Gollaher Reservoir Reservoir Report
Nearby: Dana-Cameron Ranch Gollaher #2
Last Updated: December 5, 2025
Gollaher Reservoir, located in Cascade, Montana, is a private irrigation reservoir designed by the USDA NRCS and completed in 1945.
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Summary
With a dam height of 37.7 feet and a storage capacity of 827 acre-feet, this earth dam structure on Willow Creek serves as a vital source of water for agricultural purposes in the area. The reservoir covers a surface area of 41.3 acres and has a drainage area of 10.25 square miles, making it a significant resource for sustaining local farming operations.
Managed by the DNRC and regulated by the state of Montana, Gollaher Reservoir plays a crucial role in water resource management and climate resilience efforts in the region. Although its condition assessment is currently marked as "Not Rated," the reservoir is considered to have a significant hazard potential. With a maximum discharge capacity of 525 cubic feet per second, the reservoir's operations are closely monitored to ensure the safety and integrity of the dam structure. As a key component of the local irrigation infrastructure, Gollaher Reservoir contributes to the sustainable utilization of water resources for agricultural production in the area.
In the Congressional District 00 of Montana, Gollaher Reservoir stands as a testament to the collaborative efforts between private owners, state agencies, and federal designers to optimize water usage for irrigation purposes. As climate change continues to impact water availability and resource management, reservoirs like Gollaher play a critical role in ensuring water security for agricultural activities in the region. With its strategic location in ULM and its historical significance dating back to the mid-20th century, Gollaher Reservoir remains a cornerstone of water management and climate adaptation efforts in Montana.
Year Completed |
1945 |
Dam Length |
1130 |
Dam Height |
37.7 |
River Or Stream |
WILLOW CREEK |
Primary Dam Type |
Earth |
Surface Area |
41.3 |
Hydraulic Height |
33 |
Drainage Area |
10.25 |
Nid Storage |
827 |
Structural Height |
37.7 |
Hazard Potential |
Significant |
Nid Height |
38 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Missouri River At Cascade Mt
|
3090cfs |
Smith River Near Eden Mt
|
119cfs |
Missouri River Near Ulm Mt
|
3160cfs |
Sun River Near Vaughn Mt
|
2680cfs |
Dearborn River Near Craig Mt
|
36cfs |
Muddy Creek At Vaughn Mt
|
86cfs |
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.
Area Campgrounds
| Location | Reservations | Toilets |
|---|---|---|
American Legion/Lions Park - Cascade
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Pelican Point FAS
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Prewett Creek FAS
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Mountain Palace FAS
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Gollaher Reservoir