Walnut Creek and its tributaries traverse 97 miles and drain 52,643 acres in Dallas and Polk Counties. Sixty percent of the watershed is rural/agriculture and forty percent is urban. This figure is changing rapidly.
The watershed includes the communities of Clive, Dallas Center, Des Moines, Grimes, Urbandale, Waukee, West Des Moines, and Windsor Heights.
Walnut Creek Watershed is one of the most critical watersheds in Iowa. The Des Moines Water Works intake valve is located one mile downstream from where Walnut Creek empties into the Raccoon River. Consequently, this watershed is a source of drinking water for 350,000 residents in Polk and Dallas Counties.