Rancho Cuyamaca was a 35,501-acre (143.67 km2) Mexican land grant in the Cuyamaca Mountains and Laguna Mountains, in present-day San Diego County, California, United States. It was given in 1845 by Governor Pío Pico to Agustin Olvera. The grant extended south of present-day Julian and encompassed Cuyamaca Rancho State Park, Lake Cuyamaca, and Cuyamaca Peak.