Ruins Detention Dam Reservoir Report
Nearby: Finale Detention Dam Toprail Dam
Last Updated: December 20, 2025
Ruins Detention Dam, located in Nashua, Montana, was completed in 1965 by the Bureau of Land Management for fire protection, stock, and small fish pond purposes.
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Summary
This gravity dam, with a structural height of 35 feet and a hydraulic height of 29 feet, stands on Willow Creek near the Milk River. With a storage capacity of 201.5 acre-feet and a surface area of 17.6 acres, the dam serves its primary purpose effectively.
Despite its low hazard potential, Ruins Detention Dam is in poor condition, as per a 2019 inspection report. The dam has an uncontrolled spillway and no outlet gates, posing a moderate risk (3) to the surrounding area. The Bureau of Land Management is responsible for the construction, regulation, inspection, and operation of the dam, with no state jurisdiction or permitting involved. Climate and water resource enthusiasts may find the structural and operational details of Ruins Detention Dam intriguing, as it plays a crucial role in managing water resources and protecting against wildfires in the area.
Year Completed |
1965 |
Dam Length |
536 |
River Or Stream |
WILLOW CK./MILK RIVER |
Primary Dam Type |
Gravity |
Surface Area |
17.6 |
Hydraulic Height |
29 |
Drainage Area |
0.6 |
Nid Storage |
201.5 |
Structural Height |
35 |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
35 |
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.
Ruins Detention Dam