Cosumnes River floodplain unflooded. The Cosumnes is one of the last free-flowing rivers west of the Sierra Nevada. Without extensive dam control, the river overtops its banks annually, nourishing the riparian habitat. Fish, such as the threatened Chinook salmon, forage for food in this floodplain and seek cover from predators. These floodplain areas are critical in the life cycle of native fish, as fingerlings grow quickly in these protected backwater areas and therefore have an increased chance of survival when they return to the river channel. © USFWS