The Anne Arundel County FY25 NPDES MS4 Annual Report Is Now Available!
Annapolis (January 13, 2026) – The National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) Permit is a State-issued permit that regulates stormwater runoff, which is rainwater that flows over pavement and carries trash, oil, and fertilizers into storm drains. This report documents the comprehensive County activities that demonstrate compliance with Permit requirements, as well as County progress toward achieving State clean water goals. These activities demonstrate compliance with the Permit terms beginning July 1, 2024, and ending June 30, 2025.
Key Highlights from the Report:
90% of County’s Restoration Goal Met - "The cornerstone of the County’s MS4 program is the mandated restoration of 2,998 equivalent impervious acres by November 2026. Through a combination of structural Best Management Practices (BMPs) and alternative control practices, the County successfully completed a cumulative restoration total of 2,697 acres...90% of the permit goal."
Pollutant Source Identification & Reduction - "In FY25, the IDDE [Illicit Discharge Detection and Elimination] program successfully conducted annual field screening on 163 major and minor outfalls within the targeted southern portion of the County, alongside visual surveys of 267 private commercial and industrial sites to identify potential upland pollutant sources."
Community Partnerships - "The [Watershed Stewards] Academy successfully reached over 47,000 Anne Arundel County residents with technical assistance or environmental education, including over 6,000 children. Furthermore, its efforts resulted in significant on-the-ground change: Over 30,000 native plants (perennials, shrubs, and trees) were planted, and stewards led more than 728 new restoration projects alongside 342 maintenance events."
Good Housekeeping - Just as you might have rules in your own home to keep chemicals away from the drain or to keep the driveway clear of oil leaks, the County uses these plans to ensure that public properties—like maintenance yards—don't accidentally pollute our local water. "As of June 30, 2025 all applicable County-owned properties were assessed, and draft GHPs [Good Housekeeping Plans] were developed for 73 additional qualifying properties [beyond the initial 10 that were developed in FY24]."
Access the report and learn more about the County's NPDES MS4 Permit here: https://www.aacounty.org/public-works/bwpr/npdes-ms4-permit