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Maryland State Government Maryland Department of the Environment

Maryland's Stormwater Management Program

Urban development has a significant influence on the quality of Maryland’s waters. To start, construction activities remove trees and meadow grasses that had intercepted and absorbed rainfall. In addition, natural depressions that had temporarily ponded water are graded to a uniform slope and severely compacted. These cleared and graded sites erode and no longer can prevent rainfall from converting into stormwater runoff.

After construction, rooftops, roads, parking lots, driveways, and other impervious surfaces no longer allow rainfall to soak into the ground. Consequently, most rainfall converts directly to runoff. This increase is sometimes too much for the natural system to handle, and the system is "improved" using curb and gutter, enclosed storm drains, and lined channels to rapidly collect runoff and quickly convey it downstream. This reduces groundwater recharge and degrades receiving streams.

The State of Maryland has developed comprehensive stormwater management, and erosion and sediment control programs to reduce the adverse impacts of development on stormwater runoff. This program addresses both the temporary and the permanent impacts associated with development activities. The information found on this site describes this program and its requirements, and presents guidance on how to implement stormwater management in Maryland.

  • NEED TO REPORT POLLUTION PROBLEMS?   - Please click here!
  • New Item  (04/15/2015) Maryland's online Responsible Personnel Certification course ("green card class") is currently undergoing maintenance and enhancements. It is expected that the course will be available by April 27, 2015. Please check back at around that time. If you have any questions or concerns contact Maria Warburton at 410-537-3632 or maria.warburton@maryland.gov.
  • (02/27/2015) MDE held the Public Hearing regarding Maryland Department of the Environment's (MDE) Tentative Determination to issue the Maryland State Highway Administration's (SHA) National Pollutant Discharge Elimination System (NPDES) Permit on Thursday, February 26, 2015 at 5:00 PM.  Anyone that was unable to attend due to the weather may still submit comments to MDE until March 13, 2015.
  • Looking for information concerning the Final Determinations to issue an NPDES stormwater permit to Howard County (December 18, 2014), Charles County (December 26, 2014), and Carroll, Frederick, and Harford Counties (December 30, 2014)? Click here for details. 

  • Looking for information concerning the Tentative Determination to issue and NPDES stormwater permit to the Maryland State Highway Administration (SHA) (December 30, 2014)? Click here for details. 

  • MDE is pleased to announce the release of the updated version of our National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) guidance document, “Accounting for Stormwater Wasteload Allocations and Impervious Acres Treated,” August 2014.  The document includes an Executive Summary, which provides a list of acceptable water quality and alternative best management practices (BMPs), and tabulates the credit granted toward meeting MS4 permit requirements.  The document may be found here. 
  • Maryland Stormwater Seminars - In October 2013, the Maryland Department of the Environment (MDE) conducted three regional seminars focusing on the implementation of environmental site design (ESD) throughout the State. These seminars were held on the Eastern Shore (October 8th), Western Maryland (October 17th) and Central Maryland (October 29th).  For a brief summary of these seminars, Please click here!
  • Looking for information concerning the Final Determination to issue NPDES stormwater permits to Anne Arundel County, Baltimore County, Baltimore City, and Prince George's County? (February 12, 2014)  Click here for details.
  • Stormwater Design Guidance - Environmental Site Design and Innovative Technology (May 2013) Click here for details.
  • Erosion and Sediment Control Update - All regulated projects must comply with the revised stabilization requirements beginning January 9, 2013.  For more information, please click here!
  • Looking for information on the “2011 Maryland Standards and Specifications for Soil Erosion and Sediment Control” and recently adopted regulatory changes?  Click here for details.
  • Looking for information on Maryland's Dam Safety program? - Please click here!
  • Looking for fact sheets or additional resources? -  Please click here!

Maryland's Stormwater Management Program

Stormwater Management Act

The “Stormwater Management Act” (Act) became effective on October 1, 2007.  MDE is responsible for implementing the Act and it's provisions for improving stormwater management in Maryland.  More information on the Stormwater Management Act may be found here:

Maryland's Stormwater Management Act

Stormwater Management Regulations

The regulations governing Maryland's stormwater management program, Code of Maryland Regulations (COMAR) 26.17.02, are available from the Office of the Secretary of State, Division of State Documents (DSD) (www.dsd.state.md.us).  The official regulations may be accessed through DSD's website here:

"COMAR Online"

2000 Maryland Stormwater Design Manual

The 2000 Maryland Stormwater Design Manual, Volumes I & II is available in print for $25.00 per copy. This is the official version and includes changes made prior to adoption. The Design Manual also may be downloaded in "PDF" format here:

2000 Maryland Stormwater Design Manual

Watershed Protection and Restoration Program

The Watershed Protection and Restoration Program (HB987) was signed into law in April 2012. The program establishes a system of stormwater remediation fees and a local watershed protection and restoration fund (WPRF) that must be implemented by counties and municipalities that are subject to a National Pollutant Discharge Elimination System (NPDES) Phase I Municipal Separate Storm Sewer System (MS4) permit in Maryland.

More information on the Watershed Protection and Restoration Program may be found here:

Watershed Protection and Restoration Program Fact Sheet

Stormwater Design Guidance

MDE has published guidance on various technical procedures and calculations relevant to implementing environmental site design (ESD) for both new development and redevelopment.  The following publications provide additional information for use when designing or reviewing stormwater plans:

 Alternative/Innovative Technology Practice Guidance

MDE recognizes that new and innovative technologies for stormwater management are being developed, including many proprietary designs.  The following publications provide additional information and guidance on the use of alternative/innovative technologies for addressing Maryland's stormwater management requirements:

New Item Stormwater Management and Erosion and Sediment Control Guidelines for State & Federal Projects

MDE maintains the publication entitled "Maryland Stormwater Management and Erosion and Sediment Control Guidelines for State & Federal Projects". These Guidelines supplement the Stormwater Management Regulations (COMAR 26.17.02) and the "2000 Maryland Stormwater Design Manual, Volumes I & II". The Guidelines provide information necessary for submittal of stormwater management and erosion and sediment control plans by State and federal agencies to MDE's Water Management Administration for review and approval.  The guidelines may be downloaded here:

Guidelines for State & Federal Projects

Questions about the Guidelines should be directed to Ms. Amanda Malcolm at (410) 537-3551 or by email at Amanda.Malcolm@maryland.gov.

Standard Plan for Poultry House Site Development on the Eastern Shore - MODEL

MDE, in conjunction with the Maryland Department of Agriculture (MDA), the Natural Resource Conservation Service (NRCS), and the Soil Conservation Districts (SCDs) has published the “2011 Model Stormwater Management Standard Plan for Poultry House Site Development on Maryland Eastern Shore.”  The Standard Plan is a single design option that is intended to be used by the SCDs, County stormwater management authorities, and local designers to address stormwater requirements for poultry operations on the Eastern Shore.

MDE also has developed a stormwater management “calculator” to assist in sizing of the stormwater management practices for the “Model Standard Plan for Poultry House Site Development on the Eastern Shore.”   Copies of the model standard plan and calculator are available here:

Model Stormwater Management Standard Plan for Poultry House Site Development

Calculator for Poultry House Development

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Erosion and Sediment Control

Grandfathering of approved plans.

  1. This chapter applies to all projects that do not have final approval for erosion and sediment control plans by January 9, 2013.

  2. A plan that has received final approval by January 9, 2013 may be reapproved under its existing conditions if grading activities have begun on the site by January 9, 2015, with the exception of stabilization requirements.
  3. Stabilization practices on all projects must be in compliance with the requirements of this chapter by January 9, 2013, regardless of when an erosion and sediment control plan was approved.

This notice is a reminder that all regulated projects must comply with the revised stabilization requirements beginning January 9, 2013. These requirements include shorter timeframes for the temporary and permanent stabilization of all inactive, disturbed areas; specifically three (3) calendar days for perimeter sediment controls and slopes steeper that 3:1 and seven (7) calendar days for all other areas not under active grading.

Statewide compliance with these regulations will help limit the adverse impacts associated with erosion and sedimentation during construction and serve to protect water quality in Maryland’s streams and Chesapeake Bay. If there are any questions regarding this, or any other issue related to erosion and sediment control, please call the Sediment, Stormwater, and Dam Safety Program at 410-537-3543.

Maryland's NPDES Municipal Stormwater Permits

The Environmental Protection Agency’s (EPA) National Pollutant Discharge Elimination System (NPDES) stormwater regulations were published in 1990. Phase I of these regulations require large (greater than 100,00 in population) urban jurisdictions to control pollution in stormwater to the maximum extent practicable.  Municipalities with less than 100,000 are permitted separately under Phase II NPDES stormwater rules.

Click here for more information on Maryland's NPDES Municipal Stormwater Permits.

Guidance for Maryland's NPDES Stormwater Permits

NPDES municipal separate storm sewer system permits in Maryland require the restoration of a certain percent of a jurisdiction's impervious surface area (e.g., 20%) that has little or no stormwater management. How to calculate impervious surface requirements and treatment credits has generated numerous questions. This document standardizes procedures for reporting of traditional, new, and alternative best management practices (BMPs) and the impervious area each controls. The draft guidance may be found here:

Accounting for Stormwater Wasteload Allocations and Impervious Acres Treated

Contact Us

Please direct comments or questions concerning Maryland's stormwater management program to the Sediment, Stormwater, and Dam Safety Program at (410) 537-3543 or email at Brian.Clevenger@maryland.gov

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