The
Klamath Basin is the region in the
U.S. states of
Oregon and
California drained by the
Klamath River. It contains most of
Klamath County and parts of
Lake and
Jackson counties in Oregon, and parts of
Del Norte,
Humboldt,
Modoc,
Siskiyou, and
Trinity counties in California. The
drainage basin is 35% in Oregon and 65% in California. In Oregon, the watershed typically lies east of the Cascade Range, while California contains most of the river's segment that passes through the mountains. In the Oregon-far northern California segment of the river, the watershed is
semi-desert at lower elevations and dry
alpine in the upper elevations. In the western part of the basin, in California, however, the climate is more of
temperate rainforest, and the Trinity River watershed consists of a more typical alpine climate.