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Scientific research conclusively shows that water quality on Long Island is declining precipitously.

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.

Long Island's nitrogen pollution from septic systems
Credit: Dr. Christopher Gobler

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.

Long Island Brown Tide caused by Nitrogen Pollution
Credit: Suffolk County Department of Health Services
Harmful Algae Blooms on Long Island
Credit: Dr. Christopher Gobler

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.

Salt Marshes Protect Coastlines from Storm Surge on Long Island
Credit: Chris Bason, Delaware Center for the Inland Bays

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.

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.

While the problems are serious, solutions exist. New kinds of septic systems safely remove far more nitrogen from human waste than current septic systems and cesspools. Sewage treatment plants can be upgraded to remove more nitrogen, and fertilizer and pesticide application can be significantly reduced. There is a role for everyone to play in saving Long Island’s waters, at home. Find out how you can protect water at home and send a letter to your elected officials in support of clean water initiatives on Long Island.


Nitrogen Pollution Explained

Long Island Water Quality Crisis
This map highlights water quality impairments across Long Island from 2015.
Nearly every major bay and estuary was afflicted by a harmful algae bloom, oxygen-starved waters, or both. 
Suffolk led all New York counties in incidents of toxic blue-green algae last year, with 16 different lakes and ponds experiencing the algae blooms.

Long Island Water Quality Crisis 2014
This map highlights water quality issues across Long Island from 2014.
Long Island Water Quality Crisis 2013

This map highlights water quality issues across Long Island from 2013.