Watch the weather when planning your trip. It seems like the colder the better. If much of the river is frozen over the Eagles will concentrate below the dam. The best conditions are a bright sunny day with the wind coming from the West-Southwest or from the Southwest. The Eagles will fly in to the wind as they swoop down to grab a fish from the river and this will put them facing toward the sun or with the sun slightly to their right, and facing the right direction for photography from the viewing platform. At some times the action is very fast with several Eagles fishing at the same time. At other times you may sit for a long time with no action. Bring a stool or you'll be standing a long time.
I had a good day photographing Bald Eagles and got many shots that I liked. I especially liked the one below of the Eagle looking at the fish that he had just snared. You can see more Eagle pictures here.
Getting there: Take I-80 to the Le Claire, IA exit just before the bridge crosses the river to Illinois. It is exit 308. Go south on US Highway 67 (S. Cody Rd) for a couple of miles and turn left (East) in to a drive for the Lock and Dam 14. There is a large parking area below the lock next to the river and a long paved sidewalk for viewing and photography.