Upper Big Nemaha J-11 Reservoir Report
Last Updated: December 6, 2025
Upper Big Nemaha J-11 is a locally owned earth dam located in Johnson County, Nebraska, along the TR-N FK BIG NEMAHA RIVER.
°F
°F
mph
Wind
%
Humidity
Summary
Built in 1980 by the USDA NRCS, this dam stands at a height of 22 feet and has a maximum storage capacity of 63 acre-feet. With a primary purpose of flood risk reduction, Upper Big Nemaha J-11 plays a crucial role in protecting the surrounding area from potential flooding events.
Managed by the Nebraska Department of Natural Resources, Upper Big Nemaha J-11 has been deemed to have a low hazard potential and is in satisfactory condition as of its last assessment in 2016. The dam has a drainage area of 0.4 square miles and a maximum discharge capacity of 174 cubic feet per second. While it has not undergone any modifications in recent years, regular inspections are conducted every five years to ensure its continued safe operation.
With its stone core and soil foundation, Upper Big Nemaha J-11 serves as a vital infrastructure for flood risk management in the region. Its strategic location and design make it a key asset in safeguarding the community against potential water-related emergencies. As water resource and climate enthusiasts, understanding the importance of structures like Upper Big Nemaha J-11 is crucial in ensuring the resilience of our water management systems in the face of changing environmental conditions.
Year Completed |
1980 |
Dam Length |
782 |
Dam Height |
22 |
River Or Stream |
TR-N FK BIG NEMAHA RIVER |
Primary Dam Type |
Earth |
Surface Area |
3 |
Hydraulic Height |
21 |
Drainage Area |
0.4 |
Nid Storage |
63 |
Structural Height |
21 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
22 |
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.
Upper Big Nemaha J-11