Casto is a privately owned irrigation dam situated in Gateway, Mesa County, Colorado. Built in 1940, this Earth-type dam stands at 26 feet high with a storage capacity of 1298 acre-feet to support agricultural activities in the region. The dam, located on Gill Creek, has a spillway width of 50 feet and an uncontrolled spillway type, with a significant hazard potential but assessed to be in fair condition as of June 2020.

Managed by the Colorado Department of Water Resources, Casto Dam plays a crucial role in water resource management and irrigation in the area. With a drainage area of 9 square miles and a maximum discharge capacity of 1470 cubic feet per second, the dam serves as a vital infrastructure for maintaining water supply and controlling downstream flows. Despite its age, the dam continues to be inspected regularly to ensure its structural integrity and safety.

Even though Casto Dam has a moderate risk profile and is categorized as having a significant hazard potential, it remains an essential component of the water resource infrastructure in Mesa County. With its strategic location and function in supporting agricultural activities, the dam contributes to the overall water management efforts in the region. As climate change continues to impact water availability and usage, structures like Casto Dam play a crucial role in ensuring sustainable water resource development and utilization.