Article 24 Freshwater Wetlands Permit

Who this triggers for

• ›Regulated activities (fill, excavation, grading, drainage alteration, structures, clearing of vegetation) in a mapped freshwater wetland — see 6 NYCRR §663.4 for the full list.
• ›The same activities in the 100-foot "adjacent area" surrounding a regulated wetland — the adjacent area is statutory, not mapped, and extends from the wetland edge regardless of parcel lines.
• ›Under the 2022 amendments (ECL §24-0107 as amended by Part TT of Chapter 58 of the Laws of 2022), wetlands ≥7.4 acres starting January 1, 2025, and all jurisdictional wetlands regardless of size starting January 1, 2028.
• ›Wetlands of "unusual importance" at any size — including those within a 100-year floodplain, containing threatened or endangered species, providing vernal pool habitat, associated with a Class AA or A water body, located in an urbanized area, or otherwise meeting 11 criteria in §664.7.
• ›Amendments to prior permits — expansion of disturbance, new building footprints inside the adjacent area, or changes in stormwater routing all require a new or modified Article 24 permit.

1. 01

   Desktop screen and on-site delineation

   2–6 weeks

   Start with the NYSDEC Environmental Resource Mapper to check for mapped wetlands, then commission a wetland delineation using the 1987 Corps Manual plus the applicable regional supplement. Post-2022, the DEC map is not dispositive — wetlands meeting jurisdictional criteria are regulated whether mapped or not.

2. 02

   Jurisdictional determination (JD) request

   1–3 months

   Submit a JD request to the NYSDEC regional office with the delineation, photographs, and a site survey. DEC's wetland biologist performs a site visit and issues a written JD confirming wetland boundaries, class, and whether the 100-foot adjacent area is invoked. Separate USACE §404 JD may run in parallel for federal jurisdiction.

3. 03

   Classification under 6 NYCRR Part 664

   Concurrent with JD

   DEC assigns the wetland a class from I (most protective) to IV (least) based on cover types, hydrology, and ecological functions. Class I wetlands are presumptively protected — permits issue only on compelling economic or social need with no practicable alternative. Class III and IV allow broader weighing of project benefits against wetland value.

4. 04

   Permit application and completeness review

   2–4 weeks to complete

   File the Article 24 permit application (combined with the Uniform Procedures Act forms) with a mitigation plan, alternatives analysis, SEQR documentation, and proof of compliance with §663.5 weighing standards. DEC has 15 days to determine completeness; Notices of Incomplete Application restart that clock.

5. 05

   Public notice, comment, and potential hearing

   30–90 days (longer if adjudicated)

   DEC issues public notice in the Environmental Notice Bulletin; 30-day comment period is standard. For Class I wetlands or controversial projects, a legislative hearing or full adjudicatory hearing may be convened under 6 NYCRR Part 624 — adjudication adds 6–18 months.

6. 06

   Decision and permit conditions

   Included in 3–9 month window

   DEC issues a permit, a permit with modifications (smaller footprint, redesigned grading, compensatory mitigation at 1:1 to 3:1 ratios), or a denial. Permits run 5 years and typically include pre-construction notification, protective fencing, post-construction monitoring, and a mitigation maintenance bond.

• ✕

  Relying on the DEC wetland map alone

  The 2022 amendments make the map informational, not jurisdictional. A wetland that is not on the map but meets the class criteria and any of the 11 "unusual importance" factors in §664.7 is regulated. Budgeting a project on the assumption that an unmapped wetland is unregulated is the single most common post-2022 error.

• ✕

  Forgetting the 100-foot adjacent area

  The adjacent area is statutory and extends from the wetland edge regardless of parcel lines, fences, or prior disturbance. A driveway, stormwater pond, or staging area wholly on private land but within 100 feet of a regulated wetland needs an Article 24 permit.

• ✕

  Underestimating Class I constraints

  Class I wetlands carry a presumption against permit issuance — §663.5(e)(2) requires a showing of compelling economic or social need and no practicable alternative. Applicants who file a Class I application without a rigorous alternatives analysis draw denials or adjudication.

• ✕

  Missing the federal overlay

  Article 24 is a state permit. The same activity in the same wetland often also triggers USACE §404 (Clean Water Act) and §401 Water Quality Certification. The reviews are separate, substantively overlap, and can require different mitigation. File both JDs up front.

• ✕

  Treating the 2028 all-wetlands rule as far away

  Projects being delineated in 2026–2027 for construction in 2028+ must plan for jurisdiction over wetlands of any size. Phasing earthwork to precede the 2028 effective date is not a reliable strategy — DEC has signaled aggressive enforcement of the amended thresholds and the SEQRA segmentation doctrine limits phased avoidance.

• SEQRA (6 NYCRR Part 617)
  Article 24 permits almost always pull a project into SEQRA as an involved-agency approval.
• New York regulatory stack
  Article 24 is one of six NY layers TierraLens models — Article 25 tidal, SEQRA, ORES, NYC DEP, CEHA.
• NYSDEC Environmental Resource Mapper
  The official GIS viewer for mapped wetlands — use it as a starting point, not the final word.
• USACE New York District — §404 permits
  Federal wetlands review that runs in parallel with Article 24 for most projects.

• statuteECL Article 24 — Freshwater Wetlands Act
• rule6 NYCRR Part 663 — Freshwater Wetlands Permit Requirements
• rule6 NYCRR Part 664 — Freshwater Wetlands Mapping and Classification
• agencyNYSDEC Freshwater Wetlands Program
• guideNYSDEC — 2022 Freshwater Wetlands Law amendments summary
• mapNYSDEC Environmental Resource Mapper
• agencyUSACE NY District — §404 regulatory program