High Quality Content by WIKIPEDIA articles! The Sacramento River is an important watercourse of Northern and Central California in the United States. The largest river in California, it rises on the eastern slopes of the Klamath Mountains, and after a journey south of over 400 miles (640 km), empties into Suisun Bay, an arm of the San Francisco Bay, and thence to the Pacific Ocean. The river drains an area of about 27,500 square miles (71,000 km2) in the northern half of the state, mostly within a region bounded by the Coast Ranges and Sierra Nevada known as the Sacramento Valley. Its extensive watershed also reaches to the volcanic plateaus of Northeastern California, and a tiny portion of southern Oregon.