San Francisco Chronicle: Thirty years ago, a chunk of chain, an eyebolt and Mark Dubois helped end the era of big dam building in California. Dubois, a bearded, 6-foot-8, 30-year-old river guide from Sacramento, chained himself to a rocky outcropping on the north bank of the Stanislaus River and stayed there for a week, determined to prevent the U.S. Army Corps of Engineers from filling the canyons behind New Melones Dam and submerging the limestone caves, verdant meadows and petroglyphs of the river …