Marion Dam, also known as Marion Reservoir, is a gravity dam located on the Cottonwood River in Marion, Kansas. Built in 1968 by the US Army Corps of Engineers, the dam serves primarily for flood risk reduction but also supports recreation and water supply purposes. With a height of 67 feet and a length of 8375 feet, Marion Dam has a storage capacity of 189,200 acre-feet and covers a surface area of 6210 acres.

The dam is classified as having a high hazard potential, primarily due to the risk of water erosion leading to breach. In the event of a failure, downstream communities such as Marion, Florence, Cedar Point, Elmdale, and Strong City would be impacted. Despite this risk, the USACE has implemented various risk management measures including emergency exercises, regular inspections, and a detailed communication plan. Additionally, the dam is equipped with instrumentation and monitoring systems to detect any changes in conditions.

Overall, Marion Dam plays a crucial role in mitigating flood risks in the region and is actively maintained to ensure the safety of surrounding communities. Its strategic location on the Cottonwood River underscores the importance of proper risk management practices to safeguard against potential threats.