Upper Big Nemaha 20-b
Upper Big Nemaha 20-b is an earth dam located in Johnson County, Nebraska, built in 1973. It carries a Low hazard potential classification and has a satisfactory condition assessment.
About Upper Big Nemaha 20-b
The primary purpose of Upper Big Nemaha 20-b is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by Nemaha Natural Resources District (local government). It impounds the Tr-n Fk Big Nemaha River near Sterling.
The dam stands 42 feet tall and stretches 1,127 feet across, creates a reservoir covering 24 acres, has a maximum storage capacity of 430 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1973, the structure is well into its service life at over 50 years old.
This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected loss of life. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. The most recent inspection on record was 06/16/2021.
At 42 feet, this dam is taller than 89% of dams nationwide.
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Location
| State | Nebraska |
| County | Johnson |
| Nearest City | Sterling |
| River/Stream | Tr-n Fk Big Nemaha River |
| Coordinates | 40.51432, -96.44885 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 42 ft |
| Dam Height | 38 ft |
| Dam Length | 1,127 ft |
| Year Completed | 1973 (53 years old) |
Storage & Hydraulics
| NID Storage | 430 acre-ft |
| Max Storage | 430 acre-ft |
| Normal Storage | 91 acre-ft |
| Surface Area | 24 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 939 cfs |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | Nemaha Natural Resources District |
| Owner Type | Local Government |
| Hazard Classification | Low |
| Condition Assessment | Satisfactory |
| Last Inspection | 06/16/2021 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | NE00644 |
| Federal ID | NE00644 |
| More Info | State Dam Safety Program |