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Bioassessment and Biocriteria Program Status for Mississippi: Streams and Wadeable Rivers

State Program Contact

Mississippi Department of Environmental Quality Surface Water Quality Assessments Exit

Water Quality Standards

WQS Information
The link to Mississippi's WQS that are in effect for Clean Water Act purposes is provided. These are the WQS approved by EPA.
The state of Mississippi provided information and links to sections of their administrative code on designated aquatic life use, biological criteria, antidegradation as well as technical support documents and information on its bioassessment and biocriteria programs. These are included for your convenience and may or may not reflect the most recently EPA approved WQS. The following links exit the site Exit

You may need a PDF reader to view some of the files on this page. Refer to EPA’s about PDF page to learn more.

Designated Aquatic Life Uses
The state of Mississippi has 5 Waterbody Classification categories including: Fish and Wildlife Support, Recreation, Public Water Supply, Shellfish Harvesting, and Ephemeral Stream. All State Waters are classified as Fish and Wildlife Support. Waters classified as Fish and Wildlife Support should support the designated uses of aquatic life use, fish consumption, and secondary contact recreation. 

The classifications of Recreation, Public Water Supply, or Shellfish Harvesting may be assigned to waters in addition to the Fish and Wildlife Classification. Ephemeral Waters are waters that do not support a fisheries resource and are not usable for human consumption or aquatic life. Ephemeral streams normally are natural watercourses, including natural watercourses that have been modified by channelization or a manmade drainage ditch, that without the contribution of point source discharges, flow only in direct response to precipitation or irrigation return-water discharge in the immediate vicinity and whose channels are normally above the groundwater table.

Biological Criteria
__X__ Narrative statement
_____ Numeric
_____ No criteria

Refer to Part 6: Chapter 2: Rule 2.1.H, Rule 2.2.A, Rule 2.2.F.5, and Rule 2.3.E

Antidegradation Policy
Refer to Part 6: Chapter 2: Rule 2.1.A
Refer to Part 6: Exhibit E to Chapter 1, Subchapters 1 and 2 - Antidegradation Implementation Methodology

Biological Assessment

What biological assemblages are used in the bioassessment program?
Benthic macroinvertebrates

Are bioassessments used to support 303(d) listings?
Yes. Listing Methodology: Mississippi Consolidated Assessment and Listing Methodology 2020 Assessment and Listing Cycle (PDF)(19 pp, 492 K)

How are assemblages used to make impairment decisions?
If an MBISQ sample score is below the 25th percentile of reference for the bioregion in which the station is located, the waterbody is considered impaired. The waterbody is added to the 303(d) List for biological impairment. The Stressor ID/Causal Analysis process is then used to identify the primary probable stressors to be used for subsequent TMDL development.

Other uses of biocriteria or bioassessment within the water quality program:
Non-point source assessments, 305(b) surface water condition assessments, and BMP evaluation

Technical Support Information and Documents:

Reference condition:
The Mississippi Department of Environmental Quality (MDEQ) uses a benthic macroinvertebrate multimetric index to assess stream degradation relative to least-disturbed streams throughout the state.

Technical reference material:
Surface Water Quality Assessments

Not available.

Stressor identification/causal analysis approach:
Data from co-occurring biological and water quality samples are used for the stressor identification and causal analysis efforts. Also, additional recon sampling is done after an impairment call is made to further evaluate the decision(s).

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