Boulder Canyon (Colorado River) steamboats as they passed over the dangerous rapids of Devil's Gate Canyon, during their high water runs to the mouth of the Virgin River at Rioville, Nevada. Boulder Canyon (Colorado River) Boulder Canyon, originally Devils Gate Canyon, is a canyon on the Colorado River, above Hoover Dam, now flooded by Lake Mead. It lies between Clark County, Nevada and Mohave County, Arizona. It heads at western end of the Virgin River Basin of Lake Mead, at about . Boulder Canyon divides the Black Mountains into the Black Mountains of Arizona, and the Black Mountains of Nevada. Its mouth is now
Big Bend of the Colorado State Recreation Area Big Bend of the Colorado State Recreation Area Big Bend of the Colorado State Recreation Area is a public recreation area located in the Lower Colorado River Valley within the city of limits of Laughlin in southern Clark County, Nevada. The park is located directly across the Colorado River from Bullhead City, Arizona, and is approximately downstream of the Davis Dam. The park has two miles of shoreline and riparian areas. The majority of its consists of canyons and washes. The Fort Mohave Land Act of 1960 saw the transfer of of federal land in the Laughlin Big Bend area