Klamath River
The Klamath River is a long river in southern Oregon and northern California. Beginning near Klamath Falls in the Oregon high desert, it flows west through the Cascade Range and Klamath Mountains before reaching the temperate rainforest of California's North Coast, where it empties into the Pacific Ocean. The Klamath River is the third-largest salmon and steelhead producing river on the west coast of the contiguous United States. The river's watershed – the Klamath Basin – encompasses more than, and is known for its biodiverse forests, large areas of designated wilderness, and freshwater marshes that provide key migratory bird habitat.
Native Americans have used the river as a source of food and trade for thousands of years, and it continues to hold great cultural significance for tribes. Most lands along the upper Klamath were settled by Euro-Americans following exploration by fur trappers in the early to mid-19th century. Violent conflict and displacement of tribes occurred during the California Gold Rush as prospectors pushed into the lower Klamath basin, leading to a bitter fight over establishing reservation lands. In the early 20th century, the federal government drained the upper basin's once extensive lakes and wetlands for agriculture, while private utilities constructed hydroelectric dams along the river. As salmon runs declined in the mid-20th century, tribes pushed for legal recognition of their senior water rights to support Klamath River fisheries, which have led to controversial reductions in irrigation water supply.
In the 21st century, the Klamath River hosts a wide variety of uses, including tribal subsistence fishing and ceremonies, recreational fishing and whitewater boating, and agricultural and domestic water supply. Starting in 1981, much of the Klamath River and its tributaries have been designated National Wild and Scenic Rivers. Four hydroelectric dams on the Klamath River were demolished by October 2024, following almost two decades of negotiations between local representatives, tribes, conservation groups and the utility company operating the dams. This enabled salmon migration to the Upper Klamath Basin for the first time in over 100 years, and established new guidelines for Klamath water use to achieve a compromise between agricultural needs and fishery flows.
Course
The official beginning of the Klamath River is at Lake Ewauna, a small natural lake near Klamath Falls, Oregon. The primary inflow of Lake Ewauna is the short Link River, which connects it to Upper Klamath Lake. Upper Klamath, in turn, is fed by the Williamson River and Wood River. For the first below Lake Ewauna, the Klamath River takes a slow meandering course through what was formerly the Klamath Marshes, which were drained for agriculture in the early 20th century. An artificial channel diverts water from the Lost River, which normally flows into Tule Lake, into the Klamath during periods of high runoff.Below Keno Dam, the river flows swiftly through the narrow Klamath River Canyon, which cuts through volcanic rock of the southern Cascade Range. Entering Siskiyou County, California, it passes the former sites of four hydroelectric dams operated by PacifiCorp until their demolition in 2024. After passing under Interstate 5, the Klamath receives the Shasta River from the left then flows west into the Siskiyou Mountains, entering the Klamath National Forest. It receives the Scott River from the left, passing through Seiad Valley and Happy Camp. Turning south, it flows towards Somes Bar, where it receives the Salmon River from the left as it enters Humboldt County and the Six Rivers National Forest. After passing Orleans, the Klamath reaches Weitchpec, where it receives the Trinity River, its largest tributary, from the left. State Route 96 follows the Klamath River for from Hornbrook to Weitchpec.
Downstream of the Trinity River, the Klamath turns sharply northwest. The entire lower section of the river flows through coast redwood forests in the Yurok Indian Reservation. State Route 169 follows most of this section of the river, except for an unconstructed segment between river miles 8–23 which is only accessible by boat. The river enters Del Norte County, where Highway 101 bridges it at the town of Klamath. The river empties into the Pacific Ocean at a tidal estuary near Requa, in an area shared by the Yurok Reservation and Redwood National and State Parks, about south of Crescent City.
Watershed
The Klamath River watershed, known as the Klamath Basin, drains parts of Klamath, Lake and Jackson Counties in Oregon and Siskiyou, Modoc, Trinity, Humboldt and Del Norte Counties in California. About 37 percent of the basin is in Oregon and 63 percent is in California. More than half of the Klamath Basin is managed by the U.S. Forest Service, on the Fremont, Winema, and Rogue River National Forests in Oregon and the Modoc, Klamath, Shasta-Trinity and Six Rivers National Forests in California. The Klamath Basin borders the Smith, Rogue and Umpqua River watersheds to the northwest, the Mad and Eel River watersheds to the southwest, the Sacramento River watershed to the southeast, and various closed basins of interior Oregon to the northeast.Hydrologically, the Upper Klamath Basin is considered to be upstream from the former site of Iron Gate Dam, about from the river's mouth. Most of the Upper Klamath Basin is in Oregon, with some parts extending south into California. Situated between the Cascades and the Oregon high desert and northwest of the Modoc Plateau, it features a semi-arid climate and is characterized by large, flat alluvial valleys separated by long mountain ridges. Elevations range from in the valleys to in the Cascades. The mountain ridges are forested, while the valleys mostly consist of wetlands or farmland. Although many streams flowing into Upper Klamath Lake derive their flow from snowmelt, its largest sources – the Williamson and Wood Rivers – are predominantly fed by large springs.
Upper and Lower Klamath Lakes and Tule Lake were once part of of connected wetlands, over three-quarters of which have been drained for agriculture. The Lost River basin, situated east and south of Klamath Falls, was historically a closed basin terminating at Tule Lake. During high water events, the Klamath River overflowed into Lost River Slough near Klamath Falls and flow into Tule Lake. A topographic constriction occurred further west at the Keno Reef, a bedrock barrier where water backed up during flood events and flowed south along Klamath Straits into Lower Klamath Lake. Since the 20th century, the Lost River and Lower Klamath Lake basins – as well as the neighboring Butte Valley–Meiss Lake basin – have been artificially altered to discharge floodwaters into the Klamath River via diversion dams and drainage facilities.
The Lower Klamath Basin, consisting mostly of mountains and coniferous forest, is located almost entirely in California except for the headwaters of a few tributaries that flow south from Oregon. The Klamath Mountains include numerous sub-ranges, with the Siskiyou Mountains to the north and west of the river, and the Marble Mountains and Salmon Mountains to the east and south. These mountains experience heavy winter snowfall, while summers are warm and dry with little precipitation. Closer to the coast, winters are cool with heavy rainfall, while summer temperatures are mild and often foggy. About 88 percent of the Klamath River's total flow originates in the Lower Basin, even though it only accounts for 62 percent of the land area. The Trinity River is the largest sub-basin of the Lower Klamath; the main stem originates in the Trinity Alps west of Redding, while the South Fork Trinity River's origin at North Yolla Bolly Mountain is the southernmost point in the entire Klamath Basin. Much of the Lower Klamath and Trinity River basins are bounded on the west by South Fork Mountain, which forms one of the longest continuous ridgelines in North America. South Fork Mountain defines much of the boundary between the Klamath Mountains and the Northern Coast Ranges.
Most of the Lower Klamath Basin is remote and rugged, with limited access routes. In California, SR 96 provides access to the entire stretch of the middle Klamath River from Hornbrook to the Trinity River, while SR 299 runs along the Trinity River between Willow Creek and Junction City. SR 169 follows most of the lower Klamath below the Trinity, except for an unconstructed segment between river miles 8–23 which is only accessible by boat. Although the Lower Klamath Basin is almost entirely covered by mountains, there are also several prominent valleys used for agriculture. Shasta Valley in Siskiyou County is the largest, and is characterized by volcanic features such as basalt flows and lava caves. The Shasta River flows northwest through the valley from Mount Shasta, the highest point in the Klamath River basin at. Yreka and Montague are located within Shasta Valley. To the west is the smaller Scott Valley, which includes the towns of Fort Jones, Etna, Greenview and Callahan. Hayfork Valley and the community of Hayfork are located in Trinity County, while Hoopa Valley and the surrounding Hoopa Reservation are on the Trinity River in Humboldt County.
Tributaries and sub-basins
The below table lists major sub-basins of the Klamath River system.Flooding
The lower and middle sections of the Klamath River are vulnerable to flooding, and major floods have occurred in years where major flooding has taken place in Northern California, particularly in the wake of Pineapple Express storms that bring large amounts of warm rain to Northern California. Fort Ter-Waw, located at what is now the town of Klamath Glen, was destroyed by the flood in December 1861 and abandoned on June 10, 1862. Other significant floods on the Klamath River have occurred in 1926–1927, 1955, 1964, 1997, and 2005, in several cases changing the course of the river. The Christmas flood of 1964 was particularly devastating. The Klamath River reached flows of,with high water reaching, inundating the towns of Klamath and Klamath Glen under as much as of water, and destroying most of the Highway 101 bridge crossing the river. The highway bridge was rebuilt in a different location, though entrances to the old bridge still stand.
The mouth of the Klamath and nearby sections of the river are also susceptible to oceanic tsunami surges, and fatalities have occurred there during the 1964 Alaskan and 2011 Japanese tsunamis.