Erramouspe, also known as Poston Reservoir, is a private water resource located in Sublette, Wyoming, specifically in the city of Farson. Completed in 1957, this earth dam serves multiple purposes including fire protection, stock watering, and providing a small fish pond. With a dam height of 15 feet and a storage capacity of 509 acre-feet, Erramouspe plays a crucial role in water management in the area.

Managed by the Wyoming State Engineer's Office, Erramouspe has a low hazard potential and is classified as being in fair condition as of the last inspection in August 2021. The reservoir has a surface area of 26 acres and is regulated and inspected by the state to ensure its safety and functionality. Situated on Elk Wash, a stream in Wyoming, Erramouspe serves as a vital resource for the surrounding community and ecosystem.

Despite its modest size and operational history, Erramouspe has a moderate risk assessment rating of 3, indicating the need for ongoing monitoring and risk management measures. With Liz Cheney representing the area in Congress, this reservoir highlights the intersection of water resource management, climate resilience, and local governance. For water resource and climate enthusiasts, Erramouspe offers a fascinating case study of a privately owned dam contributing to the sustainability and well-being of its region.