NPDES MS4 Permitting

The National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) Program is mandated under the federal Clean Water Act.  In North Carolina, the EPA has delegated MS4 Program oversight to the Department of Environmental Quality (DEQ).  An NPDES MS4 permit is required for all MS4 owners and operators that are located in a U.S. Census Bureau designated Urbanized Area, or are designated under state rules [Ref. 15A NCAC 02H .0151].

MS4 News & Current Events

  • You can access all of the MS4 permit files on the public DEQ Stormwater Program Laserfiche Repository.
  • The statewide MS4 Permit Compliance Initiative is now in its second year of implementation, and DEQ has audited 35 stormwater programs for compliance with their MS4 permit.  The audit results are:

Audit Results


Notice of Compliance (NOC)


Notice of Deficiency (NOD)


Notice of Violation (NOV)


Compliance Decision Pending


Total Audits Completed


  • The most common deficiencies have been lack of required documentation, insufficient MS4 mapping, reactive rather than proactive illicit discharge programs, and poor housekeeping practices at municipal facilities.
  • The first new MS4 permit under the statewide compliance initiative was issued on Feb. 12, 2020.  A total of 23 comments were received on the draft permit. You can view the final permit, approved Stormwater Management Plan and response to comments by clicking here.
  • There is new guidance for developing a Stormwater Management Plan (SWMP) in the Phase II MS4 Toolbox.
  • 2020 is a U.S. Census year, and that means that additional entities will likely be designated for coverage under a NPDES MS4 permit once the census data has been processed.  DEQ expects to receive data in 2021 and publish designations in 2022. 
  • Click here for a short presentation on the current MS4 Program status (Feb. 2020).  This presentation is appropriate for elected officials!

MS4 Audit Schedule

In 2018, the EPA began a statewide compliance initiative in North Carolina.  In 2019, MS4 Permit compliance audits were incorporated into the NPDES MS4 Permitting Program as a routine component of the permit renewal process, and an MS4 Audit Schedule was instituted for renewal of 20% of the MS4 permits each year.   

Manage Information for an Existing MS4 Permit

Enter your stormwater permit number into the Stormwater Permit Summary Report and you will see a form that includes the address of the facility, contact information for the permit, and the regulated stormwater outfall(s) for the facility.

To update the:

Electronic payment of annual permit fees is convenient and quick! Click on "Stormwater ePayments" on the lower right corner of this page. There is no fee for eCheck. The convenience fee for a credit card is 2.65% and the convenience fee for a debit card is $3.95. 

Six Minimum Measures

NPDES MS4 permits require the implementation of a comprehensive stormwater management program to reduce pollutants in stormwater runoff to the Maximum Extent Practicable (MEP).  The MEP is based upon implementation of six Minimum Control Measures (MCMs) throughout the MS4s jurisdictional area:

  • Public Education & Outreach
  • Public Involvement & Participation
  • Illicit Discharge Detection & Elimination
  • Construction Site Runoff Controls
  • Post-Construction Site Runoff Controls
  • Pollution Prevention & Good Housekeeping for Municipal Operations

MS4 Tipped Areas

Some development activities occurring within the unincorporated area of a county (outside of permitted MS4 areas) are considered to be “urbanizing areas”, and are subject to the MS4 Post-Construction Site Runoff Control requirements [Ref. 15A NCAC 02H .1017].   These urbanizing areas lie within a U.S. Census designated Urbanized Area or the municipal sphere of influence around an MS4 [Ref. 15A NCAC 02H .1016].  In these areas, a stormwater post-construction permit is required for development that disturbs one acre or more of land.  The counties with urbanizing areas are called “Tipped Counties” because they are subject (or tipped in) to just the post-construction portion of the MS4 requirements, but they do not receive MS4 permits.  Post-Construction stormwater permitting for development in these areas may be performed by either the county, local government or DEQ:

Evolution of the MS4 Program

The evolution of the NPDES MS4 Program from inception in 1990 through 2011 is summarized in the MS4 Background Information Document.  This document was included with notification letters that DEQ sent to potential MS4s/candidate coverage areas in 2011.  In 2014, the cities of Statesville, Lexington and New Bern were also notified that they are subject to NPDES MS4 permitting. 

    If you have questions, please contact Jeanette Powell, MS4 Program Coordinator, at 919-707-3620.

      Associated Files