Triple Crossing Detention Dam is a gravity dam located in Valley County, Montana, built in 1957. It carries a Low hazard potential classification and has a poor condition assessment.
Dam profile
NID height · 34 ft34 ft tall and 2,328 ft long, taller than 78% 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 Triple Crossing Detention Dam
The primary purpose of Triple Crossing Detention 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 Willow Ck./milk River near Nashua.
The dam stands 34 feet tall and stretches 2,328 feet across, creates a reservoir covering 376 acres, has a maximum storage capacity of 2,977 acre-feet, and collects water from a drainage area of 43 square miles. Completed in 1957, 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 poor, meaning the dam has recognized safety deficiencies that require remediation to address risks. The most recent inspection on record was 10/24/2017.
At 34 feet, this dam is taller than 78% of dams nationwide.
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Location
| State | Montana |
| County | Valley |
| Nearest City | Nashua |
| River/Stream | Willow Ck./milk River |
| Coordinates | 47.98063, -107.12184 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 34 ft |
| Dam Length | 2,328 ft |
| Year Completed | 1957 (69 years old) |
Storage & Hydraulics
| NID Storage | 2,977 acre-ft |
| Max Storage | 2,977 acre-ft |
| Surface Area | 376 acres |
| Drainage Area | 43 sq mi |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | Doi BLM |
| Owner Type | Federal |
| Hazard Classification | Low |
| Condition Assessment | Poor |
| Last Inspection | 10/24/2017 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MT03142 |
| Federal ID | MT03142 |
| More Info | State Dam Safety Program |