Rock Rapids Milldam in Iowa, built in 1931, serves as a crucial water supply structure for the region. It is a gravity dam standing at 7 feet high and 220 feet long, with a storage capacity of 75 acre-feet and a normal storage of 49 acre-feet. Located on the Rock River in Lyon County, this dam is state-regulated by the Iowa Department of Natural Resources, ensuring proper permitting, inspection, and enforcement measures are in place.

The dam's primary purpose is water supply, supporting the surrounding community with its storage capacity and surface area of 10 acres. Though categorized as low hazard potential with a moderate risk assessment, its condition has not been rated since its last inspection in 1989. Despite its age, the Rock Rapids Milldam continues to play a vital role in water resource management and climate resilience efforts in the area, with the state ensuring regulatory oversight to safeguard its operations and structural integrity for years to come.

With a state-regulated status and low hazard potential, the Rock Rapids Milldam stands as a testament to effective water management practices in Iowa. Its historical significance and role in water supply underscore the importance of maintaining and monitoring such structures to ensure their continued functionality and safety. As climate change impacts water resources, the presence of well-regulated dams like Rock Rapids Milldam becomes increasingly crucial for sustainable water supply and management in the region, making it a notable site for water resource and climate enthusiasts to study and appreciate.