Pensacola East Spillway 1 Reservoir Report

Last Updated: December 7, 2025

Pensacola East Spillway 1, located in Mayes, Oklahoma, is an impressive gravity dam completed in 1940 for the primary purpose of hydroelectric power generation.


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Summary

Standing at a structural height of 48 feet and a hydraulic height of 15 feet, this dam plays a crucial role in flood risk reduction and energy production in the region. With a normal storage capacity of 1,630,000 acre-feet and a maximum storage capacity of 2,197,000 acre-feet, Pensacola East Spillway 1 serves as a vital water resource management structure in the Tulsa District.

The controlled spillway at Pensacola East Spillway 1 features a width of 407 feet and utilizes Tainter (radial) gates for water release. The dam is associated with two other structures and is regulated by the Federal Energy Regulatory Commission, ensuring compliance with safety standards and inspections. Despite its high hazard potential, the condition assessment for Pensacola East Spillway 1 is currently not available, highlighting the need for ongoing monitoring and risk management measures to safeguard the surrounding area from potential emergencies.

With a history of serving the community for over 80 years, Pensacola East Spillway 1 remains a key infrastructure for water resource management and flood control in the Neosho River watershed. As climate change impacts intensify, the importance of maintaining and updating this critical structure is paramount to ensure the safety and resilience of the region against extreme weather events. The continued collaboration between state and federal agencies will be essential in implementing effective risk management strategies and emergency preparedness measures for Pensacola East Spillway 1.

Year Completed

1940

Dam Length

505

Dam Height

12.5

River Or Stream

Neosho

Primary Dam Type

Gravity

Surface Area

46500

Hydraulic Height

15

Drainage Area

10192

Nid Storage

2197000

Structural Height

48

Outlet Gates

Tainter (radial) - 11

Hazard Potential

High

Nid Height

48
       
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.