The Mason City-Lehigh Cement Milldam is a historic structure located in Cerro Gordo County, Iowa, along the Calmus Creek. Built in 1924, this gravity dam serves as a vital water supply source for the area, with a storage capacity of 150 acre-feet and a normal storage level of 75 acre-feet. The dam has a height of 8 feet and a length of 71 feet, helping to regulate the flow of water and maintain a surface area of 20 acres.

Managed by a private owner, the Mason City-Lehigh Cement Milldam is regulated by the Iowa Department of Natural Resources and undergoes regular inspections to ensure its structural integrity and safety. Despite its low hazard potential, the dam is classified as having a moderate risk level due to its age and lack of recent condition assessments. While the dam's spillway type is listed as uncontrolled, the risk management measures and emergency action plans for the structure are currently not rated or prepared.

For water resource and climate enthusiasts, the Mason City-Lehigh Cement Milldam represents a piece of Iowa's water infrastructure history. With its unique design and role in providing water supply, this gravity dam serves as a reminder of the importance of maintaining and monitoring our water resources to ensure safety and sustainability for future generations.