The Sierra Club president forbade any chapter from opposing Diablo Canyon, so The San Luis Obispo Chapter formed the Shoreline Preservation Conference to oppose the construction on the grounds that the area had been proposed as a state park, was a sacred Chumash Indian site, had some of the largest oak trees on the West Coast, was located on the second-to-last coastal wilderness area in California, and could be sitting on the fault that lightly shook Santa Barbara in a 1927 earthquake.
The Sierra Club president prohibited any chapter from opposing Diablo Canyon; therefore, The San Luis Obispo Chapter established the Shoreline Preservation Conference to oppose its construction. They argued that the area was proposed as a state park, held sacred by Chumash Indians, featured large oak trees on the West Coast, was part of the second-to-last coastal wilderness in California, and lay near the fault that experienced minor shaking from an earthquake in 1927.