To establish the Carmel River arm of the reservoir as a permanent sediment storage area, the river was rerouted into the adjacent San Clemente Creek, upstream of this area. This was accomplished by cutting a “Reroute Channel” through the narrow ridge separating the two waterways, approximately one-half mile upstream of the dam. The natural confluence of the Carmel River and San Clemente Creek was within the current dam reservoir, so the project in effect moved this confluence approximately one-half mile upstream.
Rock excavated from the Reroute Channel was then used to build a structure that blocks the river from entering the reach that became the sediment disposal area. This structure, the “Diversion Dike”, diverts the river into the newly cut Reroute Channel. The Diversion Dike is essentially a new ridge cutting across the valley floor.