Maryland Department of the Environment

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

 

Announcements​​​​

Notice of Public Solicitation of Water Quality Data for the 2026 Integrated Report of Surface Water Quality in Maryland. 

 

The Maryland Department of the Environment (MDE) is currently requesting data for the 2026 Integrated Report (IR) of Surface Water Quality in Maryland. As part of the federal Clean Water Act, MDE submits a biennial Integrated Report to the Environmental Protection Agency (EPA) that provides information on both impaired and non-impaired waters within the State of Maryland. In order to provide the most comprehensive report, the D​epartment relies on water quality data from a variety of sources including Federal and State agencies, local government agencies, researchers, students, and watershed organizations.


If your organization collected water quality data in Maryland within the past five-year period (January 1, 2019- December 31, 2023), please consider submitting your data. MDE is particularly interested in water quality data that are comparable to state water quality standards and criteria (e.g., dissolved oxygen, pH, turbidity, various toxics, benthic macroinvertebrate and fish community data). Other water quality data, including conductivity, nutrient species, chlorophyll, habitat conditions, and field observations may also be used to assess ambient water quality.


To submit data, please complete this 2026 Integrated Report Submittal Form and follow the appropriate data pathway. For additional information on the types of data accepted and how to submit data, please visit MDE's Data Solicitation webpage.


Because the IR is a regulatory document, some data received may not be suitable for water quality assessments. However, the Department will track all data received and data submitters can contact MDE to inquire how their data were used and why.  Please contact Becky Monahan at Becky.Monahan@maryland.gov with any questions. ​

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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).

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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 becky.monahan@maryland.gov.​
Maryland Department of the Environment
1800 Washington Blvd
Baltimore, MD 21230