New Septic Systems to Reduce Nitrogen Pollution into Long Island Sound

The New York State Department of Environmental Conservation has received an initial grant of $2.25 million through the federal Bipartisan Infrastructure Law to advance Suffolk and Nassau counties’ septic replacement programs.

A house in Centerport Harbor gets an enhanced nitrogen removal septic system to replace a cesspool. Jim Ammerman/LISS photo
A house in Centerport Harbor gets an enhanced nitrogen removal septic system to replace a cesspool. BIL funding is supporting New York State’s effort to replace outdated systems to reduce nitrogen pollution into Long Island Sound. Photo by Jim Ammerman/LISS
This article was originally published in December 2022 as part of the Bipartisan Infrastructure Law fact series.

The New York State Department of Environmental Conservation has received an initial grant of $2.25 million through the federal Bipartisan Infrastructure Law to advance Suffolk and Nassau counties’ septic replacement programs. The funds are an incentive for homeowners to replace outdated septic tanks and cesspools with equipment that is going to lead to a cleaner Long Island Sound.

The enhanced nitrogen removal septic systems reduce the amount of nitrogen that traditional septic systems and cesspools discharge into groundwater that flows into Long Island Sound. Nitrogen is a nutrient that in excess leads to waters with low oxygen levels (hypoxia), often called “dead zones,” which can result in fish kills. Excess nitrogen also contributes to harmful algal blooms, and deterioration of storm-resilient marshlands.

The $2.25 million grant awarded in 2022 is the first installment of the BIL funds in a multi-year anticipated partnership with the Long Island Sound Study. The funds will significantly increase funding available to replace outdated septic systems in Suffolk and Nassau. Over the course of five years, an anticipated $8 million from the BIL program will help support state- and locally-driven water quality improvements.

A lawn sign promotes the new enhanced septic systems.
A lawn sign promotes the new enhanced septic systems. Photo by Jim Ammerman/LISS

New York will distribute the funds to Suffolk County’s Septic Improvement Program and Nassau County’s Septic Environmental Program to Improve Cleanliness Program. These county-led programs will provide funds to reimburse eligible property owners for a portion of the cost of replacing cesspools and inadequate septic systems and installing more environmentally effective systems. Homeowners can receive funds from both county and state programs, resulting in at least $20,000 in grants to install the more environmentally effective systems that remove more nitrogen than a conventional septic system.

A conventional septic system releases around 40 pounds of nitrogen per year, which contributes to unhealthy water conditions in the Sound. The enhanced systems have the potential to reduce up to 70 percent of this nitrogen, depending on the specific brand and model. These systems have biological treatment steps which use anaerobic and aerobic bacteria to remove nitrogen from the wastewater. Septic systems have become a focal point for reducing nutrients, since many of the Sound’s municipalities have upgraded wastewater treatments to reduce nitrogen.

Compared to other regions, Nassau and Suffolk both have unusually high numbers of septic systems. Approximately 74 percent of the 1.5 million residents of Suffolk are not on a sewer system. In total, Suffolk County has around 380,000 buildings on a septic system; Nassau has an additional 40,000.

To learn more, visit the nassaucountyny.gov or suffolkcountyny.gov website and search for “septic.”

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