Maryland's 2023 Interim Update to Water Quality Standards

​​Maryland's 2023 Interim Update to Water Quality Standards

In the 2019 Triennial Review of Water Quality Standards, the Department updated the freshwater aquatic life water quality criteria for ammonia. These ammonia criteria were derived from recent toxicology studies and represent the best available science. For more information on Maryland’s 2019 Triennial Review of Water Quality Standards, please click here​. 

After these changes to the ammonia water quality criteria were finalized, errors were noted in three tables and for one equation in the regulation (in Code of Maryland Regulations). In addition, a table footnote related to Pentachlorophenol (PCP) required revision for clarity.  The purpose of the 2023 Interim Update is to correct these issues in COMAR

MDE published a notice ​of proposed action in the November 17, 2023 issue of the Maryland Register​The public comment period for this regulation change was open from November 17, 2023 to December 22, 2023.  During the public comment period, the Department held a virtual public hearing for​ the proposed action on December 13, 2023. No comments were received on the proposed action during the public comment period or during the virtual public hearing. MDE published a notice of final action in the January 26, 2024 issue of the Maryland Register

Materials from the Public Hearing on December 13, 2023

Materials for Regulation​​ Change

Please click ​the link below to access the proposed COMAR regulatory changes for the 2023 Interim Update. ​

Contact Information

​For more information, please contact Melinda Cutler​​ at

This page was last updated on 3/2024.​

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