Dd No 20, located in Lyon County, Kansas, is a flood risk reduction structure built in 2001 and owned by the local government. The dam, with a height of 23 feet and a length of 1555 feet, serves the primary purpose of flood risk reduction along Dow Creek. With a storage capacity of 661.58 acre-feet and a normal storage volume of 68.89 acre-feet, the dam plays a crucial role in mitigating flood hazards in the area.

Managed and regulated by the Kansas Department of Agriculture, Dd No 20 has a low hazard potential and is currently rated as "Not Rated" in terms of condition assessment. The dam has a spillway width of 120 feet and is classified as an uncontrolled spillway type. Despite not having outlet gates, the structure is designed to effectively manage water flow during heavy rainfall events. The risk assessment for Dd No 20 is moderate, indicating a potential for moderate consequences in the event of a failure.

Overall, Dd No 20 is a vital infrastructure for flood risk reduction in Lyon County, Kansas. Its strategic location along Dow Creek and its efficient design make it an essential component of the local water resource management system. As climate change continues to impact precipitation patterns and increase the frequency of extreme weather events, structures like Dd No 20 play a crucial role in protecting communities and infrastructure from flooding and its associated risks.