Upper Big Nemaha 21-b is an earth dam located in Lancaster County, Nebraska, built in 1973. It carries a Low hazard potential classification and has a satisfactory condition assessment.
Dam profile
NID height · 42 ft42 ft tall and 1,440 ft long, taller than 88% of U.S. dams with a recorded height. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic embankment section and the water level is illustrative.
About Upper Big Nemaha 21-b
The primary purpose of Upper Big Nemaha 21-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 1,440 feet across, creates a reservoir covering 54 acres, has a maximum storage capacity of 1,890 acre-feet, and collects water from a drainage area of 5 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 04/27/2022.
At 42 feet, this dam is taller than 88% of dams nationwide.
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Location
| State | Nebraska |
| County | Lancaster |
| Nearest City | Sterling |
| River/Stream | Tr-n Fk Big Nemaha River |
| Coordinates | 40.54044, -96.48624 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 42 ft |
| Dam Height | 42 ft |
| Dam Length | 1,440 ft |
| Year Completed | 1973 (53 years old) |
Storage & Hydraulics
| NID Storage | 1,890 acre-ft |
| Max Storage | 1,890 acre-ft |
| Normal Storage | 337 acre-ft |
| Surface Area | 54 acres |
| Drainage Area | 5 sq mi |
| Max Discharge | 787 cfs |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | Nemaha Natural Resources District |
| Owner Type | Local Government |
| Hazard Classification | Low |
| Condition Assessment | Satisfactory |
| Last Inspection | 04/27/2022 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | NE01217 |
| Federal ID | NE01217 |
| More Info | State Dam Safety Program |