January Detention Dam Reservoir Report
Last Updated: December 19, 2025
Located in Nashua, Montana, the January Detention Dam serves multiple purposes, including fire protection, stock containment, and as a small fish pond.
°F
°F
mph
Wind
%
Humidity
Summary
Built in 1960 by the Bureau of Land Management, this gravity dam stands at a structural height of 31 feet and has a hydraulic height of 26 feet. With a storage capacity of 520 acre-feet, the dam covers a surface area of 38.59 acres and has a drainage area of 6.1 square miles.
Operating under the jurisdiction of the DOI BLM, the January Detention Dam also serves as a vital component for the Willow Creek/Milk River system. Despite being classified with a low hazard potential, the dam's condition assessment is currently marked as unsatisfactory. With an inspection frequency of 5 years, the last inspection took place in November 2019. While the risk assessment is moderate, the dam does not have an Emergency Action Plan (EAP) prepared, raising concerns about its readiness in the event of an emergency.
Despite its essential role in the local ecosystem and community, the January Detention Dam faces challenges in maintaining its structural integrity and operational efficiency. As water resource and climate enthusiasts, it is crucial to monitor the dam's condition closely and advocate for necessary repairs and updates to ensure its continued functionality and safety for all stakeholders involved.
Year Completed |
1960 |
Dam Length |
946 |
River Or Stream |
WILLOW CK./MILK RIVER |
Primary Dam Type |
Gravity |
Surface Area |
38.59 |
Hydraulic Height |
26 |
Drainage Area |
6.1 |
Nid Storage |
520 |
Structural Height |
31 |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
31 |
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.
January Detention Dam