Mcginnis Evaporation, located in Sublette, Wyoming, is a privately owned earth dam structure designed by Joseph C. Lord in 1984. This offstream reservoir has a dam height of 24 feet and a length of 456 feet, providing a storage capacity of 64 acre-feet. With a surface area of 5 acres, the dam serves a primary purpose other than flood control or water supply, reflecting its unique role in managing water resources in the region.

Despite its low hazard potential and fair condition assessment, Mcginnis Evaporation poses a high risk due to its location and design characteristics. The dam lacks a spillway and outlet gates, potentially increasing the risk of flooding in the event of heavy rainfall or snowmelt. Regular inspections are conducted every 5 years to ensure the structure's integrity and safety, with the last assessment performed in May 2021.

For water resource and climate enthusiasts, Mcginnis Evaporation presents an intriguing case study in dam design and risk management. Understanding the complexities of this earth dam structure, its purpose, and the challenges it faces in a changing climate can provide valuable insights into the sustainable management of water resources in arid regions like Wyoming.