Some time this spring, beavers will return to the ancestral lands of the Tule River Tribe in the Southern Sierra Nevada. It will be a moment tribal leaders have spent a decade preparing for, hoping the once thriving and now missing aquatic rodent can help return the forest’s natural drought resistance … Beaver dams naturally filter silt that otherwise clogs streams, while creating wetlands that preserve water on the land for longer periods. As beavers were wiped out, the waterways no longer reached ancient floodplains. This has led to increasing pollution and erosion, as well as more flooding and drought.