Born of the spring snowmelt from Mount Dana and Mount Lyell, the Tuolumne starts in Yosemite National Park and runs for over fifty miles before entering the Stanislaus National Forest and public land managed by the Federal Bureau of Land Management. Flowing through some of America’s most glorious scenery, its whitewater rapids require respect as well as permits before entering its turbulent rifts. If you choose to float the river, the optimal time is between May and September. Water levels vary according to releases made by the Hetch Hetchy Water and Power agency as they manage the dam. Permits can be obtained from the Stanislaus National Forest’s Groveland Ranger District Office or by visiting the US Forest Service website.