Construction of the Susquehanna and Tidewater Canal changed the area around the mouth of Deer Creek. A 246-foot-long dam, built of a heavy timber frame filled with rocks and covered with planking, raised the creek level and supplied water for the canal downriver to Havre de Grace. The higher water also allowed barges to be towed upstream to the flint mill at Stafford. Near the dam, a three-span wooden towpath bridge crossed the creek and was wide enough for small work wagons, carriages, and the mules that pulled canal barges. Southbound boats entered the creek below Lock #7 and were towed one mile in the creek to Lock #8. This lock did not raise or lower boats but served as a guard lock that protected the canal by preventing excess water from Deer Creek from flowing into it. Remnants of the stone abutments for the towpath bridge and the dam are still visible, and some of the dam's wood timbers can still be seen at low water. The current bridge was built for the railroad spur used during construction of the Conowingo Dam, and the large stones in the chamber of Lock #8 were dumped there during construction of the railroad.