Dd No 242 is a local government-owned earth dam in Lyon, Kansas, designed by King Engineering and completed in 1999. The dam's primary purpose is flood risk reduction, with additional functions including debris control. It stands at 24 feet high, with a length of 1200 feet, offering a storage capacity of 186.39 acre-feet and a surface area of 6.99 acres. The dam's location on Buff Creek-TR in the Kansas City District makes it a vital structure for managing water resources in the area.

Despite its low hazard potential, Dd No 242 plays a crucial role in mitigating flood risks in the region, with a moderate risk rating. The dam features an uncontrolled spillway with a width of 55 feet and has not been subject to any modifications since its construction. While the dam's condition has not been officially assessed, its emergency action plan status and risk management measures are currently unlisted. With its strategic positioning and functionality, Dd No 242 serves as a key asset for water resource management and climate resilience efforts in Lyon, Kansas.