Mc Millan Dam in Decatur, Iowa, is a privately owned structure that serves multiple purposes including fire protection, stock, and small fish pond management. Completed in 1987, this earth dam stands at a height of 28 feet and stretches 510 feet in length, with a storage capacity of 71 acre-feet. Situated on the TR-LITTLE river, this dam is regulated by the Iowa Department of Natural Resources and is subject to regular inspections, permitting, and enforcement to ensure its safety and compliance with state regulations.

With a low hazard potential and a moderate risk assessment rating, Mc Millan Dam is considered to be in good condition but has not been formally assessed. Despite its uncontrolled spillway type and lack of outlet gates, this structure plays a vital role in water resource management for the local area. While it may not be a high-profile dam, its importance for fire protection and environmental conservation makes it a significant asset in the region. For water resource and climate enthusiasts, Mc Millan Dam serves as a reminder of the diverse ways in which dams can contribute to sustainable water management practices.