Arcadia Upper Reservoir Report

Last Updated: December 5, 2025

Arcadia Upper, located in St.


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Summary

Anthony, Idaho, is a privately-owned irrigation dam with a rich history dating back to its completion in 1912. This earth dam, constructed with stone core types on rock and soil foundations, stands at a height of 21 feet and spans 550 feet in length. Its primary purpose is irrigation, serving as a vital resource for managing water from Sand Creek and Henrys Fork.

Despite its age, Arcadia Upper faces challenges with a poor condition assessment, indicating the need for potential improvements. The dam's hazard potential is classified as low, but its risk assessment is very high, emphasizing the importance of ongoing monitoring and management. With a normal storage capacity of 300 acre-feet and a drainage area of 69 square miles, this structure plays a crucial role in water resource management in Fremont County, Idaho.

The dam's infrastructure includes a controlled spillway, slide gates for outlet control, and a spillway width of 2 feet. Although inspections are conducted every five years, the last assessment in 2017 revealed a poor condition. As water resource and climate enthusiasts, staying informed about the state of Arcadia Upper is essential for ensuring the safety and sustainability of this vital irrigation structure in Idaho's landscape.

Year Completed

1912

Dam Length

550

Dam Height

21

River Or Stream

SAND CREEK HENRYS FORK

Surface Area

40

Hydraulic Height

13.3

Drainage Area

69

Nid Storage

300

Outlet Gates

Slide (sluice gate)

Hazard Potential

Low

Foundations

Rock, Soil

Nid Height

21
       
Seasonal Comparison

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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.