Shasta River

The Shasta River is a tributary of the Klamath River, approximately 58 miles (93 km) long, in northern California in the United States. It drains the Shasta Valley on the west and north sides of Mount Shasta in the Cascade Range.

The river rises in southern Siskiyou County on the edge of the Shasta-Trinity National Forest, approximately 10 miles (16 km) southwest of Weed. It flows generally northwest through the Shasta Valley, past Weed, through Lake Shastina, and past Montague. It joins the Klamath from the south approximately 8 miles (13 km) north-northeast of Yreka.

The Shasta Valley is dominated by nearby Mount Shasta and underlain with volcanic basalt from eruptions of the mountain in recent geologic time. Pluto's Cave is an example of voids remaining after highly fluid lava drained from underground conduits which were fed by volcanic vents to the east. The Shasta Valley is covered with small hillocks extending from the base of Mt. Shasta north to just beyond the city of Montague, that are the debris from the liquefication of the ancestral Mount Shasta sometime within the past 400,000 years.