Thompson Dam, located in Decatur, Iowa, is a privately owned structure designed by USDA NRCS for fire protection, stock, or small fish pond purposes. Completed in 1990, this earth dam stands at a height of 26 feet and spans 400 feet in length. With a storage capacity of 86 acre-feet, the dam serves as a crucial water resource in the area, providing irrigation and livestock watering needs.

Managed by the Iowa Department of Natural Resources, Thompson Dam is regulated, inspected, and enforced to ensure its safety and functionality. The dam has a low hazard potential and a moderate risk assessment rating, indicating a need for ongoing monitoring and maintenance. While the dam has not been rated for its condition, it continues to play a vital role in water management and conservation efforts in the region.

The dam's location on TR- Lick Branch, in close proximity to the Rock Island District, highlights its importance in safeguarding against potential flooding and ensuring water availability for various uses. Despite its age, Thompson Dam remains a key infrastructure supporting the local ecosystem and agricultural activities, making it a significant asset for water resource and climate enthusiasts interested in sustainable water management practices.