Maryland's Surface Water Quality Standards
Maryland's Triennial Review of Water Quality Standards and Regulation Changes
The Clean Water Act (CWA) requires that States review their water quality standards every three years (Triennial Review) and revise the standards as necessary. Consistent with this requirement, MDE published a notice of proposed action in the March 11, 2022 issue of the Maryland Register, held a public comment period that ended on April 11, 2022, and held a virtual public hearing on March 30, 2022 to present on the proposed changes. After responding to all submitted comments, MDE finalized the regulation changes as proposed in the October 21, 2022 edition of the Maryland Register and EPA approved the Triennial Review on June 28, 2023.
The regulatory changes and all supporting materials associated with this Triennial Review of Water Quality Standards can be accessed here.
The purpose of water quality standards is to protect, maintain and improve the quality of Maryland surface waters. The following make up the three components of water quality standards:
- Designated Uses,
- Water quality criteria, and
- Antidegradation policy.
A designated use is a goal for water quality. Typically, the goal is the description of an appropriate intended use by humans and/or aquatic life for a water body. Designated uses for a particular waterbody may include recreation, shellfishing, water supply and/or aquatic life habitat. The designated uses established may or may not be met currently, but must be attainable. In Maryland these designated uses are grouped into "Use Classes" (e.g. Use Class I, I-P, II, III, IV-P) so as to describe a unique combination of designated uses that apply to a single water body. Each stream segment, lake, bay, etc. in Maryland is assigned to a use class.
For more detailed information about Maryland’s designated uses and use class groupings, please click HERE. To go directly to maps of surface waters and their associated use classes, please click HERE.
Water quality criteria are expressions of the quality of water as a concentration, level, or narrative statement that, if met, will generally protect a particular designated use. Maryland has many numeric criteria for protecting aquatic life and human health including for toxics (e.g., lead), physical characteristics of water (e.g., temperature, dissolved oxygen), bacteriological indicators, and even biological endpoints (e.g., quantity of submerged aquatic vegetation). Where specific numeric criteria are not available (e.g., oil, grease, odor, nuisance), narrative criteria apply.
Maryland’s antidegradation policy and implementation procedures, consistent with the Clean Water Act, provides a framework for maintaining and protecting water quality that has already been achieved. Maryland’s Antidegradation regulations provide for three tiers of protection:
For the full text of Maryland Water Quality Standards please visit COMAR
Online to access 26.08.01 and 26.08.02.
Changes to the Water Quality Standards are implemented through regulatory changes which are subject to the normal promulgation process. Every three years, the Clean Water Act requires that States review their water quality standards in what is called the Triennial Review of Water Quality Standards (TR). The TR includes a robust public participation process prior to adoption of new or revised regulations. This process generally includes an Advanced Notice of Public Rule-Making (ANPRM) and solicitation of comments followed later by a more formal public comment period during which a hearing takes place (the formal comment period and hearing are required). Comments are incorporated and/or responded to in what becomes a public document as part of the TR package that EPA reviews. To see materials from Maryland's past Triennial Review actions please click here.