The Grand Falls of the Little Colorado River are located in the high desert of northeast Arizona, 30 miles northeast of Flagstaff on the Navajo Indian Reservation. The Little Colorado River drains a large portion of northeast Arizona, its waters becoming extremely muddy as they pass through the sandstone of the Colorado Plateau. At Grand Falls, the river is diverted from its original bed by an ancient lava flow dam and drops 185 feet back into the side of the canyon over a wide escarpment. After passing over the falls, the waters of the Little Colorado pass through ever-deeper gorges cut into the Colorado Plateau, eventually to join the Colorado River in the Grand Canyon some 70 miles downstream.
During dry periods, the falls are reduced to a bare trickle and can even completely dry up. In late February 2010 the flow was measured by a USGS streamflow gauge at less than one cubic foot per second (cfs). But the flow rate can surge dramatically, due to runoff from storms or rapid snowmelt high in the White Mountains of eastern Arizona. One such surge occurred in late March 2010 due to an above-average snowpack and a sudden warm spell. On the day these photos were taken, April 12, 2010, the flow was 1,100 cfs, making a spectacular waterfall. But even this is nowhere near as good as it gets; the highest recorded peak flow, on September 20, 1923, was an incredible 120,000 cfs.
The photograph at the top of this page appeared on NASA/USRA's Earth Science Picture of the Day site on April 23, 2010. For comparison, the June 1, 2004 EPOD shows Grand Falls at minimal flow.