The cornerstone of the park is the , Lake Pleasant, one of the important artificial reservoirs surrounding the Phoenix metropolitan area. Created by the Carl Pleasant Dam, which was finished in 1927, and upon completion, was the largest multi-arch dam in the world. The lake originally had a surface area of and served as a private irrigation project. At high and long, the original Carl Pleasant Dam was, at its completion, the largest agricultural dam project in the world. The lake was filled by the Agua Fria River, capturing a large watershed throughout Yavapai County.