Frd No 21, also known as Little Walnut Hickory WS Dam 21, is a vital flood risk reduction structure located in Leon, Butler County, Kansas. Built in 1965 by the USDA NRCS, this earth dam stands at a height of 32 feet and has a hydraulic height of 29 feet. With a storage capacity of 1511 acre-feet and a spillway width of 100 feet, Frd No 21 plays a crucial role in protecting the surrounding area from potential flooding events.

Managed by the Kansas Department of Agriculture, this dam is state-regulated and undergoes regular inspections to ensure its structural integrity. Despite being classified as having a low hazard potential, Frd No 21 is considered to have a moderate risk level. With its primary purpose being flood risk reduction, this dam serves as a key component in safeguarding the local community and infrastructure from the impacts of extreme weather events. Water resource and climate enthusiasts can appreciate the engineering and regulatory efforts that go into maintaining structures like Frd No 21 to protect against flooding and ensure public safety.