Rancho El Rio de Santa Clara o la Colonia was a 44,883-acre (181.64 km2) Mexican land grant in present-day Ventura County, California, given in 1837 by Governor Juan B. Alvarado to seven people. The grant extended from the Santa Clara River south to the present-day Point Mugu Naval Air Station, and the boundary of Rancho Guadalasca, and east from the Pacific Ocean to the present-day 101 Freeway, and the boundary of Rancho Santa Clara del Norte. The grant encompassed much of the Oxnard Plain.