Hopkinton Milldam, located in Delaware County, Iowa, is a gravity dam constructed in 1925 along the Maquoketa River. With a height of 10 feet and a length of 175 feet, the dam serves primarily for recreational purposes, providing a surface area of 90 acres and a storage capacity of 433 acre-feet. Despite being uncontrolled, the spillway width is not specified, indicating a potential risk for overflow during periods of heavy rainfall.

Managed by the local government and regulated by the Iowa Department of Natural Resources, the dam is classified as low hazard potential with a moderate risk assessment rating of 3. The condition of the dam is currently labeled as "Not Rated," with the last inspection conducted in June 1999. Although the dam has not been modified in recent years, it remains subject to state permitting, inspection, and enforcement to ensure public safety and environmental protection.

With its picturesque location and historical significance, Hopkinton Milldam stands as a vital recreational landmark along the Maquoketa River. Its presence not only enhances the local scenery but also serves as a reminder of the importance of maintaining and monitoring water resources in the face of changing climate conditions. Enthusiasts of water resource management and climate resilience will find Hopkinton Milldam a fascinating case study in dam infrastructure and regulatory oversight.