Fishermen try their luck in the South Platte River as it crosses from Douglas into to Jefferson County, Colorado, in Waterton Canyon, south of Denver. The 6.2-mile trail along the canyon, which is managed by the Denver Water utility and the U.S. Forest Service, is one of fitness-conscious Coloradans' favorite hiking, biking, and horseback-riding venues. Photo by Carol Highsmith, 2016.