Longhorn #1/horny Detention Dam
Longhorn #1/horny Detention Dam is a gravity dam located in Valley County, Montana, built in 1966. It carries a Low hazard potential classification and has a fair condition assessment.
About Longhorn #1/horny Detention Dam
The primary purpose of Longhorn #1/horny 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 21 feet tall and stretches 666 feet across, creates a reservoir covering 23 acres, has a maximum storage capacity of 100 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1966, 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 fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. The most recent inspection on record was 12/02/2019.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Montana |
| County | Valley |
| Nearest City | Nashua |
| River/Stream | Willow Ck./milk River |
| Coordinates | 47.98157, -107.19659 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 21 ft |
| Dam Length | 666 ft |
| Year Completed | 1966 (60 years old) |
Storage & Hydraulics
| NID Storage | 100 acre-ft |
| Max Storage | 100 acre-ft |
| Surface Area | 23 acres |
| Drainage Area | 0 sq mi |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | DOI BLM |
| Owner Type | Federal |
| Hazard Classification | Low |
| Condition Assessment | Fair |
| Last Inspection | 12/02/2019 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MT00737 |
| Federal ID | MT00737 |
| More Info | State Dam Safety Program |