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The Hudson Estuary: A River That Flows Two Ways

Bear Mountain BridgeThe Hudson River is the defining natural feature of a major region of New York State, familiar to millions who drive across its bridges, admire its grandeur from parks and historic sites, or commute to work on the Hudson River Line railroad. Familiar as it may be, the Hudson is more than it seems.

Take its name, for example. In 1609 Henry Hudson, an Englishman sailing for Holland's East India Company, captained a Dutch ship up this river in search of the fabled Northwest Passage. He referred to the river as the "Manhatees." Dutch colonists who followed named it "River of the Prince Mauritius" and "North River." Hudson's name wasn't applied until 1664, as England tried to justify its takeover of the region. The English argued that since the explorer was a subject of England's king, Hudson's river belonged to them, not to the Dutch.

Mahicantuck

Of course, native tribes had named the river long before Hudson's arrival. One of their names-Mahicantuck-means "great waters in constant motion" or, more loosely, "river that flows two ways." It highlights the fact that this waterway is more than a river-it is a tidal estuary, an arm of the sea where salty sea water meets fresh water running off the land.

troy dam - head of the Hudson EstuaryThe Hudson estuary stretches 153 miles from Troy to New York Harbor, nearly half the river's 315 mile course between Lake Tear of the Clouds, in the Adirondacks and the Battery at the tip of Manhattan. The estuary feels the ocean's tidal pulse all the way to Troy. Push a stick into the beach at the water's edge, or note the water's height on a piling or rock. Check back in 20 minutes. Is the water level the same? The estuary usually has two high and two low tides in twenty-four hours. With this rise and fall come changes in the direction of flow. In general, a rising tide is accompanied by a flood current flowing north towards Troy, a falling tide by an ebb current flowing seaward.

The Hudson Estuary at NYCSalty sea water also pushes up the estuary, diluted by freshwater runoff as it moves north. In years with average precipitation falling in usual seasonal patterns, spring runoff holds the leading edge of dilute sea water-the salt front-downriver in the Tappan Zee. As runoff slackens in summer, the salt front pushes northward to Newburgh Bay, and further-to Poughkeepsie-in droughts.

An Estuary's Bounty

Estuaries are among the most productive of Earth's ecosystems. Native Americans discovered the Hudson's bounty thousands of years ago; evidence of their repasts remains in heaps of oyster shells on its shores. Hudson and Dutch traders wrote of a river teeming with striped bass, herring, and giant sturgeon. More than 200 species of fish are found in the Hudson and its tributaries. The estuary's productivity is ecologically and economically valuable to much of the Atlantic Coast; key commercial and recreational species like striped bass, bluefish, and blue crab depend on nursery habitat here. Bald eagles, herons, waterfowl, and other birds feed from the river's bounty. Tidal marshes, mudflats, and other significant habitats in and along the estuary support a great diversity of life.

The region's human residents have also flourished thanks to the Hudson estuary. Its course through the Hudson Highlands, the only sea-level breach in the Appalachian Mountain Range, allowed nineteenth century engineers to realize their visions of links between seacoast and heartland. The river was a key leg in the transport of goods between New York Harbor and the Great Lakes via the Erie Canal, which made New York the Empire State. The Hudson eventually became a source of drinking water for cities, process water for industry, recreation for picnickers and boaters, and soul-stirring inspiration for artists.

Returning the River to Health

However, as population increased, the Hudson's natural resources were abused. Sewage discharges led to high bacteria counts and low oxygen levels. Valuable wetlands were filled in, scenic vistas desecrated by quarrying, millions of fish killed in cooling water intakes, and food webs contaminated by toxic chemicals. Dismayed at such abuse, citizens took action. In the late nineteenth century, New York and New Jersey residents mounted an interstate effort to preserve the Palisades cliffs. In the 1960s the battle to save Storm King Mountain in the Highlands helped found today's national environmental movement. New York voters passed a bond act for sewage cleanup in 1965; the federal Clean Water Act was enacted in 1972. These measures significantly improved water quality in the Hudson estuary. The Hudson River National Estuarine Research Reserve and other preserves were established to protect critical wetland habitat.

Today the Hudson River is one of the healthiest estuaries on the Atlantic Coast. Its rich history and striking environmental recovery have made it one of the nation's fourteen American Heritage Rivers. In partnership with DEC's Hudson River Estuary Program, citizen groups and government agencies continue to make progress in restoring and protecting this great river for generations to come.


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