Upper Big Nemaha J-12a 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.
Dam profile
NID height · 28 ft28 ft tall and 570 ft long, taller than 62% 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 J-12a
Upper Big Nemaha J-12a is a dam in Johnson, Nebraska. 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 28 feet tall and stretches 570 feet across, creates a reservoir covering 8 acres, has a maximum storage capacity of 147 acre-feet, and collects water from a drainage area of 0 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 05/24/2023.
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Location
| State | Nebraska |
| County | Johnson |
| Nearest City | Sterling |
| River/Stream | Tr N Fk Big Nemaha River |
| Coordinates | 40.50963, -96.41752 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 28 ft |
| Dam Height | 26 ft |
| Dam Length | 570 ft |
| Year Completed | 1973 (53 years old) |
Storage & Hydraulics
| NID Storage | 147 acre-ft |
| Max Storage | 147 acre-ft |
| Normal Storage | 29 acre-ft |
| Surface Area | 8 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 787 cfs |
Ownership & Safety
| Purpose | Other |
| Owner | Nemaha Natural Resources District |
| Owner Type | Local Government |
| Hazard Classification | Low |
| Condition Assessment | Satisfactory |
| Last Inspection | 05/24/2023 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | NE00640 |
| Federal ID | NE00640 |
| More Info | State Dam Safety Program |