The Santa Ynez River is one of the largest rivers on the Central Coast of California. It is 92mi long, flowing from east to west through the Santa Ynez Valley, reaching the Pacific Ocean at Surf, near Vandenberg Air Force Base and the city of Lompoc.The river drains the north slope of the Santa Ynez Mountains, the south slope of the San Rafael Mountains, as well as much of the southern half of Santa Barbara County. Its drainage basin is 896sqmi in area. The river's flow is highly variable. It usually dries up almost completely in the summer, but can become a raging torrent in the winter. The river has three dams which can impound a total of 210000acre.ft of water in wet years.HistoryThe river was first named by the Spanish Portolà expedition, first European land exploration of Alta California, which camped near the river mouth on August 30, 1769. Apparently unable to agree on a single name, expedition diarists recorded three. Engineer Miguel Costanso wrote "Río Grande de San Verardo". Franciscan missionary Juan Crespi noted two additional names; "San Bernardo" and "Santa Rosa". None of the three names remain attached to any feature in the area.Instead, the river and mountains took the name of Mission Santa Inés (also spelled "Ynés" or "Ynéz" in New Spain), which was established in 1804 (named for Saint Agnes of Rome, Virgin and Martyr). According to the USGS, variant and historical names of the Santa Ynez River include La Purisima River, Rio De La Purisima, Rio De Calaguasa, Rio Santa Rosa, Rio De Santa Ines, and Rio De Santa Ynes.
