The Whitewater River run in Colorado spans from Flat Tops Wilderness Boundary to Nf Boundary. The ideal streamflow range for this run is between 350-1500 cfs, with the peak season in May and June. The class rating for this run is Class III-IV, which requires moderate to advanced skill level and experience. The segment mileage for this run is approximately 9 miles.

The Whitewater River run features several challenging rapids and obstacles, including the Yarmony Rapid, Eye of the Needle, Sledgehammer, and Pinball. The Yarmony Rapid is the first major rapid on this run, which is a Class IV rapids with a steep drop and a tight left turn. The Eye of the Needle is another significant feature, which is a narrow channel that requires precise maneuvering. The Sledgehammer and Pinball are two other notable rapids that require strong technical skills.

As for regulations, all river users are required to have a valid permit for commercial or private use. The maximum group size for commercial use is 25 people, and for private use, it is 15 people. Additionally, all river users must adhere to Leave No Trace principles and must not disturb the natural environment, including wildlife and vegetation.

In conclusion, the Whitewater River run in Colorado is a challenging yet rewarding run for experienced river users. With its Class III-IV rapids, ideal streamflow range, and beautiful scenery, this run is a must-visit spot for adventure seekers. However, it is crucial to follow all regulations and safety guidelines to ensure a safe and enjoyable experience.