Black Canyon of the Colorado the Nevada side of the canyon is the Sauna Cave. This cave was drilled by miners working on Hoover Dam while it was being constructed. It is a deep cave with calcium carbonate crystals on the walls. At the end of the cave is a hot spring, which causes temperatures in the cave to reach . One prominent canyon that splits from this canyon south of the Hoover Dam is Boy Scout Canyon. Boy Scout Canyon has water running through it that is warmed from a geothermal source. On the Arizona side of the river, there are several large hot
Course of the Colorado River flows through the Parker Valley, much of which belongs to the Colorado River Indian Reservation, and then the Palo Verde Valley, where it is crossed by Interstate 10 near Blythe, California. The small Headgate Rock Dam removes water for irrigation in the Parker Valley and the Palo Verde Dam provides water to the Palo Verde Valley. The river then flows through a canyon in the Trigo Mountains, where the Cibola and Imperial National Wildlife Refuge encompass the wetland areas formed above Imperial Dam, which filled with silt shortly upon its completion in the 1930s. Most of the Colorado's remaining flow