Monroe Reservoir Report

Last Updated: December 14, 2025

Monroe is a private-owned dam located in Washington, Idaho, built in 1916 with a primary purpose of irrigation.


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Summary

Situated along Jenkins Creek and the Snake River, Monroe serves as a crucial water resource for the region, with a storage capacity of 272 acre-feet and a surface area of 20 acres. The dam stands at a height of 36.2 feet and has a hydraulic height of 34 feet, making it a vital infrastructure for agricultural purposes in the area.

Despite being classified as having a low hazard potential and fair condition assessment, Monroe's risk assessment is moderate, signaling the need for ongoing monitoring and maintenance. The dam features a multi-arch masonry design and an uncontrolled spillway type with a width of 12 feet. With the dam being regulated, inspected, and permitted by the Idaho Department of Water Resources, it plays a critical role in ensuring water security and supply for the surrounding communities. Overall, Monroe stands as a testament to the intersection of water resource management, climate resilience, and agricultural sustainability in the region.

Year Completed

1916

Dam Length

285

Dam Height

36.2

River Or Stream

JENKINS CREEK SNAKE RIVER

Surface Area

20

Hydraulic Height

34

Drainage Area

1.3

Nid Storage

272

Hazard Potential

Low

Foundations

Rock, Soil

Nid Height

36
       
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.