The proposed whitewater river run Boundary Addition in the Cabinet Mountains Wilderness, Sec. to Cabinet Gorge Reservoir in Idaho is a thrilling stretch of water ideal for intermediate to advanced paddlers. The ideal streamflow range for this run is between 800 and 2500 cfs, which generally occurs during the early summer months. The segment mileage is approximately 8 miles with a class rating of III-IV, featuring a mix of continuous rapids and challenging drops.

The specific river rapids and obstacles along this stretch include the "Guardrail" rapid, which is a technical Class IV drop with a narrow chute and a tight turn. Another prominent feature is the "Super Slide" rapid, where paddlers must navigate through a steep, narrow chute. Along with rapids, paddlers must also navigate around rocks and boulders.

There are specific regulations for this area that must be followed, including obtaining a permit for overnight camping, adhering to Leave No Trace principles, and respecting the wildlife and natural resources in the area. Additionally, the use of motorized equipment is prohibited in the wilderness area.