Upper Little Nemaha 18 Reservoir Report
Last Updated: December 5, 2025
Upper Little Nemaha 18, located in Unadilla, Nebraska, is a vital flood risk reduction structure on Hooper Creek managed by the local government.
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Summary
Constructed in 1996, this earth dam stands at a height of 38 feet and has a storage capacity of 1735 acre-feet, serving a drainage area of 6.5 square miles. With a satisfactory condition assessment and low hazard potential, this structure plays a crucial role in mitigating flood risks and ensuring the safety of the surrounding community.
Managed by the Nebraska Department of Natural Resources, Upper Little Nemaha 18 is subject to state regulation, permitting, inspection, and enforcement. It is designed to withstand maximum discharges of up to 3798 cubic feet per second and has a spillway type and width not specified in the data. The dam's primary purpose is flood risk reduction, with a normal storage capacity of 200 acre-feet and a surface area of 35 acres. This structure reinforces the resilience of the local area against potential flooding events.
Congressional District 01's representative, Jeff Fortenberry, oversees Upper Little Nemaha 18 as part of the Kansas City District. The dam has a history of satisfactory inspections, last assessed in August 2016, with a regular inspection frequency of 5 years. With no documented emergency action plan or risk assessment, the structure's risk management measures and potential hazards are currently unspecified. As a crucial component of water resource management in Otoe County, Nebraska, Upper Little Nemaha 18 stands as a testament to proactive flood risk reduction efforts in the region.
Year Completed |
1996 |
Dam Length |
1185 |
Dam Height |
38 |
River Or Stream |
HOOPER CREEK |
Primary Dam Type |
Earth |
Surface Area |
35 |
Hydraulic Height |
38 |
Drainage Area |
6.5 |
Nid Storage |
1735 |
Structural Height |
49 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
49 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Stevens Creek Nr. Lincoln
|
3cfs |
Salt Creek At Roca
|
5cfs |
Salt Creek At 70th St. At Lincoln
|
92cfs |
Salt Creek At Lincoln
|
77cfs |
Salt Creek At Pioneers Blvd At Lincoln
|
11cfs |
Salt Creek At Greenwood
|
125cfs |
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.
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