Greene Mill Dam, located in Greene, Iowa along the Shell Rock River, is a historic gravity dam that was completed in 1925 for hydroelectric purposes. With a height of 10.67 feet and a length of 282 feet, the dam has a normal storage capacity of 385 acre-feet and serves as a vital water resource in the region. Managed by a private owner, the dam is regulated by both state and federal agencies, including the Iowa Department of Natural Resources and the Federal Energy Regulatory Commission.

Despite its age, Greene Mill Dam has a low hazard potential and is considered to be in moderate risk condition. With an uncontrolled spillway and a maximum discharge capacity, the dam plays a crucial role in managing water flow and storage in the area. Regular inspections are conducted by regulatory agencies to ensure the structural integrity and safety of the dam, with the most recent inspection taking place in July 2018. Additionally, emergency action plans are in place to mitigate any potential risks and ensure the protection of downstream communities in case of a dam failure.

Overall, Greene Mill Dam stands as a testament to early 20th-century engineering and continues to contribute to the region's water resource management and hydroelectric power generation. As an integral part of the Shell Rock River watershed, the dam's historical significance and functional importance make it a focal point for water resource and climate enthusiasts interested in sustainable infrastructure development and management.