Mile 5.64 - The dam at Little Falls is dangerous for people on the river and NPS has erected this huge sign on the banks of the canal and also on couple of bouys out in the Potomac. This dam works in conjuction with the inlet lock at Lock 5 to keep the canal watered.
From Little Falls to Seneca Creek was the first completed section of the canal. You can see the remains of the feeder dam which helped keep the canal watered.
There's a kayak course set up here.