Looks like the bottom end of the Wilmington Flume. There is a bridge that crosses the river and you park at one end. There is a restaurant on the other end of the bridge and a KOA (I think) campground on the other side of the road. There are trails on both sides of the river that lead down to the bottom pool. There are a couple of falls within the flume as well, you can see them from the top of the cliffs, or if you're adventurous, there are a couple of places you can climb down to look at them, but it's tricky. There is also a set of falls above the bridge just down from the parking area. Watch out for poison ivy, though this time of year it's probably gone by now.
I have a ton of pictures of the place, but never got around to posting them.
Google map