Bioassessment and Biocriteria Program Status for Texas: Streams and Wadeable Rivers
State Program Contact
Water Quality Standards
The link to Texas' WQS that are in effect for Clean Water Act purposes is provided. These are the WQS approved by EPA.
Procedures to Implement the Texas Surface Water Quality Standards – June 2010 (RG-194)
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Designated Aquatic Life Uses
Aquatic life designations are described by short narrative "aquatic life attributes" for habitat characteristics, species assemblage, sensitive species, diversity, etc. These ALU designations are based on five categories as described in the Texas Surface Water Quality Standards. The five categories are associated with the dissolved oxygen criteria (refer to RULE §307.4 General Criteria). Thresholds and methods for establishing and assessing aquatic life categories are included in the Draft 2020 Guidance for Assessing and Reporting Surface Water Quality Data in Texas (PDF) (169 pp, 16 MB) and in the Surface Water Quality Monitoring Procedures, Volume 2: Methods for Collecting and Analyzing Biological Assemblage and Habitat Data (RG-416).
Aquatic Life Use Subcategories (PDF)(2 pp, 13 K)
__X__ Narrative statement
_____ No criteria
RULE §307.7 Site-Specific Uses and Criteria
(b) (3) Aquatic life. The establishment of numerical criteria for aquatic life is highly dependent on desired use, sensitivities of aquatic communities, and local physical and chemical characteristics. Six subcategories of aquatic life use are established. They include minimal, limited, intermediate, high, and exceptional aquatic life and oyster waters. Aquatic life use subcategories designated for segments listed in Appendix A of §307.10 of this title recognize the natural variability of aquatic community requirements and local environmental conditions
307.5 – Antidegradation
What biological assemblages are used in the bioassessment program?
Benthic macroinvertebrates and fish
Are bioassessments used to support 303(d) listings?
Yes. Listing methodology: Draft 2014 Guidance for Assessing and Reporting Surface Water Quality in Texas – Appendix D (PDF) (142 pp, 2 MB)
How are assemblages used to make impairment decisions?
Assessments conducted by the TCEQ to evaluate aquatic life use attainment are based on the average of the total scores. Scores are derived for each of two or more bioassessment events as described in Surface Water Quality Monitoring Procedures, Volume 2: Methods for Collecting and Analyzing Biological Assemblage and Habitat Data (RG-416). The assessment of the data is outlined in the Draft 2020 Guidance for Assessing and Reporting Surface Water Quality Data in Texas (PDF) (169 pp, 16 MB) (Page 3-22), Appendix D.
Other uses of biocriteria or bioassessment within the water quality program:
Refining ALU, TMDL development and assessment, antidegradation, non-point source assessments, BMP evaluation, and 305(b) surface water condition assessments
Technical Support Information and Documents:
The Texas Commission on Environmental Quality (TCEQ) has identified a set of least disturbed reference sites in each of the Level III Ecoregions (except for the Arizona/New Mexico Mountains ecoregion) in the state. The following watershed characteristics are used as guidelines to define candidate least disturbed reference streams:
- entire watershed within an ecoregion,
- minimal urban development,
- no atypical sources of nonpoint source pollution,
- no major point sources of pollution,
- no channelization,
- watershed is characterized by perennial flow or perennial pools.
Recently, TCEQ has begun to collect GIS data in order to conduct a more in-depth watershed evaluation for each candidate least disturbed site. TCEQ is continuing its ongoing efforts for the Texas Least Disturbed Streams Project to conduct aquatic life monitoring at newly identified candidate least disturbed reference sites as well as at established sites. These data will be used to develop/revise/calibrate the Index of Biotic Integrity (IBI) metric sets for fish, benthic macroinvertebrates and physical habitat in each Level III ecoregion.
Technical reference material:
Surface Water Quality Monitoring Procedures, Volume 2: Methods for Collecting and Analyzing Biological Assemblage and Habitat Data: Chapter 2: Biological Monitoring Requirements (PDF) (12 pp, 177 K)
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:
Draft 2020 Guidance for Assessing and Reporting Surface Water Quality Data in Texas (PDF) (169 pp, 16 MB)
Regionalization of the Index of Biotic Integrity for Texas Streams – TPWD Rivers Studies Report No. 17 June 2002 (PDF) (140 pp, 10 MB)
Surface Water Quality Monitoring Procedures, Volume 2: Methods for Collecting and Analyzing Biological Assemblage and Habitat Data: Appendix B: Reference Materials And Criteria For Biological Assessment (PDF) (48 pp, 1 MB)
Stressor identification/causal analysis approach: