M1L2NPDES_SWprogram

Module I

Lesson Two: NPDES Stormwater Permit Program

NPDES Stormwater Program

The NPDES Stormwater Program is a comprehensive two-phased national program using a permitting mechanism to require the implementation of controls designed to prevent harmful pollutants from being washed by stormwater runoff into local water bodies and cause adversely effects on the quality of our nation's waters. There are two phases of the NPDES Stormwater Program:

Phase I

In 1990, Phase I of the NPDES Stormwater Program was developed by the U.S. EPA in response to the 1987 CWA Amendments. Sources of stormwater runoff that had the greatest potential to negatively impact water quality were addressed in the Phase I program. Operators of the systems, facilities, and construction sites regulated under the Phase I NPDES Stormwater Program must obtain permit coverage for the stormwater discharges from:

Medium and large municipal separate storm sewer systems (MS4s) located in incorporated places or counties with populations of 100,000 or more
Eleven categories of industrial activity(Table 2-1) which includes construction activity that disturbs five or more acres of land

A Summary of the Phase I Stormwater Program is available in the EPA’s website.

Phase II

In December 8, 1999 U.S. EPA published stormwater Phase II Final Rules in the Federal Register to address discharges that are not covered by Phase I. Operators of facilities and construction sites are required to obtain a NPDES Stormwater Permit for stormwater discharges from:

Certain regulated small municipal separate storm sewer systems (MS4s)
Construction activity disturbing between 1 and 5 acres of land (i.e., small construction activities)

In addition to expanding the NPDES Stormwater Program, the Phase II Final Rule revises the no exposure exclusion and the temporary exemption for certain industrial facilities under Phase I of the NPDES Storm Water Program and certain exemptions relating to ISTEA. The Phase II Rule also established two potential waivers (Rainfall-Erosivity Waiver and Water Quality Waiver) for small construction activities.