Torrents of meltwater coursed down the granite crevices below the moonscape of the Desolation Wilderness. Just miles from its source in the High Sierra, the South Fork of the American River was already roaring down toward the oaken foothills, bursting over the spillways of dams that humans had erected to control it. As it moved, it gathered streams and rivulets — pink and brown and orange from the minerals they leached. The heavy rain turned dusty creek beds into full-fledged tributaries. Running through narrowing clefts they burst forth as from hydraulic jets.