Dead Horse Detention Dam Reservoir Report
Last Updated: December 20, 2025
Dead Horse Detention Dam, located in Nashua, Montana, is a federal-owned structure designed and constructed by the Bureau of Land Management for flood risk reduction along Willow Creek and the Milk River.
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Summary
Completed in 1960, this gravity dam stands at a structural height of 16 feet with a hydraulic height of 11 feet, and spans a length of 1024 feet to provide protection to the surrounding Valley County. With a storage capacity of 246.5 acre-feet and a surface area of 40.62 acres, the dam plays a crucial role in managing water flows in the region.
Despite its low hazard potential and satisfactory condition assessment, Dead Horse Detention Dam undergoes regular inspections every 5 years to ensure its effectiveness in mitigating flood risks. The dam features an uncontrolled spillway, with associated structures, such as outlet gates, yet to be installed. Managed by the Bureau of Land Management, the dam's risk assessment categorizes it as moderate, highlighting the importance of continued monitoring and risk management measures to safeguard the local community and surrounding areas from potential flooding events. Water resource and climate enthusiasts can appreciate the engineering marvel of this vital infrastructure that serves to protect the natural landscape and inhabitants of the region.
Year Completed |
1960 |
Dam Length |
1024 |
River Or Stream |
WILLOW CK./MILK RIVER |
Primary Dam Type |
Gravity |
Surface Area |
40.62 |
Hydraulic Height |
11 |
Drainage Area |
2.9 |
Nid Storage |
246.5 |
Structural Height |
16 |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
16 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.
Hazard Potential Classification
HighDams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.
Dead Horse Detention Dam