Attril Dam in Sioux City, Iowa, is a privately owned structure designed by USDA NRCS for fire protection, stock, or small fish pond purposes. Completed in 1962, this earth dam stands at a height of 32 feet and spans 464 feet in length, with a storage capacity of 58 acre-feet. Situated on the TR-West Branch Perry Creek, the dam is regulated by the Iowa DNR and undergoes regular inspections, with a low hazard potential and moderate risk assessment.

Despite its age, Attril Dam continues to serve its primary functions effectively, with a surface area of 3.4 acres and a drainage area of 0.34 square miles. The dam features an uncontrolled spillway and soil foundation, contributing to its overall structural integrity. While its condition assessment is currently not rated, the dam's risk management measures are in place to ensure the safety of the surrounding area in the event of an emergency. With its strategic location and purposeful design, Attril Dam remains a noteworthy feature for water resource and climate enthusiasts in the region.