A hiker has been missing in Yosemite National Park since last weekend after being swept away by a cold and fast-flowing creek as California’s epic winter snowpack melts. The National Park Service says Hayden T. Klemenok vanished while backpacking with a group at Upper Chilnualna Fall on July 2. The section of creek is a dozen miles south of Yosemite Valley and features a series of waterfalls and cascades that plunge hundreds of feet. Klemenok’s parents told The San Francisco Chronicle that his friends say the 24-year-old from Petaluma, California, had gotten down on all fours to wet his face, but his hands slipped and he went into the water.