Sierra Azul is the largest preserve in the Midpenninsula Regional Open Space District covering over 17,000 acres of rugged and steep terrain (map). The region is on the east side of the Santa Cruz Mountains so the vegetation consists primarily of chaparral, bay trees, and oak woodland. The preserve is largely undeveloped and the trails system consists of fireroads that existed prior to the formation of the preserve. Large sections of the preserve, including the summits of Mount Thayer and Mount Umunhum, are closed to the public. These summits are the site of the former Almaden Air Force Station and have toxic materials and unsafe structures. Hopefully they will be cleaned up and restored for public access soon. There are essentially three access points to the park: Kennedy Road, Hicks Road, and Alma Brige Road. All of the trails climb up the slopes of 2,999 ft Mount El Sombroso. The Kennedy Trail approaches from the north (Kennedy Road TH), the Limekiln and Priest Rock Trails approach from the West (Alma Bridge Road), and the Woods trail approaches from the East (Hicks Road TH).
The running in this preserve is difficult due to steep hills, particularly on the Priest Rock and Kennedy Trails, which are two of the most challenging hill climbs in all of the Bay Area. These trails are also exposed and heat is a major issue of consideration from late spring through fall so come prepared with water and electrolytes. In my opinion, the best aspect of this park is the fantastic views of the Silicon Valley, Diablo Range, and Santa Cruz Mountains. On this day, I took the Priest Rock Trail up to the Kennedy Trail and then the Woods Trail to the summit of Mt. El Sombroso. The actual summit of El Sombroso is covered with brush precluding views into the Silicon Valley but there is a nice view of 3,790 ft Loma Prieta (the highest point in the Santa Cruz Mountains) and 3,486 ft Mount Umunhum. The best views are seen from below El Sombroso and along the Kennedy Trail.
More photos after the jump!