Costich Dam Reservoir Report
Nearby: Eureka Holding Pond Dike Glen Lake
Last Updated: December 24, 2025
Costich Dam, located in Eureka, Montana, is a vital water resource structure designed by the USDA NRCS for irrigation purposes.
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Summary
Completed in 1956, this earth dam stands at a height of 29 feet and has a hydraulic height of 24 feet. With a storage capacity of 570 acre-feet and a drainage area of 0.5 square miles, it plays a crucial role in water management for the surrounding area.
Despite its age, Costich Dam has a satisfactory condition assessment and is regulated by the Montana Department of Natural Resources and Conservation (DNRC). The dam has a high hazard potential, but regular inspections are conducted to ensure its safety. With a maximum discharge capacity of 82 cubic feet per second and a spillway width of 36 feet, the dam is well-equipped to manage high water levels and control the flow of the Tobacco River offstream.
Overall, Costich Dam is a key infrastructure for irrigation in Lincoln County, Montana. Its role in water resource management, coupled with its high hazard potential and consistent regulatory oversight, highlights the importance of this structure in maintaining water security and climate resilience in the region.
Year Completed |
1956 |
Dam Length |
215 |
Dam Height |
29 |
River Or Stream |
TR-TOBACCO RIVER OFFSTREAM |
Primary Dam Type |
Earth |
Surface Area |
44.1 |
Hydraulic Height |
24 |
Drainage Area |
0.5 |
Nid Storage |
570 |
Hazard Potential |
High |
Foundations |
Rock, Soil |
Nid Height |
29 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Tobacco River Near Eureka Mt
|
388cfs |
Flathead River At Flathead British Columbia
|
841cfs |
Kootenai River Bl Libby Dam Nr Libby Mt
|
22100cfs |
Fisher River Near Libby Mt
|
923cfs |
Yaak River Near Troy Mt
|
1540cfs |
N F Flathead River Nr Columbia Falls Mt
|
3540cfs |
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.
Costich Dam