EPA's Stormwater Phase II Rule and the Stormwater Managers Resource Center

Many communities are facing the prospect of needing to address the impacts of stormwater runoff as part of the Environmental Protection Agency's (EPA) National Pollution Discharge Elimination System (NPDES), Phase II Stormwater Program, commonly referred to as simply the Phase II Rule. Phase II, is the second component of a two part program to improve the quality of the nation's streams, rivers, lakes, and estuaries by managing stormwater runoff from urban and suburban areas, construction projects, and industrial sites. Phase I, promulgated by EPA in 1990, covered medium and large municipalities (i.e, populations over 100,000), construction sites over 5 acres in size, and 10 categories of industrial activity.

The Phase II program is the next step and covers smaller municipalities, urban areas adjacent to municipalities, and construction sites over 1 acre. Guidance on who is considered a "small municipality," an "adjacent urban area," and "automatically designated regulated areas" is provided at EPA's website. The Phase II Rule sets forth the following three primary requirements for these smaller municipalities and adjacent urban areas:

  1. To develop, implement and enforce a stormwater management program designed to minimize the discharge of pollutants into receiving waters
  2. To ensure that the program includes provisions to address six minimum measures to promote pollutant load reduction:
  3. To identify appropriate STPs with measurable performance criteria


Small construction sites will be expected to provide pollution prevention plans and appropriate construction site runoff controls to meet the goal of reduced pollutant discharge to receiving waters. The actual requirements will be defined by the NPDES permitting authority on a state-by state basis.

The Phase II Rule also includes a provision that industrial activity operators (covered under Phase I) can be excluded from the provisions of the Rule if they can certify that all industrial materials and activities are protected by a storm resistant shelter to prevent exposure to rain, snow, snowmelt and/or runoff.

Implementation of the Phase II is being phased over a reasonable time, where the NPDES permitting authority will issue general permits to cover small municipalities and small construction site activities by December 9, 2002. Operators of "automatically designated" regulated municipalities must then obtain permit coverage within 90 days of the general permit issuance.

A major commitment from EPA is to provide guidance and resources to local communities to implement the provisions of the Phase II Rule. One component is through the creation of a so called "tool box" for Phase II program implementation. This includes technical guidance on stormwater management to help communities develop cost effective and efficient programs that address the goals of reducing pollutant load to, and improving the overall quality of receiving waters. The tool box will ultimately include the following:

This Stormwater Managers Resource Center web site is one component of the "tool box." For more detailed information and guidance, click here!