Big (Phillips) Reservoir Report
Last Updated: December 5, 2025
Big (Phillips) is a privately owned irrigation dam located in Saco, Montana, along the John Brown Coulee.
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Summary
Built in 1956 by the USDA NRCS, this earth dam stands at a height of 25 feet and has a storage capacity of 98 acre-feet. With a low hazard potential and a condition assessment of "Not Rated," the dam serves primarily for irrigation purposes in the region.
Managed by the Montana DNRC, Big (Phillips) is regulated and inspected by state authorities to ensure its structural integrity and compliance with safety standards. The dam has a spillway width of 200 feet and a maximum discharge capacity of 1000 cubic feet per second, providing a crucial water resource for agricultural activities in the area. Although the dam's inspection frequency, emergency preparedness, and risk assessment details are not provided, its significance in water management for the region is evident.
Located in Phillips County, Montana, Big (Phillips) plays a vital role in water resource management and irrigation for the local community. With its historical significance dating back to the mid-20th century, the dam continues to support agricultural activities along the John Brown Coulee. As enthusiasts of water resources and climate, understanding the infrastructure and operation of dams like Big (Phillips) is essential in ensuring sustainable water usage and conservation practices in the region.
Year Completed |
1956 |
Dam Length |
600 |
Dam Height |
25 |
River Or Stream |
JOHN BROWN COULEE |
Primary Dam Type |
Earth |
Hydraulic Height |
21 |
Drainage Area |
1.41 |
Nid Storage |
98 |
Hazard Potential |
Low |
Nid Height |
25 |
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.
Big (Phillips)