Strong Arm No 2 (Lower) Reservoir Report

Last Updated: December 6, 2025

Strong Arm No 2 (Lower) is a privately-owned irrigation structure located in Warm Springs, Idaho, within the beautiful Franklin County.


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Summary

Built in 1897, this earth dam stands at a height of 26.9 feet and has a storage capacity of 377 acre-feet, serving the primary purpose of irrigation for the surrounding area. The dam, constructed with stone core and rock and soil foundations, spans 660 feet and impounds water from Battle Creek and Bear River.

Despite its historical significance and vital role in water management, Strong Arm No 2 (Lower) is currently rated as having a poor condition assessment and a significant hazard potential, with a moderate risk level. The dam features an uncontrolled spillway and a slide gate outlet, with regular state inspection, permitting, and enforcement to ensure public safety. While the structure has not undergone recent modifications, it is essential for water resource and climate enthusiasts to stay updated on its maintenance and potential risks, as it continues to play a crucial role in the local irrigation system.

Year Completed

1897

Dam Length

660

Dam Height

26.9

River Or Stream

BATTLE CREEK BEAR RIVER

Surface Area

24

Hydraulic Height

23.4

Drainage Area

1.7

Nid Storage

377

Outlet Gates

Slide (sluice gate)

Hazard Potential

Significant

Foundations

Rock, Soil

Nid Height

27
       
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.