North Fork Big Nemaha 23-B Reservoir Report

Last Updated: December 5, 2025

North Fork Big Nemaha 23-B is a vital flood risk reduction structure located in Lancaster, Nebraska, along the North Fork Big Nemaha River.


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Summary

Built in 1976 by the USDA NRCS, this earth dam stands at a height of 29 feet and has a storage capacity of 1370 acre-feet, serving its primary purpose of flood risk reduction effectively. With a drainage area of 3.5 square miles and a maximum discharge capacity of 1016 cubic feet per second, this dam plays a crucial role in managing water flow and protecting the surrounding area from potential flooding events.

Managed by the local government and regulated by the Nebraska Department of Natural Resources, North Fork Big Nemaha 23-B is regularly inspected to ensure its structural integrity and overall condition. Despite being classified as having low hazard potential, its fair condition assessment and inspection frequency of every 5 years indicate a commitment to maintaining its functionality and safety standards. With a surface area of 43 acres and a normal storage capacity of 184 acre-feet, this dam contributes to water resource management in the region while also providing recreational opportunities for the community.

In the event of an emergency, the dam's emergency action plan and risk management measures are essential tools to mitigate potential risks and ensure a coordinated response. Although further details on the risk assessment and management strategies are not currently available, the presence of a structured inspection schedule and a designated state regulatory agency demonstrate a proactive approach to maintaining the safety and effectiveness of North Fork Big Nemaha 23-B for the benefit of both the environment and the local population.

Year Completed

1976

Dam Length

1158

Dam Height

29

River Or Stream

N FK BIG NEMAHA RIVER

Primary Dam Type

Earth

Surface Area

43

Hydraulic Height

28

Drainage Area

3.5

Nid Storage

1370

Structural Height

30

Hazard Potential

Low

Foundations

Soil

Nid Height

30
       
Seasonal Comparison

Weather Forecast

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Nearby Streamflow Levels

North Fork Big Nemaha 23-BSALT CREEK AT ROCA Preview Salt Creek At Roca
4.93cfs
5cfs
North Fork Big Nemaha 23-BSALT CREEK AT PIONEERS BLVD AT LINCOLN Preview Salt Creek At Pioneers Blvd At Lincoln
10.5cfs
11cfs
North Fork Big Nemaha 23-BHAINES BRANCH AT SW 56th ST. AT LINCOLN Preview Haines Branch At Sw 56th St. At Lincoln
1.33cfs
1cfs
North Fork Big Nemaha 23-BSTEVENS CREEK NR. LINCOLN Preview Stevens Creek Nr. Lincoln
2.69cfs
3cfs
North Fork Big Nemaha 23-BSALT CREEK AT LINCOLN Preview Salt Creek At Lincoln
76.6cfs
77cfs
North Fork Big Nemaha 23-BMIDDLE CREEK AT SW 40th ST. AT LINCOLN Preview Middle Creek At Sw 40th St. At Lincoln
1.26cfs
1cfs

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.
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