Septic Systems in Greene County, New York: The NYC Watershed Layer

Two approvals, not one, inside the watershed

Everywhere in New York outside New York City, county health departments administer septic (onsite wastewater treatment) system permitting under the New York State Department of Health's Appendix 75-A, the statewide baseline standard covering soil testing, tank sizing, and setbacks for systems handling under 1,000 gallons per day. That's the whole story for most of Greene County. But for a parcel within the delineated New York City drinking-water watershed -- roughly the county's western towns, in the upper Schoharie Creek drainage feeding the Schoharie Reservoir -- a second, separate approval is required: review and sign-off from the NYC Department of Environmental Protection (DEP), the agency responsible for protecting the water supply that serves millions of downstream New York City residents.

This isn't a rubber-stamp add-on. DEP's own Watershed Rules and Regulations can impose siting, design, and setback requirements stricter than the statewide Appendix 75-A baseline alone -- for example, tighter separation distances from watercourses, wetlands, and reservoirs than a non-watershed county would require. A prospective buyer planning new construction, or an addition/renovation that would trigger septic system replacement or expansion, needs to budget for both a county health department review and a DEP review before a system can be legally installed.

Where this applies: confirming watershed status

The New York City watershed footprint spans five counties -- Delaware, Greene, Schoharie, Sullivan, and Ulster -- but within each county, the watershed boundary follows drainage basins, not town or county lines. In Greene County, the towns of Windham and Prattsville are confirmed, through local reporting on NYC-funded municipal wastewater infrastructure upgrades, to have an active watershed relationship with DEP. Neighboring towns in the same upper-Schoharie-Creek drainage -- Ashland, Jewett, Hunter, and Lexington -- plausibly share similar status given their position in the same basin, but this page has not independently confirmed a complete, town-by-town watershed boundary, and treats that as a reasonable inference rather than a confirmed fact. The eastern and central parts of the county, including the Hudson River corridor around the county seat of Catskill, are outside this watershed drainage.

Because the practical stakes of getting this wrong are real -- a septic system built to standard Appendix 75-A specifications alone, without DEP sign-off, on a watershed parcel would not be a legally complete installation -- the single most important early step for any Greene County parcel near the Catskill Park boundary or west of the Schoharie Creek corridor is to confirm watershed status directly. DEP maintains its own delineated watershed maps, and the Greene County Soil & Water Conservation District and the county Public Health Department can both help confirm a specific parcel's status before a buyer commits to a purchase contingent on septic feasibility.

The 1997 Watershed Memorandum of Agreement and DEP homeowner programs

The current watershed regulatory relationship traces back to a 1997 New York City Watershed Memorandum of Agreement between the city, watershed counties and towns, environmental groups, and state and federal agencies -- a negotiated framework intended to protect the city's water supply while addressing the economic and land-use impact on watershed communities. As part of that ongoing relationship, DEP funds infrastructure programs for eligible watershed municipalities and, in some cases, individual homeowners, including septic system repair or replacement assistance and municipal wastewater treatment plant upgrades -- Windham and Prattsville's discussions with DEP over wastewater treatment plant funding are a direct example of this relationship in practice in Greene County.

For a buyer evaluating an existing home on a watershed parcel with an aging or failing septic system, it's worth asking DEP and the county health department directly whether the property may be eligible for one of these homeowner assistance programs -- the answer varies by program funding cycle and property eligibility criteria, and this page does not track current program availability or eligibility rules.

Practical steps for a Greene County septic-dependent purchase

1. Confirm directly with NYC DEP's Bureau of Water Supply, or the Greene County Soil & Water Conservation District, whether the specific parcel sits within the delineated NYC watershed -- don't rely on the general town-level pattern described here as parcel-specific proof.
2. If the parcel is within the watershed, budget realistic time and cost for a DEP review in addition to the standard county health department Appendix 75-A permitting process -- treat these as two sequential (or, in practice, often coordinated) approvals rather than one.
3. Ask the seller or listing agent whether an existing septic system on a watershed parcel was originally approved under current DEP standards, or predates them -- an older system may not meet current setback or design requirements if it ever needs replacement.
4. If a septic system is failing or near end-of-life on a watershed parcel, ask DEP and the county health department about current homeowner assistance program eligibility before assuming the full replacement cost falls entirely on the buyer.
5. For parcels outside the delineated watershed (most of central and eastern Greene County), the standard Appendix 75-A county health department process applies with no DEP involvement -- confirm this status too, rather than assuming either way.