The Raccoon River is a tributary of the Des Moines River in central Iowa in the United States. As measured using the longest of its three forks, its length increases to . Via the Des Moines River, it is part of the watershed of the Mississippi River. The river runs through an intensely cultivated area of croplands and livestock farming, receiving Tile drainage from slow-draining rich natural bottomland. The Des Moines metropolitan area has been obtaining its drinking water from the Raccoon River just before it empties into the Des Moines River through water utilities since the 19th century. During the Great Flood of 1993, the Raccoon River flooded the water treatment facility of Des Moines, shutting off the city's supply of drinking water. History The Racoon River was first documented on the 1814 map by Lewis and Clark, though the USGS references the name to a later map from 1843 named Hydrological Basin of the Upper Mississippi River based on field measurements by Joseph N. Nicollet during his Midwestern expeditions in the 1830s. Course The Raccoon River is a tributary of the Des Moines River in central Iowa in the United States. It flows for much of its length as three streams and when measured using the longest of its three forks, its length increases to . The river runs through an intensely cultivated area of croplands mostly of corn and soy and livestock farming, where slow-draining rich natural bottomlands have been tiled to drain them for agricultural cultivation. The North Raccoon River is, by far, the longest of the three, at . It rises north of Marathon in northeastern Buena Vista County and initially flows southwardly into Sac County, where it turns southeastward for the remainder of its course through Calhoun, Carroll, Greene and Dallas counties. It passes the towns of Sac City, Jefferson, Perry and Adel. The Adel Island dam in Adel is the only dam along its course. The Middle Raccoon River, long, rises in northwestern Carroll County and flows generally southeastwardly through Guthrie and Dallas counties, past Carroll, Coon Rapids, Springbrook State Park, Panora, Linden, and Redfield. The three dams located along its course are the Lake Panorama dam and the Lennon Mill dam at Panora, and the Redfield dam at Redfield. Even though the Lake Panorama dam, completed in 1970, was built for recreational purposes only, it has provided some additional benefits by controlling