National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) Permit
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.
Stormwater draining from SHA Property, within the NPDES MS4 Permit Area, is regulated by MDE oversight and enforcement of the NPDES MS4 Permit issued to SHA.
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
SHA Total Maximum Daily Load (TMDL) Implementation Plans
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 TMDL within the areas covered by the permit. To learn more about SHA’s TMDL Implementation Plans, submit comments or request copies of specific plans, please visit
TMDL Implementation Plan Public Notice and Participation. Additional information on TMDLs and wasteload allocations is available from the
Maryland Department of the Environment.