Suffolk County Works to Address Nitrogen Pollution

Suffolk County officials recently revealed a $4 billion plan to fight nitrogen pollution on Long Island’s surface waters. The 50-year Subwatersheds Wastewater Plan aims to upgrade and replace aging septic systems in hundreds of thousands of homes and replace them with modern sewage systems. 

Nitrogen concentrations have been increasing on Long Island surface waters for decades. According to a study by the Long Island Commission for Aquifer Protection, nitrogen levels in the main Long Island aquifer rose 200% between 1987 and 2005, and are expected to continue to rise. This type of contamination has already contributed to the decline of the once-thriving shellfish industry, which supported 6,000 jobs, and the loss of submerged aquatic vegetation (SAV). This vegetation includes grasses that grow in shallow waters and plays an important role in protecting the shoreline against storm surge. The high amounts of nitrogen has also fueled the growth of Harmful Algae Blooms (HABs) in the county’s lakes and bays.

Algae usually cause no problems and are an essential part of marine ecosystems, converting water and carbon dioxide into oxygen. However, sometimes they can grow uncontrollably and cover large amounts of surface water. These HABs produce toxins that are detrimental to the water and the surrounding organisms. 

The blooms are caused by an excess of nitrogen from chemical wastes, such as agricultural fertilizer and biowaste. When these wastes contaminate lakes and bays, the results pose severe public health issues. The toxins from HABs can enter tap water sources and threaten the safety of the county’s drinking water. Toxins from algae can cause nausea, vomiting, skin irritation, and even liver damage if ingested. 

The growth of these HABs in Suffolk County is largely due to the outdated sewage system that the region uses. Health officials said that 74% of the county isn’t connected to the public sewer system and 70% of the nitrogen in local bays comes from over 360,000 cesspools and septic systems. Houses that aren’t connected to public sewer systems don’t properly capture and treat wastewater. As a result, nitrogen and other chemicals produced by waste often end up in waterways.

The Subwatersheds Wastewater Plan aims to change that. The first step in the plan divides the county up into 190 watershed areas and sets goals to reduce nitrogen pollution in each. It outlines areas that would benefit most from the immediate replacement of old cesspools. It recommends that all homeowners in these areas replace their current septic systems with nitrogen-reducing septic systems. These new waste management units, called Innovative Alternate (IA) systems, use chemical processes to remove nitrates from the wastewater and reduce the nitrogen output overall. Alternatively, homeowners can choose to connect their homes to existing sewer lines if possible, which eliminates the need for a cesspool or septic system.

Phase one calls for an initial replacement of 9,000 cesspools in residences along the South Shore by 2024 including 4,000 brand new septic systems and connecting 5,000 cesspools to existing sewer lines. These upgrades each cost close to over $20,000. The WMD will grant up to $10,000 and provide low-interest loans to home-owners who volunteer to get their home’s sewage system changed in this phase.

The second phase, which would run over the next 30 years, would integrate greener septic systems into a large portion of the county. It aims to replace 177,000 cesspools and construct 30,000 new IA units in houses that are near lakes and shores where wastewater most quickly pollutes surface water. The $1.9 billion needed for this would initially be funded by federal and state grants while a permanent revenue stream is developed by the NYS Department of Environmental Conservation.

The third phase would initiate the installation of  299,000 more IA systems in all other priority areas and would be completed between 2054 and 2068. 

A fourth and final phase covers the remaining towns, primarily in central Suffolk where the threat of nitrogen pollution is less severe. This phase plans a total of 430,000 sewage upgrades, costing $67 million a year. The price tag for all four phases would reach $4 billion. 

If the county follows the timeline that this plan sets, scientists from Stony Brook University claim that reversal of water deterioration could take place within a decade. The goal is to diminish all nitrogen pollution and create a cleaner, healthier future for Suffolk county’s water.

Opponents of the plan question the affordability of the plan both for the county and for homeowners. Environmental groups have since responded with proposed legislation for a surcharge on water bills to raise the $70 million needed for phase one, but no action has been taken by Albany lawmakers.

Currently, the plan is being reviewed by Suffolk County’s Council on Environmental Quality, which is developing a statement on the environmental impact of the plan. The county will start a 30-day comment period beginning on August 14th and also plan to hold public hearings about the proposal on August 28th and 30th, though a location has not been decided yet. To get involved with these events visit for more information.

The county legislature will later vote on whether to approve the Subwatersheds Wastewater Plan. 

The comprehensive plan helps clean one of Suffolk County’s most valuable assets: water.

NYLCV will continue to advocate for policies that combat water pollution and encourage the replacement of ineffective cesspools with more green systems. We will also continue to educate the public on how they can stay aware of dangers to public health and how they can help to create a cleaner future.