California's Central Valley is a large, flat valley that dominates the geographical center of the U.S. state of California. It is wide and stretches approximately from north-northwest to south-southeast, inland from and parallel to the Pacific Ocean coast. It covers approximately , about 13.7% of California's total land area (slightly smaller than the state of West Virginia), and is home to some of California's most productive agricultural areas.
The Central Valley comprises multiple major watershed systems: the Sacramento Valley, which receives well over of rain annually, in the north, and the drier San Joaquin Valley in the south, with the Tulare Basin and its semi-arid desert climate at the southernmost end. The Sacramento and San Joaquin river systems drain their respective valleys and meet to form the delta, a large expanse of interconnected canals, stream beds, sloughs, marshes and peat islands, ultimately flowing to the Pacific by way of San Francisco Bay. The waters of the Tulare Basin essentially never flow to the ocean, though they are connected by man-made canals to the San Joaquin and could drain there again naturally if they were ever to rise high enough.
The valley encompasses all or parts of 19 counties: Butte, Colusa, Glenn, El Dorado, Fresno, Kern, Kings, Madera, Merced, Placer, San Joaquin, Sacramento, Shasta, Stanislaus, Sutter, Tehama, Tulare, Yuba, and Yolo.