Long Dam Reservoir Report
Nearby: Blackfoot Detention Dam Cline #2
Last Updated: December 5, 2025
Long Dam, located in Carter, Montana, is a gravity dam managed by the Bureau of Land Management for flood risk reduction on an unnamed drainage.
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Summary
Built with buttress and stone core types, the dam stands at a structural height of 14 feet with a hydraulic height of 9 feet, spanning a length of 4026 feet. It has a storage capacity of 60.7 acre-feet, with a normal storage level of 28.59 acre-feet and a surface area of 32.2 acres.
Despite being classified as low hazard potential with a fair condition assessment, Long Dam has a moderate risk rating. The dam features an uncontrolled spillway with a width of 2 feet and has a biennial inspection frequency. The last inspection was conducted in September 2018. With its primary purpose being flood risk reduction, the dam serves as a vital infrastructure for managing water resources in the region.
Managed and funded by the Bureau of Land Management, Long Dam plays a crucial role in protecting the surrounding areas from potential flooding. With its strategic location and design elements, the dam stands as a testament to the importance of effective water resource management and climate adaptation strategies in safeguarding communities and ecosystems against the impacts of changing weather patterns.
Dam Length |
4026 |
River Or Stream |
UNNAMED DRAINAGE |
Primary Dam Type |
Gravity |
Surface Area |
32.2 |
Hydraulic Height |
9 |
Nid Storage |
60.7 |
Structural Height |
14 |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
14 |
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.
Long Dam