Stormwater Management

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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 an​d 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.

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