Little Onion Dam, located in Humboldt, Nevada, is a private-owned structure designed by Sprout Engineering for irrigation purposes along Alder Creek. The earth dam stands at 31 feet high with a hydraulic height of 26 feet and a structural height of 35 feet, providing a maximum storage capacity of 325 acre-feet. With a spillway width of 36 feet and a maximum discharge of 4000 cubic feet per second, the dam serves multiple purposes including fire protection, stock, small fish pond, irrigation, and recreation.

The dam, built in 1959 and last inspected in June 2019, has a significant hazard potential and fair condition assessment. Despite its age, the structure meets regulatory standards set by the Nevada Department of Water Resources, with regular inspections and enforcement ensuring its safety. While the risk assessment categorizes it as moderate, with a risk score of 3, the dam's emergency action plan and inundation maps status remain unclear. Little Onion Dam plays a crucial role in water resource management in the region, highlighting the intersection of infrastructure, climate adaptation, and environmental stewardship.