Reclamation Information Sharing Environment (RISE)

The Klamath River flows northeast to southwest from its headwaters near Crater Lake in southern Oregon to its outflow at the Pacific Ocean in northern California. The Klamath River Basin is typically divided into two regions: The Upper Klamath River Basin and Lower Klamath River Basin. The Upper Klamath River Basin drains all catchments above the former Iron Gate Dam (lowest former dam on the Klamath River) in California. Located in the rain shadow on the eastern side of the Cascade Mountain Range, the Upper Klamath River Basin has an arid climate. The Upper Klamath River Basin features Oregon’s largest natural lake by surface area—Upper Klamath Lake—and relatively high urban and agricultural development. In contrast, the Lower Klamath River Basin, which is in the Pacific Coastal Range and encompasses the watershed downstream of former Iron Gate Dam, receives more precipitation than the Upper Klamath River Basin. The Lower Klamath River Basin encompasses large areas of northern California and Pacific Northwest conifers and hardwoods. The Lower Klamath River Basin has no major natural lakes and less urban and agricultural development than in the Upper Klamath River Basin.