High Quality Content by WIKIPEDIA articles! The Conowingo Dam is a large hydroelectric dam in the Lower Susquehanna River. The dam, one of the largest non-federal hydroelectric dams in the US, is classified as a medium height, masonry gravity type dam. The dam is located in Maryland, spanning the Cecil and Harford county border u2014 9.9 miles from the river mouth at the Chesapeake Bay, about 5 miles south of the Pennsylvania border and 45 miles northeast of Baltimore. The dam is named for the town of Conowingo, Maryland. The original location of Conowingo is now under the waters of the reservoir created by the dam. The town was relocated during construction of the dam to its present location about 1-mile northeast of the dam's eastern end. The area, as per the 1612 John Smith map, was originally known as Smyth's Falls.