Does your New York project need a SWPPP?

A Stormwater Pollution Prevention Plan (SWPPP) describes how a construction site will keep soil and pollutants out of storm drains and waterways while work is underway. Whether you need one depends on how much ground you disturb and where the site is.

New York State: the one-acre trigger

Across New York State, projects that disturb one or more acres of soil must get coverage under the SPDES General Permit for Stormwater Discharges from Construction Activity before construction starts. The current permit, GP-0-25-001, took effect on January 29, 2025 and runs to January 28, 2030.

Coverage is requested by filing an electronic Notice of Intent (NOI) with NYSDEC. In most cases the SWPPP must be prepared before you apply for coverage, so it belongs early in the schedule, not at the end.

New York City: lower thresholds

NYC's Unified Stormwater Rule, in effect since February 15, 2022, brings many smaller sites into DEP's stormwater permitting. It applies to projects that disturb 20,000 square feet or more of soil, or that create 5,000 square feet or more of new impervious surface. Sites in the city can have both state and city requirements, so check both.

What a SWPPP has to cover

• Erosion and sediment controls, such as silt fence, inlet protection, and a stabilized construction entrance, shown on plans with details.
• How controls change as the site is graded, built, and stabilized.
• Inspection and maintenance of those controls during construction.
• Post-construction stormwater management, where the permit requires it.

Keep it current

A SWPPP is a working document. When the site layout, phasing, or controls change, the plan should be amended to match what is actually on the ground. Inspectors compare the two.

Thresholds and exceptions have details that depend on the site, watershed, and sewer type. Confirm with NYSDEC, NYC DEP, or an engineer before you rely on a general rule.