Historically the mouth of Rock Creek and up to the fall line was protected by statute: there was a law against any fish weirs within two miles of its mouth, meant to keep as much of the waterway open to navigation as possible. When the C&O Canal company built a "mole," or broad earthen dam, across the mouth of Rock Creek, the lower one-quarter mile of the river turned into a basin easily navigated by the canal barges. Oceangoing ships were loaded across the mole from the barges docked on the basin side, and a small tidal lock relieved the flow of the river, allowing small vessels to enter the canal from the Potomac.
Though the canal company built the mole and Georgetown merchants benefited from their proximity to the waterfront, disputes arose over who was responsible for the maintenance of the basin, which was prone to silting. Merchants and mariners also squabbled over rights to tie up at the mole, as docking privileges were ill-defined and often disputed.