Draft Updates to Maryland’s Regulations and Stormwater Design Manual (September 19, 2025) NEW!
The Maryland Department of the Environment (MDE) has issued an Advanced Notice of Proposed Rulemaking (ANPRM) to update stormwater regulations in COMAR 26.17.02 and the Maryland Stormwater Design Manual. For more information on the ANPRM, draft regulations and design manual updates, follow the links below:
To ensure broad participation in this process, MDE will host three listening sessions as follows:
- October 22, 2025 – Virtual Session, 7:00–9:00 PM
- October 28, 2025 – Virtual Session, 2:00–4:00 PM
- November 13, 2025 – In-person Session at MDE Headquarters (1800 Washington Boulevard, Baltimore, MD), 10:00 AM.
Registration details for these events will be forthcoming.
MDE invites written comments on this ANPRM through December 19, 2025. Please include your name/organization and, where possible, cite specific sections of the draft regulations or design manual your comments address. Attachments and supporting analyses are welcome. All comments received will inform the development of formal proposed regulations.
Stormwater, Dam Safety, and Flood Management Program
Maryland Department of the Environment
1800 Washington Boulevard, Baltimore, MD 21230.
Maryland's Stormwater Management Program
Maryland’s stormwater management program works to mitigate the impacts of new development and redevelopment activities through the implementation of stormwater best management practices (BMPs). Stormwater BMPs are intended to address the impacts of impervious surfaces such as rooftops, paved streets, and parking lots. These hard surfaces prevent rainwater from soaking into the ground which results in an increased volume of runoff that is funneled into storm drains and discharged into streams and rivers. Stormwater management is necessary to reduce the amount and velocity of runoff across the land and into stream channels, pollutants, and local flooding.
Maryland’s first Stormwater Management Law was passed in 1982 and focused on controlling flooding associated with new development. Stormwater BMPs implemented under the early law resulted in centralized structural practices or flood control impoundments. These designs were less able to mimic pre-development conditions because they focused on managing large volumes of stormwater runoff in a central area rather than treating runoff closer to the source.
Advancements in the field have led to the development of a strategy for stormwater management known as Environmental Site Design (ESD). ESD relies on integrating site design and smaller controls to capture and treat runoff closer to, or at the source, to more closely mimic natural hydrology. This advancement was reflected in State law with the passing of the “Stormwater Management Act of 2007” (Act). The Act requires implementing ESD to the maximum extent practicable (MEP), ensuring that structural practices are used only where absolutely necessary. Full
provisions of the Stormwater Management Act (Environment Article 4 §§201 - 215) are available at the General Assembly of Maryland's website
here. Maryland’s stormwater management regulations are updated to comply with legislation as necessary. Access the Code of Maryland Regulations
here.
Information on the Department's regulatory process may be found in the State Government Article §10 (see here) and on the Department's website here: Maryland Environmental Regulations.
In Maryland, stormwater management is implemented at the local level and the Department is responsible for providing oversight and assistance to local programs.
To assist local authorities in meeting regulations, the Department provides technical guidance including
the Maryland
Stormwater Design Manual. which establishes performance standards and design criteria for stormwater best management practices. Stormwater design criteria to comply with ESD is found in Chapter 5 of the Stormwater Design Manual. Additional guidance related to ESD, stormwater management ordinances, standard plans, and poultry house development has been developed to support compliance with SWM regulations and can be found at the
Stormwater Design Guidance page here.
For information or questions about your local stormwater management program, or
to report a problem, please visit
our directory to find the contact information for your jurisdiction.
What's New?
Stormwater Seminars
