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Triennial review of Mississippi's water quality standards: Updates and revisions
Proceedings of the 2020 Mississippi Water Resources Conference

Year: 2020 Authors: Felch P.


The Clean Water Act (CWA) requires each State to establish and maintain water quality standards (WQS) to meet the two objectives expressed in Section 101(a), which are as follows: (1) restore and maintain the chemical, physical, and biological integrity of the Nation's waters and (2) wherever attainable, achieve a level of water quality that provides for the protection and propagation of fish, shellfish, and wildlife and recreation in and on the water. Consequently, WQS serve as the foundation for a wide range of water quality management programs under the CWA. WQS serve multiple purposes that include defining the water quality goals for a specific waterbody and providing the regulatory basis for establishing water quality-based effluent limits (WQBELs) beyond the technology-based levels of treatment required by CWA Sections 301(b) and 306. WQS also serve as a target for CWA restoration activities such as total maximum daily loads (TMDLs).

The CWA also requires that each state's WQS contain three components: (1) designated use(s) of the State's waterbodies; (2) the water quality criteria (narrative or numeric) necessary to protect those uses; and (3) antidegradation provisions to protect water quality. Every three years these standards must be reviewed, revised and adopted in a process known as the triennial review. The current triennial review process for revisions to MS's WQS is currently underway.

The proposed modifications are scientifically-based and will allow for effective and improved protection of the state of Mississippi's surface waters and ecosystems. All proposed modifications must have a public comment period and public hearing in order for MDEQ to receive any feedback and comments regarding the proposed revisions. Any proposed revisions to the WQS must be adopted by the Mississippi Commission on Environmental Quality and then approved by the Environmental Protection Agency before they are used by the state for any Clean Water Act programs.

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