Montana #31 Reservoir Report
Nearby: Big Timber #53 Hougan #5
Last Updated: December 5, 2025
Montana #31 is a state-regulated dam located in Mosby, Musselshell County, Montana.
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Summary
Built in 1950, this earth dam stands at a height of 12 feet and stretches 250 feet in length. With a primary purpose of providing fire protection, stock watering, and serving as a small fish pond, the dam has a storage capacity of 71 acre-feet, with a normal storage level of 21 acre-feet. Situated on the TR-North Willow Creek, this dam plays a crucial role in water resource management in the area.
Owned by the state of Montana and regulated by the Department of Natural Resources and Conservation (DNRC), Montana #31 poses a low hazard potential and has not been rated for its condition assessment. Despite lacking a current inspection date, the dam is equipped with state permitting, inspection, and enforcement protocols. While the dam does not fall under the jurisdiction of the US Army Corps of Engineers, it plays a vital role in supporting local water resource needs in the region. Enthusiasts of water resource management and climate resilience will find Montana #31 an essential component of the area's water infrastructure.
With its strategic location and multi-purpose design, Montana #31 serves as a vital asset for fire protection, stock watering, and aquatic habitat support in the region. Managed by state authorities and situated within a low hazard potential area, this dam stands as a testament to effective water resource management in Montana. Climate enthusiasts and water resource advocates can appreciate the role of Montana #31 in ensuring water security and environmental sustainability in the Musselshell County area.
Year Completed |
1950 |
Dam Length |
250 |
Dam Height |
12 |
River Or Stream |
TR-NORTH WILLOW CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
12 |
Nid Storage |
71 |
Hazard Potential |
Low |
Nid Height |
12 |
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.
Montana #31