Carbon River Fishing Best Time to Fish: September and October Species: Salmon, Steelhead This river originates from the Carbon Glacier on the northwest side of Mt. Rainier and flows into the Puyallup River. The river is prone to flooding due to its high glacial sediment content which deposits into the river valley. The river valley is known as a temperate rain forest due to the high annual rainfall, (70-90 inches). Best known for winter salmon and steelhead. ACCESS Easy access between Carbonado and Carbon River Entrance to the park.