West Alkali Reservoir Reservoir Report
Nearby: Mitchell One Pr-161 Retention Dam
Last Updated: December 5, 2025
West Alkali Reservoir, located in Phillips County, Montana, is a privately owned irrigation structure designed by USDA NRCS and completed in 1902.
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Summary
The reservoir is situated on West Alkali Creek and has a significant hazard potential, with a dam height of 25 feet and a storage capacity of 1941 acre-feet. The primary purpose of the reservoir is irrigation, serving the agricultural needs of the region.
Managed by the Montana Department of Natural Resources and Conservation (DNRC), West Alkali Reservoir is regulated, inspected, and enforced by state authorities to ensure its structural integrity and compliance with safety standards. The reservoir has a spillway width of 30 feet and a maximum discharge capacity of 150 cubic feet per second. Despite being categorized as "not rated" in terms of condition assessment, the reservoir plays a crucial role in water resource management and agricultural sustainability in the area.
Congressman Greg Gianforte represents the area where West Alkali Reservoir is located, under the jurisdiction of the Omaha District of the US Army Corps of Engineers. The reservoir's location, at coordinates 48.2016° N, -108.0759° W, makes it a vital component of the local water infrastructure, supporting the needs of farmers and landowners in Malta and surrounding areas. With its historical significance dating back to the early 20th century, West Alkali Reservoir remains a key resource for irrigation and water management in Montana.
Year Completed |
1902 |
Dam Length |
504 |
Dam Height |
25 |
River Or Stream |
WEST ALKALI CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
25 |
Drainage Area |
16.41 |
Nid Storage |
1941 |
Hazard Potential |
Significant |
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.
West Alkali Reservoir