An estuary is a transitional area along the coast where salt water from the ocean mixes with fresh water from the land and creates a unique and special place for marine species to live, feed, and reproduce. Estuaries are partially enclosed bodies of water and often have restrictions across the mouth, like a barrier beach or sand bar, which allows for tidal influence, but also offers protection from the full force of ocean waves and storms. Within an estuary there are many different marine habitat types including tidal wetlands, mudflats, rocky shores, oyster reefs, freshwater wetlands, sandy beaches, and eelgrass beds.
Estuaries are a critical part of the life cycle of many different species. They are the spawning and nursery areas for thousands of animals, such as fish and crabs, who seek the quieter waters of estuaries to provide a protected nursery for their offspring. Estuaries also provide a food-rich resting area for migrating waterfowl and shorebirds like black ducks, harlequin ducks, scoters, scaup, and red knot. Wading birds like the great blue heron, great egret, glossy ibis, and snowy egret nest in colonies on islands found in New York Harbor, Long Island Sound, and Gardiners Bay. Raptors like osprey and northern harriers also nest and feed throughout the marine district of New York.
New York's Marine and Coastal District has five estuaries which are managed cooperatively by DEC and other state, local, and federal government agencies, the scientific community, and direct input from private citizens. They include:
- The Peconic Estuary
- Long Island South Shore Estuary
- New York/New Jersey Harbor
- Long Island Sound
- Hudson River Estuary
- Hudson River Estuary Program
- Hudson River National Estuarine Research Reserve
Peconic Estuary Partnership

The Peconic Estuary system is located on the eastern end of Long Island, between the North and South Forks. The estuary includes more than 100 distinct bays, harbors, embayments and tributaries, including bays such as Flanders Bay, Great Peconic Bay, Little Peconic Bay, Shelter Island Sound, and Gardiners Bay.
The Peconic Estuary Partnership (PEP) is a cooperative effort between the state of New York State, Suffolk County, the United States Environmental Protection Agency (EPA), the scientific community, and the citizens of the Peconic Estuary watershed. PEP's mission is to protect and restore the Peconic Estuary and its watershed. In 2020 a new Comprehensive Conservation and Management Plan (CCMP) was adopted. Below are the 4 pillars of its foundation.
- Strong Partnerships and Engagement
Partnership is an integral part of PEP. PEP's partners work together and play different roles in accomplishing the CCMP actions. PEP's strongest partnership is with local governments and non-government organizations (NGOs) because their work influences the estuary most directly. Engaging with people who live and work in the Peconic Estuary and watershed is also a big priority. It is vital to empower the surrounding community to get involved and act in support of PEP's mission. - Resilient Communities Prepared for Climate Change
Climate change is one of the most substantial threats to the long-term health of the Peconic Estuary. Changes in air and water temperature, increased storm intensity and frequency, sea level rise, rising groundwater and ocean acidification are all potential risk factors. PEP is actively working to help reduce the negative impacts that climate change will have on the estuary and its wildlife. PEP monitors and protects essential coastal ecosystems such as seagrass beds and salt marshes. These ecosystems provide coastal protection from storms, act as nursery grounds for fish, and are considered "carbon sinks." The plants and sediments in these ecosystems capture and store large quantities of carbon from the atmosphere and ocean, making them an important part of the solution. - Clean Water for Ecosystem Health and Safe Recreation
Clean water allows for safe recreation in and on the water as well as seafood that is safe for consumption. An excess of nitrogen in the Peconic Estuary has been one of the most serious issues affecting the water quality. Nitrogen loading can cause harmful algal blooms (HABs) and degraded aquatic habitats. Some other contributors to water pollution in the estuary are pathogens and toxic contaminants, which can make fish and shellfish unsafe to eat. Marine debris is an increasing concern due to its persistence and effect on the environmental, wildlife, and human health. PEP and its partners collect and analyze water quality data in order to identify problem areas. - Healthy Ecosystems with Abundant, Diverse Wildlife
Physical alterations such as channel dredging, hardening of shorelines, and clearing of land, all harm the habitats and living resources in and around the Peconic Estuary. Critical habitats such as pine barrens, eelgrass beds, marshes, and diadromous fish habitat have all been degraded by these alterations along with climate change and pollution. PEP conducts scientific studies in order to better understand the Peconic Estuary ecosystem and how to manage it. The 2020 PEP Habitat Restoration Plan identifies goals, objectives, and actions that guide habitat restoration over the next 10 years. Check out this interactive map created by PEP and NYSDEC to learn more about all the completed, ongoing, and priority habitat restoration projects in the Peconic Estuary Watershed.
South Shore Estuary Reserve
The Long Island South Shore Estuary Reserve encompasses one of New York State's most diverse estuaries and its 326 square mile watershed in Nassau and Suffolk Counties. The Reserve extends from the Queens/Nassau County line eastward about 75 miles to the Village of Southampton in Suffolk County. From south to north, the Reserve extends from the mean high tide line on the ocean side of the barrier island to the inland limits of the estuary's watershed. The Reserve's shallow, interconnected bays and tidal tributaries provide highly productive habitats and support the largest concentration of water-dependent businesses in the State. Home to 1.5 million people, the Reserve is the anchor of the region's tourism, seafood, and recreation industries, attracting millions of visitors each year to enjoy its beauty and bounty.
The Reserve was created by the Long Island South Shore Estuary Reserve Act, enacted by the New York State Legislature, at the urging of Long Islanders concerned with the future health and management of the estuary. The Act called for the Reserve's protection and prudent management and created the South Shore Estuary Reserve Council, chaired by the New York State Secretary of State. The Reserve Council is a group of representatives from south shore towns and villages, Nassau and Suffolk counties and the City of Long Beach, State agencies, and recreation, business, academic, environmental and citizens interests. The Act charged the Council with the preparation of a comprehensive management plan for the Reserve.
The Reserve Comprehensive Management Plan addresses these five major areas:
- Water Quality
Nonpoint source pollution is the primary water quality concern in the South Shore Estuary Reserve. Elevated levels of coliform bacteria in stormwater runoff, an indicator of the potential presence of pathogens, are responsible for the closures of shellfish beds and bathing beaches. Sediment and excessive nutrients in stormwater runoff have pronounced negative effects on the Reserve's living resources. Improving water quality in the Reserve is dependent on federal, State and local governments, and private sector partners, implementing a strategy to protect lands that provide significant pollution abatement functions, retrofit existing stormwater infrastructure, adopt best management practices, and increase education and outreach to modify resident and user behavior. - Living Resources
The Reserve is a encompasses a rich and complex ecosystem. Its beaches, shallow bays, tidal marshes, tributaries and upland areas makes it one of the most ecologically productive regions in the United States. Productivity has been negatively impacted by habitat loss and degradation, largely due to the filling of low-lying lands for human development and water quality decline. To sustain and improve the living resources of the Reserve, the CMP recommends incorporating an ecosystem perspective into resource management; protecting, restoring, and improving habitat; improving the productivity of living resources; and addressing scientific information needs. - Public Use and Enjoyment
The public's ability to use and enjoy the natural and recreational resources of the Reserve depends upon appropriate access to its tributaries, bays, and shoreline. The number of formal, dedicated shoreline public access sites and recreational facilities is finite, and additional opportunities to increase public access will become fewer as private shoreline development continues. All levels of government must work together in cooperation with private development interests to preserve open space for public enjoyment and access, buffer sensitive habitats, improve water quality and retain the visual landscape of the estuary. - Estuary-related Economy
The relatively calm, protected waters and abundant natural resources of the South Shore estuary provide the basis for the water-related economic activities that have evolved from the harvesting of oysters, hard clams, and salt hay, and boat building, to recreational boating, sport fishing, waterborne transportation and tourism. Changes in the nature of these water-dependent businesses reflect the influence of a growing population and market demand, transportation improvements and increased recreational demands. The amount of estuary shoreline suitable for establishing new water-dependent uses or expanding existing ones is limited, while, at the same time, some existing water-dependent uses are gradually being displaced by more economically-competitive non water-dependent uses. To maintain the viability of the estuary-related economy, water-dependent businesses should be supported and maritime centers should be enhanced. - Education, Outreach and Stewardship
Public awareness, understanding, and stewardship of the Reserve is raised through outreach to general and specific audiences and through formal education activities. Individuals of all ages and local governments and non-governmental groups are encouraged to become stewards of the estuary.
New York-New Jersey Harbor and Estuary Program
The New York/New Jersey Harbor complex sits in a unique geographic as well as economic region. The natural diversity of this area is caused in part by the fact that it is nestled in the landward corner of the area known as the New York Bight. Prevailing ocean currents carry fish and other sea creatures northward from Florida and the Carolinas parallel to the coast. The shape of the New York and New Jersey coastlines "funnel" these currents into the harbor before they make a sharp eastward turn along the coast of Long Island. In addition, the harbor sits at the mouth of the Hudson River which provides a conduit for more northerly interior species to move southward toward the coast.
This position in the coastal landscape makes New York/New Jersey Harbor estuary one of the most diverse places on the eastern seaboard. All of this natural diversity is juxtaposed with one of the nations most densely populated metropolitan areas which supports a multi-billion dollar port, industrial, and transportation complex, making the human pressures on the wildlife intense. By working through the New York New/Jersey Harbor Estuary Program, DEC is helping to reverse long standing degradation of the harbor environment. Together with the State of New Jersey, the U.S. Environmental Protection Agency, the City of New York, the scientific community, and the citizens of both states, the New York State agencies, DEC and Department of State, have prepared a Comprehensive Conservation and Management Plan (CCMP) for the harbor which was finalized in 1996. More information is available on the New York/New Jersey Harbor estuary program at the EPA's Harbor Estuary Program web page.
The CCMP outlines five priority areas of concern. These are summarized below:
- Habitat Loss and Degradation
The impairments caused by habitat loss and degradation include the loss of the natural functions of coastal ecosystems like flood and erosion control, and wildlife habitat. These impairments are caused by physical alteration of the habitats through dredging and filling, development, and hardening of shorelines with seawalls. Actions to be taken to remedy this loss include identification and implementation of habitat restoration projects within the harbor, targeting critical areas for special protection (e.g. Jamaica Bay), acquiring key habitat areas, and others. - Toxic Contamination/Dredged Material Management
The impairments caused by toxic contaminants include restrictions on human consumption of fish species from the harbor, restrictions on port dredging within the harbor, and interference with reproduction in coastal species. These impairments are caused by discharge from sewage treatment plants, combined sewer overflows, storm water inputs and historic inputs to the sediment from coastal industry. All of these impairments are the subject of a cooperative effort between government agencies and involved parties to track down and eliminate sources of toxic contamination. - Pathogen Contamination
Pathogens are disease causing microorganisms. The impairments caused by pathogens include the closure of shellfish beds and potential closure of public bathing beaches following heavy rainfall events. Pathogen contamination in the harbor is primarily from combined sewer overflows. Corrections to the problem of combined sewer overflows are currently underway. - Floatable Debris
Floatable debris is human produced garbage, other items which are washed down storm drains into the harbor during rainfall events or are blown off landfills into the water. The impairments caused by floatable debris are floatable-related beach closures, injury to marine species from entanglement or ingestion of debris, and navigational hazards. Actions are underway to reduce floatable debris in the harbor, including reduction of rainfall related discharges, and improved management measures at landfills and solid waste handling facilities. - Nutrient and Organic Enrichment
Low levels of dissolved oxygen in the harbor are caused by algal blooms which are fueled by elevated nutrient levels. Low dissolved oxygen levels reduce the amount of habitat available for fish and shellfish.
Long Island Sound Study
Long Island Sound is an estuary approximately 110 miles long (east to west) and 21 miles across at its widest point, and covers an area of 1320 square miles with 600 miles of coastline. It is located in one of the most densely populated areas in the United States, particularly along the Nation's coastal areas, within the jurisdiction of two states, New York and Connecticut. Its valuable recreational and commercial uses make it one of the most important estuaries in the nation. In 1985, Congress allocated funds for the U.S. Environmental Protection Agency (EPA) to research, monitor, and assess the water quality of Long Island Sound. In March 1988, Long Island Sound was identified as an Estuary of National Significance and the Long Island Sound Study (LISS) became a part of EPA's National Estuary Program. In March 1994, LISS released its Comprehensive Conservation and Management Plan (CCMP) to guide restoration and protection activities. In October 2015, the LISS released a new CCMP to incorporate scientific and technological advances, respond to changing community needs, and to address new environmental challenges such as climate change, sustainability, environmental justice, and ecosystem-based management. The new CCMP is organized around four central themes:
- Clean Waters and Healthy Watersheds
- Thriving Habitats and Abundant Wildlife
- Sustainable and Resilient Communities
- Sound Science and Inclusive Management
The new CCMP also sets 20 key ecosystem targets for the Long Island Sound to be achieved over the next 20 years. The CCMP was developed through a collaborative process involving federal, state and local governments, university scientists, and interested representatives of business, environmental, and community groups.