after the nearby Salinas River < L salina (see salina): for the salt marshes at its mouth
See Salinas in American Heritage Dictionary 4
A city of western California east-northeast of Monterey on the Salinas River, about 241 km (150 mi) long, near its outlet on Monterey Bay. The city is a processing center and the birthplace of John Steinbeck, who based many of his stories on the migratory farm workers of the Salinas Valley. Population: 145,000.