Three Mile Creek Watershed Site U-3 is a critical water resource located in Union, Iowa, and managed by the local government. Designed by USDA NRCS, this earth dam stands at a height of 23 feet and serves multiple purposes including fire protection, stock, and small fish pond management, as well as flood risk reduction. Completed in 1980, the dam has a storage capacity of 180 acre-feet and covers a surface area of 7.5 acres, with a drainage area of 0.55 square miles.

Despite its low hazard potential and moderate risk assessment, Three Mile Creek Watershed Site U-3 is regulated by the Iowa DNR and undergoes regular state inspections, permitting, and enforcement. Located along the TR-Three Mile Creek, this dam plays a crucial role in managing water resources in the region. With a spillway type of uncontrolled, the dam does not have outlet gates and is not currently rated for its condition assessment. Overall, this site is a key asset for water resource and climate enthusiasts interested in the management of dams and flood control structures in the area.