On June 9, 1972, a storm system approximately 80 miles long and 12 miles wide stalled on the eastern slope of the Black Hills, dropping 12 to 14 inches of rain at its center and producing more than 800,000 acre-feet of water, enough to fill Pactola Dam 15 times over. More than 10 inches of rain fell in the 60 square miles of the Rapid Creek basin, and the crest of this water hit Canyon Lake around 10 p.m., carrying debris from the canyon environment above Rapid City. The storm and flood caused 238 deaths, left five persons missing, and injured 3,057 people, including 118 hospitalized; 770 homes and 565 mobile homes were destroyed, 2,035 homes and 785 mobile homes were damaged, 36 businesses were destroyed and 236 damaged, 5,000 vehicles were destroyed, and the financial loss was $165 million. The flood took such a terrible toll because the floodplain was filled with homes, businesses, public facilities, a nursing home, a hospital, mobile home parks, and car lots. Paleoflood investigations indicate that in the last 2,000 years multiple large floods have occurred in this basin, with the largest 700 years ago, and that in the lower reaches of Rapid Creek during the last 1000 years two paleofloods, in 1103 and 1570, would have exceeded the 1972 flood flow, with the 1570 event four times greater. The drainage area between Pactola Reservoir and Canyon Lake covers about 51 square miles and drops more than 1,000 feet in elevation, with several large and numerous smaller sub-basins that can contribute substantial runoff to Rapid Creek during intense thunderstorms.