Dry Poison Irrigation, located in Johnson County, Wyoming, is a privately owned earth dam built in 1970 for the primary purpose of irrigation along the Murphy Draw river system. With a structural height of 36 feet and a capacity of 122 acre-feet, the dam services a surface area of 5 acres and has a spillway width of 10 feet. Despite its low hazard potential, the dam's condition assessment is deemed poor, highlighting the need for regular inspections and maintenance to ensure its structural integrity.

The irrigation dam is under state regulation and jurisdiction, with permitting, inspection, and enforcement carried out by the Wyoming State Engineer's Office. The last inspection in July 2019 revealed a moderate risk level, prompting the need for risk management measures to mitigate potential hazards. While the dam's hazard potential is low, its poor condition assessment underscores the importance of proactive maintenance to prevent any unforeseen emergencies that could impact the surrounding area.

As a crucial component of water resource management in the region, Dry Poison Irrigation plays a vital role in supporting agricultural activities in Arvada, Wyoming. With its close proximity to the Murphy Draw river system, the dam serves as a key infrastructure for water storage and distribution, highlighting the need for continued monitoring and maintenance to ensure the long-term sustainability of water resources in the area.