Rivnuts from Homestead. PA on 6/4/2019 5:19:24 AM:
Although quite different in nature Great Falls in the Potomac River  along the C&O is more impressive than those along the GAP  including Ohiopyle on the Youghiogheny River..  As for "mountainous" waterfalls themselves I can't think of any of note along the C&O.  The terrain along the C&O is much different (flatter) and doesn't facilitate the formation of  hillside waterfalls.