Number Twenty Reservoir Reservoir Report
Nearby: Barnard Dam Stratton Reservoir
Last Updated: December 6, 2025
Number Twenty Reservoir, located in Phillips County, Montana, is a privately owned water resource with a primary purpose of fire protection, stock, and small fish pond management.
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Summary
Completed in 1950, this Earth-type dam stands at 10 feet high and spans 300 feet in length, providing a storage capacity of 132 acre-feet. Situated on TR-Second Creek, the reservoir offers vital water supply for various uses while also serving as a low-hazard potential structure with a not yet rated condition assessment.
Managed by the Department of Natural Resources and Conservation (DNRC) in Montana, Number Twenty Reservoir plays a crucial role in maintaining water resources in the region. With a normal storage capacity of 17 acre-feet and a maximum storage of 132 acre-feet, this reservoir contributes to the local ecosystem and serves as a valuable asset for fire protection and livestock water needs. While the dam's condition assessment is not yet rated, its low hazard potential ensures safe operation for the surrounding community.
As a significant water resource in Montana, Number Twenty Reservoir stands as a testament to sustainable water management practices. With state regulatory oversight and inspection ensuring its safety and functionality, this reservoir serves as a key component in water supply management, supporting various needs while maintaining a low hazard potential. Its completion in 1950 reflects a commitment to responsible water resource development and underscores the importance of private ownership in preserving vital water sources for current and future generations.
Year Completed |
1950 |
Dam Length |
300 |
Dam Height |
10 |
River Or Stream |
TR-SECOND CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
10 |
Nid Storage |
132 |
Hazard Potential |
Low |
Nid Height |
10 |
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.
Number Twenty Reservoir