MDE Cold Water Advisory Committee


Maryland’s Use Classification System for surface waters is a vital component of Maryland’s Water Quality Standards. The Use Classification System categorizes the Aquatic Life Designated Use of water bodies as Non-tidal Warmwater, Estuarine and Marine Aquatic Life, Non-tidal Cold Water, and Recreational Trout Waters. In many cases, the Use Class of a waterbody determines which water quality criteria are used to identify impaired waters and write permit requirements. Therefore, the Use Class of a waterbody has significant policy implications.
Interactions with various stakeholder groups as well as internal discussions have highlighted certain issues associated with Maryland’s Use Classification System that need to be addressed:

  • ​Certain streams classified as Use Class I (warmwater aquatic life) or Use Class IV (trout-stocking waters) have been shown to support naturally reproducing trout populations. This situation implies that the stream has an ‘existing use’ that is different from the current designated use. 
  • Certain streams support an aquatic life community that is ecologically distinct from Use Class I, III or IV streams. These streams may need to be protected under updated water quality criteria associated with one or more new Use Classes. 
  • Similarly, the method for identifying Use Class IV waters does not take into account the large variety of “put and take” fisheries that exist in Maryland. 
  • Maryland does not currently have a policy for determining the attainability (also known as a Use Attainability Analysis or UAA) of a given use class.
To help inform the Department’s efforts on these issues, the Water Quality Standards Section formed an advisory committee composed of stakeholders and subject matter experts. To date, the committee has completed the first objective to address waters with existing uses that require cooler water than what their designated uses specify.  

The text below provides the mission of this advisory committee along with the four main objectives. Below the objectives are the materials from past committee meetings.
Mission Statement of the Committee: To provide policy recommendations to the Maryland Department of the Environment that protect Maryland’s cold and coolwater streams and the aquatic life dependent on these streams.
The Committee will accomplish the mission by achieving four separate but related objectives that will help to provide regulatory certainty while at the same time protect cold and coolwater aquatic life species found in Maryland’s surface waters:

Objective 1: Develop Departmental policy for protecting streams with cold or coolwater species in advance of changing the Use Class.


Stream data sometimes shows cold or coolwater species living in streams with a warmer Use Class designation (e.g. Class I, IV).  Since use class re-designation in Code of Maryland Regulations (COMAR) can be a lengthy process, the Department needed to adopt interim protection measures to ensure that these resources are protected. ​

Status: Objective 1 is complete

The Committee developed policy and procedure regulations under the Tier I Antidegradation Implementation Section (COMAR to better protect the coldwater obligate species and water quality in these waters. To view MDE’s policy and procedures for cold water existing use determinations, please click here. Additionally, where this situation appli​es, waters are now recognized as having unique existing uses on MDE’s online Designated Use Map and on MDE’s Existing Use Determinations page, as referenced in regulation.

Committee Document Archive

Comments received in response to the First Draft Existing Use Identification Procedure Document
Comments received in response to the Second Draft Existing Use Identification Procedure Document
Meetings related to this Objective:

Objective 2: Propose a new “coolwater” use classification based on analyses conducted by Maryland Department of Natural Resources (DNR) and consideration of current stream scenarios.

Field studies have identified streams that exhibit “cool water” aquatic communities.  These communities are dependent on temperature regimes that fall between Use Class I and Use Class III and are not currently protected or acknowledged under the current Use Classification system.  ​

Status: To be completed.

Objective 3: Propose changes to Class IV (or IV-P) recreational trout waters. Clarification is needed to improve the identification and protection of Class IV designations.

Class IV waters include some impoundments where the 75°F water temperature criterion is not appropriate.  In addition, there are other waters such as “put and grow” trout-stocking locations that are not currently designated as Class IV.  This objective will be to revise Class IV to account for the variety of trout stocking scenarios to apply the most appropriate protection measures.  

Status: To be completed.

Objective 4: Develop a process for conducting Use Attainability Analyses (UAA) for surface waters that support self-sustaining trout populations but which do not currently attain Class III (or III-P) water quality criteria.

Certain waters of the state which currently support coldwater species may not meet the temperature criteria for Class III.  The UAA process would help inform the determination of the designated use class, either indicating that the stream is capable of supporting Class III temperature criteria under a future scenario or that it is not.

 ​​Status: To be completed.

Meeting Archive

Contact Information 

For more information, please contact Matthew Stover at​ or at (410) 537-3611.​​​

Last Updated 08/2023

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