OVERLOOK   Big swaths of land around Mount Diablo State Park are protected. But there are still development threats.

Learn about successful efforts to curb sprawl in this episode of our guide to Black Diamond Mines Regional Preserve, presented by Save Mount Diablo, with help from Mount Diablo Interpretive Association and East Bay Regional Park District. Photos by Scott Hein. Featuring Seth M. Adams, Heath Bartosh, Kevin Dixon, Robert Doyle, Scott Hein, Ken Lavin, and Ray Sullivan. Production by Joan Hamilton.