Integrated Report of Surface Water Quality [303(d) List] Assessment Methodologies



The public comment period for the final draft assessment and listing methodologies for the 2024 Integrated Report of Surface Water Quality closed on November 13, 2023.  

MDE thanks the reviewers for their comments and suggestions.  Please see the document below for a list of all comments and MDE's responses. 

Assessment Methodologies

Provided below are links to Maryland’s Assessment Methodologies (AMs) used in water body impairment determinations for the Integrated Report (IR) of Surface Water Quality. The AMs provide a consistent logical framework for ​reviewing​ water quality data. The public is invited to comment on any of the assessment methodologies during the public comment period for assessment methodologies that occurs during each IR cycle.  ​

All files below are in portable document format (PDF).

Summary of 2024 Assessment Methodology Updates

  1. The Listing Methodology for Identifying Waters Impaired by Bacteria in Maryland’s Integrated Report  
    • Both sections of this methodology, The Interpretation of Fecal Coliform Data for Assessing Use II Shellfish Harvesting Areas, and The Interpretation of Bacteria Data for Water Contact Recreation Use, were updated to be more consistent with the criteria and determine which Maryland waters require restoration.  Changes include larger sample sizes and assessment decisions over a longer term to identify chronic bacteria issues.  There are also updates regarding the use of best professional judgement in reviewing data that doesn’t meet the minimum data requirements and in identifying chronic impairments from individual exceedances.  
  2. ​​The Fish Tissue Assessment Methodology section which is part of the Methodology for Determining Impaired Waters by Chemical Contaminants for Maryland’s Integrated Report of Surface Water Quality  
    • The Fish Tissue section of this methodology was updated with concentration thresholds for Perfluorooctane sulfonic acid (PFOS).
  3. ​The Temperature Assessment Methodology for Use III(-P) Streams in Maryland  
    • ​The Temperature Assessment Methodology was updated to include information on the minimum sample size for impairment determinations, decisions for multiple monitoring locations on a single segment, and additional details on delisting a stream segment. 

There were no other substantive changes in any other assessment methodology for the 2024 IR cycle.  

Please direct any questions or comments to Becky Monahan at​

Human Trafficking GET HELP

National Human Trafficking Hotline - 24/7 Confidential

1-888-373-7888 233733 More Information on human trafficking in Maryland

Customer Service Promise

The State of Maryland pledges to provide constituents, businesses, customers, and stakeholders with friendly and courteous, timely and responsive, accurate and consistent, accessible and convenient, and truthful and transparent services.

Take Our Survey

Help Stop Fraud in State Government

The Maryland General Assembly’s Office of Legislative Audits operates a toll-free fraud hotline to receive allegations of fraud and/or abuse of State government resources. Information reported to the hotline in the past has helped to eliminate certain fraudulent activities and protect State resources.

More Information