Long Island’s Water

Water defines life on Long Island. In addition to an ocean, we have three major estuaries: The Long Island Sound, which receives freshwater (via the Connecticut River) from as far away as Quebec; the Peconic Estuary in eastern Suffolk between the north and south forks; and a collection of south shore bays, including the Great South Bay in the west and Shinnecock Bay in the east, which together make up the South Shore Estuary Reserve.

Estuaries, where fresh and salt water mix, are some of the most productive habitats on earth. Long Island’s estuaries have historically produced tons of shellfish annually, supported numerous species of finfish and birds, and provided jobs, recreation and flood protection for humans. Along southern Long Island, we have the Atlantic Ocean and our world-famous beaches. Not only is Long Island surrounded by salt water, but beneath our forests, fields, lawns, homes and streets, the ground is saturated with our only source of fresh drinking water. This water supply serves 2.8 million residents and thousands of businesses in Nassau and Suffolk Counties, providing them with more than 375 million gallons of water per day (according to the USGS Estimated Use of Water in the United States in 2000).

There’s a vital connection between our drinking and surface waters. Because of Long Island’s geology, everything that flows from our toilets and drains, roadways, storm drains, and farms, has the potential to travel into our sole-source drinking water aquifers and from there into our surface waters.

As Long Island’s population has grown—from 600,000 in 1940 to 2.8 million today—the quantity of pollutants generated by our everyday living has dramatically increased. The most harmful of these for our natural systems is nitrogen. 

the value of clean water

Clean water is a driving force in our economy. A 2013 study by the University of Connecticut and supported by the Nature Conservancy, determined that nearly half of Long Island’s gross metropolitan product - $153 billion – comes from businesses that are water-reliant. Learn more here.

nitrogen pollution

The biggest threat to Long Island’s water quality is nitrogen pollution from sewage. From 1987 to 2005, the Magothy aquifer, which supplies most of Long Island’s drinking water, experienced a 200% increase in nitrogen pollution. In some parts of Long Island, nitrate concentrations exceed the EPA’s maximum safe contaminant level for drinking water, requiring water utilities to close affected wells and/or blend in cleaner water from different areas. 
 
The dominant local source of nitrogen pollution is human wastewater from septic systems and cesspools. In Suffolk County, 70% of homes (90% in Eastern Suffolk) are not hooked up to sewers and rely instead on individual septic tanks or cesspools, which were designed to remove pathogens, not nitrogen.

Our actions on land affect the water that flows into our aquifers and eventually our bays and harbors, lakes, ponds and streams, where excess nitrogen promotes the growth of “algae blooms,” most often referred to in the media as red tides, brown tides or rust tides. This can cause aquatic dead zones, removing life-giving oxygen from the water and killing fish and shellfish. Sometimes neurotoxins are produced that can taint shellfish. Humans who consume poisoned shellfish can become sick, weak or even die. This human health risk from pollutants can result in the closure of our beaches and shellfish beds, which are important assets to Long Island’s economy and way of life.

Excess nitrogen also weakens and kills eelgrass, which provides vital underwater habitat for scallops and finfish. Coastal salt marshes suffer from vegetation loss as a result of too much nitrogen. This loss prevents their serving as a buffer from storm waves and surges. 

This natural resource decline on Long Island has serious economic impacts, from loss of jobs to reductions in tourism revenue (estimated at $5.2 billion in 2012). The most notable example is that until the 1970s, half of the clams eaten in the United States came from the Great South Bay, but due to overfishing and nitrogen pollution, that number is less than one percent today.

other contamination threats

Pesticides, pharmaceutical drugs and volatile organic compounds (VOCs) have also become an increasing concern.  Pesticides are found in 1 of 4 community supply wells throughout Long Island. Pharmaceutical drugs and VOCs (toxic chemicals used to manufacture cleaning products, building supplies and personal care products) have entered our groundwater through improper disposal. The presence of VOCs in our groundwater has quadrupled since 1987. Many Long Island residents are still illegally dumping these substances down the drain, instead of taking them to proper collection sites. Contact your local town hall to find a hazardous waste and/or pharmaceutical collection site near you. In addition, Long Island is home to more than 250  Superfund toxic-waste sites. Water contamination has been detected at 90% of these sites and soil contamination at  79%. It is still unclear how low-dose, long-term exposure to pesticides, pharmaceutical drugs and VOCs can affect our health over time.