Sacramento River - Upper, CA

The Sacramento River is the longest river entirely within the state of California. Starting at the confluence of the South Fork and Middle Fork of the Sacramento River, near Mount Shasta in the Cascade Range mountains, the Sacramento flows south for 447 miles (719 km)  (various other sources list the river length from 320 to 450 miles (720 km)) through the northern Central Valley of California, between the Pacific Coast Range and the Sierra Nevada.

Not far downstream from its confluence with the American River, the Sacramento River joins the San Joaquin River in the Sacramento River Delta, which empties into Suisun Bay, the northern arm of San Francisco Bay. It is the second largest river by average volume of water emptying into the Pacific Ocean in the Contiguous United States, behind only the Columbia River.

The chief tributaries of the Sacramento River are the Pit River, Feather River, McCloud River, and the American River. The Pit River is the longest of these, but the Feather and American rivers carry larger volumes of water. Lesser tributaries include Dye Creek.

It rises at an elevation of 3600 feet (1100 m) in the Shasta National Forest, southwest of Mount Shasta (41°19′43″N 122°19′38″W / 41.32874°N 122.32711°W / 41.32874; -122.32711). The USGS cites the river's source as the confluence of the South Fork Sacramento River and Middle Fork Sacramento River.

Big Springs feeds Big Springs Creek which flows south into Lake Siskiyou. However, feeding Lake Siskiyou from the west are the North, Middle, and South Forks of the Sacramento River which bring water from much higher elevations, including from Castle Lake (elevation 5,440 ft (1,660 m) The South Fork originates at 5,912 feet (1,802 m) at Cedar Lake (41°12′28″N 122°29′46″W / 41.20791°N 122.49601°W / 41.20791; -122.49601), the Middle Fork originates at 6,359 feet (1,938 m) in several headwater streams near Chipmunk Lake (41°15′08″N 122°29′39″W / 41.25234°N 122.49415°W / 41.25234; -122.49415), and the North Fork originates from springs at about 7,900 feet (2,408 m) near 41°12′28″N 122°29′46″W / 41.20791°N 122.49601°W / 41.20791; -122.49601.

These various headwaters flow into Lake Siskiyou near the city of Mt. Shasta. From there the river flows generally south, closely followed by Interstate 5. Just north of the city of Redding, the river is impounded by Shasta Dam, which creates a reservoir called Shasta Lake. The Pit River and McCloud River tributaries join the Sacramento in Shasta Lake. The Pit River is actually longer than the Sacramento River above Shasta Lake.

Below Shasta Dam, the Sacramento River continues to flow south, passing Redding and collecting many small streams. The river passes by Red Bluff and near Chico. It bends slightly west around Sutter Buttes, then collects the tributary waters of the Feather River just north of the City of Sacramento. In Sacramento, the American River joins the Sacramento River.

During the Memorial Day weekend, and again in mid summer each year Red Bluff Diversion Dam creates Lake Red Bluff. Lake Red Bluff supplies water to the Tehama-Colusa and Corning Canals providing water for 100,019 acres (404.76 km2), and $88,529,000 worth of crops. Lake Red Bluff also provides recreational opportunities in the form of sailing, jet skiing, water skiing, and drag boat racing. Tourism and recreation revenues are important part of the region’s economy. Lake Red Bluff is of great environmental importance since the Tehama-Colusa Canal supplied water for 20,000 acres (81 km2) of the Sacramento Valley (wildlife) Refuges.

Below Sacramento, the river enters the Sacramento River Delta, where it is joined by the San Joaquin River. The combined waters then exit into Suisun Bay, San Pablo Bay, and San Francisco Bay, before finally entering the Pacific Ocean at the Golden Gate.

Every year in October, California's native King Salmon (Chinook) return to the river from the Pacific Ocean to migrate upstream to spawning grounds. This migration attracts thousands of sport fisherman from all over America. Yearly salmon runs can stretch all the way through December.