Castle Rock Reservoir Dam
Castle Rock Reservoir Dam is an earth dam located in Rosebud County, Montana, built in 1976. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Castle Rock Reservoir Dam
Castle Rock Reservoir Dam is a dam in Rosebud, Montana. The dam is owned by Talen Energy (public utility). It impounds the Tr-east Fork Armells Creek near Forsyth.
The dam stands 67 feet tall and stretches 1,095 feet across, creates a reservoir covering 140 acres, has a maximum storage capacity of 3,540 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1976, the structure is 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 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 07/15/2015. That was 10 years ago — unusually long for a high-hazard dam, which typically requires more frequent inspections.
At 67 feet, this dam is taller than 96% 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 | Rosebud |
| Nearest City | Forsyth |
| River/Stream | Tr-east Fork Armells Creek |
| Coordinates | 45.89500, -106.63640 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 67 ft |
| Dam Height | 67 ft |
| Dam Length | 1,095 ft |
| Year Completed | 1976 (50 years old) |
Storage & Hydraulics
| NID Storage | 3,540 acre-ft |
| Max Storage | 3,540 acre-ft |
| Normal Storage | 2,930 acre-ft |
| Surface Area | 140 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 2,820 cfs |
Ownership & Safety
| Purpose | Other |
| Owner | TALEN ENERGY |
| Owner Type | Public Utility |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 07/15/2015 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MT01982 |
| Federal ID | MT01982 |
| More Info | State Dam Safety Program |