Rathbun Irrigation No. 1 is a privately owned irrigation facility located in Kirby, Hot Springs County, Wyoming. This earth dam structure, completed in 1956, serves as a crucial resource for agricultural water management in the region. The dam has a height of 29 feet and a storage capacity of 38 acre-feet, providing essential water for irrigation purposes along Dry Fork W Kirby Creek.

Despite being classified as having a low hazard potential and fair condition assessment, Rathbun Irrigation No. 1 is regulated by the state of Wyoming and subject to regular inspections to ensure its structural integrity. The dam features a slide gate outlet system and an uncontrolled spillway, with a moderate risk assessment rating of 3. While the facility has not been significantly modified in recent years, it remains an important component of the local water resource infrastructure, contributing to the sustainable management of water resources in the area.

Managed by the Omaha District of the US Army Corps of Engineers, Rathbun Irrigation No. 1 plays a vital role in supporting agricultural activities in Hot Springs County. With its strategic location and reliable water supply, this irrigation facility continues to be a cornerstone of the region's water management efforts, highlighting the importance of maintaining and monitoring such infrastructure for the benefit of both the community and the environment.