J & J is an earth dam located in Natrona County, Wyoming, built in 1942. It carries a Low hazard potential classification and has a poor condition assessment.
Dam profile
NID height · 25 ft25 ft tall and 918 ft long, taller than 50% 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 J & J
The primary purpose of J & J is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Wild Horse Basin Ranch (private). It impounds the Poison Spider Cr near Casper.
The dam stands 25 feet tall and stretches 918 feet across, creates a reservoir covering 173 acres, and has a maximum storage capacity of 2,449 acre-feet. Completed in 1942, the structure is well-established, with more than 75 years of service.
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 06/21/2023.
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Location
| State | Wyoming |
| County | Natrona |
| Nearest City | Casper |
| River/Stream | Poison Spider Cr |
| Coordinates | 42.86472, -106.91972 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 25 ft |
| Dam Height | 25 ft |
| Dam Length | 918 ft |
| Year Completed | 1942 (84 years old) |
Storage & Hydraulics
| NID Storage | 2,449 acre-ft |
| Max Storage | 2,449 acre-ft |
| Normal Storage | 1,423 acre-ft |
| Surface Area | 173 acres |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | Wild Horse Basin Ranch |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Poor |
| Last Inspection | 06/21/2023 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | WY00239 |
| Federal ID | WY00239 |
| More Info | State Dam Safety Program |