purpose | Irrigation |
| Owner | STATE WATER PROJECTS |
| Owner Type | State |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 04/01/2024 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MT00011 |
| Federal ID | MT00011 |
| More Info | State Dam Safety Program |