Swan Falls Reservoir Report

Last Updated: December 24, 2025

Swan Falls, located in Ada County, Idaho, is a private-owned hydroelectric dam on the Snake River with a primary purpose of generating electricity.


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Summary

Constructed in 1901, this concrete gravity dam stands at a height of 88 feet and spans 1150 feet in length. With a normal storage capacity of 7425 acre-feet, Swan Falls also serves recreational purposes in addition to its hydroelectric function.

Managed by the Federal Energy Regulatory Commission, Swan Falls is regulated by the Idaho Department of Water Resources, ensuring proper inspection, permitting, and enforcement measures are in place. The dam has a spillway width of 434 feet and features 12 Tainter radial gates for water control. Despite its high hazard potential, the condition assessment of Swan Falls is currently not available, reflecting the need for ongoing risk assessment and management measures to ensure the safety and integrity of this critical water resource infrastructure.

Swan Falls plays a crucial role in water resource management and energy production in Idaho, serving as a key asset in the state's infrastructure. With its historic significance and continued operational importance, Swan Falls stands as a testament to the intersection of human innovation, environmental stewardship, and sustainable energy practices in the face of changing climate dynamics.

Year Completed

1901

Dam Length

1150

Dam Height

88

River Or Stream

Snake River

Primary Dam Type

Concrete

Surface Area

1525

Hydraulic Height

25

Drainage Area

41900

Nid Storage

7425

Structural Height

34

Outlet Gates

Tainter (radial) - 12

Hazard Potential

High

Nid Height

88
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No 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

High
Dams 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.