Mincoff Reservoir #1 Reservoir Report
Nearby: Magnesia Mincoff #2
Last Updated: December 6, 2025
Mincoff Reservoir #1, located in Garfield County, Montana, is a privately owned earth dam constructed in 1937 by the USDA NRCS.
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Summary
With a primary purpose of fire protection, stock, or small fish pond, this reservoir has a storage capacity of 260 acre-feet and serves as a crucial water resource for the surrounding area. Situated on Middle Phillips Creek, the reservoir has a drainage area of 22.66 square miles and a maximum discharge capacity of 300 cubic feet per second.
Despite being classified as having a low hazard potential, Mincoff Reservoir #1 is under state regulation by the DNRC, with regular inspections and enforcement to ensure its safety and functionality. The spillway, with a width of 60 feet, is uncontrolled, and the dam stands at a height of 22 feet. The risk assessment for this reservoir is moderate, indicating potential risks that are being managed through proper risk management measures. With its historical significance and ongoing role in providing water for various purposes, Mincoff Reservoir #1 is a valuable asset in the water resource infrastructure of Montana.
Year Completed |
1937 |
Dam Length |
528 |
Dam Height |
22 |
River Or Stream |
MIDDLE PHILLIPS CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
22 |
Drainage Area |
22.66 |
Nid Storage |
260 |
Hazard Potential |
Low |
Nid Height |
22 |
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.
Mincoff Reservoir #1