Integrated Report of Surface Water Quality [303(d) List] Assessment Methodologies
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Announcements
Approval of the Final 2024 Integrated Report (IR) of Surface Water Quality
In compliance with Sections 303(d), 305(b), and 314 of the Clean Water Act, the Maryland Department of the Environment (MDE) is pleased to announce that the Final 2024 Integrated Report of Surface Water Quality (IR) was approved by EPA on September 4, 2024.
The Final IR is posted on MDE's website here.
Please note that it will take time to update MDE's IR web tools like the Water Quality Assessment Map and the Searchable Integrated Report with the 2024 information. Please check the date of last update on each of these tools before using them.
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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).
2024 Assessment Methodology Comment Response Document
Summary of 2024 Assessment Methodology Updates
- 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.
- 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).
- 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.