Horseshoe Bend Diversion Reservoir Report

Last Updated: December 19, 2025

Horseshoe Bend Diversion, located in Boise, Idaho, is a private hydroelectric facility on the Payette River.


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Summary

Completed in 1995, this dam stands at 8 feet tall and spans 220 feet in length, providing a storage capacity of 116 acre-feet. With a low hazard potential and moderate risk assessment, this diversion is regulated by both state and federal agencies, including the Idaho Department of Water Resources and the Federal Energy Regulatory Commission.

Despite its small size, Horseshoe Bend Diversion plays a crucial role in water resource management and renewable energy production in the region. The dam's uncontrolled spillway has a width of 220 feet, allowing for the safe release of excess water during periods of high flow. The facility's emergency action plan, last revised in December 2020, ensures that proper measures are in place to address any potential risks associated with the dam.

In addition to its primary purpose of hydroelectric power generation, Horseshoe Bend Diversion also serves as a valuable asset for recreation and wildlife habitat in the area. With its strategic location and efficient operations, this facility continues to contribute to the sustainable development and preservation of water resources and climate resilience in Idaho.

Year Completed

1995

Dam Length

220

Dam Height

8

River Or Stream

Payette River

Primary Dam Type

Other

Surface Area

6

Drainage Area

2230

Nid Storage

116

Hazard Potential

Low

Nid Height

8
       
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.