Oxbow Reservoir Report

Last Updated: December 25, 2025

Oxbow, located in Adams, Idaho, is a rockfill dam primarily designed for grade stabilization along the Snake River and Columbia River.


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Summary

Completed in 1961, this public utility-owned structure stands at a height of 145 feet with a hydraulic height of 130 feet, providing a storage capacity of 58,200 acre-feet and covering a surface area of 1,150 acres. With a drainage area of 73,000 acres, Oxbow plays a crucial role in managing water resources in the region, with a maximum discharge capacity of 300,000 cubic feet per second.

Despite its satisfactory condition assessment as of July 2020, Oxbow has a high hazard potential, necessitating a thorough inspection every two years to ensure its structural integrity and operational safety. The dam features a controlled spillway with a width of 96 feet and outlet gates controlled by valves. With its risk assessment rating at a very high level (1), Oxbow is a key component of water resource management in Idaho, serving as a vital structure for flood control, water storage, and grade stabilization, safeguarding the surrounding communities and ecosystems in times of emergencies and high water events.

Year Completed

1961

Dam Length

960

Dam Height

145

River Or Stream

SNAKE RIVER COLUMBIA RIVER

Surface Area

1150

Hydraulic Height

130

Drainage Area

73000

Nid Storage

58200

Outlet Gates

Valve

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

145
       
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.