Hawthorne Lake Dam, located in Mahaska, Iowa, is a significant earth dam completed in 1979 for the primary purpose of recreation. Managed by the Iowa Department of Natural Resources, this state-regulated structure stands at 45 feet high and spans 900 feet in length, creating a surface area of 160 acres and a drainage area of 5.2 square miles along Pleasant Creek. With a normal storage capacity of 1890 acre-feet and a maximum storage of 4100 acre-feet, this dam provides essential water resources for the surrounding area.

Despite its satisfactory condition assessment, Hawthorne Lake Dam is classified as having a significant hazard potential, prompting regular inspections every five years to ensure its structural integrity and safety. The dam's spillway type is uncontrolled, with a width of 4 feet, and it is situated in a remote location in Lace, Iowa, under the jurisdiction of the Rock Island District of the US Army Corps of Engineers. As an important landmark for water resource and climate enthusiasts, Hawthorne Lake Dam serves as a vital recreational and water management asset for the community, reflecting a moderate risk assessment score of 3.