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Municipal Separate Storm Sewer System (MS4) Program

Objectives and Overview

The purpose of the Municipal Separate Storm Sewer System (MS4) program is to maintain and benefit stormwater quality in Jefferson County’s creeks, streams, and waterways.  This program is an unfunded federal mandate.  The MS4 permit program is the result of the 1987 amendments to the Clean Water Act (CWA), commonly referred to as the Water Quality Act of 1987. In these amendments, Congress mandated that the Environmental Protection Agency (EPA) address non-point source pollution associated with stormwater runoff. In essence, EPA defined urban stormwater (previously considered a non-point source) as a point source with numerous physical locations (or points) of discharge. In response to the Congressional action, EPA and subsequently the Kentucky Division of Water (KDOW) developed a program to permit the discharge of the stormwater from the MS4. The permits are intended to operate on five-year cycles.

The MS4 Permit program activities are divided into several program areas:

  • Illicit Discharge Detection and Elimination
  • Construction Site Runoff Controls
  • Post Construction Site Runoff Controls
  • Public Involvement and Outreach Programs
  • Facility Good Housekeeping and Pollution Prevention
  • Monitoring
  • Reporting and Program Assessment

In Louisville’s MS4 Permit, MSD serves and the Administrative Lead and is joined by several city governments as co-permittees (identified below). The MS4 program activities are accomplished by the co-permittees and MSD.  Some activities are performed independently, while others are performed cooperatively.

History – First and Second Permit Cycles

In January 1999, the first MS4 Permit for Louisville and Jefferson County expired. MSD submitted the MS4 Permit reapplication to the Kentucky Division of Water (KDOW) in September 1998 on behalf of nine Co-Permittees

  • City of Anchorage
  • City of Jeffersontown
  • City of Prospect
  • City of Shively
  • City of St. Matthews
  • City of Louisville
  • Jefferson County
  • Kentucky Transportation Cabinet, District Five (KyTC)
  • MSD

The second cycle permit was approved by the KDOW in March 2000 and is effective from May 1, 2000 through April 30, 2004. While the official effective end date elapsed, the KDOW administratively extended the permit until the third cycle permit is issued. A copy of this permit can be found here.

Today – Third Permit Cycle

As part of the application process for the third MS4 permit cycle, KDOW requested in 2008 that MSD prepare a Stormwater Quality Management Plan (SWQMP).  The SWQMP is a business planning document that MSD and its co-permittees use to determine how the MS4 permit program will be administered.  While it is not a part of the MS4 permit, it provides a more detailed description of the activities in the permit.  The permit identifies requirements established by KDOW, while the SWQMP identifies a plan to meet the requirements and is established by the MSD and its co-permittees.  The pending MS4 permit specifies that the SWQMP is expected to change over time and be modified by MSD and the co-permittees and made available to the public.  MSD prepared and submitted a proposed SWQMP in October 2008.

The KDOW issued a draft permit for public comment July 15, 2010. It then issued a final permit June 7, 2011 and it became effective (start date) August 1, 2011. Click on the link KPDES MSD Final MS4 Permit for a copy of the final permit.

A significant change in the anticipated third cycle permit involves the co-permittees to include:

  • Louisville Metro
  • City of Anchorage
  • City of Jeffersontown
  • City of Shively
  • City of St. Matthews

Previously listed as two separate entities, the City of Louisville and Jefferson County are to be addressed by the merged Metro government.  The activities in the City of Prospect are now addressed by MSD and Louisville Metro.  KDOW has indicated that KYTC will be issued a MS4 permit separate from the Louisville MS4 permit.

The October 2008 Stormwater Quality Management Plan (SWQMP) can be found at following links:

The October 2011 SWQMP and MS4 annual report may be found at:

The December 2012 SWQMP and MS4 annual report may be found at:

Wastewater / Stormwater Discharge Regulations Revisions
MSD recently modified its requirements for new development construction in compliance with the EPA?s requirements. The changes, effective August 1, 2013, require the use of green infrastructure on new development construction as a means to reduce stormwater based pollution from entering the area creeks and waterways. MSD developed an Executive Summary Fact Sheet and a Frequently Asked Questions (FAQ) to help explain the stormwater quality program changes and to work transparently in providing sound public communication on this program.
Last Updated: August 1, 2013

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