Human habitation on the Klamath dates to at least 7,000 years ago.
Many of the Native American groups along the river depended on the huge runs of Pacific salmon, the third largest on the Pacific coast of what is now the United States.
These groups included the Shasta along the middle and upper parts of the river, the Yurok, Hupa, and Karuk along the canyons of the lower river, and the Modoc, Klamath and Yahooskin in the desert valleys of the upper basin.
About 129 miles (208 km) of the Klamath River, or half the river's length, was on Shasta territory.
The Yurok were the second most prominent group on the river, controlling about 30 miles (48 km) of the lower Klamath River and a large section of the Northern California coast.
Along with the Hupa and Karuk, the lower to mid-upper Tribes caught salmon from the river with weirs, basket traps and harpoons.
Ishi Pishi Falls, a set of rapids on the Klamath River near the confluence with the Salmon River, has been a traditional fishing ground for thousands of years.
Most of the upstream groups had a nomadic hunting-gathering lifestyle and did not depend on salmon as much as downstream tribes.
The Klamath River's name was recorded by Europeans in the 19th century derived from the word klamet or the Klamath Tribe.
Prior to European contact, the river was called by many different names, including Ishkêesh and Koke.
The Klamath Tribe's name came from the Upper Chinookan word /ɬámaɬ/, literally "they of the river".

In the late 1820s, fur trappers of the Hudson's Bay Company traveling south from Fort Vancouver reached the Klamath River basin.
The first party to see the Klamath River was led by Alexander McLeod in the winter of 1826–27.
In 1828, the Jedediah Smith fur trapping expedition was helped across the Trinity River by the Yurok and camped on the east side of the Trinity River.
His clerk, Harrison G. Rogers, wrote, "Mr. Smith purchases all the beaver furs he can from them," suggesting that beaver were then plentiful on the Trinity.
Joseph Grinnell, in Fur-bearing Mammals of California, noted that beaver had been present on other Klamath River tributaries such as the Scott River and Shasta River, and further cited a Fish and Game report of beaver from 1915–1917 on High Prairie Creek at the mouth of the Klamath River near Requa, California.
Within a matter of years, the plentiful beavers in the Klamath Basin had been mostly wiped out.
Beaver dams had previously been an important factor in stream habitat in the Klamath River watershed, helping to moderate the power of floods and creating extensive wetlands.
The loss of the beaver dams resulted in detrimental consequences for watercourses in the basin, exacerbating the power of winter floods, and causing severe erosion.
Trapping parties eventually moved southwest into the Sacramento Valley and blazed an extension of the Siskiyou Trail, an early path between the Oregon Territory and San Francisco Bay.
Despite the environmental implications, extensive and fertile meadows left behind by the draining of beaver ponds attracted many settlers to the region later on.
Human habitation on the Klamath dates to at least 7,000 years ago. Many of the Native American groups along the river depended on the huge runs of Pacific salmon, the third largest on the Pacific coast of what is now the United States. These groups included the Shasta along the middle and upper parts of the river, the Yurok, Hupa, and Karuk along the canyons of the lower river, and the Modoc, Klamath and Yahooskin in the desert valleys of the upper basin. About 129 miles (208 km) of the Klamath River, or half the river's length, was on Shasta territory. The Yurok were the second most prominent group on the river, controlling about 30 miles (48 km) of the lower Klamath River and a large section of the Northern California coast. Along with the Hupa and Karuk, the lower to mid-upper Tribes caught salmon from the river with weirs, basket traps and harpoons. Ishi Pishi Falls, a set of rapids on the Klamath River near the confluence with the Salmon River, has been a traditional fishing ground for thousands of years. Most of the upstream groups had a nomadic hunting-gathering lifestyle and did not depend on salmon as much as downstream tribes. The Klamath River's name was recorded by Europeans in the 19th century derived from the word klamet or the Klamath Tribe. Prior to European contact, the river was called by many different names, including Ishkêesh and Koke. The Klamath Tribe's name came from the Upper Chinookan word /ɬámaɬ/, literally "they of the river".
In the late 1820s, fur trappers of the Hudson's Bay Company traveling south from Fort Vancouver reached the Klamath River basin. The first party to see the Klamath River was led by Alexander McLeod in the winter of 1826–27. In 1828, the Jedediah Smith fur trapping expedition was helped across the Trinity River by the Yurok and camped on the east side of the Trinity River. His clerk, Harrison G. Rogers, wrote, "Mr. Smith purchases all the beaver furs he can from them," suggesting that beaver were then plentiful on the Trinity. Joseph Grinnell, in Fur-bearing Mammals of California, noted that beaver had been present on other Klamath River tributaries such as the Scott River and Shasta River, and further cited a Fish and Game report of beaver from 1915–1917 on High Prairie Creek at the mouth of the Klamath River near Requa, California. Within a matter of years, the plentiful beavers in the Klamath Basin had been mostly wiped out. Beaver dams had previously been an important factor in stream habitat in the Klamath River watershed, helping to moderate the power of floods and creating extensive wetlands. The loss of the beaver dams resulted in detrimental consequences for watercourses in the basin, exacerbating the power of winter floods, and causing severe erosion. Trapping parties eventually moved southwest into the Sacramento Valley and blazed an extension of the Siskiyou Trail, an early path between the Oregon Territory and San Francisco Bay. Despite the environmental implications, extensive and fertile meadows left behind by the draining of beaver ponds attracted many settlers to the region later on.
Klamath River