The Whitewater River Run, from the Headwaters to the North Cascades National Park Boundary in Washington State, has an ideal streamflow range of 800-3,000 cubic feet per second (cfs). The class rating for this section of the river varies between Class III and IV, depending on the segment. The segment mileage for this run is approximately 12 miles, with various rapids and obstacles throughout.

The rapids on this section of the river include popular ones such as "Falls View" and "Big Brother," which are both Class IV rapids. "Falls View" is a steep and technical rapid that requires precise maneuvering, while "Big Brother" is a longer rapid with several drops and technical moves. Other notable rapids include "Knot it All" and "The Perfect Wave."

There are specific regulations in place for this area to ensure the safety of those participating in this activity. All boaters are required to obtain a permit from the National Park Service before running this section of the river. Additionally, boaters must adhere to strict safety guidelines, including wearing a personal flotation device and carrying appropriate safety equipment.

In conclusion, the Whitewater River Run in Washington State is an exciting and challenging experience for those looking to test their whitewater skills. With its ideal streamflow range, varying class rating, and specific regulations, this run is a popular destination for experienced whitewater enthusiasts. It is important to always prioritize safety and follow all regulations when participating in any outdoor activity.