The estuary continued to be heavily used for commercial purposes throughout the 19th and early 20th centuries. Gristmills and tanneries on the rivers of the estuary contributed significantly to the chemical pollution until the mid 20th century. When the Greek entrepreneur Aristotle Onassis proposed building the Olympic Oil Refinery in the town of Durham along the shore of Great Bay in 1973, local citizens mobilized and by exercising their right to "home rule", defeated the proposal by a margin of nine to one.