NPDES Municipal Separate Storm Sewer System (MS4) Program

Phase I MS4s

In response to the 1987 Amendments to the Clean Water Act (CWA), the U.S. Environmental Protection Agency (EPA) developed Phase I of the NPDES Stormwater Program in 1990. Under Phase I, EPA required NPDES permit coverage for stormwater discharges from "Medium" and "Large" MS4s located in incorporated places or counties with populations of 100,000 or more. 

Phase I MS4s in Tennessee:

To view permits, please visit the Division of Water Resources Permits Data Viewer

Phase II MS4s

The EPA phase II final rule requires NPDES permit coverage for stormwater discharges from certain small municipal separate storm sewer systems (MS4s). In Tennessee, about 100 cities and counties are required to obtain coverage under a stormwater discharge permit and to implement a set of programs to manage the quality of stormwater runoff from their storm sewer systems.

Tennessee issued a small MS4 general permit on September 30, 2016, effective on October 1, 2016. If the division designates a municipality as a Phase II MS4, the MS4 is required to submit a NOI (below) to the division at the appropriate EFO within 180 days of notice. MS4s previously permitted must submit an NOI within 90 days of the effective date of the permit.


The Division of Water Resources proposes to issue General NPDES Permit for Small Municipal Separate Storm Sewer Systems and held a public hearing on April 26, 2022, pursuant to Rule 0400-40-05-.06 (8)

Interested persons may obtain a copy of the draft permit, rationale, forms, and related documents on TDEC’s Water Resources Permit data viewer

The Notice of Intent (NOI) for coverage under this Small MS4 permit will be received and processed electronically through the MyTDEC Forms portal.

On June 1st and 6th, 2022, the Division of Water Resources hosted two MyTDEC Forms Portal Orientation Sessions to help familiarize Small MS4 Programs with the MyTDEC Forms portal and how to register a MyTDEC Forms account. The orientation was recorded and the video is available below. 

The Division of Water Resources hosted two virtual listening sessions. During the sessions, the Division heard from parties who have an interest in the pending MS4 Rules and the upcoming NPDES General Permit for Small MS4s.

The sessions were recorded and are available by accessing the links provided below.

Tennessee-Specific Information

List of Active Phase I and Phase II MS4s

Division of Water Resources Permits DataViewer: To promote greater transparency, accountability and broader access to public information, the department has a Permits Data Viewer available to the public. This data viewer pulls information from the same consolidated database that TDEC regulatory staff uses to keep track of permit activity and status.

Discharges to Water Quality Impaired Waters: Using the Department's GIS mapping tool along with the most current 303(d) list published on the division's publications page, the MS4 must determine whether stormwater discharges from any part of the MS4 may contribute pollutants of concern to an impaired waterbody.

Compliance Resources

  • Tennessee Permanent Stormwater Management and Design Guidance Manual :  provided to assist in the design, installation and maintenance of post-construction (permanent) stormwater management practices. The Tennessee Runoff Reduction Assessment Tool (RRAT) software was developed as a complement to the guidance manual, giving practitioners a logical and easy to use tool for designing permanent stormwater management systems.
    • 2016 REVISIONS:  The Tennessee Permanent Stormwater Management and Design Guidance Manual First Edition was created in December 2014 and corresponded to the NPDES general permit for Phase 2 MS4s issued in 2010. The general permit was revised and reissued on September 30, 2016. Subsequently, TDEC staff revised Chapters one through four of the guidance manual in December 2016, to reflect and correspond to the changes in the permit requirements.

      The revised chapters are posted here to provide information to municipal stormwater professionals and the general public as they consider the available options for implementing a local program for the control of post-construction runoff.

      Chapter 1 - Introduction to the Manual
      Chapter 2 - Building a Local Program to Improve the Quality of Permanent Stormwater Discharges
      Chapter 3 - Watershed Protection and Smart Site Design Requirements
      Chapter 4 - Estimating the Level of Treatment Provided by a Site Design for Stormwater Management
  • The Tennessee Stormwater Training Program offers training classes related to the design and inspection of construction stormwater erosion prevention and sediment controls, as well as permanent stormwater management. Classes are held throughout the year at multiple locations across the state.
  • The Tennessee Erosion and Sediment Control Handbook provides standardized and comprehensive erosion prevention and sediment control best management practices for use throughout Tennessee. The handbook serves as a reference for the development and implementation of Stormwater Pollution Prevention Plans (SWPPP), as required per the Tennessee General NPDES Permit for Discharges Associated with Construction Activities and individual NPDES permits.
  • The Tennessee Stormwater Association (TNSA) is a not-for-profit statewide Association developed by MS4s with the assistance of TDEC and UT-MTAS to assist local government entities in their efforts to comply with State and Federal clean water laws and Stormwater Regulations.
  • The TN Water Resources Research Center (TN WRRC) is a federally designated state research institute supported in part by the U.S. Geological Survey. The Center serves as a primary link among water-resource experts in academia, government, and the private sector, and the diversity of its staff in terms of background and expertise enhances flexibility and positions the Center to establish productive partnerships. TN WRRC is housed within the Institute for a Secure and Sustainable Environment (ISSE) at the University of Tennessee Knoxville.​
  • University of Tennessee MTAS - This page provides resources specifically related to stormwater management and best management practices. Also find here the MTAS model ordinances related to stormwater management.​
  • Stormwater Manager's Resource Center is designed specifically for stormwater practitioners, local government officials; technical assistance on stormwater management issues; has fact sheets, slide shows, example ordinances; claims to be "everything you need to know about stormwater in a single site."
  • The EPA Stormwater Homepage contains technical and regulatory information about the NPDES stormwater program. It is organized according to the three types of regulated stormwater discharges – municipal separate storm sewer systems (MS4s), construction activities, and industrial activities. It also provides links to general stormwater topics and tools available.
  • The Center for Watershed Protection: Stormwater Management works to protect, restore, and enhance streams, rivers, lakes, wetlands, and bays. The Center creates viable solutions and partnerships for responsible land and water management and offers FREE downloads of Center resources on stormwater management.

Whom Do I Contact For Applications, Assistance And Other Sources of Information?

For more information please contact your local TDEC Environmental Field Office.

This Page Last Updated: June 10, 2022 at 9:56 AM