Longeley
Longeley is an earth dam located in Niobrara County, Wyoming, built in 1972. It carries a Low hazard potential classification and has a poor condition assessment.
About Longeley
The primary purpose of Longeley is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Tetrad Corporation (private). It impounds the Longely Draw.
The dam stands 22 feet tall and stretches 685 feet across, creates a reservoir covering 9 acres, and has a maximum storage capacity of 88 acre-feet. Completed in 1972, 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 04/22/2024.
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Location
| State | Wyoming |
| County | Niobrara |
| River/Stream | Longely Draw |
| Coordinates | 43.27222, -104.17194 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 22 ft |
| Dam Height | 22 ft |
| Dam Length | 685 ft |
| Year Completed | 1972 (54 years old) |
Storage & Hydraulics
| NID Storage | 88 acre-ft |
| Max Storage | 88 acre-ft |
| Normal Storage | 43 acre-ft |
| Surface Area | 9 acres |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | TETRAD CORPORATION |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Poor |
| Last Inspection | 04/22/2024 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | WY01743 |
| Federal ID | WY01743 |
| More Info | State Dam Safety Program |