Smokey Hollow Subwatershed Site 4, located in Smithland, Iowa, is a local government-owned flood risk reduction structure designed by the USDA NRCS and regulated by the Iowa DNR. This earth dam, completed in 1985, stands at 64 feet high and spans a length of 620 feet, providing a storage capacity of 523 acre-feet. Situated along the Smokey Hollow River, this structure serves the primary purpose of flood risk reduction for the surrounding area, with a surface area of 4.7 acres and a drainage area of 0.54 square miles.

Despite its high hazard potential, Smokey Hollow Subwatershed Site 4 is currently assessed to be in fair condition, with regular inspections conducted every two years. The dam's spillway type is uncontrolled, with a width of 3 feet, and it has a moderate risk rating of 3. While there are no associated structures or locks, this site plays a crucial role in managing water resources and mitigating flood risks in the Woodbury County area. Water resource and climate enthusiasts will find this site to be a key component in the local watershed management system, ensuring the safety and well-being of the community.