Excerpted from Gotham Unbound: The Ecological History of Greater New York, by Ted Steinberg. Simon & Schuster. Copyright © 2014.
When it came to water, New York was the new Rome. In 1917 Edward Hagaman Hall of the American Scenic and Historic Preservation Society, founded in 1895 to protect natural scenery and landmarks, observed that even “[t]he greatest of the famous Roman aqueducts was only half as long as this one, and in technical difficulty was, in comparison, like building houses with children’s ‘blocks.’” George McClellan, the former mayor, argued that the Panama Canal—opened in 1914—for all its hardships, did not compare with the aqueduct, which he dubbed “the greatest piece of water supply engineering, if not the greatest engineering achievement of any kind, in the world.” But looked at from a different perspective, the aqueduct served as an immense nutrient pipeline. In the New York metropolitan area as a whole, untreated sewage increased from 622 million gallons a day in 1910 to 739 million gallons in 1920. The nitrogen loading to the Hudson-Raritan Estuary in the period between 1880 and 1920, it is estimated, grew more than five times to over twenty-eight thousand metric tons, or more than half the peak reading (which came in 1970) for this crucial element. Nor were there any signs that the Catskills project had done anything to quench the city’s thirst. In fact, between 1916 and 1920, the annual rate of increase in demand for water stood at forty-two million gallons a day, nearly three times the rate at the turn of the century.
By the twenties, New York Harbor had a raging oxygen disaster on its hands. The problem, of course, was not all New York’s fault. Communities from Westchester to Newark had built sewers routing nutrients to the surrounding waters. Commercial fisheries in Newark Bay and the Passaic River all but ceased to exist by the early twentieth century, and avian populations declined. One study concludes that “the mid-1920s probably represented a significant low point in the health of the ecology of the estuary.” To put the problem in ecological terms, a positive feedback on oxygen had begun. In a context of imperiled oyster and menhaden fisheries, increasing amounts of organic matter in particulate form entered the harbor and settled to the bottom. That initial disturbance led to a drop in dissolved oxygen, a condition that further compromised the future of these two filter feeders because they had evolved in a more aerated environment. Without these species grazing on phytoplankton, more organic matter filled the waters. That led to still less dissolved oxygen, as bacteria set to work decomposing the surplus organic input. It was the kind of inadvertent, runaway ecological dilemma that can happen in a complex system like New York Harbor.
Once the population tributary to the harbor crossed the threshold of 3.5 million people, one study concluded, average dissolved-oxygen levels remained steady in the 40 percent range despite increasing demographic growth. But the average figures obscure the stunning change that had come over these troubled waters. In 1926 the Harlem River’s average summer oxygen saturation plummeted to just 14 percent. Oxygen in the lower East River fell to 13 percent—too low for most fish to survive. According to an Army Corps of Engineers report, in the waters north of the Narrows, there was not “enough oxygen during one third of the year to permit active fish to live and the remainder of the time it is impossible for even sluggish varieties to thrive.” While the city had spent roughly two hundred million dollars accumulating a water supply that would have made the Romans envious, it had done virtually nothing to address the Goliath flushing problem that had devastated the marine environment.
As a result, natural population densities declined, and biodiversity suffered. Consider shad, one of the most significant fish species in the New York area. The amount caught in the Hudson increased until 1901, when the catch stood at seventeen million pounds a year; three years later, the haul amounted to less than a third that amount. Whatever else might be said about the slump, the enhanced nutrient load was bound to have played a key role.
Likewise, an inventory of mollusks compiled in the late nineteenth century uncovered significant species diversity, but then things changed. By 1920, fourteen out of a total of fifty-seven species in the waters surrounding Staten Island had become either rare or especially rare. Some of the mollusks relied on subaquatic vegetation for habitat. But with all the particulates coursing into the harbor (sewage and sediment), the underwater greensward suffered as turbidity increased and the grass was forced to compete for light with phytoplankton. Another threat to the sea grass came from dead algae. A brown blanket of partially decomposed matter covered the grass leaves, reducing the available light and, thus, photosynthetic potential and oxygen produced. And as the habitat became degraded, marine life struggled. The decline of the oyster beds, in particular, had ramifying effects. Oyster reefs are important nursery grounds for fish, including shad. The compromised reefs impacted all kinds of life-forms—from sponges and anemones to barnacles and worms—that glommed onto the shell substrate etched across the bottom of the harbor.
As New York above ground grew demographically and exploded into three dimensions—giving birth to its iconic skyline—the surrounding waters flattened like a pancake. Though not widely recognized as such, the dense complexes of plants and animals found along the coast are as biologically rich as forests or savannas. Only the viscosity of seawater relative to air, some ecologists have argued, keeps us from realizing this elemental fact. The hard truth was that by early in the twentieth century, New York’s coastal waters had experienced an extraordinary transformation. In the language of ecology, New York Harbor went “from complex and diverse 3-dimensional biological habitats to simple 2-dimensional sediments and rocky surfaces populated by scattered organisms.”
In 1911, on the hundredth anniversary of the proverbial grid that had paved the way for high-density development, there was no celebration. And given what is now known about the legacy of New York’s mushrooming growth on the harbor, perhaps that was just as well.