Hornet Creek Upper South is a privately-owned irrigation dam located in Washington County, Idaho, completed in 1913. The dam, built primarily for irrigation purposes, stands at a height of 19.3 feet and has a hydraulic height of 15.3 feet. With a storage capacity of 265 acre-feet and a drainage area of 0.6 square miles, the dam serves as a crucial water resource for the surrounding area.

Although the dam's condition was assessed as fair during the last inspection in August 2017, it is classified as having a significant hazard potential. The risk assessment has categorized it as high (2), indicating the need for appropriate risk management measures. Despite the challenges posed by its condition and hazard potential, the dam continues to play a vital role in water resource management in the region, highlighting the importance of addressing maintenance and safety concerns to ensure its continued functionality for irrigation and water supply purposes.

With its historical significance and role in supporting agricultural activities, Hornet Creek Upper South serves as a reminder of the intricate relationship between water resources, climate, and human development. As climate change poses new challenges to water management, maintaining the integrity and safety of structures like this dam becomes increasingly important in ensuring sustainable water access for both current and future generations.