Complex sentence: The towns of Joshua Tree, Yucca Valley, Twentynine Palms, California, and Landers were the hardest hit; nearly every road was washed out in the Yucca Valley.
Split into simpler sentences: The towns of Joshua Tree, Yucca Valley, Twentynine Palms, California, and Landers were the hardest hit. Nearly every road was washed out in the Yucca Valley.