Mosquito Flat, located in Challis, Idaho, is a privately owned water resource site regulated by the Idaho Department of Water Resources. Constructed in 1950 by the State of Idaho in collaboration with USDA NRCS, this earth dam stands at a height of 58.4 feet and serves a primary purpose of "Other." It holds a storage capacity of 793 acre-feet, with a spillway width of 15 feet and a maximum discharge of 4360 cubic feet per second.

With a significant hazard potential and fair condition assessment as of August 2017, Mosquito Flat is closely monitored through inspections every four years. The dam's hydraulic height of 49.4 feet and stone core types contribute to its structural integrity. The site's risk assessment is moderate, indicating the need for ongoing risk management measures to ensure the safety of the surrounding areas, including Custer County, Idaho, and the Salmon River.

Despite its uncontrolled spillway type and slide outlet gates, Mosquito Flat remains a vital water management structure in the region, with a drainage area of 16.1 square miles and a surface area of 46 acres. Its location along Challis Creek and the Salmon River underscores its importance in managing water resources and mitigating potential flood risks in the area. Enthusiasts of water resources and climate management will find Mosquito Flat to be a fascinating example of collaborative efforts in water infrastructure development and regulation.