Hydrology, Ecology, and Fishes of the Klamath River BasinHydrology, Ecology, and Fishes of the Klamath River Basin The Klamath River basin, which spans parts of southern Oregon and northern California, has been the focus of a prominent conflict over competing uses for water. Management actions to protect threatened and endangered fish species in the basin have left less water available for irrigation in dry years and heightened tensions among farmers and other stakeholders including commercial fishermen,