Pr-156 Retention Dam is a gravity dam located in Phillips County, Montana, built in 1937. It carries a Low hazard potential classification.
Dam profile
NID height · 20 ft20 ft tall and 396 ft long. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic concrete gravity section and the water level is illustrative.
About Pr-156 Retention Dam
The primary purpose of Pr-156 Retention Dam is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by Doi BLM (federal). It impounds the Whitewater Ck./milk River near Hinsdale.
The dam stands 20 feet tall and stretches 396 feet across, creates a reservoir covering 16 acres, has a maximum storage capacity of 79 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1937, 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. The most recent inspection on record was 09/01/2017.
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Location
| State | Montana |
| County | Phillips |
| Nearest City | Hinsdale |
| River/Stream | Whitewater Ck./milk River |
| Coordinates | 48.97730, -107.57348 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 20 ft |
| Dam Length | 396 ft |
| Year Completed | 1937 (89 years old) |
Storage & Hydraulics
| NID Storage | 79 acre-ft |
| Max Storage | 79 acre-ft |
| Normal Storage | 79 acre-ft |
| Surface Area | 16 acres |
| Drainage Area | 0 sq mi |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | Doi BLM |
| Owner Type | Federal |
| Hazard Classification | Low |
| Condition Assessment | Not assessed |
| Last Inspection | 09/01/2017 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MT00766 |
| Federal ID | MT00766 |
| More Info | State Dam Safety Program |