Upper Big Nemaha G-20 Reservoir Report
Nearby: Markham Dam Duis Dam
Last Updated: December 6, 2025
Located in Gage County, Nebraska, the Upper Big Nemaha G-20 dam stands as a testament to effective flood risk reduction measures put in place by the USDA NRCS in 1978.
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Summary
With a dam height of 27 feet and a length of 437 feet, this earth dam serves a vital purpose in protecting the surrounding area from potential flooding events. The dam has a normal storage capacity of 17 acre-feet, with a maximum discharge of 623 cubic feet per second, ensuring efficient water management within the region.
Managed by the local government and regulated by the Nebraska Department of Natural Resources, the Upper Big Nemaha G-20 dam undergoes regular inspections to maintain its fair condition and low hazard potential. The dam's primary purpose extends beyond flood risk reduction, with a focus on other water resource management objectives. Despite its modest surface area of 3 acres and drainage area of 0.2 square miles, the dam plays a crucial role in safeguarding the community's water resources and enhancing resilience against climate variability.
As water resource and climate enthusiasts, the significance of the Upper Big Nemaha G-20 dam lies in its contribution to sustainable water management practices and climate resilience efforts. With a strong foundation of soil and core made of stone, this dam exemplifies the collaborative efforts between government agencies and local communities in addressing water-related challenges. By adhering to state regulations and undergoing regular inspections, the dam not only ensures public safety but also underscores the importance of proactive risk management in the face of changing climatic conditions.
Year Completed |
1978 |
Dam Length |
437 |
Dam Height |
27 |
River Or Stream |
TR-HOOKER CREEK |
Primary Dam Type |
Earth |
Surface Area |
3 |
Hydraulic Height |
27 |
Drainage Area |
0.2 |
Nid Storage |
43 |
Structural Height |
28 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
28 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Andrews Dam