Upper Big Nemaha G-15 Reservoir Report

Last Updated: December 5, 2025

Upper Big Nemaha G-15 is a crucial water resource structure located in Gage, Nebraska, along the TR-N FK BIG NEMAHA RIVER.


°F

°F

mph

Wind

%

Humidity

Summary

Constructed in 1968, this earth dam stands at a height of 32 feet, with a hydraulic height of 29.61 feet and a structural height of 36.5 feet. The dam serves multiple purposes, including flood risk reduction, and has a storage capacity of 51.2 acre-feet.

Managed by the Natural Resources Conservation Service, Upper Big Nemaha G-15 is regulated by the Nebraska Department of Natural Resources, with regular inspections and enforcement to ensure its safety and functionality. The dam has a fair condition assessment as of May 2016 and is designed to handle a maximum discharge of 59 cubic feet per second. With a surface area of 2.69 acres and a drainage area of 0.15 square miles, this structure plays a vital role in water management and climate resilience efforts in the region.

As a local government-owned facility, Upper Big Nemaha G-15 is a key asset in mitigating flood risks and ensuring water security in the area. With a height of 37 feet and a length of 510 feet, this dam provides critical storage capacity of 21 acre-feet under normal conditions. Supported by state permitting and inspection processes, this earth dam continues to be a vital component of water resource management in Nebraska, safeguarding communities and ecosystems along the TR-N FK BIG NEMAHA RIVER.

Year Completed

1968

Dam Length

510

Dam Height

32

River Or Stream

TR-N FK BIG NEMAHA RIVER

Primary Dam Type

Earth

Surface Area

2.69

Hydraulic Height

29.61

Drainage Area

0.15

Nid Storage

51.2

Structural Height

36.5

Foundations

Soil

Nid Height

37
       
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.