Thomsen Dam, located in Anthon, Iowa, along the TR-Little Sioux River, was completed in 1959 by the USDA NRCS and serves multiple purposes including fire protection, stock, and small fish pond. With a dam height of 38 feet and a length of 550 feet, the earth dam holds a normal storage capacity of 49 acre-feet and a maximum storage capacity of 91 acre-feet. The dam's low hazard potential and moderate risk assessment make it a crucial asset for water resource management in Woodbury County.

Managed by a private owner, Thomsen Dam is regulated by the Iowa DNR and undergoes state inspection and enforcement to ensure its structural integrity. The dam's primary source agency is the state of Iowa, and it falls under the jurisdiction of the Rock Island District. Despite its uncontrolled spillway type and lack of outlet gates, the dam's risk management measures and moderate risk assessment highlight its importance in mitigating potential flood risks and ensuring water resource sustainability in the region.

Water resource and climate enthusiasts will be captivated by Thomsen Dam's role in providing essential services such as fire protection and stock pond maintenance while also serving as a habitat for small fish species. Its location along the TR-Little Sioux River and its significant storage capacity make it a key infrastructure for water management in Woodbury County. With a focus on safety and risk management, the dam stands as a vital asset in safeguarding the surrounding communities and ecosystems from potential water-related hazards.