Expanded permit requirements and additional actions advance climate resilience, clean water goals, and healthy communities
BALTIMORE (August 22, 2025) – The Maryland Department of the Environment (MDE) today released the next five-year stormwater discharge permit for the Maryland Department of Transportation’s State Highway Administration (MDOT SHA), designed to deliver economic opportunities for communities, cleaner waterways, and enhanced climate resilience.
The new Municipal Separate Storm Sewer System (MS4) permit expands MDOT SHA’s restoration obligations to more than 4,000 acres (a nearly 40% increase in restored acres over the draft permit). The effort is supported by $216 million in combined state and federal funding and is expected to support Maryland’s growing restoration economy while protecting vulnerable communities from flooding and pollution.
“This permit strengthens our ability to protect the Chesapeake Bay and the businesses and communities that rely on it, manage stormwater in overburdened areas, and make our state an even more desirable place to live,” said Maryland Environment Secretary Serena McIlwain. “This permit and other actions the Department is announcing today will help build a more competitive Maryland – creating good-paying jobs, protecting businesses and homes from the effects of climate change, and positioning our state as a national leader in clean infrastructure.”
“Building and maintaining a safer transportation system that drives economic growth starts with protecting one of the state’s most treasured assets – our environment,” said Maryland Department of Transportation Acting Secretary Samantha J. Biddle. “MDOT continues to work toward addressing transportation-related stormwater needs to protect Marylanders from flooding and to advance clean rivers and streams in our communities.”
Permit highlights include:
- Requires MDOT SHA to restore 4,092 impervious acres through stormwater retrofits and other practices, with a focus on green infrastructure such as stream restoration and tree planting across the roadway network
- Increases equity and accountability by requiring MDOT SHA to evaluate and report on restoration opportunities and progress in communities with environmental justice concerns, while meeting annual benchmarks to ensure steady progress
- Modernizes tracking by expanding collaboration with scientists and experts on shared monitoring studies – delivering better data, faster results, and smarter decisions.
The enhanced permit reflects public input – including a public hearing and formal comment period when MDE carefully considered feedback and incorporated changes on restoration goals, equity, and monitoring – and is part of a broader package of clean water and climate initiatives that MDE is pursuing under the Moore-Miller Administration. These include:
- Updating stormwater regulations based on future climate conditions
- Updating erosion and sediment control requirements in coordination with stormwater regulations to ensure modern, climate-resilient design standards.
- Improving guidance and tools for living shorelines and resilient wetlands, including new guidance to implement the Whole Watersheds Act
- Forming a workgroup to collaborate on a long-term shared vision for future MS4 stormwater goals and regulations
- Adding nearly $2.5 million in funding for flood risk studies
