The Mill Picayune Watershed Site M-21-5 is a vital earth dam located in Shelby, Iowa, designed by the USDA NRCS and completed in 1980. This watershed site plays a crucial role in fire protection, stock, and small fish pond purposes, as well as flood risk reduction. With a dam height of 45 feet and a storage capacity of 354 acre-feet, the site covers a surface area of 12.9 acres and has a drainage area of 1.13 square miles.

Managed by the Iowa DNR, this watershed site is state-regulated and undergoes regular inspections to ensure its structural integrity. The dam has a spillway type of "Uncontrolled" with a spillway width of 3 feet, posing a significant hazard potential but currently assessed as satisfactory in condition. While the risk assessment indicates a moderate level of risk, the watershed site serves as a critical resource for water management in the region, safeguarding against potential disasters and supporting the local ecosystem.

Overall, the Mill Picayune Watershed Site M-21-5 stands as a testament to effective water resource management in Iowa, contributing to water conservation, flood control, and ecosystem preservation. With its strategic location and design, this site serves as a beacon of resilience and protection for the community, highlighting the importance of sustainable practices in safeguarding our water resources amidst changing climate conditions.