Bioassessment and Biocriteria Program Status for Virginia: Streams and Wadeable Rivers
State Program Contact
Virginia Department of Environmental Quality Exit
Water Quality Standards
The link to Virginia's WQS that are in effect for Clean Water Act purposes is provided. These are the WQS approved by EPA.
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
Virginia has a general aquatic life designated use 9VAC25-260-10.A. Virginia has seven classes of waters; open ocean, estuarine waters, non tidal waters in the piedmont and coastal zone, mountainous zone waters, stockable trout waters, natural trout waters, swamp waters. Aquatic life use is assessed using two different multimetric based macroinvertebrate indices; one index used in the piedmont and mountain- valley, and a different index used for the coastal plain.
Biological Criteria
__X__ Narrative statement
_____ Numeric
_____ No criteria
Virginia's general criteria is appliable to all state waters as described in 9VAC25-260-20.
Antidegradation Policy
Use of biocriteria or bioassessment not included in antidegradation policy.
Biological Assessment
What biological assemblages are used in the bioassessment program?
Benthic macroinvertebrates
Are bioassessments used to support 303(d) listings?
Yes. Listing methodology: 2020 Water Quality Assessment Guidance
How are assemblages used to make impairment decisions?
Benthic macroinvertebrates used to make impairment decisions as described in the above document.
Other uses of biocriteria or bioassessment within the water quality program:
Refining ALU, TMDL development and assessment, non-point source assessments, 305(b) surface water condition assessments, and restoration goals.
Technical Support Information and Documents:
Reference condition:
VDEQ uses 2-step process to identify least disturbed sites that are used in setting the assessment score. VDEQ runs the stations through a ‘reference filter’ (which changes by ecoregion) and then the biologist reviews the sites that make it through the filter to ensure the site fits into the least disturbed category.
Technical reference material:
The Virginia Coastal Plane Macroinvertebrate Index (PDF)(84 pp, 2 MB)
A Stream Condition Index for Virginia Non-Coastal Streams (PDF)(163 pp, 4 MB)
Using Probabilistic Data to Validate Virginia’s Non-Coastal Stream Condition Index (PDF)(58 pp, 1 MB)
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 included below include standard operation procedures used in data collection, compilation, technical approaches used to develop biocriteria as well as its implementation procedures.
Technical reference material:
The Virginia Coastal Plane Macroinvertebrate Index (PDF)(84 pp, 2 MB)
A Stream Condition Index for Virginia Non-Coastal Streams (PDF)(163 pp, 4 MB)
Using Probabilistic Data to Validate Virginia’s Non-Coastal Stream Condition Index (PDF)(58 pp, 1 MB)
Stressor identification/causal analysis approach:
VDEQ has a standing workgroup of biologists and TMDL coordinators that reviews stressor analysis documents when necessary. Major stressor parameters are collected at listed benthic sites.
Technical reference material:
Findings and Recommendations from the Self-Evaluation of the VADEQ Biological Monitoring Program