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 Data Viewer

Phase II MS4s in Tennessee

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 the new small MS4 general permit on August 1, 2022, effective September 1, 2022. If the Division designates a municipality or nontraditional MS4 as a small MS4, the designee is required to submit a Notice of Intent (NOI) to the Division within 180 days of notice.

Existing permittees must submit an NOI within 90 days of the effective date of this permit.
The Notice of Intent (NOI) for coverage under the new 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. 

On September 14th and 28th, 2022, the Division of Water Resources hosted two MyTDEC MS4 NOI Training Sessions to help familiarize the Small MS4 Programs with the form. The training was recorded, and the video is available below.

Additional Related Information

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 to control 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

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

Requests for information specific to the NPDES Municipal Separate Storm Sewer System (MS4) Program activities may be received at

This Page Last Updated: January 19, 2023 at 2:24 PM