On April 18, 1927, inundation from the Great Flood of Louisiana drove creation of the existing levee system. Imperfect engineering and shoddy construction has caused the collapse of dams, such as the Johnstown Flood of 1889. As noted in a previous column, on May 16, 1874, 138 people died due to poor construction and a dam break in Williamsburg, Mass. On March 12, 1928, the St. Francis Dam, in service less than two years, collapsed near Santa Paula, Calif., killing 450. Feb. 26, 1972, two coal slag dams along Buffalo Creek in southern West Virginia broke, unloading 2 miles of backed-up water into a lower dam that exploded; 4,000 homes were washed away with 125 deaths. On June 5, 1976, the 305-foot Teton Dam collapsed, releasing 80 billion gallons of water into adjoining farmland. Fastcast: Early showers.