High Quality Content by WIKIPEDIA articles! Tesoro High School is a public school found in the southern Orange County area of Las Flores, California. Established in the fall of 2001, Tesoro is 1 of 7 high schools in the Capistrano Unified School District. As of the 2009-2010 year, Tesoro serves nearly 3,000 students in grades 9-12. Students attending Tesoro are within the districted cities of Rancho Santa Margarita, Ladera Ranch, Coto De Caza and Mission Viejo.