Riley Horn Dam Reservoir Report

Last Updated: December 13, 2025

Riley Horn Dam, also known as Riley Horn Reservoir, is a gravity dam located in Malheur, Oregon, along Fort Creek.


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Summary

Built in 1961 and owned by the Bureau of Land Management, this federal structure serves primarily as a water supply source with a storage capacity of 385 acre-feet. The dam stands at a structural height of 12 feet with a hydraulic height of 9 feet, spanning 610 feet in length and covering a surface area of 65.1 acres.

Despite its low hazard potential and not being rated for its condition, Riley Horn Dam plays a crucial role in water resource management in the region. Operated and funded by the Bureau of Land Management, the dam has not undergone any significant modifications over the years and does not have an Emergency Action Plan in place. Although the dam has not been inspected since September 2018, its low-risk status and minimal impact on the surrounding area make it a reliable water supply infrastructure for the community.

Enthusiasts of water resources and climate in Oregon may find Riley Horn Dam an interesting subject for exploration and study. With its unique design features, historical significance, and the role it plays in maintaining water supply in the region, this federal structure offers valuable insights into the management of water resources and infrastructure in a changing climate. Further research and analysis of Riley Horn Dam could provide a deeper understanding of the challenges and opportunities associated with water supply systems in the face of climate change.

Year Completed

1961

Dam Length

610

River Or Stream

FORT CREEK

Primary Dam Type

Gravity

Surface Area

65.1

Hydraulic Height

9

Nid Storage

385

Structural Height

12

Outlet Gates

None

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

12
       
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.