Oak-Middle 81-A Reservoir Report

Last Updated: December 6, 2025

Oak-Middle 81-A is a crucial flood risk reduction structure located in Seward, Nebraska.


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Summary

Built in 1959 by the USDA NRCS, this earth dam stands at a height of 50 feet and spans 1326 feet in length. With a normal storage capacity of 133 acre-feet and a maximum discharge of 618 cubic feet per second, Oak-Middle 81-A plays a vital role in managing the water resources of the TR-MIDDLE OAK CREEK.

Managed by the Nebraska Department of Natural Resources, Oak-Middle 81-A has a low hazard potential and is in satisfactory condition as of the last inspection in April 2020. The structure is designed to withstand hydraulic heights of up to 47 feet, ensuring the safety and security of the surrounding area. With its primary purpose being flood risk reduction, Oak-Middle 81-A serves as a critical infrastructure for water resource management in the region.

Located in the Kansas City District and under the jurisdiction of the NE DNR, Oak-Middle 81-A exemplifies the collaboration between local and federal agencies in safeguarding communities from flood risks. As climate change continues to impact water resources, structures like Oak-Middle 81-A play a pivotal role in mitigating potential disasters and ensuring the resilience of the region's water infrastructure.

Year Completed

1959

Dam Length

1326

Dam Height

50

River Or Stream

TR-MIDDLE OAK CREEK

Primary Dam Type

Earth

Surface Area

17

Hydraulic Height

47

Drainage Area

2

Nid Storage

551

Structural Height

52

Hazard Potential

Low

Foundations

Soil

Nid Height

52
       
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.