At 11:57 p.m. on March 12 , 1928 , the dam catastrophically failed , and the resulting flood took the lives of what is estimated to be at least 431 people . The collapse of the St. Francis Dam is considered to be one of the worst American civil engineering disasters of the 20th century and remains the second-greatest loss of life in California 's history , after the 1906 San Francisco earthquake and fire . The disaster marked the end of Mulholland 's career
1906 San Francisco earthquake
1906 San Francisco earthquake
St. Francis Dam