Fillmore County Road 21 is a vital infrastructure designed by the USDA NRCS to mitigate flood risks along the Root River in Whalan, Minnesota. Completed in 1979, this earth dam stands at a height of 31 feet and spans 500 feet, providing essential flood risk reduction for the region. Owned by the local government and regulated by the MNDNR EWR, this structure plays a critical role in safeguarding the surrounding area from potential water-related hazards.

With a significant hazard potential and a satisfactory condition assessment, Fillmore County Road 21 is a key component in the area's water resource management. The dam's primary purpose is flood risk reduction, with a storage capacity of 52 acre-feet and a drainage area of 0.36 square miles. Despite its uncontrolled spillway and outlet gates, regular inspections ensure its structural integrity and functionality, with the last assessment conducted in May 2019. The dam's moderate risk level underscores the importance of continued monitoring and risk management measures to ensure the safety and resilience of the community against potential emergencies.