At , the San Joaquin River watershed proper drains a fair swath of inland central California, an area comparable to the size of the Upper Peninsula of Michigan. If combined with the Tulare Basin, which historically (and still rarely) experiences northerly outflow to the San Joaquin River, it would be the largest single drainage basin entirely in the state. The San Joaquin River basin is roughly synonymous with the San Joaquin Valley, and is bounded by the Sierra Nevada to the east, the Coast Ranges on the west, and the Tehachapi Mountains on the south.