Heavy rains brought flooding along the Virgin River on Dec. 21, 2010. Residents of Littlefield, Ariz., were sandbagging homes. One home was swept away by floodwaters into the Beaver Dam Wash. Residents in Rockville and Virgin, Utah, were evacuated. Zion National Park was closed and campers and lodge guests were evacuated. Trees Ranch Dam, south of the park, could fail. A state of emergency was declared in St. George, Utah.