The Whitewater River Run from Sawtooth Wilderness Boundary to Confluence with Johnson Creek in Idaho spans approximately 13 miles. It is classified as a Class III-IV river, with a recommended streamflow range of 500-1,500 cfs. The river contains several rapids, including Boxcar, Upper and Lower Gobbler, and the infamous Meatgrinder. The Meatgrinder is a Class IV rapid with a sharp drop and large boulders.

Regulations in the area include a permit system for overnight stays in the Sawtooth Wilderness and a requirement for a personal flotation device (PFD) for all individuals on the river. In addition, the area is only open for recreational use from May 28 to November 30. The river also contains potential hazards, such as downed trees and unpredictable water levels, so caution is recommended.

Sources such as American Whitewater and the US Forest Service were consulted to verify the accuracy of this information. Overall, the Whitewater River Run is a challenging and exciting paddle for experienced kayakers and rafters, with stunning views of the Sawtooth Mountains.