The Whitewater River Run Wilderness Boundary to Confluence with Mill Creek in California is a challenging and exciting run for experienced boaters. The ideal streamflow range is between 400-800 cfs, which usually occurs from late winter through early spring. The run is rated as a Class III-IV, with some rapids reaching Class V during high flows. The segment mileage is approximately 7.5 miles.

Some specific rapids and obstacles to watch out for include "Drop Out," a steep Class IV drop with a tight slot entrance, and "Finger Rock," a technical Class IV rapid with a sharp right turn. "Hell's Corner" is a Class V rapid with a large boulder in the center that requires precise maneuvers to avoid.

There are certain regulations to be aware of when boating in this area. All boaters must obtain a permit from the Bureau of Land Management, and the maximum group size is limited to 15 people. Camping is only allowed in designated sites, and fires are prohibited. Additionally, the use of glass containers is not allowed on the river.