Three Trees Detention Dam Reservoir Report
Last Updated: December 21, 2025
Three Trees Detention Dam, located in Valley, Montana, serves as a vital flood risk reduction structure along the Willow Creek and Milk River.
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Summary
Constructed in 1954 by the Bureau of Land Management, this gravity dam stands at a height of 16 feet and has a hydraulic height of 10 feet. With a storage capacity of 148.9 acre-feet and a surface area of 33.02 acres, Three Trees Detention Dam plays a crucial role in protecting the surrounding area from potential flooding events.
Despite being categorized as having a low hazard potential, the condition assessment of Three Trees Detention Dam is marked as unsatisfactory. This signifies the need for regular inspections and potentially necessary maintenance to ensure the dam's continued effectiveness in flood risk reduction. The risk assessment has been rated as moderate, indicating a level of concern that should prompt proactive risk management measures to be put in place by the Bureau of Land Management.
Water resource and climate enthusiasts will find Three Trees Detention Dam to be a significant structure in the effort to protect the local community from flooding. As an essential piece of infrastructure managed by the federal government, this dam highlights the ongoing need for proper maintenance and risk management to ensure its continued functionality and effectiveness in mitigating flood risks in the area.
Year Completed |
1954 |
Dam Length |
1224 |
River Or Stream |
WILLOW CK./MILK RIVER |
Primary Dam Type |
Gravity |
Surface Area |
33.02 |
Hydraulic Height |
10 |
Drainage Area |
8.9 |
Nid Storage |
148.9 |
Structural Height |
16 |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
16 |
Seasonal Comparison
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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.
Three Trees Detention Dam