Upper Lone Tree Detention Dam Reservoir Report
Nearby: Clover Drop Dam Tepee Detention Dam
Last Updated: January 2, 2026
The Upper Lone Tree Detention Dam, located in Valley County, Montana, along the Milk River, was completed in 1952 by the Bureau of Land Management for fire protection, stock, and small fish pond purposes.
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Summary
This gravity dam stands at a hydraulic height of 12 feet and a structural height of 16 feet, with a length of 740 feet and a storage capacity of 80.87 acre-feet. Despite being classified as low hazard potential, the dam's condition assessment is currently marked as unsatisfactory, indicating a need for maintenance and repairs.
With a spillway type of uncontrolled and a spillway width of 2 feet, the Upper Lone Tree Detention Dam serves as a crucial infrastructure for managing water resources in the area. However, the dam's risk assessment is moderate, highlighting the importance of implementing risk management measures to ensure its continued safety and functionality. While the dam is not under the jurisdiction of the state and does not require state permitting or inspection, it remains a significant structure for the Bureau of Land Management and the local community in Nashua.
As water resource and climate enthusiasts, understanding the intricacies of the Upper Lone Tree Detention Dam's design, purpose, and current condition sheds light on the critical role it plays in water management and environmental protection. With a focus on fire protection and supporting local wildlife, this dam serves as a reminder of the importance of maintaining and monitoring our water infrastructure to safeguard against potential risks and ensure sustainable water resource management in the region.
Year Completed |
1952 |
Dam Length |
740 |
River Or Stream |
MILK RIVER |
Primary Dam Type |
Gravity |
Surface Area |
19.57 |
Hydraulic Height |
12 |
Drainage Area |
2.9 |
Nid Storage |
80.87 |
Structural Height |
16 |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
16 |
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.
Upper Lone Tree Detention Dam