Moulton Falls is another park along the Lewis River here in Clark County, WA. We explored it on Saturday. The weather was cooler and we were almost the only ones there:
You are allowed to swim here, if you dare. There are some really deep pools and the water is cold and clear. There were two scuba divers training there, and some crazy kids came and jumped in too. We dipped our feet in and that was enough. We walked up and over the bridge and along the trail on the other side of the river for a ways. Mostly we climbed on the rocks and looked at the deep pools and rapids. It was a relaxing Saturday.