Onapa Lake Reservoir Report

Last Updated: December 6, 2025

Onapa Lake, also known as Checotah City Lake, is a local government-owned reservoir located in McIntosh County, Oklahoma.


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Summary

This picturesque lake serves as a crucial flood risk reduction structure, with a primary purpose of mitigating potential disasters in the surrounding area. Completed in 1935, the earth dam stands at a height of 58 feet, with a hydraulic height and structural height matching this measurement.

Covering a surface area of 49 acres, Onapa Lake boasts a maximum storage capacity of 2,520 acre-feet and a normal storage level of 1,137 acre-feet. The controlled spillway, measuring 4 feet in width, ensures effective water management during periods of excess flow. Despite being rated as low hazard potential, the risk assessment for Onapa Lake is identified as very high, highlighting the importance of consistent monitoring and maintenance practices. As water resource and climate enthusiasts, the intricate details of this reservoir's design and purpose make it a compelling subject for exploration and study.

Year Completed

1935

Dam Length

594

Dam Height

58

River Or Stream

TR-LAKE EUFAULA

Primary Dam Type

Earth

Surface Area

49

Hydraulic Height

58

Nid Storage

2520

Structural Height

58

Outlet Gates

Valve - 1

Hazard Potential

Low

Foundations

Soil

Nid Height

58
       
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.