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

State Program Contact

Missouri Department of Natural Resources

Water Quality Standards

WQS Information

The link to Missouri's WQS that are in effect for Clean Water Act purposes is provided. These are the WQS approved by the U.S. Environmental Protection Agency.

• Water Quality Standards Regulations: Missouri

The state of Missouri 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.

• Water Quality Standards

Designated Aquatic Life Uses

Streams are designated to aquatic habitat protection uses based on watershed size, scale within the stream network, and other hydrological and physical data. 

• Warm Water Habitat
• Cool Water Habitat
• Cold Water Habitat
• Modified Aquatic Habitat
• Limited Aquatic Habitat

Biological Criteria

__X__ Narrative, with quantitative implementation procedures or translators
_____ Numeric
_____ No criteria

10 CSR 20-7.031 Water Quality Standards (pdf)
(1)(C)  Biocriteria – Numeric values or narrative expressions that describe the reference biological integrity of aquatic communities inhabiting waters that have been designated for aquatic-life protection

• General Criteria, (4)(H) - Waters shall be free from physical, chemical, or hydrologic changes that would impair the natural biological community; (page 15)
• Specific Criteria, (5)(R) - The biological integrity of waters, as measured by lists or numeric indices of benthic invertebrates, fish, algae, or other appropriate biological indicators, shall not be significantly different from reference waters. Waters targeted for numeric biological criteria assessment must be contained within the Missouri Use Designation Dataset and shall be compared to reference waters of similar size, scale within the stream network, habitat type, and aquatic ecoregion type. Reference water locations for some aquatic habitat types are listed in Table I; (page 18)

Antidegradation Policy

(3) - The antidegradation policy shall provide three (3) levels of protection; (page 15). Use of biocriteria or bioassessments not included in the antidegradation policy.

Biological Assessment

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

Are bioassessments used to support 303(d) listings?
Yes. Listing methodology: Missouri’s 2020 Listing Methodology Document (pdf)

How are assemblages used to make impairment decisions?
The two main biological assemblages used are fish and aquatic macroinvertebrates. The method followed for making an assessment decision is described in Appendix C (a description of biological data assessment starts on page 59) of the 2024 listing methodology.

Other uses of biocriteria or bioassessment within the water quality program:
TMDL development and assessment, non-point source assessments, BMP evaluation, 305(b) surface water condition assessments, and restoration goals

Technical Support Information and Documents

Reference condition

MDNR reference streams are considered the “best available and least impacted.”  The DNR’s current reference site selection process has its origins in a paper written by Hughes et al. (1986), which was then cited by Sarver et al. (2002). The reference stream selection process presented in these two papers includes the following six steps (identification criteria):

1. Evaluate human disturbance
2. Evaluate stream size
3. Evaluate stream channel
4. Locate refuges (e.g. public-owned property such as parks, natural areas, state/national forests, etc.)
5. Determine migration barriers, historical connections among streams, and known zoogeographical patterns
6. Suggest reference sites

Reference streams are grouped by Ecological Drainage Unit (EDU), which generally allows for the comparison of test streams with similar references. More recently, ArcGIS has been used to further refine the selection process by looking at land cover and Valley Segment Type (VST). The 5-digit VST codes account for the following five stream attributes:  temperature; stream size; flow; geology; and relative gradient.

Reference streams are characterized by being the best available/least impacted streams and are used to generate numeric biological criteria, which are ultimately used to determine a test stream’s compliance with its “protection of warm water habitat” beneficial use designation as defined in Missouri’s Water Quality Standards (MDNR 2019). Reference streams are grouped within the same EDU whenever possible.

Technical reference material

• Hughes, R.M., D.P. Larsen, and J.M. Omernick. 1986. Regional reference sites: a method for assessing stream pollution. Environmental Management 10(5): 625-629.
• Missouri Department of Natural Resources. 2014. Title 10. Rules of Department of Natural Resources Division 20-Clean Water Commission, Chapter 7-Water Quality. 10 CSR 20-7.031 Water Quality Standards. 151 pp. 
• Sarver, R., S. Harlan, C. Rabeni, S. Sowa. 2002. Biological Criteria for Wadeable/Perennial Streams of Missouri. Missouri Department of Natural Resources, Environmental Services Program, Jefferson City, Missouri. 47 pp. (pdf)

Biocriteria

Development of biocriteria involves the collection and interpretation of biological data –e.g. benthic macroinvertebrates, fish, and periphyton. During this process entities typically use biological metrics (usually aggregated into a multimetric index) and/or multivariate analysis to assess whether a waterbody is meeting its designated aquatic life use(s). The reference materials include standard operation procedures used in data collection, compilation, technical approaches used to develop biocriteria as well as its implementation procedures.

Technical reference material

Appendix C of the 2024 listing methodology describes how a numeric translator is followed during a listing determination. 

• Missouri’s 2024 Listing Methodology Document (pdf)

Stressor identification/causal analysis approach

An information process is followed and may vary depending on the specific stream and/or current available data. In the absence of a known source, when a biological community has been identified as impaired, additional monitoring and/or studies will be conducted to gather enough information to determine potential contributing factors. When analyzing the data, a weight of evidence approach will be followed to identify the source(s) contributing to aquatic life impairment.

Technical reference material

A formal written procedure is not available at this time.