This is a picture of me standing atop the sediment retention structure (SRS). The SRS is essentially a dam across the Toutle river valley. It was consrcuted to slow the flow of water in the river to allow sediment to precipitate. Most of the sediment in the river is eroded ash and debris from the 1980 eruption of Mt. St. Helens. If the sediment was allowed to continue flowing down the river it would have blocked the shipping chanels of the Columbia river and caused flooding.
