On July 1, 2026, the New York State Department of Environmental Conservation ("NYSDEC") published proposed amendments to 6 NYCRR Parts 360 and 363 that would fundamentally change how landfill leachate is managed throughout the State. If adopted, the proposal would require municipal solid waste ("MSW") landfills and certain construction and demolition ("C&D") debris landfills to treat landfill leachate before it may be discharged to the environment.
The proposal, which was originally proposed by Governor Hochul as part of her 2026 State of the State agenda to “instruct landfills to treat leachate for harmful contaminants at the source before discharge and provide funding for local governments to comply,” represents a significant shift. For decades, landfill operators have relied on municipal wastewater treatment plants as the primary endpoint for managing collected leachate. NYSDEC now proposes to regulate landfill leachate as a waste stream requiring contaminant removal before it leaves the solid waste management system. NYSDEC describes the proposal as an effort to reduce the reintroduction of contaminants, including emerging contaminants such as per- and polyfluoroalkyl substances ("PFAS") and 1,4-dioxane, into New York's waters.
Why NYSDEC Is Proposing These Changes
Landfill leachate is generated when precipitation and liquids move through disposed waste, creating a liquid waste stream containing dissolved organic matter, salts, heavy metals, and a variety of organic and inorganic contaminants. While modern landfill liner and collection systems are designed to capture leachate before it reaches groundwater, the collected leachate has traditionally been transported to municipal wastewater treatment plants for disposal.
According to NYSDEC, conventional wastewater treatment processes are generally not designed to remove many contaminants commonly found in landfill leachate, particularly emerging contaminants. As a result, those contaminants may ultimately be discharged to receiving waters or accumulate in biosolids. The Department therefore concludes that improved management of landfill leachate has become the next major evolution in landfill regulation.
What Would Change?
The proposal would eliminate existing regulatory exclusions that have historically allowed landfill leachate to be sent to wastewater treatment facilities without first complying with landfill treatment requirements. Instead, landfill leachate would become subject to a new treatment regime requiring removal of contaminants before discharge. After leachate has been treated to meet Subpart 363-12 requirements, the treated effluent may be discharged either to a publicly or privately owned treatment works or directly to a water body under a SPDES permit—meaning the water resource recovery facility (“WRRF”) endpoint that operators currently rely on is optional once the treatment standard is met, not required.
The proposal also would prohibit covered landfill leachate from being discharged directly to the environment or to a wastewater treatment facility unless it has first been treated in accordance with new Subpart 363-12. Rather than prescribing a particular treatment technology, NYSDEC has proposed a performance-based standard requiring a 99.9% removal of specified contaminants. As an alternative to landfills directly treating leachate, the proposal also creates an entirely new category of regulated landfill leachate treatment facilities subject to separate permitting, operational, monitoring, and reporting requirements.
The proposal also expands closure and post-closure obligations by requiring continued treatment and management of landfill leachate after landfill operations cease.
Key Takeaways
NYSDEC recognizes that compliance may be achieved through on-site treatment systems or by contracting with other landfills with on-site treatment systems or regional or third-party leachate treatment facilities. Capital costs are estimated to range from approximately $3 million to $50 million, with annual operating costs estimated between $1.5 million and $8 million—whether the facility is located on-site at the generating landfill or at a separate third-party location. Landfills that elect to contract with an existing third-party facility rather than build their own would instead pay a per-gallon treatment fee, similar in structure to what landfills currently pay WRRFs—though at higher rates, given the treatment standard required. The Department also anticipates that regional treatment facilities may emerge and that some costs may ultimately be passed on to landfill customers.
If adopted, these amendments would represent one of the most significant revisions to New York's solid waste regulations in decades. Landfill owners, municipalities, waste management companies, and entities evaluating opportunities to develop regional leachate treatment facilities should begin evaluating how the proposal could affect existing operations and consider participating in the rulemaking process.
Public Comment Period: NYSDEC is accepting public comments on the proposed rulemaking through September 9, 2026.
