Black Canyon of the Gunnison: The Gorge That Took Forty-Eight Miles to Form

The Gunnison River drops more elevation per mile than almost any other river in North America. Through the Black Canyon, the steepest section, it falls as much as two hundred forty feet per mile in its steepest stretch, carving through roughly one point seven billion year old Precambrian schist and gneiss that is among the oldest exposed rock on the continent. The result is a canyon forty-eight miles long with walls that drop two thousand seven hundred feet at the deepest point, walls so sheer and the canyon so narrow that some sections receive only thirty minutes of sunlight per day.

The rock is dark, a combination of the schist and gneiss and the dark vertical streaks of lighter pegmatite intrusions running through it, which gives the canyon both its name and its visual character. The entire canyon corridor is managed across two jurisdictions: Black Canyon of the Gunnison National Park at the deepest, most dramatic central section, and the Curecanti National Recreation Area upstream, where three Bureau of Reclamation dams have turned the upper Gunnison into a series of reservoirs. The Grand Mesa, Uncompahgre, and Gunnison National Forests surround the canyon rim on multiple sides.

Water from the Gunnison was the subject of an early twenty-first-century legal agreement that guaranteed a minimum flow through the canyon after the upstream dams had reduced the river significantly. The agreement required releasing enough water to maintain the trout fishery and prevent further canyon floor erosion. The legal category for this type of agreement, federal reserved water rights for national parks and wilderness, was established in part through litigation involving the Gunnison itself.

The canyon is viewable from the rim. The river is reachable, but only by technical rappels on routes that require a permit and a tolerance for several hundred feet of vertical descent on Precambrian schist.