Little Hyatt Dam Reservoir Report

Last Updated: December 5, 2025

Little Hyatt Dam, also known as Little Hyatt Reservoir, is a captivating federal-owned structure located in Jackson, Oregon, along the Keene Creek.


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Summary

Managed by the Bureau of Land Management, this arch-type dam stands at a hydraulic height of 18 feet and has a structural height of 18 feet, with a length of 77 feet. The reservoir has a storage capacity of 59 acre-feet and covers a surface area of 10.9 acres, making it a popular destination for recreational activities.

Despite its low hazard potential, the dam is rated as having a poor condition assessment, with the last inspection conducted in July 2020. It has a moderate risk assessment rating of 3, indicating some level of vulnerability. The dam has not been modified in recent years, with the last modification dating back to 2008 when the foundation was addressed. With no outlet gates and an uncontrolled spillway, the dam relies on natural overflow mechanisms for water management.

Water resource and climate enthusiasts would find Little Hyatt Dam an intriguing structure to study due to its unique design and location. Situated in a remote area with no nearby towns, the dam feeds water into the Copco Reservoir in California, providing essential water resources for the region. While the dam serves primarily for recreation, its condition and risk assessments highlight the importance of regular maintenance and monitoring to ensure the safety and functionality of this vital water infrastructure.

Years Modified

2008 - Foundation

Dam Length

77

River Or Stream

KEENE CREEK

Primary Dam Type

Arch

Surface Area

10.9

Hydraulic Height

18

Nid Storage

59

Structural Height

18

Outlet Gates

None

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

18
       
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.