On this date in 1977, 1500 people gather outside the construction site of the Diablo Canyon nuclear power plant, on the Pacific shore between San Francisco and Los Angeles, marching and picketing in protest of the project, drawing attention to the danger of nuclear reactors in a region known for seismic activity. 47 people are arrested. The next year at this time, thousands more show up, and 487 protesters are arrested.

By 1981, the annual demonstration is attracting tens of thousands, including celebrities. Activists stage blockades and sit-ins. 1,900 arrests are made.

A 25-year-old engineer discovers major building errors — one building has been built backwards from spec — forcing an expensive three year delay before the plant can open. Today, the plant supplies 10% of California’s power.