Arkansas River

The Arkansas River is a major tributary of the Mississippi River. The Arkansas generally flows to the east and southeast as it traverses the US states of Colorado, Kansas, Oklahoma, and Arkansas. The river's initial basin starts in the western United States in Colorado, specifically the Arkansas River Valley, where the headwaters derive from the snowpack in the Collegiate Peaks. Then it flows east into the Midwest via Kansas, and finally into the South through Oklahoma and Arkansas.

At 1,469 miles (2,364 km), it is the sixth-longest river in the United States, the second-longest tributary in the Mississippi–Missouri system, and the 45th longest river in the world. Its origin is in the Rocky Mountains in Lake County, Colorado, near Leadville.

Arkansas River in Supervolcano
When Vanessa Ferguson fled Denver, Colorado after the Yellowstone Supervolcano eruption, her route east from Pueblo to Garden City took her near the banks of the Arkansas River. As she drove, it began to rain and Ferguson was surprised at how turbulent the river became since the rainfall wasn't particularly hard. She eventually realized that the ash being washed into the river was causing blockages in the flow, making the water levels higher than would be expected from the amount of rain falling.

Ferguson ended up in Camp Constitution, located between Muskogee, Oklahoma and Fayetteville or Fort Smith, Arkansas, just beyond the limits of ashfall. The first spring after the eruption, the ash in the Arkansas River caused some flooding during the snow melt and runoff. The following spring, a year later, was even worse due to the previous ash not being completely washed away. The floods were severe enough to force the refugees in Camp Constitution to be evacuated to a new camp further east and on higher ground.