The Westlake South Ranch Open Space was donated to COSCA in 1986 by the Prudential Insurance Company, and comprises 662 acres. This area protects a significant portion of the ridgeline south of the Ventura (101) Freeway, extending toward Lake Eleanor. A variety of habitats occur in this area, including chaparral, coastal sage scrub, and coast live oak woodlands, as well as a significant portion of the Los Robles Trail. Principal access points include Triunfo Community Park, and East Potrero Road on the west side of Vista Oaks Way. Deer, bobcat, and rabbits are commonly seen in this area.