Posy No. 1
Posy No. 1 is an earth dam located in Johnson County, Wyoming, built in 1995. It carries a Low hazard potential classification and has a fair condition assessment.
About Posy No. 1
The primary purpose of Posy No. 1 is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Ttt Ranch Co (private). It impounds the Posy Creek near Sussex.
The dam stands 52 feet tall and stretches 1,788 feet across, creates a reservoir covering 125 acres, has a maximum storage capacity of 2,162 acre-feet, and collects water from a drainage area of 15 square miles. Completed in 1995, the structure is 31 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 fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. The most recent inspection on record was 06/12/2025.
At 52 feet, this dam is taller than 93% of dams nationwide.
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Location
| State | Wyoming |
| County | Johnson |
| Nearest City | Sussex |
| River/Stream | Posy Creek |
| Coordinates | 43.51300, -106.69130 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 52 ft |
| Dam Height | 51 ft |
| Dam Length | 1,788 ft |
| Year Completed | 1995 (31 years old) |
Storage & Hydraulics
| NID Storage | 2,162 acre-ft |
| Max Storage | 2,162 acre-ft |
| Normal Storage | 1,537 acre-ft |
| Surface Area | 125 acres |
| Drainage Area | 15 sq mi |
| Max Discharge | 6,650 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | TTT RANCH CO |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Fair |
| Last Inspection | 06/12/2025 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | WY02048 |
| Federal ID | WY02048 |
| More Info | State Dam Safety Program |