Owens River Gorge is a steep 10-mile canyon in eastern California where the upper Owens River leaves Long Valley and enters Owens Valley. The river carved the gorge through Bishop Tuff left by the Long Valley Caldera eruption, exposing layered volcanic rock and unusual columnar rhyolite that give the canyon its dramatic walls and attract climbers. Its modern history is also tied to river management: Long Valley Dam, built in 1941 for hydropower, led to complete dewatering of the lower gorge from 1953 to 1991. Since 1991, limited flows have returned to restore habitat and a brown trout fishery while hydropower diversions continue.