Upper Big Nemaha L-17 Reservoir Report

Last Updated: December 5, 2025

Upper Big Nemaha L-17 is a local government-owned dam located in Lancaster, Nebraska, designed by the USDA NRCS and regulated by the Nebraska Department of Natural Resources.


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Summary

Completed in 1971, this earth dam stands at 24 feet tall and spans 542 feet in length, serving primarily for flood risk reduction along the TR-MID BR Big Nemaha River. With a storage capacity of 65 acre-feet, it covers a surface area of 3 acres and drains a 0.3 square mile watershed, with a low hazard potential and satisfactory condition assessment as of the last inspection in August 2016.

Managed by the Omaha District of the US Army Corps of Engineers, Upper Big Nemaha L-17 incorporates buttress and stone core types on a soil foundation, with a maximum discharge capacity of 291 cubic feet per second. The dam's primary purpose, aside from flood risk reduction, falls under the category of "Other," with a normal storage capacity of 21 acre-feet. Despite its relatively low hazard potential, the dam is subject to regular state inspection, permitting, and enforcement to ensure its continued safety and functionality in the face of a changing climate and water resource management challenges.

For water resource and climate enthusiasts, Upper Big Nemaha L-17 presents a fascinating case study of local dam infrastructure in Nebraska. With its historical significance dating back to the early 1970s and its critical role in mitigating flood risks along the Big Nemaha River, this dam exemplifies the intersection of engineering, regulatory oversight, and environmental stewardship in safeguarding communities and ecosystems against water-related hazards. As climate change continues to impact precipitation patterns and hydrological dynamics, understanding the design, operation, and maintenance of structures like Upper Big Nemaha L-17 becomes increasingly crucial in ensuring resilience and sustainability in water resource management practices.

Year Completed

1971

Dam Length

542

Dam Height

19

River Or Stream

TR-MID BR BIG NEMAHA RIVER

Primary Dam Type

Earth

Surface Area

3

Hydraulic Height

19

Drainage Area

0.3

Nid Storage

65

Structural Height

24

Hazard Potential

Low

Foundations

Soil

Nid Height

24
       
Seasonal Comparison

Weather Forecast

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Nearby Streamflow Levels

Upper Big Nemaha L-17SALT CREEK AT ROCA Preview Salt Creek At Roca
4.93cfs
5cfs
Upper Big Nemaha L-17SALT CREEK AT PIONEERS BLVD AT LINCOLN Preview Salt Creek At Pioneers Blvd At Lincoln
10.5cfs
11cfs
Upper Big Nemaha L-17HAINES BRANCH AT SW 56th ST. AT LINCOLN Preview Haines Branch At Sw 56th St. At Lincoln
1.33cfs
1cfs
Upper Big Nemaha L-17TURKEY CREEK NEAR DE WITT Preview Turkey Creek Near De Witt
10.1cfs
10cfs
Upper Big Nemaha L-17BIG BLUE RIVER NEAR CRETE Preview Big Blue River Near Crete
94.8cfs
95cfs
Upper Big Nemaha L-17MIDDLE 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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Nearby Reservoirs

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