Pr-40 Retention Dam is a gravity dam located in Phillips County, Montana, built in 1942. It carries a Low hazard potential classification.
Dam profile
NID height · 18 ft18 ft tall and 357 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-40 Retention Dam
The primary purpose of Pr-40 Retention Dam 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 Doi BLM (federal). It impounds the Larb Ck./milk River near Hinsdale.
The dam stands 18 feet tall and stretches 357 feet across, creates a reservoir covering 22 acres, has a maximum storage capacity of 127 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1942, 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 08/16/2016. That was over 10 years ago.
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Location
| State | Montana |
| County | Phillips |
| Nearest City | Hinsdale |
| River/Stream | Larb Ck./milk River |
| Coordinates | 48.43750, -107.44142 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 18 ft |
| Dam Length | 357 ft |
| Year Completed | 1942 (84 years old) |
Storage & Hydraulics
| NID Storage | 127 acre-ft |
| Max Storage | 127 acre-ft |
| Surface Area | 22 acres |
| Drainage Area | 0 sq mi |
Ownership & Safety
| Purpose | Fire Protection, Stock, Or Small Fish Pond |
| Owner | Doi BLM |
| Owner Type | Federal |
| Hazard Classification | Low |
| Condition Assessment | Not assessed |
| Last Inspection | 08/16/2016 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MT00781 |
| Federal ID | MT00781 |
| More Info | State Dam Safety Program |