The Colorado River is the major body of water that flows through the Grand Canyon. Two dams affect the flow of the river through the canyon: the Hoover Dam at the lower end of the canyon and the Glen Canyon Dam at the upper end, according to Arizona State University.
The river's headwaters are found at Colorado's Rocky Mountain National Park, according to About.com. The river travels throughout the Southwest, including the 217-mile length of the Grand Canyon, before reaching Mexico. Individuals who wish to travel along the river through the canyon need a permit for the trip, according to the National Park Service.