File:Sacramento River Spillway, Interstate 5, Near Woodland, California (216231429).jpg

The Sacramento River is the principal river of Northern California in the United States. Rising in the Klamath Mountains, the river flows south for 445 miles (716 km) before reaching the Sacramento–San Joaquin River Delta and San Francisco Bay. The river drains about 27,500 square miles (71,000 km2) in 19 California counties, mostly within a region bounded by the Coast Ranges and Sierra Nevada known as the Sacramento Valley, but also extending as far as the volcanic plateaus of Northeastern California. Historically, its watershed has reached farther, as far north as south-central Oregon where the now, primarily, endorheic (closed) Goose Lake rarely experiences southerly outflow into the Pit River, the most northerly tributary of the Sacramento.

The Sacramento and its wide natural floodplain were once abundant in fish and other aquatic creatures, notably one of the southernmost large runs of chinook salmon in North America. For about 12,000 years, native peoples have drawn upon the vast natural resources of the watershed, which had one of the densest American Indian populations in California. The river has also been used as a trade and travel route since ancient times. Hundreds of tribes sharing regional customs and traditions inhabited the Sacramento Valley, though they received little disturbance upon the arrival of Europeans in the 1700s. The Spanish explorer Gabriel Moraga named the river Rio de los Sacramentos in 1808, later shortened and anglicized into Sacramento.

In the 19th century the discovery of gold in the Sierra Nevada led to an enormous population influx of American settlers. Overland trails such as the California Trail and Siskiyou Trail followed the Sacramento and other tributaries, guiding hundreds of thousands of people to the goldfields and the growing agricultural region of the Sacramento Valley. By the late part of the century, many populous communities had been established along the Sacramento River, chief of which was the booming city of Sacramento. Intensive agriculture and mining contributed to pollution in the Sacramento, and significant changes to the river's hydrology and environment.

Since the 1950s the watershed have been intensely developed for water supply and the generation of hydroelectric power. Today, large dams impound the river and almost all of its major tributaries. The Sacramento is used heavily for irrigation and serves much of Central and Southern California through the canals of giant state and federal water projects. While now providing water to over half of California's population and supporting one of the most productive agricultural areas in the nation, these changes have left the Sacramento greatly modified from its natural state and have caused the decline of its once-abundant fisheries.

<a href="http://en.wikipedia.org/wiki/Sacramento_River" rel="nofollow">en.wikipedia.org/wiki/Sacramento_River</a>