Donley Reservoir (rosebud) is an earth dam located in Rosebud County, Montana, built in 1930. It carries a Low hazard potential classification.
Dam profile
NID height · 38 ft38 ft tall and 400 ft long, taller than 84% of U.S. dams with a recorded height. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic embankment section and the water level is illustrative.
About Donley Reservoir (rosebud)
The primary purpose of Donley Reservoir (rosebud) is fire protection, stock, or small fish pond. The dam maintains a small impoundment used for fire suppression, livestock watering, or as a fish pond. The dam is owned by Joe Donley (private). It impounds the Larson Coulee near Forsyth.
The dam stands 38 feet tall and stretches 400 feet across, has a maximum storage capacity of 654 acre-feet, and collects water from a drainage area of 4 square miles. Completed in 1930, the structure is well-established, with more than 75 years of service.
This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected loss of life.
At 38 feet, this dam is taller than 84% of dams nationwide.
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Location
| State | Montana |
| County | Rosebud |
| Nearest City | Forsyth |
| River/Stream | Larson Coulee |
| Coordinates | 46.45730, -106.92990 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 38 ft |
| Dam Height | 38 ft |
| Dam Length | 400 ft |
| Year Completed | 1930 (96 years old) |
Storage & Hydraulics
| NID Storage | 654 acre-ft |
| Max Storage | 654 acre-ft |
| Normal Storage | 391 acre-ft |
| Drainage Area | 4 sq mi |
| Max Discharge | 3,500 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Fire Protection, Stock, Or Small Fish Pond |
| Owner | Joe Donley |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Not assessed |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MT00066 |
| Federal ID | MT00066 |
| More Info | State Dam Safety Program |