Hornet Creek Lower is a privately-owned irrigation structure situated in the remote areas of Washington County, Idaho. Built in 1913, this earth dam stands at a height of 26.3 feet and has a hydraulic height of 23 feet, serving the primary purpose of irrigation for the surrounding agricultural lands. The dam boasts a storage capacity of 150 acre-feet and covers a surface area of 16 acres, drawing water from Hornet Creek and Weiser River.

Maintained and regulated by the Idaho Department of Water Resources, Hornet Creek Lower has a low hazard potential and is currently assessed to be in fair condition as of the last inspection in August 2017. The dam features an uncontrolled spillway with a width of 9 feet and outlet gates that consist of slide (sluice gate) mechanisms. With a moderate risk rating of 3, the structure is inspected every 4 years to ensure its continued safe operation. Despite its age, Hornet Creek Lower plays a crucial role in the local irrigation system, contributing to the agricultural productivity of the region while complying with state regulations and enforcement measures.