The whitewater river run from Outlet Alteras Lake to Confluence with Salmon River in Idaho is a thrilling adventure for kayakers and rafters. The ideal streamflow range for this section is between 800-2,000 cfs. This section is rated Class III-IV, making it suitable for intermediate to advanced paddlers. The segment mileage is approximately 26 miles, offering a challenging and exciting experience for those who choose to embark on this journey.

The river features several notable rapids, including Deer Creek Falls, which is a Class IV rapid that requires technical maneuvering skills. The Lunch Counter is another rapid that is infamous for its large waves, making it a Class III+ rapid. Additionally, Big Mallard Creek and Elkhorn Rapids provide exciting challenges for paddlers.

There are specific regulations to be aware of in this area. All paddlers must wear a personal flotation device (PFD) and a helmet. The use of alcohol is strictly prohibited, and all waste must be packed out. Campfires are only allowed in designated areas, and visitors must obtain a permit before camping.

In conclusion, the whitewater river run from Outlet Alteras Lake to Confluence with Salmon River in Idaho provides an exhilarating experience for intermediate to advanced paddlers. With a range of class III-IV rapids and specific regulations to adhere to, this section of the river offers a challenging and exciting adventure for those who choose to tackle it.