San Joaquin River

The San Joaquin River ( /ˈsæn wɑːˈkiːn/) is the largest river of Central California in the United States. The 366-mile (589 km) long river starts in the high Sierra Nevada, and flows through a rich agricultural region known as the San Joaquin Valley before reaching Suisun Bay, San Francisco Bay, and the Pacific Ocean. An important source of irrigation water as well as a wildlife corridor, the San Joaquin is among the most heavily dammed and diverted of California's rivers.

People have inhabited the San Joaquin Valley for more than 8,000 years, and it was long one of the major population centers of pre-Columbian California. Starting in the late 18th century, successive waves of explorers then settlers, mainly Spanish and American, emigrated to the San Joaquin basin, first exploiting then driving out the indigenous tribes. The newcomers quickly appropriated the rich natural and hydrologic resources of the watershed for use in farms and cities, but found themselves plagued by flood and drought. Because of the uniform topography of the San Joaquin Valley, floods once transformed much of the lower river into a huge inland sea.

In the 20th century, many levees and dams were built on the San Joaquin and all of its major tributaries. These engineering works changed the fluctuating nature of the river forever, and cut off the Tulare Basin from the rest of the San Joaquin watershed. Once habitat for thousands of spawning salmon and millions of migratory birds, today the river is subject to tremendous water-supply, navigation and regulation works by various federal agencies, which have dramatically reduced the flow of the river since the 20th century.