History of New York Habitats
Estuaries and Salt Marshes

Estuaries are geologically rare ecosystems that form only when sea level reaches a certain point. New York City’s estuaries were formed after the last glacier receded and the sea flooded the continental shelf, drowning the old Hudson Canyon. As rivers like the Hudson were released from their impoundment behind glacial moraines to flow into their present-day channels, the commingling of fresh and salt waters in shallow bays created estuaries, which are really tidal rivers. At high tide, the sea pushes upriver, and at low tide, the sea withdraws - hence the Lenape name given to the Lower Hudson, Mahicanituk, which eighteenth-century Mahican scholar Hendrick Apaumaut translated as "the great waters or sea, which are constantly in motion, either ebbing or flowing." In the shallow waters of estuaries, sediments eroded by tidal action are deposited along the shores, building mudflats where cordgrasses take root and grow into salt marshes. The estuaries, bays and salt marshes that fringe the New York City region have supported a diversity of species for millennia.

A History of Pollution of New York’s Estuaries

The pollution of New York waters during the nineteenth and twentieth centuries was staggering in its scale. Its sources were domestic and industrial.

Domestic Pollution

In the early 1900s, raw sewage from a population of six million emptied into New York waters, polluting beaches and bays, causing a major health crisis. Between 1914 and 1917, it was reported that oxygen content in New York’s waters was reduced as much as 68 percent, and zero percent in some of the worst places, such as the Harlem River. Pollution was so bad as to warrant closing of the beaches and prohibition against swimming in 1927. The Harlem and East rivers, Newtown and Coney Island creeks, and the Gowanus Canal had become cesspools. People were dying of typhoid and dysentery because of eating contaminated shellfish or swimming in the waters; massive fishkills covered the bays. New York had truly become, as a Public Health Committee report declared, “a body of land entirely surrounded by sewerage.”

Sewage plants were built as early as 1887 on Coney Island and in 1891 at Sheepshead Bay, serving as models of sewage treatment using chemical precipitation. According to this method, lime and perchloride of iron are added to sewage in tanks, the sludge is disinfected and deodorized by chlorine, and the effluent is discharged into salt water. A Sewerage Commission was formed in 1903, and a sewage treatment plan based on the natural drainage system of the region was adopted in 1920. By 1927, the Jamaica Bay plant was built, followed by three more plants by 1952. A major trunk sewage system in New Jersey was completed in 1958, resulting in a dramatic increase in invertebrate species within a year in the waters of Raritan Bay, according to a contemporary study.

Industrial Pollution

Chemical effluents from New York industries added to the toxic stew. Since the late 1800s, petroleum refineries and chemical plants discharged their wastes directly into the tidal creeks and rivers where they were clustered, especially along Newtown Creek in Queens. An 1881 report describes “the hundreds of acres of marsh saturated with the drainage and soakage of filth,” and the slime-coated banks of Newtown Creek. The tidal creek, which once meandered through an extensive salt marsh, had now become a toxic cesspool.

Dumping, both legal and illegal, also poisoned the waters. In the late nineteenth century, nearly all the refuse produced by the city was dumped directly into the sea a mere 16 3/4 miles from Long Island’s south shore and 21 miles from the Jersey shore – and that was only the legal dumping. Private contractors for beachfront hotels and industries illegally dumped far more. And no matter how many miles from shore it was dumped, the garbage would float back to the shore, carried by tides and prevailing winds. One of the dumping sites was the drowned Hudson River Canyon, known as the “Mud Hole” to fisherman, used legally until dumping was prohibited in 1988. Now the problem is what to do to cap the dumping sites so that they do not continue leaching into the waters.

Oil Pollution

Presaging the massive oil spills of the 1980s, oil was already threatening New York waters in the late nineteenth century. Oil was discharged from steamers into the bay, and oil run-off from garages and street surfaces drained into sewers that discharged directly into the bay, poisoning thousands of shellfish and waterfowl. Not until the passage of the 1888 New York Harbor Act, and the 1899 River and Harbor Act, was such discharging prohibited. But this would not prevent accidental oil spills, or the flaunting of the law. The New York State Conservation Law of 1911 prohibited the pollution of streams by oil refineries, but the prohibition was largely ignored, as indicated by a 1926 report by a state legislative committee that decried the killing by oil of “great quantities of fish and thousands of wild fowl which the state has been trying to conserve.” That same year, an International Conference on Oil Pollution was convened in Washington, D.C., with thirteen nations participating; they agreed to prohibit oil discharge into waters within 50 to 150 miles of shore. Still, oil pollution continued to threaten New York waterways. As noted by the Regional Plan Committee, “government regulation alone cannot remedy conditions unless public sentiment is ready to demand a strict enforcement of the necessary laws.”

For further information on efforts to clean up New York waters, go to the habitat restoration page.


For at least 5000 years prior to European settlement, it's estimated that 95% of the Northeast was covered by forest. A mere 1.5 million acres remain of an original 822 million acres, according to a survey conducted by Mary Byrd Davis in 1993. The thickest forests were north of New York City, which was a mosaic of grasslands, wetlands, sand plains, and parkland-type forest - a land long managed by the village agriculturalists who lived in the region (see the page Native New Yorkers).

When Europeans colonized the region, they quickly depleted the old-growth forests. Shipbuilding, in particular, required steady supplies of timber; a single warship, for example, consumed 2,000 old oak trees.

Colonial farmers cut trees with wasteful abandon, clear-cutting to create cropland and pastures. Domestic animals like cows and hogs trampled the understory and compacted the soil, which reduced the soil's water-retaining capacity and prevented saplings from growing to maturity. Between 1700 and 1900, 75% of New York State was deforested.

Industrialization in the nineteenth century stepped up the rate of destruction. The iron industry was particularly fuel-intensive, writes Robert Boyle in his history of the Hudson River, "and the end result was that much of the [Hudson] valley was clear cut every thirty or forty years." The steam which powered the factories, steam-boats and trains was produced by the burning of wood until coal began to be used. Boyle writes: "As early as 1825, the thirteen steamers on the Hudson and the ferries in the harbor used one hundred thousand cords of wood in the eight months of the year the river was free of ice. Wood was cut on the top of the Palisades and slid down the cliffs to deep water. Thus the name High Gutter Point on the New York-New Jersey state line."

Ironically, the decline of agriculture in New York State in the 20th century has helped the recovery of woodlands. In 1993, according to U.S. Forest Service statistics, New York was 62% forest, 14% cropland, 4% pasture, and 20% urban/suburban.

For more information on woodland restoration, go to the habitat restoration page.


Hempstead Plains was once the only extensive prairie east of the Alleghenies. It covered 60,000 acres of western Long Island, of which a fraction remain - three parcels totalling 62 acres saved from development and restored by the Friends of Hempstead Plains and the Nature Conservancy.

The original short-grass prairie had established itself on glacial outwash after the last glacier receded, and was a climax eco-system - one that had evolved over millennia to reach its grassland state, which if left undisturbed would have remained a prairie forever.

What happened to the prairie? Carole Neidich, Senior Curator of Life Sciences at the Nassau County Museum, gives us a snapshot history of the plains. The Indians, of course, were the first human inhabitants, having lived in the region at least 5,000 years. The first European colonists to inhabit the region were a group of English Dissenters led by Reverend Richard Denton, who purchased the "Great Plains" in 1643. Daniel Denton, son of Richard, describes the plains: "Toward the middle of Long Island lyeth a plain, sixteen miles long and four broad, upon which the plain grows very fine grass that makes excellent good hay, and is very good pasture for sheep and other cattle, where you shall find neither stick nor stone to hinder the horses' heels or endanger them in their races."

The Plains were eventually subdivided among different families, and fenced, leaving 17,000 acres as common land well into the nineteenth century. These common lands came to be used as military bases and later, air fields - hence its name, "Cradle of Aviation in America."

The earliest suburb on the Plains was Garden City, developed out of a 7500-acre tract bought by Alexander T. Stewart in 1869. In the post-war baby boom following World War II, suburban developments spread like wildfire across the former prairie, beginning with Levittown. 17,000 houses in this development alone also meant 17,000 lawns, which introduced alien grasses and other invasive flora. Suburbanization brought shopping malls in their wake: Roosevelt Field is one of the oldest shopping malls, smothering the old grassland with acres and acres of concrete.

For more information on grassland restoration, go to the habitat restoration page.

--Betsy McCully

Reading List

Albion, Robert G.
Forests and Sea Power: The Timber Problem of the Royal Navy, 1652-1862 (1926; Hamden, Ct.: Archon Books, reprint, 1965).

Anderson, Tom.
This Fine Piece of Water: An Environmental History of Long Island Sound. New Haven and London: Yale University Press, 2002.

Boyle, Robert.
The Hudson River: A Natural and Unnatural History. New York: W.W. Norton, 1973).

Cronon, William.
Changes in the Land: Indians, Colonists and the Ecology of New England (New York: Hill & Wang, 1983).

Davis, Mary Byrd, ed.
Eastern Old Growth Forests: Prospects for Rediscovery and Recovery. (Washington, D.C.: Island Press, 1996).

McCully, Betsy. City at the Water's Edge: A Natural History of New York (Rivergate/Rutgers, 2007).

Teal, John and Mildred.
Life and Death of a Salt Marsh. New York: Ballantine, 1969.
Jamaica Bay
Cow Meadow, Long Island
Updated August 2011
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