Riordan Dam, located in Monroe, Iowa, is a privately owned structure designed by USDA SCS and completed in 1967. This earth dam stands at a height of 22 feet and stretches 403 feet in length, with a primary purpose of providing fire protection and serving as a stock or small fish pond. With a storage capacity of 60 acre-feet, the dam covers a surface area of 3.7 acres and has a drainage area of 0.21 square miles.

Managed by the Iowa DNR, Riordan Dam is regulated by the state and undergoes regular inspections to ensure its safety and integrity. Despite being classified as having a low hazard potential, the dam is considered to have a moderate risk level. The spillway type is uncontrolled, and the dam is situated on the TR-Cedar Creek river or stream, serving the community of Tyrone. Enthusiasts of water resources and climate will find Riordan Dam to be a fascinating structure that plays a crucial role in providing essential services while mitigating risks associated with water management in the region.