What Is Stormwater Phase II?

In response to the 1987 Amendments to the Clean Water Act (CWA), the US Environmental Protection Agency (EPA) developed Phase I of the National Pollutant Discharge Elimination System (NPDES) Storm Water Program in 1990. The Phase I program addressed sources of storm water runoff that had the greatest potential to negatively impact water quality. The New York State Department of Environmental Conservation (NYS DEC) is responsible for administering the program in NYS as part of the State Pollutant Discharge Elimination System (SPDES). Under Phase I, SPDES permit coverage was required for storm water discharges from medium and large municipal separate storm sewer systems (MS4s) located in incorporated places or counties, eleven categories of industrial activity and construction activity that disturbed five or more acres of land.

The Phase II Final Rule, published in the Federal Register on December 8, 1999, expanded the stormwater permit program to include stormwater discharges from certain regulated small MS4s and construction activity that disturbs between 1 and 5 acres of land. On January 8, 2003, the DEC finalized two-new general permits for stormwater discharges in NYS as required by the Federal EPA; the small MS4 and small construction permits. These permits were renewed three times, with additional requirements, effective May 1, 2008, May 1, 2010, and May 1, 2015.

The MS4 permit requires regulated municipal MS4s (those with a minimum population density of 1,000 people per square mile and are located in urban areas as defined by the U.S. Census Bureau) to develop and fully implement a stormwater management program. Stormwater management programs must contain appropriate management practices in each of the following minimum control measure categories: Public Education and Outreach; Public Involvement and Participation; Illicit Discharge Detection and Elimination; Construction Site Stormwater Runoff Control; Post-Construction Site Stormwater Runoff Control; and Pollution Prevention for Municipal Employees.

As a first step toward obtaining SPDES general permit coverage regulated MS4s are required to submit a Notice of Intent (NOI) form to NYS DEC. The NOI requires MS4s to provide an initial outline of planned management practices and to identify measurable goals to annually assess progress toward the full implementation of an appropriate stormwater management plan. Although NYS DEC has specified a few required actions and provided a list of approved management practices for each minimum control category, regulated MS4s are encouraged to tailor the development of their stormwater management programs to best meet local stormwater problems.

NYS DEC is encouraging MS4s to take a watershed approach to local stormwater management by working with neighboring MS4s to develop complementary or cooperative programs for solving shared problems. By combining efforts, sharing costs and working together, regulated municipalities will recognize a higher level of environmental benefits at a decreased program cost.

The small construction permit is somewhat different in that it is a statewide requirement. Owners of all small construction activities disturbing at least one acre of soil must obtain a general construction permit prior to breaking ground regardless of whether or not the construction takes place within a regulated MS4. Small construction operators must file an NOI form and develop an approved stormwater management plan that includes provisions for managing post-construction stormwater runoff over the life of the project. The one-acre soil disturbance is a cumulative threshold. In other words, if a construction activity disturbs less than one acre of soil, but is part of a common development plan that will cumulatively disturb one-acre or more, a construction permit is required for the entire development.