Dry Poison Irrigation
Dry Poison Irrigation is an earth dam located in Johnson County, Wyoming, built in 1970. It carries a Low hazard potential classification and has a poor condition assessment.
About Dry Poison Irrigation
The primary purpose of Dry Poison Irrigation is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by James R. Purdy Revocable Trust (private). It impounds the Murphy Draw near Arvada.
The dam stands 36 feet tall and stretches 415 feet across, creates a reservoir covering 5 acres, and has a maximum storage capacity of 122 acre-feet. Completed in 1970, 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 08/12/2024.
At 36 feet, this dam is taller than 83% of dams nationwide.
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Location
| State | Wyoming |
| County | Johnson |
| Nearest City | Arvada |
| River/Stream | Murphy Draw |
| Coordinates | 44.10361, -106.73778 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 36 ft |
| Dam Height | 32 ft |
| Dam Length | 415 ft |
| Year Completed | 1970 (56 years old) |
Storage & Hydraulics
| NID Storage | 122 acre-ft |
| Max Storage | 122 acre-ft |
| Normal Storage | 61 acre-ft |
| Surface Area | 5 acres |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | JAMES R. PURDY REVOCABLE TRUST |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Poor |
| Last Inspection | 08/12/2024 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | WY00603 |
| Federal ID | WY00603 |
| More Info | State Dam Safety Program |