North Beaver Detention Dam Reservoir Report
Last Updated: December 25, 2025
The North Beaver Detention Dam, located in Nashua, Montana, was completed in 1957 by the Bureau of Land Management to reduce flood risks in the area.
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Summary
This Federal-owned gravity dam on Willow Creek/Milk River stands at a structural height of 19 feet and has a hydraulic height of 15 feet. With a drainage area of 7.3 square miles, the dam has a storage capacity of 208.7 acre-feet and covers a surface area of 52.61 acres.
Despite being classified as having a low hazard potential, the dam's condition assessment was marked as unsatisfactory during its last inspection in 2014. The dam's spillway is uncontrolled with a width of 2 feet, and it has no outlet gates or associated structures. The risk assessment for the North Beaver Detention Dam is moderate, with a rating of 3, indicating that there are potential risks associated with the dam that may require management measures in the future. As a key infrastructure for flood risk reduction in the region, the dam plays a crucial role in safeguarding the surrounding communities from potential disasters.
As water resource and climate enthusiasts, understanding the intricacies of structures like the North Beaver Detention Dam is essential for managing and protecting our natural environment. By staying informed about the vital role that dams play in water resource management and climate resilience, we can work towards ensuring the safety and sustainability of our water systems for generations to come.
Year Completed |
1957 |
Dam Length |
1741 |
River Or Stream |
WILLOW CK./MILK RIVER |
Primary Dam Type |
Gravity |
Surface Area |
52.61 |
Hydraulic Height |
15 |
Drainage Area |
7.3 |
Nid Storage |
208.7 |
Structural Height |
19 |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
19 |
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.
North Beaver Detention Dam