A-20, located in Fort Lupton, Colorado, is a privately owned irrigation dam that was completed in 1927. Standing at 16 feet high with a hydraulic height of 20 feet, this earth dam spans 1431 feet along Big Dry Creek-TR. It has a maximum storage capacity of 104 acre-feet and a normal storage of 64 acre-feet, serving the vital purpose of irrigation in the region.

Despite its age, A-20 has been well-maintained with a fair condition assessment as of the last inspection in September 2013. The dam has a low hazard potential, but a high risk assessment rating of 2 indicates a need for continued monitoring and management. While no spillway is present, the dam's design and structure have proven effective in managing the maximum discharge of 757 cubic feet per second.

This historic dam plays a crucial role in water resource management in Adams County, Colorado, serving as a reliable source for irrigation purposes. Its strategic location and design along Big Dry Creek-TR highlight the importance of sustainable water infrastructure in supporting agricultural activities and local communities in the face of changing climate conditions.