Rancho Guadalasca was a 30,594-acre (123.81 km2) Mexican land grant in present-day Ventura County, California given in 1836 by Governor Mariano Chico to Ysabel Yorba. The grant was in the southern part of the county, bordering on Los Angeles County. The grant extended along the Pacific coast near Point Mugu for about eight miles, and extending into the interior along Guadalasca Creek in the Santa Monica Mountains for about ten miles.This rancho lies in the extreme southern part of Ventura, southeast of the colonia. It borders on Los Angeles County about two miles, on the coast about eight miles, and extends about ten miles into the interior. The place is historical, being the site of Xucu or "The Town of the Canoes," described in the voyage of Cabrillo, 300 years ago, and having been the most densely populated portion of the coast. One of the valleys, La Jolla, seems to have been a favorite ground of the Indians, being rich in kitchen middens, bones, etc., and having a trail, worn deep, from the landing over the hill. The Guadalasca was a grant of 30,593.85 acres, made May 6, 1846, to Ysabel Yorba, whose title was confirmed by the United States Land Commissioners. Of the estate, 23,000 acres were later purchased by William Richard Broome, an English gentleman of leisure, living in Santa Barbara. Several thousand of these acres are on the fertile Colonia plain, where flowing wells of artesian water can be had at 100 to 150 feet deep. "The Estero" is the termination of the Guadalasca Creek, being a basin some four miles long, in some parts 1,000 feet wide, and deep enough to float large vessels. Near Point Mugu there is a landing for vessels, safe in any weather, and considered one of the best harbors on the coast.