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Key Understandings for K-12 Study of the Hudson River

1. The lower Hudson is an estuary in which salty seawater pushes upriver, diluted by fresh water as it moves inland. The leading edge of dilute seawater generally ranges between the Tappan Zee and Newburgh, depending on the volume of freshwater runoff from the watershed. The plants and animals found at any place in the estuary reflect the prevailing salinity at that site.

2. Ocean tides influence the Hudson north to Troy, NY. The estuary typically experiences two high tides and two low tides each day. Organisms living in its shallows are adapted to survive and prosper while alternating between exposure to the air and submergence in water.

3. In the Hudson, as in most ecosystems, solar energy captured by green plants is made available to food webs. However, much of the energy that fuels this ecosystem does not come from plants living in the estuary. Instead, it comes from the watershed as detritus - decaying organic matter such as tree leaves - that enters food webs via bacteria and invertebrates that eat detritus.

4. Erosion, deposition, and other forces create habitats that support distinct communities of diverse plants and animals along the Hudson. Life in these habitats varies according to a mix of physical and chemical factors including depth, tides, salinity, and exposure to waves and ice.

5. The Hudson estuary is an important component of larger regional ecosystems such the coastal Atlantic Ocean. It provides critical spawning habitat for valuable coastal fish including striped bass, wintering habitat for eagles from northern Canada, and rest stops for migratory species that travel through the system and beyond.

6. The Hudson was a linchpin in Revolutionary War strategies, and as a result was memorialized as our first national river.

7. The Hudson's sea level course through the Highlands was key to realizing the dream of the Erie Canal, which made New York the Empire State and vaulted New York City to its leading role as a center of finance and trade. The river remains an important route for commerce today.

8. Early in our history, Americans forged a national identity that valued the wild landscape of the Hudson Valley. The aesthetic appeal of wild nature, celebrated by painters and writers, led to the preservation movement and, in the crucible of the Storm King battle, the modern environmental movement.

9. Once badly polluted with human sewage and industrial wastes, the Hudson is healthier now, thanks mainly to the Clean Water Act, which required sewage treatment and regulated other waste discharges. Remaining issues include non-point source pollution from the watershed and a legacy of toxic pollutants in sediments. The scale of physical alteration of the estuary by humans makes restoration of an idealized, pre-industrial ecosystem virtually impossible.

10. Estuary management programs encourage input from many stakeholders to formulate policies guiding development in a context of environmental protection. Disputes over environmental impacts do arise and are resolved through the political process and a framework of legislation interpreted and enforced by regulatory agencies and the courts. Citizens play crucial roles as participants in this process and as stewards of the river.


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  • The Hudson River Estuary Program
    NYSDEC Region 3
    21 S. Putt Corners Rd
    New Paltz, NY 12561
    845-256-3016
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