Little Yellow 20, located in Necedah, Wisconsin, is a state-regulated dam with a primary purpose of irrigation. Completed in 1936, this gravity dam stands at a height of 8 feet and has a storage capacity of 70 acre-feet. The dam serves multiple purposes including irrigation, recreation, and water supply, with a drainage area of 3.9 square miles and a maximum discharge of 486 cubic feet per second.

Despite its low hazard potential, Little Yellow 20 is classified as having a very high risk level, emphasizing the importance of effective risk management measures. The dam has not been rated for its condition assessment, with the last inspection taking place in June 2007. With a controlled spillway type and a surface area of 10 acres, this dam plays a crucial role in the water resource management of the area. Water and climate enthusiasts will find Little Yellow 20 to be an intriguing structure with a rich history and significant impact on the local ecosystem.