National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) Permit

In 2015, the Maryland Department of Transportation State Highway Administration (MDOT SHA) received an NPDES MS4 permit (No. 11-DP-3313) from the Maryland Department of the Environment (MDE) to control storm-drain-system pollutant discharges in MS4-designated areas (see map below). The permit requires that we use restoration practices to treat 20% of existing MDOT SHA impervious surfaces and address stormwater wasteload allocations (WLAs) established under US Environmental Protection Agency (EPA)-approved Total Maximum Daily Loads (TMDL).  

MDOT SHA also performs the following activities to control storm drain system pollutants along MDOT SHA roads.:

  • Map MDOT SHA's storm drain system.
  • Assess the effectiveness of restoration projects through chemical, physical and biological monitoring.
  • Implement comprehensive management programs for -
    • Stormwater management.
    • Erosion and sediment control.
    • Illicit discharge detection and elimination.
    • Public education and outreach.
    • Property management and maintenance.

MS4 Phase 1 Permit Coverage map 

Impervious Restoration and Coordinated TMDL Implementation Plan

​Review and Comment on Draft Implementation Plans

2023 TMDL Implementation Plan

2020 TMDL Implementation Plans

2019 TMDL Implementation Plans

Current MS4 Permit and Annual Reports

Related Documents