The Maryland Department of the Environment (MDE), acting on behalf of the U.S. Environmental Protection Agency (EPA), will issue a five-year, NPDES MS4 stormwater discharge permit to government agencies, cities, and towns that own and operate large-scale infrastructure used to collect or transport stormwater (e.g., ponds, storm drains, pipes and ditches). Stormwater is the term used by EPA for rainwater or melted snow that runs/drains off streets, lawns and other sites.​

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On August 22, 2025, MDE issued the Maryland State Highway Administration (SHA) its current NPDES MS4 stormwater discharge permit (no. 24-DP-3313 MD0068276). To comply, SHA must continuously manage, implement and enforce a stormwater management program to prevent or eliminate pollution in stormwater draining from SHA properties located within the permit area. The current permit area covers stormwater drainage from SHA properties in 15 Maryland counties and the Town of Easton (see map above). SHA must report to MDE annually to demonstrate compliance with all NPDES MS4 permit requirements. Links to the current NPDES MS4 permit and previously submitted annual reports are provided below.

Current MS4 Permit and Annual Reports

• ​Maryland SHA NPDES MS4 Permit issued August 22, 2025
  
• ​2025 MS4 Annual Report.​
  
• ​2024 MS4 Annual Report.​
  
• 2023 MS4 Annual Report.
  
• 2022 MS4 Annual Report.
• 2021 MS4 Annual Report.
• 2020 MS4 Annual Report.
• 2019 MS4 Annual Report.   
• 2018 MS4 Annual Report (122 MB).
• 2017 MS4 Annual Report (488 MB).
• 2016 MS4 Annual Report (91.9 MB).  ​  ​​

As a condition of the NPDES MS4 permit, SHA must also comply with all plans and schedules developed to meet ‘wasteload allocations’ for each established or approved Total Maximum Daily Load (TMDL) within the areas covered by the permit. Links to all applicable, SHA TMDL Implementation Plans are provided below. Visit MDE’s website for more information about TMDLs and associated wasteload allocations.​

2018 Impervious Restoration and Coordinated TMDL Implementation Plan

• Part I – Program Introduction 
• Part II – Impervious Restoration Plan & Chesapeake Bay TMDL Compliance 
• Part III – Coordinated TMDL Implementation Plan 
• Part IV – MDOT SHA Watershed TMDL Implementation Plans 
• Entire Plan​

2019 TMDL Implementation Plans

• Other West Chesapeake Watershed Sediment TMDL Implementation Plan.
• Non-Tidal Back River Watershed Sediment TMDL Implementation Plan.
• Non-Tidal Patuxent River Lower Watershed Sediment TMDL Implementation Plan.
• Non-Tidal Patuxent River Middle Watershed Sediment TMDL Implementation Plan.

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2020 TMDL Implementation Plans

• Implementation Plan for Various TMDLs In Maryland.
• Marsh Run Watershed Sediment TMDL Implementation Plan.
• Non-Tidal West River Watershed Sediment TMDL Implementation Plan.
• Piscataway Creek Watershed Sediment TMDL Implementation Plan.

2023 TMDL Implementation Plan

• ​Non-Tidal Baltimore Harbor Watershed Sediment TMDL Implementation Plan​​
  

​​Review and Comment on SHA TMDL Implementation Plans

The SHA encourages the public to participate in SHA restoration planning by submitting comments on SHA TMDL Implementation Plans. Learn more about how you can participate at the SHA TMDL Implementation Plan Public Notice and Participation webpage​.