Nassau County
Nassau County Department of Public Works / Individual town/village building departments
CountyMS4 Phase IVerified 2026-03
Local Permit / Authorization
- Permit Required
- Yes
- Permit Name
- Nassau County DPW Stormwater Management Approval / Town-level Building Permit
- Submit To
- Nassau County Department of Public Works / Individual town/village building departments
- Lead Time
- County stormwater review 4–8 weeks; town permits concurrent
- Application Method
- County stormwater plans submitted to Nassau County DPW; building permits via individual town/village
- Fee
- County review fees vary; town permit fees per project scope
Water Quality Standards
- Impervious Cover Limit
- No countywide cap; post-construction management required per NYSDEC MS4 permit; county reviews drainage for projects impacting county infrastructure
- On-Site Treatment Required
- Yes
- Detention Required
- Yes
- Detention Standard
- Manage the first 1 inch of rainfall on-site per NYS Stormwater Management Design Manual; leaching basins and drywells historically common on Long Island due to sandy soils
- Turbidity Standard
- Must comply with NYSDEC SPDES CGP; Long Island Sound and South Shore Estuary protections apply
Local SWPPP / Drainage Plan
- Local Plan Required
- Yes
- Plan Name
- SWPPP per NYSDEC; drainage/stormwater plan per Nassau County DPW for projects affecting county drainage infrastructure
- PE Stamp Required
- Yes
Plans must be prepared by a NY-licensed PE. Nassau County's sandy, permeable soils and sole-source aquifer status make groundwater protection a critical consideration.
Local Inspection Requirements
- Requirements
- Town/village inspections at permit milestones. County DPW inspects stormwater facilities connected to county drainage. Post-construction BMPs require maintenance agreements.
- Inspector Qualification
- NYSDEC-approved QI/TC per SPDES CGP; no additional county certification
Special Overlay Zones
Sole Source Aquifer / Groundwater Protection
Trigger: All of Nassau County (entire county overlies the Long Island sole source aquifer designated by EPA)
Restriction: No contaminated stormwater infiltration without pre-treatment; enhanced spill prevention; underground storage tank regulations; pesticide/fertilizer management; virtually all stormwater infiltrates to groundwater
South Shore Estuary Reserve
Trigger: Properties draining to South Shore bays and the South Shore Estuary Reserve
Restriction: Enhanced water quality treatment for nitrogen and pathogens; wetland buffer requirements; NYSDEC South Shore Estuary Reserve Comprehensive Management Plan
Design Manual
- Manual Name
- NYS Stormwater Management Design Manual / Nassau County DPW Standards
Official Resources
Jurisdiction Notes
Nassau County's stormwater management is dominated by the sole source aquifer designation — virtually all stormwater infiltrates to groundwater that supplies drinking water. Drywells and leaching basins are the traditional BMPs, but nitrogen loading to the aquifer and South Shore bays is driving a shift toward enhanced treatment. The county's fragmented governance (two cities, three towns, 64 villages) means permitting involves multiple jurisdictions.
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 Nassau County Department of Public Works / Individual town/village building departments and the agency website before beginning construction.