Eightmile Spring Reservoir Report
Nearby: Bees Hive Sour Apple
Last Updated: December 5, 2025
Eightmile Spring is a privately owned water resource located in Chouteau, Montana, with a primary purpose of providing fire protection, stock, and small fish pond services.
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Summary
The earth dam, completed in 1953, stands at a height of 15 feet and has a storage capacity of 85 acre-feet. Situated along Eightmile Coulee, the dam's low hazard potential and "Not Rated" condition assessment make it a reliable source of water for the local community. The Montana Department of Natural Resources and Conservation regulates and inspects the site, ensuring its safety and functionality for its intended purposes.
The dam at Eightmile Spring serves as an essential water source for fire protection and livestock in the Tunis area. With a storage capacity of 85 acre-feet and a normal storage level of 44 acre-feet, the dam provides a reliable water supply for both emergency situations and agricultural needs. The site's location within Congressional District 00 of Montana, under the representation of Greg Gianforte (R), highlights its importance in the local water resource management system. Despite its low hazard potential, the dam plays a crucial role in sustaining the surrounding ecosystem and supporting various water-dependent activities.
Eightmile Spring's history dates back to its construction in 1953, showcasing a long-standing commitment to water resource management in the region. The dam's earth structure and 800-foot length demonstrate its resilience and capacity to withstand the test of time. While its condition remains "Not Rated," the site's continuous regulation and inspection by the Montana DNRC ensure its ongoing safety and effectiveness. As a key contributor to water security in Chouteau County, Eightmile Spring stands as a testament to sustainable water management practices in the face of changing climate conditions.
Year Completed |
1953 |
Dam Length |
800 |
Dam Height |
15 |
River Or Stream |
EIGHTMILE COULEE |
Primary Dam Type |
Earth |
Hydraulic Height |
15 |
Nid Storage |
85 |
Hazard Potential |
Low |
Nid Height |
15 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Missouri River At Fort Benton Mt
|
4720cfs |
Marias River Near Loma Mt
|
335cfs |
Teton River At Loma Mt
|
30cfs |
Missouri River Near Great Falls Mt
|
3530cfs |
Lake Creek Near Power Mt
|
30cfs |
Missouri River At Virgelle Mt
|
4290cfs |
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.
Eightmile Spring