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
Colorado City, Nevada Nevada. In 1866, Colorado City became the site of two stamp mills, located there for ease of supplying wood to operate its steam driven mechanism. One was the old Colorado Mill brought down the canyon from El Dorado City, and refurbished. The other was the new New Era Mill. The site of Colorado City, and the Colorado River it was adjacent to, was submerged under Lake Mohave following the construction of the Davis Dam in 1951. What remains of Colorado City lies offshore from the site of Nelson's Landing. Colorado City, Nevada Colorado City is now a ghost town, in