Hyrum Reservoir Report

Last Updated: December 5, 2025

Hyrum Dam, located in Cache County, Utah, is a federal irrigation structure managed by the Bureau of Reclamation and funded by the same agency.


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Summary

Completed in 1934, this earth dam on the Little Bear River stands at a height of 116 feet and serves multiple purposes including irrigation, recreation, and water supply. With a storage capacity of 18,685 acre-feet and a maximum discharge rate of 6,000 cubic feet per second, Hyrum Dam plays a crucial role in managing water resources in the region.

Despite its age, Hyrum Dam is regularly inspected by the Bureau of Reclamation to ensure its safety and functionality. The dam has a high hazard potential and a very high risk assessment rating, necessitating proper risk management measures. The emergency action plan for the dam was last revised in September 2020, emphasizing the importance of preparedness and adherence to safety guidelines. With its controlled spillway and strategic location in the Little Bear River watershed, Hyrum Dam remains a vital infrastructure for water resource management in Utah.

Hyrum Dam's historical significance, combined with its modern-day importance in irrigation and water supply, makes it a focal point for water resource and climate enthusiasts. The dam's role in managing water flow, providing recreational opportunities, and ensuring a stable water supply for the surrounding area highlights the critical need for sustainable water management practices. As the Bureau of Reclamation continues to monitor and maintain Hyrum Dam, it stands as a testament to the ongoing efforts to balance water resource utilization with environmental conservation in the region.

Years Modified

2004 - Structural

Year Completed

1934

Dam Length

540

Dam Height

116

River Or Stream

LITTLE BEAR RIVER

Primary Dam Type

Earth

Surface Area

480

Hydraulic Height

82

Drainage Area

220

Nid Storage

18685

Structural Height

116

Hazard Potential

High

Nid Height

116
       
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.