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 is removed for irrigation here. The Gila Gravity Main Canal provides water for the Gila Valley in Arizona. The All-American Canal, which runs west to the Imperial Valley of California, is the largest irrigation canal in the world, capable of carrying – the entire natural flow of the Colorado prior to damming. The canal supplies more than half a million acres (2000 km) which due to its mild climate grows most of the winter produce in the United States. Below Imperial Dam the remnants of the Colorado river lessen in gradient and in its lower course flows through the Colorado