A boring made in 1879 at the West Thirteenth Street outfall in New York City illustrated the scale of the pollution. The drill passed through 175 feet of sewage and sludge before it found the bottom of the harbor. The combination of nitrogen from the decaying wastes of urban areas and phosphorus that entered the rivers with the deforestation of the Hudson River Valley produced eutrophication. The declining level of oxygen in urban waters meant many could not sustain life. As the amount of sediments and eutrophication increased, urban fisheries declined, eliminating another cheap and common
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