The Thunder Bay Lake Dam in Altoona, Iowa, is a privately owned structure designed by Snyder & Associates to address flood risk reduction in the area. Completed in 2010, this earth dam stands at a height of 19 feet and has a storage capacity of 119 acre-feet. Situated on the TR-Four Mile Creek, it covers a surface area of 5.6 acres and serves a drainage area of 0.63 square miles.

Managed by the Iowa Department of Natural Resources, the Thunder Bay Lake Dam is deemed to have a significant hazard potential but has not been rated for its condition. While it lacks certain regulatory and inspection data, its primary purpose of flood risk reduction is evident in its design and storage capacity. The dam plays a crucial role in managing water flow and protecting the surrounding area from potential flooding events.

With its strategic location and design, the Thunder Bay Lake Dam is a vital infrastructure for water resource management in Polk County, Iowa. Water and climate enthusiasts can appreciate the engineering efforts behind this structure, which serves as a key component in safeguarding the community against flood risks and ensuring the sustainable use of water resources in the region.