Don Alt Dam is an earth dam located in Polk County, Nebraska, built in 1969. It carries a Low hazard potential classification and has a poor condition assessment.
Dam profile
NID height · 21 ft21 ft tall and 610 ft long. 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 Don Alt Dam
The primary purpose of Don Alt Dam 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 Polk County (local government). It impounds the Tr-big Blue River near Surprise.
The dam stands 21 feet tall and stretches 610 feet across, creates a reservoir covering 5 acres, has a maximum storage capacity of 110 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1969, 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 poor, meaning the dam has recognized safety deficiencies that require remediation to address risks. The most recent inspection on record was 06/21/2022.
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Location
| State | Nebraska |
| County | Polk |
| Nearest City | Surprise |
| River/Stream | Tr-big Blue River |
| Coordinates | 41.09044, -97.43107 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 21 ft |
| Dam Height | 19 ft |
| Dam Length | 610 ft |
| Year Completed | 1969 (57 years old) |
Storage & Hydraulics
| NID Storage | 110 acre-ft |
| Max Storage | 110 acre-ft |
| Normal Storage | 14 acre-ft |
| Surface Area | 5 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 673 cfs |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | Polk County |
| Owner Type | Local Government |
| Hazard Classification | Low |
| Condition Assessment | Poor |
| Last Inspection | 06/21/2022 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | NE00012 |
| Federal ID | NE00012 |
| More Info | State Dam Safety Program |