Water Quality Standards and Classification
The Connecticut Water Quality Standards and Classifications
NEW! The Translation of Connecticut Narrative Water Quality Criteria Webpage is now live!
Select the image to learn more about the CT Water Quality Standards
The Connecticut Water Quality Standards
The Connecticut Water Quality Standards (CT WQS) establish goals to restore and maintain the chemical, physical, and biological integrity of CT's surface waters and, wherever attainable, provide for the protection and propagation of fish, shellfish, and wildlife and for recreation in and on the water. The Water Quality Classification Maps are an element of the CT WQS and show the class assigned to each surface water and ground water resource throughout the state. The Connecticut Water Quality Classifications relate designated uses and the applicable Standards and Criteria for each class of surface and ground water resource to a specific location. The maps are available in an interactive platform, (CT Water Quality Classification Interactive Map) and on the Water Quality Classification Map Webpage in a static format. The CT WQS are required under Section 303 (c) of the Clean Water Act. They convey state policies and provide the numeric and narrative criteria necessary to support the designated uses of CT waterbodies. Numeric criteria provide concentration values for pollutants. Narrative criteria provide a description of acceptable water quality conditions to support those uses. CT has developed translators of Narrative Criteria for toxics and nutrients. For more information visit the Translation of Narrative Criteria in Connecticut webpage.
The Water Quality Standards form the foundation of Connecticut’s water management programs, including:
- CT Water Quality Action Plans
- National Pollution Discharge Elimination System (NPDES) permit issuance program
- Water quality certification programs
- Remediation programs
- State-led monitoring and assessment programs
- Total Maximum Daily Load development
The Connecticut Water Quality Standards Triennial Review
This process occurs every three years and provides an opportunity to:
- Request public input on the Standards.
- Update the Standards to include the latest scientific understanding of water pollution effects.
- Incorporate changes in state and federal law.
CT DEEP 2019 Triennial Review
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Connecticut Water Quality Standards Regulations adopted October 10, 2013
- Water Quality Classification Maps
- CT DEEP Ground and Surface Water Quality GIS Data
The water quality classification information is located under the Environmental: Natural Resource Management header on this web page - Federal EPA Water Quality Standards (leaving CT DEEP web site)
- 2019 Triennial Review of the Connecticut Water Quality Standards
- Triennial Review Process
Join our Water Quality Planning ListServ to receive updates and information about water quality.
Contact us for more information at the CT DEEP Bureau of Water Protection and Land Reuse at (860) 424-3020.
Content last updated on September 4, 2020.