If you are fortunate enough to have a dam that you can fish, then you can catch some of the biggest catfish imaginable. The bottom of the dam where the water falls provides the perfect areas for the catfish to congregate, and if you know how you can easily reel them in.
The first thing you want to do is find a good vantage point to fish the dam. Ideally, you can set up in front of the dam either by sitting on rocks or other structures. If you can not fish there, then you can fish from the bank as well. Make sure you are careful that the area is safe and legal to fish.
The next thing you need is some decent fishing rods and heavy duty line. You do not need salt water line, but you do not want to use light fishing lines either. Something in between the two is ideal. Then rig up some hooks and add a couple of weights to the line about 12 inches above the bait.
Now that you have your gear rigged, then you are ready to begin fishing for catfish. If you are fishing from in front of the dam, then cast as close to the wall of the dam as possible. This is ideal because the catfish sit there to get the food that falls over the dam.
At the local dam where I fish, I have literally gotten bites before my line even sinks to the bottom. The catfish are extremely active in the early morning and evening, and night fishing in particular can be great fun.
If you are fishing from the bank, it can be more of a challenge to get the bait near the dam. Sometimes it helps to use a bit more weight on the line, but you do not want so much that you can not feel the catfish taking your bait. With the smaller catfish, you need to know how to recognize the smaller bites. This requires that you hold the line in with your finger so you feel the vibrations.
As for bait, catfishing at a dam is like catfishing anywhere else. Anything that has a pungent odor seems to do well. Nightcrawlers are effective, as is any kind of smelly bait. Many people have homemade catfish bait they use around dams made of things such as peanut butter. Most anything gets a bite from a catfish if it is capable of staying on the hook.