A watershed is an area of land that drains to a common point. The 3,600 square miles of the Raccoon River Watershed drains to the confluence of the Raccoon and Des Moines Rivers in downtown Des Moines. The Raccoon River rises in Buena Vista County and travels approximately 200 miles to its mouth. The mainstem of the Raccoon is known as the North Raccoon River in its upper stretches and has two main tributaries: the Middle and South Raccoon Rivers. The Middle Raccoon River begins in northwest Carroll County and flows 76 miles to join the South Raccoon near Redfield, IA. The South Raccoon River starts near the Guthrie–Audubon County line and flows 50 miles until its confluence with the Middle Raccoon. The combined flows of the Middle and South Raccoon join the North Raccoon near Van Meter, a few miles downstream from Redfield.
The watershed mainly lies in the Des Moines Lobe, a remnant of the last Wisconsinan ice age. The Middle Raccoon traces the furthest edge of glacial advance, also known as the terminal moraine. This landscape was shaped only 12,000 years ago, much more recently than the rest of Iowa. Soils are among the most fertile on earth, and 80% of the area is cultivated for corn and soybeans.
In 1844, Captain James Allen and his Dragoon explorers were first Europeans to explore the watershed. His journals describe numerous lakes scattered throughout wet and dry prairie, and bears and elk being killed for food during the expedition. A grizzly bear was spotted on the ridge that separates Beaver Creek from the North Raccoon.
No one alive today has seen the Raccoon River in its natural state. Early settlers transformed the landscape into agricultural land through removal of native plants and systematic drainage, a process that continues to this day. The prairies and wetlands of the region were largely gone by 1900. This landscape modification dramatically altered the character, appearance, and water quality of the river to the extent that the river would be largely unrecognizable to people who saw it prior to 1860.