I think every "large dam" has a hydroelectric power station associated with it in the US. One can of course count dams and many of them will be rather on the small side. Maybe there is one somewhere 100 feet tall or more without a power plant, but not many.
Dams on the Ohio River, for example, are for navigation, with locks, and they were maybe 50 feet high, and not enough reason to try and generate power from that.
Hydro is basically tapped out in the US today, with more dams disappearing for environmental reasons than being built (which is zero for larger dams). The TVA area has a lot of dams of course, many built in part for flood control. Any areas left where a dam might generate power are protected areas.