Little Wood River Reservoir Report

Last Updated: December 13, 2025

Little Wood River, located in Blaine County, Idaho, is a federal irrigation project managed by the Bureau of Reclamation.


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Summary

The primary purpose of the Little Wood River dam, completed in 1941, is to provide irrigation water for agricultural activities in the region. The dam, standing at a height of 129 feet and with a length of 3100 feet, has a storage capacity of 33,300 acre-feet and serves a drainage area of 286 square miles.

The dam's spillway, which is uncontrolled and 250 feet wide, has a maximum discharge capacity of 9,200 cubic feet per second. With a surface area of 590 acres, the dam plays a crucial role in water resource management in the area, ensuring a stable supply of water for irrigation purposes. Despite being classified as having a high hazard potential, the condition assessment of the dam is currently not available, highlighting the need for ongoing monitoring and maintenance to ensure its safety and reliability for the future. Enthusiasts of water resources and climate in the region can appreciate the significance of the Little Wood River dam in sustaining agricultural activities and managing water resources effectively.

Year Completed

1941

Dam Length

3100

Dam Height

129

River Or Stream

LITTLE WOOD RIVER MALAD RIVER

Primary Dam Type

Earth

Surface Area

590

Drainage Area

286

Nid Storage

33300

Structural Height

169

Outlet Gates

Slide (sluice gate) - 0

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

169
       
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.