Many people use a river outfitter to enjoy the whitewater of the Arkansas River. Look up an AHRA river rafting or fishing outfitter, photographer or shuttle service in the Outfitter List for 2013.
You can also go to the Arkansas River Outfitters Association Web site and learn how to choose a river outfitter.
Other links that are useful for Arkansas River outfitters are:
2012-2013 Arkansas River Commercial Boating Use Reports