Forrest Detention Dam Reservoir Report
Last Updated: December 21, 2025
Forrest Detention Dam, located in Nashua, Montana, was completed in 1957 and is owned and operated by the Bureau of Land Management.
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Summary
The primary purpose of this gravity dam is for fire protection, stock watering, and small fish pond creation. With a structural height of 20 feet and a hydraulic height of 15 feet, the dam has a storage capacity of 808 acre-feet and covers a surface area of 117.6 acres.
Situated on Willow Creek/Milk River, Forrest Detention Dam serves as a crucial water resource for the surrounding area, providing essential water storage for various purposes. Despite its low hazard potential, the dam's condition assessment is rated as poor, highlighting the need for maintenance and repair to ensure its continued effectiveness and safety. The dam's uncontrolled spillway and moderate risk assessment further emphasize the importance of ongoing monitoring and management to mitigate potential risks.
With its historical significance and vital role in water resource management, Forrest Detention Dam stands as a testament to the importance of infrastructure for climate adaptation and water conservation efforts. As climate change impacts continue to pose challenges to water availability and quality, maintaining and enhancing structures like this dam are essential for sustainable water resource management in the region.
Year Completed |
1957 |
Dam Length |
2951 |
River Or Stream |
WILLOW CK./MILK RIVER |
Primary Dam Type |
Gravity |
Surface Area |
117.6 |
Hydraulic Height |
15 |
Drainage Area |
90 |
Nid Storage |
808 |
Structural Height |
20 |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
20 |
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.
Forrest Detention Dam