Suffolk County
Suffolk County Department of Public Works / Individual town building departments
CountyMS4 Phase IVerified 2026-03
Local Permit / Authorization
- Permit Required
- Yes
- Permit Name
- Suffolk County DPW Drainage Review / Town-level Building Permit
- Submit To
- Suffolk County Department of Public Works / Individual town building departments
- Lead Time
- County drainage review 4–8 weeks; town permits concurrent
- Application Method
- County drainage plans submitted to Suffolk County DPW; building permits via individual town
- Fee
- County review fees vary; town permit fees per project scope
Water Quality Standards
- Impervious Cover Limit
- No countywide cap; post-construction management per NYSDEC MS4 permit; Suffolk County Sanitary Code Article 7 governs on-site stormwater disposal
- On-Site Treatment Required
- Yes
- Detention Required
- Yes
- Detention Standard
- Manage the first 1 inch of rainfall on-site per NYS Design Manual; drywells and leaching pools historically primary BMPs; enhanced nitrogen-reducing systems now required in some areas
- Turbidity Standard
- Must comply with NYSDEC SPDES CGP; Peconic Estuary, Long Island Sound, and Great South Bay protections apply
Local SWPPP / Drainage Plan
- Local Plan Required
- Yes
- Plan Name
- SWPPP per NYSDEC; drainage plan per Suffolk County DPW / Suffolk County Department of Health Services for groundwater discharge
- PE Stamp Required
- Yes
Plans must be prepared by a NY-licensed PE. Suffolk County Health Department regulates subsurface discharge including stormwater drywells. Nitrogen reduction is a major focus.
Local Inspection Requirements
- Requirements
- Town inspections at permit milestones. County DPW and Health Department may inspect stormwater facilities. Post-construction maintenance required.
- Inspector Qualification
- NYSDEC-approved QI/TC per SPDES CGP; no additional county certification
Special Overlay Zones
Sole Source Aquifer / Special Groundwater Protection Areas (SGPAs)
Trigger: Entire county overlies the Long Island sole source aquifer; SGPAs designated in areas critical for drinking water recharge
Restriction: Suffolk County Sanitary Code Article 7 applies; enhanced stormwater treatment before infiltration; nitrogen-reducing technologies required for new development in some areas; restricted land uses in SGPAs
Peconic Estuary / Pine Barrens
Trigger: Properties in the Central Pine Barrens region or draining to the Peconic Estuary
Restriction: Central Pine Barrens Joint Planning and Policy Commission review; compatible growth area limits; core preservation area restrictions; Peconic Estuary CCMP water quality protections
South Shore Estuary / Great South Bay
Trigger: Properties draining to Great South Bay and South Shore estuaries
Restriction: Enhanced nitrogen and pathogen controls; wetland buffer requirements; shellfish area protections
Design Manual
- Manual Name
- NYS Stormwater Management Design Manual / Suffolk County Standards and Specifications for Drainage
Official Resources
Jurisdiction Notes
Suffolk County faces the most acute nitrogen crisis on Long Island — excess nitrogen from stormwater and septic systems is causing harmful algal blooms, beach closures, and fish kills in the Peconic Estuary and South Shore bays. The county's Subwatersheds Wastewater Plan is driving adoption of nitrogen-reducing stormwater BMPs. The Central Pine Barrens region has the strongest land use protections on Long Island.
Remember: These local requirements are in addition to the NYSDEC state construction permit. Both must be satisfied before breaking ground.
Disclaimer: This information is provided for general reference only. Always verify requirements directly with Suffolk County Department of Public Works / Individual town building departments and the agency website before beginning construction.