Rivers

Like veins and arteries transecting our land, rivers are the lifeblood of our state. From historic exploration to transportation, recreation, and drinking water, Iowa’s rivers—all 70,247 miles of them—are an ever-present pulse on our landscape, connecting cities, towns, people, and the land itself.

Rivers are dynamic systems, constantly moving and changing. Erosion is responsible for stream/river formation, and continues to be an active process today. Rivers move side-to-side, meandering across the land—lateral erosion, or valley widening. Rivers move vertically, with the power of water eroding sediment and cutting deeper into the land—down-cutting, or valley deepening. Headward erosion is the uphill growth of a river valley, happening along tributaries—valley lengthening. Erosive processes also happen in-stream due to differences in water velocity.

Rivers have the power to transport sediment and nutrients from upland areas of the watershed, carrying them downstream, depositing the sediment when currents slow. Rivers are ever-changing and intricately connected with the land—the watershed—around them!

The direction and path of river flow is determined by the topography of the land, with water always flowing from higher elevations to lower elevations. It’s a myth that all rivers run north to south in the northern hemisphere—instead, it’s all about the slope of the land. The Missouri-Mississippi Divide, hills/high points in western Iowa, defines where water flows in our state. All water west of this divide flows to the Missouri River, and all water east of this divide flows to the Mississippi River.