The Great Mississippi River Flood of 1927 affected an area of 27,000 square miles, destroyed more than 130,000 homes, and displaced 700,000 people. Congress responded by passing the Flood Control Act of 1936. The U.S. Army Corp of Engineers began work on Grenada Dam in 1947, and the dam became operational in 1954 at a cost of $32 million. At its summertime height, Grenada Lake is the largest body of water in Mississippi, with 35,820 surface acres of water.