The ramp Larry mentioned is a TVA ramp. It is the one most people use to fish the tail waters, as it is just a short ride up stream to the dam....you can see the dam from the ramp.
A few words of warning about it though. That ramp is off the main road and you don't want to be the last vehicle in the parking lot if you catch my drift. Vehicles are bad about getting broken into there. Certain times of the year, the vultures will come roost there around the parking lot. I don't know what it is about them, but they like rubber and they will land on your vehicles and eat your windshield seals, wipers, etc. The ramp itself is a steep ramp. I've seen many a vehicle end up down in the water right there from the ramp getting slick and inexperienced drivers trying to pull their boat back up it. If they are running flood gates or a lot of turbines, the way the current angles toward the ramp, it can make it hard to load and unload there if you've never done it. The current will want to push you sideways.
There's another ramp at the Hwy 30 crossing of the river but that would be a decent far run to get to the dam from there.
Some people will put in at the ramp above the dam and just lock through...it is a much nicer ramp with a dock, and the Meigs County police do patrol it quite a bit BUT then you have the hassle of locking thru twice if you are fishing the tail water. Your best bet is to go early and fish while the thugs are still in bed lol. They don't start stirring til the after noon.