The Klamath River enters the Pacific Ocean at the community of Requa, about 52 miles (84 km) north of Eureka and 16 miles (26 km) south-southeast of Crescent City, California. The river flows 257 miles (414 km) from the Upper Klamath Basin in southern Oregon to the Pacific, draining a watershed of roughly 7.7 million acres (3.1 million ha) from a broad patchwork of lakes and marshes at the edge of the Oregon high desert, through the Cascade Range and the Klamath Mountains. The region’s geology reflects millions of years of tectonic activity: successive fragments of oceanic crust, volcanic arcs and other rock formations were accreted to the western edge of North America. The Klamath Mountains comprise multiple geological terranes, assembled over a long period through subduction and plate movement. The river is a superimposed stream, having cut through rising terrain while maintaining its established course toward the Pacific. Its lower reaches pass through a rugged landscape shaped by tectonic uplift, erosion and river incision.

The Klamath River basin has sustained Indigenous communities for thousands of years, providing salmon, steelhead and other resources central to food systems, cultural practices and trade. The river and its tributaries are ancestral lands of several Native nations, including the Yurok, Karuk, Hupa, Shasta, and Klamath peoples, whose histories and relationships with the river differ. Upstream communities traditionally relied more heavily on hunting and gathering than did some downstream communities, where salmon fishing was especially important. Indigenous names for the river included Ishkêesh and Koke; the origin and meaning of the name Klamath have been explained in different ways, but is likely derived from the Upper Chinookan word “klamet“ meaning “they of the river.” European fur traders reached the basin in the early 19th century, followed by miners and settlers during the California gold rush. Commercial salmon fishing subsequently expanded near the river mouth, and canneries operated in the area. Fishing, mining, logging and other development transformed the basin and disrupted Indigenous traditions. The river became renowned for its salmon runs, but fish populations declined under mounting pressure from habitat degradation, fishing and dams.

Dams, water diversions and other human activities severely disrupted the Klamath’s migratory fish populations during the 19th and 20th centuries. Four hydroelectric dams on the river’s main stem, J.C. Boyle, Copco No. 1, Copco No. 2 and Iron Gate, blocked access to more than 400 miles (640 km) of historical salmon and steelhead habitat. Separately, the federal Central Valley Project began diverting water from the Trinity River in 1963, altering flows in that tributary. After years of negotiations among tribes, government agencies, conservation groups and dam owner PacifiCorp, removal of the four Klamath River dams was completed in 2024. The reservoirs were drained and the former dam sites opened access to previously blocked habitat. In October 2024, California wildlife officials documented Chinook salmon spawning upstream of the former Iron Gate Dam for the first time since 1961. By November 2025, state biologists reported salmon returning widely to newly accessible habitat. Restoration and monitoring continue, while the river’s long-term ecological recovery remains a work in progress. Read more here and here. Explore more of the Klamath River and Requa here: