Municipal Separate Storm Sewer System (MS4) Program

ms4 thumbnail

What role does the
ALDOT MS4 program play in stormwater management?

The MS4 program manages stormwater discharge from ALDOT property in particular urban areas and factors that may affect stormwater discharge.

The program is a joint effort in which multiple bureaus in the ALDOT central office and offices in ALDOT Regions, Areas, and Districts throughout the state participate.

ADEM issues MS4 permits to ALDOT and other public entities. The permit currently in effect for ALDOT can be viewed by following the link below:

MS4 Permit (issued by ADEM 30 Sep 2019)

To meet the requirements of the MS4 permit and other urban stormwater management objectives, ALDOT develops and maintains continually a “Stormwater Management Program Plan” (SWMPP) that governs the ALDOT MS4 program. A link to the current version of the SWMPP is below. For convenience and better understanding, a link to a slideshow giving an overview of the ALDOT MS4 program is also provided.

Stormwater Management Program Plan (revised 30 Jan 2024)
Slideshow (PDF): “The Alabama DOT MS4 Program” (21 Oct 2016)

We welcome citizen feedback on the MS4 program, especially regarding the SWMPP specifically. Feedback can be sent to us using the environmental concern submission form.

ALDOT compiles an MS4 annual report for every fiscal year (Oct. 1 - Sep. 30). The annual report explains the MS4 program-relevant activities that were conducted during the fiscal year in question and the progress made in accomplishing goals set in the Stormwater Management Program Plan. Below are links to recent MS4 annual reports archived:

FY 2014 MS4 Annual Report
FY 2015 MS4 Annual Report
FY 2016 MS4 Annual Report
FY 2017 MS4 Annual Report
FY 2018 MS4 Annual Report
FY 2019 MS4 Annual Report
FY 2020 MS4 Annual Report
FY 2021 MS4 Annual Report
FY 2022 MS4 Annual Report
FY 2023 MS4 Annual Report

ALDOT MS4 permit requirements apply at locations that are regulated by another public entity’s MS4 permit. ALDOT has delineated the areas within Alabama that are eligible for such MS4 permit regulation. Below is a link to a map of the MS4 regulation-eligible areas applicable to ALDOT as well as a link to shapefiles of the areas that can be actively used with GIS software. The Stormwater Management Program Plan also contains maps of the MS4 regulation-eligible areas.

MS4 Regulation-Eligible Areas (as of 2013): Map (PDF)
MS4 Regulation-Eligible Areas (as of 2013): GIS Shapefiles (ZIP)

Note that the MS4 regulation-eligible areas ALDOT has delineated serve only as a “starting point” for determining whether a specific location is truly under MS4 permit regulation. As MS4 permits are issued and terminated by ADEM continually, a user of this MS4 regulation-eligible area data should rely on the language of ADEM-issued MS4 permits in effect to determine regulation eligibility definitively.

To learn more about other ALDOT environmental activities, visit ALDOT’s Environmental Information page. For questions pertaining to the Municipal Separate Storm Sewer System (MS4) Program please email Dr Scott Rogers, PE, CPMSM, Environmental Coordination Engineer at or call (334) 353-6214.