High Quality Content by WIKIPEDIA articles! Saddleback Valley is located in South Orange County, California and is home to the cities of Mission Viejo, Ladera Ranch, Rancho Santa Margarita, Lake Forest among others. Orange County is a county in California, within the United States. Its county seat is Santa Ana. As of the 2000 census, its population was 2,846,293, while a July 2008 estimate placed the population at 3,010,759, making it the second most populous county in California, behind Los Angeles County and ahead of San Diego County.