Mosier No. 1 is a privately owned earth dam located on Little Boggy Creek in Niobrara, Wyoming. Built in 1974 by designer J. H. Coffman, this dam serves primarily for irrigation purposes, with a storage capacity of 60 acre-feet and a normal storage level of 35 acre-feet. The dam stands at a height of 22 feet, with a hydraulic height of 17 feet and a structural height of 26 feet, spanning a length of 350 feet.

Despite its low hazard potential and fair condition assessment, Mosier No. 1 has a moderate risk rating, indicating a need for ongoing monitoring and potential risk management measures. The dam features an uncontrolled spillway with a width of 298 feet, capable of handling a maximum discharge of 1686 cubic feet per second. With an inspection frequency of 5 years, the last assessment was conducted in May 2017, highlighting the importance of regular maintenance to ensure the continued safety and functionality of this essential water resource infrastructure in Wyoming.

As climate change continues to impact water resources and infrastructure, the significance of dams like Mosier No. 1 in supporting agricultural irrigation and water supply systems becomes increasingly apparent. With its strategic location and key role in water management for the region, ongoing monitoring and risk assessment are crucial to mitigate potential hazards and ensure the resilience of this vital structure in the face of evolving environmental challenges.