In the nineteenth century, the two river mouths were developed as harbours - Victoria Dock for general coastal trade, and the Slate Quays as a specialist harbour for the export of slate.
Yn y bedwaredd ganrif ar bymtheg, datblygwyd aberoedd yr afonydd fel harbwrs - Doc Fictoria ar gyfer masnach arfordirol gyffredinol, a'r Cei Llechi fel harbwr arbenigol ar gyfer allforio llechi.