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NPDES MS4 Permitting

MS4 Overview

The NPDES (National Pollutant Discharge Elimination System) MS4 Program is mandated under the federal Clean Water Act and is delegated to DEMLR by the EPA. This program applies to owners and operators of MS4s (Municipal Separate Storm Sewer Systems) located in US Census Bureau designated "urbanized areas". Permitted MS4s must develop and implement a comprehensive stormwater management program.

In North Carolina, there are currently 122 MS4 entities covered by 109 NPDES MS4 individual permits.  The permits include measurable goals to satisfy each of the federally mandated six minimum control measures:

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

The MS4 Map Viewer provides MS4 permit information at the click of a button.

List of MS4 permittees

PDF map of MS4 areas


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

Permit Compliance Audits

EPA and their contractor audited Lenoir, Asheville, Hickory, Maiden, and Newton in December 2018.  No additional EPA audits are scheduled at this time. 

MS4 Permit compliance audits will become a regular part of DEMLR's MS4 Program beginning in 2019.  Each MS4 will be audited at least once per permit term, typically right before the permit renewal application is developed.  The MS4 Audit Schedule balances DEMLRs work load by auditing 20% of MS4 permittees each year.  In the short term, this will result in 42 MS4 permits being short cycled, 25 being extended and 55 that will have no change in their expiration/renewal dates. 

All Phase II MS4 audits and self-audits will utilize the MS4 Permit Compliance Audit Report Template, which is part of the MS4 Toolbox currently under development.  Learn more about permit compliance audits by viewing the MS4 Permit Compliance Audit presentation and visiting the Audits page.

The Phase II MS4 Toolbox

The Phase II MS4 Toolbox will include:

Training for Phase II MS4s

There will be five opportunities throughout the state to learn more about the Phase II MS4 requirements, tools and processes.  The dates and locations for these trainings are: 

  • March 14    Jacksonville
  • March 26   Cary
  • April 4       Charlotte
  • April 5       Hickory
  • April 11      Kernersville

The agenda will be:

  • Morning: Six Minimum Measures
  • Afternoon:  Audits, Compliance, and Enforcement, DEMLR MS4 Toolbox and Other Stormwater Tools