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:

• Knoxville: TNS068055  City of Knoxville Stormwater Web Page
• Nashville: TNS068047  City of Nashville Stormwater Web Page
• Memphis: TNS068276  City of Memphis Stormwater Web Page
• Chattanooga: TNS068063  City of Chattanooga Stormwater Web Page
• Tennessee Department of Transportation (TDOT): TNS077585  TDOT MS4 Permit & Facility Compliance Program  

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.

Small MS4 Annual Reports must be submitted on or before September 30th of each calendar year. The Small MS4 Annual Reports will be received and processed electronically through the MyTDEC Forms portal.

The Division hosted five (5) virtual training sessions to help familiarize the MS4 Programs with the new MyTDEC Small MS4 Annual Report form. The descriptions and links to each training session are provided below.

Please note that each session is unique.
(click each section below to see what is covered in that session)

Additional Related Information

• List of Active Phase I and Phase II MS4s
• MS4 effluent limitations to manage post-construction stormwater TDEC Rules
  
  • Chapter 0400-40-05-.15 Individual NPDES Permits
  • Chapter 0400-40-10-.04 NPDES General Permits
• NPDES Permit - Guidance for Permanent Stormwater Implementation Plan Submittals for Municipal Separate Storm Sewer Systems (MS4)
• Tennessee Water Resources Data and Map Viewers
• EPA Water Quality Scorecard
• Tennessee Stormwater Association (TNSA)
• Municipal Technical Advisory Service (MTAS)
• County Technical Assistance (CTAS)
• Tennessee Permanent Stormwater Management Training (University of Tennessee Knoxville)
• Tennessee Permanent Stormwater Management and Design Guidance Manual (University of Tennessee Knoxville)
  provided to assist in designing, installing, and maintaining 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 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

• Stormwater Discharges from Municipal Sources |US EPA
  
• Land Use and Green Infrastructure Scorecard |US EPA

Helpful Resources

Below you will find a curated selection of resources that have undergone review by the Division of Water Resources staff for their relevance, accuracy, and overall utility. Inclusion in this list signifies that the Division recognizes these resources as valuable references offering guidance in various areas within stormwater management. Users are encouraged to explore these materials and consider how they may inform their understanding and decision-making. Your access to these vetted resources aligns with our commitment to providing reliable information to support informed actions in the realms of environmental stewardship and water quality management.

• Bioretention Design Handbook: Designing Holistic Bioretention for Performance and Longevity | US EPA
• Tools for Treatment: The Science Behind Treatment Strategies for New NPDES Rules Compliance in TN | Contech Engineered Solutions
• Water Quality Treatment Volume (WQTV) Calculation | Civil & Environmental Consultants, Inc.

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 water.permits@tn.gov.