Lower Willow Creek Dam Reservoir Report
Last Updated: December 5, 2025
Lower Willow Creek Dam, located in Granite County, Montana, is a crucial piece of infrastructure for irrigation, flood risk reduction, and recreation purposes.
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Summary
Constructed in 1962 by the USDA NRCS, this earth dam stands at a height of 85 feet and has a structural height of 96 feet, providing a storage capacity of 6230 acre-feet. The dam spans 970 feet in length and has a spillway width of 241 feet, with a maximum discharge capacity of 7400 cubic feet per second.
Despite its importance, Lower Willow Creek Dam has been assessed as having a high hazard potential and poor condition, with the last inspection conducted in September 2021. The dam is under state jurisdiction, regulated by the DNRC, and subject to regular inspections and enforcement to ensure public safety. With its location in the Lower Willow Creek watershed, this dam plays a critical role in managing water resources in the region and highlights the ongoing challenges of maintaining aging infrastructure in the face of changing climate conditions. For water resource and climate enthusiasts, Lower Willow Creek Dam serves as a reminder of the importance of sustainable water management practices and the need for continued investment in dam safety and maintenance.
Year Completed |
1962 |
Dam Length |
970 |
Dam Height |
85 |
River Or Stream |
LOWER WILLOW CREEK |
Primary Dam Type |
Earth |
Surface Area |
174 |
Hydraulic Height |
85 |
Drainage Area |
71.8 |
Nid Storage |
6230 |
Structural Height |
96 |
Hazard Potential |
High |
Foundations |
Rock, Soil |
Nid Height |
96 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Boulder Creek At Maxville Mt
|
79cfs |
Flint Creek At Maxville Mt
|
235cfs |
Flint Creek Near Drummond Mt
|
109cfs |
Clark Fork Near Drummond Mt
|
469cfs |
Clark Fork At Goldcreek Mt
|
248cfs |
Rock Creek Near Clinton Mt
|
202cfs |
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.
Lower Willow Creek Dam