The whitewater river run from Mainstream to Confluence with Cooper Canyon and then to Confluence with South Fork Little Rock Creek in California is a popular destination for outdoor enthusiasts. The ideal streamflow range for this run is between 200-400 cfs, which typically occurs during the spring snowmelt or after heavy rainfall.

This section of the river has been given a Class III-IV rating, making it best suited for intermediate to advanced paddlers. The total segment mileage for this run is approximately 8.5 miles. Along the route, paddlers will encounter several notable rapids and obstacles, including Pinball, Squeeze, and S-Turn, which require technical maneuvering and careful navigation.

Specific regulations to the area include the requirement for all paddlers to wear personal flotation devices and helmets while on the river. Additionally, camping and fires are only permitted in designated areas, and visitors are expected to follow Leave No Trace principles and pack out all trash. Local outfitters offer guided tours and equipment rentals, and it is recommended that paddlers have experience and proper gear before attempting this challenging whitewater run.