Yellowtail Reservoir Report
Nearby: Yellowtail Afterbay Erb #1
Last Updated: December 5, 2025
Yellowtail, also known as Bighorn Lake, is a federal water resource located in Montana on the Bighorn River.
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Summary
The dam, completed in 1966, is a concrete structure standing at 525 feet tall with a length of 1480 feet. It has a storage capacity of over 1.3 million acre-feet and a surface area of 17,958 acres, serving various purposes related to water management and control.
Managed by the Bureau of Reclamation, Yellowtail plays a crucial role in regulating water flow, with a maximum discharge capacity of 93,000 cubic feet per second. The dam is equipped with a controlled spillway and has a hazard potential rated as high, reflecting the importance of its risk management measures. Despite its age, the condition assessment of Yellowtail is not available, highlighting the need for continued monitoring and maintenance to ensure its safety and efficiency in the face of changing climate conditions.
For water resource and climate enthusiasts, Yellowtail presents an intriguing case study of a significant federal structure in the water management landscape. Its location in Big Horn County, Montana, and its critical role in controlling the Bighorn River flow make it a focal point for understanding the intersection of water resource management, infrastructure design, and environmental stewardship. With its high hazard potential and very high risk assessment rating, Yellowtail represents a complex system that requires ongoing attention and careful planning to ensure its continued function and resilience in the face of potential challenges posed by climate change and other factors.
Year Completed |
1966 |
Dam Length |
1480 |
Dam Height |
491 |
River Or Stream |
BIGHORN RIVER |
Primary Dam Type |
Concrete |
Surface Area |
17958 |
Hydraulic Height |
494 |
Drainage Area |
19650 |
Nid Storage |
1331725 |
Structural Height |
525 |
Hazard Potential |
High |
Foundations |
Unlisted/Unknown |
Nid Height |
525 |
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.
Area Campgrounds
| Location | Reservations | Toilets |
|---|---|---|
Afterbay Campground
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Afterbay - Bighorn Canyon National Rec Area
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Bighorn FAS
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Yellowtail
Southeastern Boundary Of Bighorn Canyon National Recreation Area To Confluence With Bighorn River