January Detention Dam is a gravity dam located in Valley County, Montana, built in 1960. It carries a Low hazard potential classification and has a unsatisfactory condition assessment.
Dam profile
NID height · 31 ft31 ft tall and 946 ft long, taller than 72% 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 concrete gravity section and the water level is illustrative.
About January Detention Dam
The primary purpose of January Detention 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 Willow Ck./milk River near Nashua.
The dam stands 31 feet tall and stretches 946 feet across, creates a reservoir covering 38 acres, has a maximum storage capacity of 387 acre-feet, and collects water from a drainage area of 6 square miles. Completed in 1960, the structure is well into its service life at over 50 years old.
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. Its condition is rated unsatisfactory, indicating serious safety deficiencies exist that require immediate attention or remedial action. The most recent inspection on record was 11/02/2019.
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Location
| State | Montana |
| County | Valley |
| Nearest City | Nashua |
| River/Stream | Willow Ck./milk River |
| Coordinates | 48.08066, -106.75672 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 31 ft |
| Dam Length | 946 ft |
| Year Completed | 1960 (66 years old) |
Storage & Hydraulics
| NID Storage | 520 acre-ft |
| Max Storage | 387 acre-ft |
| Normal Storage | 520 acre-ft |
| Surface Area | 38 acres |
| Drainage Area | 6 sq mi |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Fire Protection, Stock, Or Small Fish Pond |
| Owner | Doi BLM |
| Owner Type | Federal |
| Hazard Classification | Low |
| Condition Assessment | Unsatisfactory |
| Last Inspection | 11/02/2019 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MT00672 |
| Federal ID | MT00672 |
| More Info | State Dam Safety Program |