Union Grove Lake Dam, located in Garwin, Iowa, is a state-regulated structure with a primary purpose of recreation. Completed in 1920, this earth dam stands at a height of 29 feet and has a length of 1205 feet. The dam provides a storage capacity of 2120 acre-feet, with a normal storage level of 770 acre-feet and a surface area of 117 acres.

Managed by the Iowa Department of Natural Resources, Union Grove Lake Dam has a significant hazard potential and was last assessed to be in fair condition in June 2018. The dam features an uncontrolled spillway with a width of 76 feet and is situated on the Deer Creek, within the Detroit District of the US Army Corps of Engineers. With a moderate risk assessment rating of 3, the dam undergoes inspections every five years to ensure its safety and functionality for water resource and climate enthusiasts who enjoy the recreational activities offered at the lake.