Runholt-Mellenthin is a privately owned earth dam located in Lyon County, Minnesota, on the Redwood River. Constructed in 1958 by the USDA NRCS, this dam serves multiple purposes including fire protection, stock, and small fish pond management. With a height of 18 feet and a length of 340 feet, it has a storage capacity of 55 acre-feet and a drainage area of 0.5 square miles. The dam has a low hazard potential and a satisfactory condition assessment, last inspected in March 2017.

Managed by the Minnesota Department of Natural Resources, the Runholt-Mellenthin dam is regulated, permitted, inspected, and enforced by state agencies. It falls under the jurisdiction of the MNDNR EWR and the primary source agency is the state of Minnesota. The dam has uncontrolled spillways and outlet gates, with a maximum discharge of 140 cubic feet per second. The risk assessment for this dam is moderate, indicating potential hazards that require ongoing management and monitoring to ensure public safety and environmental protection.

In the event of an emergency, there are procedures in place to address potential risks associated with the dam. While the dam has not been modified in recent years, regular inspections every 8 years help assess its condition and identify any necessary maintenance or improvements. With its critical role in water resource management and protection, Runholt-Mellenthin serves as a vital infrastructure for the local community and ecosystem along the Redwood River in Minnesota.