Three Mile Creek Watershed Site 42 in Union, Iowa, is a water resource managed by the local government with oversight from the Iowa DNR. This site, designed by USDA NRCS, serves multiple purposes including flood risk reduction. The primary dam type is earth with a height of 35 feet and a length of 504 feet, completed in 1970 to store a maximum of 91 acre-feet of water for a drainage area of 0.12 square miles.

Located in Talmage along TR-Three Mile Creek, this low hazard potential dam has a moderate risk assessment rating. While not currently rated for condition assessment, the site has not been subject to inspection or maintenance updates. Despite these challenges, the watershed site provides crucial flood mitigation and water storage capabilities for the surrounding area. For water resource and climate enthusiasts, Three Mile Creek Watershed Site 42 offers a unique case study in local government water management and the challenges of maintaining aging infrastructure in the face of changing climate conditions.