Upper Salmon Falls A-Plant Diversion Dam Reservoir Report
Last Updated: December 17, 2025
The Upper Salmon Falls A-Plant Diversion Dam, located in Twin Falls, Idaho, is a private hydroelectric facility with a concrete gravity dam completed in 1937 by EBASCO.
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Summary
The dam stands at 9 feet high and spans 1380 feet in length, with a normal storage capacity of 150 acre-feet and a maximum discharge of 84,000 cubic feet per second. Despite its low hazard potential, the dam is regulated by the Federal Energy Regulatory Commission and undergoes inspections every 3 years to ensure safety and compliance.
Situated on the Snake River, the Upper Salmon Falls Dam plays a crucial role in water resource management and power generation in the region. With a drainage area of 32,200 square miles, the dam contributes to the irrigation and flood control efforts in the area while also supporting renewable energy production. The risk assessment for the dam is rated as moderate, emphasizing the importance of ongoing monitoring and management strategies to mitigate potential hazards and ensure the continued functionality of the facility.
Overall, the Upper Salmon Falls A-Plant Diversion Dam represents a significant piece of infrastructure in Idaho's water resource and energy landscape. As a key player in the hydroelectric sector, the dam underscores the intersection of water management, climate resilience, and sustainable energy production. With a focus on safety, regulatory compliance, and risk management, the dam exemplifies the ongoing efforts to balance environmental protection and energy generation in the region.
Year Completed |
1937 |
Dam Length |
1380 |
Dam Height |
9 |
River Or Stream |
Snake River |
Primary Dam Type |
Concrete |
Surface Area |
9 |
Hydraulic Height |
9 |
Drainage Area |
32200 |
Nid Storage |
150 |
Structural Height |
9 |
Hazard Potential |
Low |
Nid Height |
9 |
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.
Upper Salmon Falls A-Plant Diversion Dam
Snake River
Box Canyon