Bioassessment and Biocriteria Program Status for California: Streams and Wadeable Rivers
State Program Contact
Water Quality Standards
The link to California's WQS (i.e. Regional Basin Plans) that are in effect for Clean Water Act purposes is provided. These are the WQS approved by EPA.
Each of the 9 regions has their own Basin Plan which includes all the applicable Beneficial Use information for the water bodies in their Region. The Basin Plans can be accessed by going to each Region’s Basin Plan page.
Region 1: North Coast Basin Plan
Region 2: San Francisco Bay Basin Planning
Region 3: Central Coast Region – Basin Plan
Region 4: Los Angeles Basin Plan
Region 5: Central Valley Basin Planning
Region 6: Lahontan Basin Plan
Region 7: Colorado River Basin – Basin Planning
Region 8: Santa Ana Region Basin Plan
Region 9: San Diego Region - The Basin Plan
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.
California has several Beneficial Uses that protect aquatic life or rely on aquatic ecosystems. These uses vary by Region and by water body.
Warm freshwater habitat
Cold freshwater habitat
Rare and endangered species
Inland saline water habitat
Contact recreation (fishing)
Limited warm water habitat
__X__ No criteria
The State Water Resources Control Board does not have adopted numeric or narrative biocriteria and there is no biocriteria being developed. However, there is a Statewide implementation plan for assessing biological integrity in perennial streams that is under development at this time.
What biological assemblages are used in the bioassessment program?
Benthic macroinvertebrates and periphyton
Are bioassessments used to support 303(d) listings?
Yes. Listing methodology: Water Quality Control Policy for Developing California’s Clean Water Act Section 303(d) List (PDF) (32 pp, 306 K)
From the Water Quality Control Policy for Developing California’s Clean Water Act Section 303(d) List (Listing Policy), Section 3.9: “A water segment shall be placed on the section 303(d) list if the water segment exhibits significant degradation in biological populations and/or communities as compared to reference site(s) and is associated with water or sediment concentrations of pollutants including but not limited to chemical concentrations, temperature, dissolved oxygen, and trash. This condition requires diminished numbers of species or individuals of a single species or other metrics when compared to reference site(s). The analysis should rely on measurements from at least two stations. Comparisons to reference site conditions shall be made during similar season and/or hydrologic conditions. Association of chemical concentrations, temperature, dissolved oxygen, trash, and other pollutants shall be determined using sections 3.1, 3.2, 3.6, 3.7, 126.96.36.199, or other applicable sections.
For population or community degradation related to sedimentation, the water segment shall be placed on the section 303(d) list if degraded populations or communities are identified and effects are associated with clean sediment loads in water or with loads stored in the channel when compared to evaluation guidelines (satisfying the conditions of section 6.1.3) using the binomial distribution as described in section 3.1 or as compared to reference sites. Bioassessment data used for listing decisions shall be consistent with section 188.8.131.52. For bioassessment, measurements at one stream reach may be sufficient to warrant listing provided that the impairment is associated with a pollutant(s) as described in this section.”
How are assemblages used to make impairment decisions?
Historically, individual Benthic Macro Invertebrate assemblage data were assessed using a Regional Index of Biological Integrity (IBI) score. The score from each assemblage was summarized in a Line of Evidence and considered along with all other water quality data from the same water body in order to make 303(d) Listing/Delisting decision recommendations. In the future, the Regional IBIs will be replaced with the new California Stream Condition Index (CSCI) scoring tool for water quality assessment purposes to determine impairment.
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:
The State’s Surface Water Ambient Monitoring Program (SWAMP) has developed “Recommendations for the Development and Maintenance of a Reference Condition Management Program (RCMP) to Support Biological Assessment of California’s Wadeable Streams”
Technical reference material:
Recommendations for the Development and Maintenance of a Reference Condition Management Program (RCMP) to Support Biological Assessment of California’s Wadeable Streams (PDF) (47 pp, 1 MB)
California has not adopted numeric or narrative biocriteria. However, the state is currently developing an implementation plan for assessing biological integrity in perennial streams.
Technical reference material:
Proposed Biological Integrity Assessment Implementation Plan for (Perennial Streams & Rivers of) the State of California
Stressor identification/causal analysis approach:
Building on the existing CADDIS tools developed by USEPA, California has funded four causal assessment pilot projects and developed “Causal Assessment Evaluation and Guidance for California”. This document evaluates the US Environmental Protection Agency's Causal Analysis/Diagnostic Decision Information System. Associated strengths and shortcomings of CADDIS for California are presented to provide regulated and regulatory agencies a path forward for improving future Causal Assessments.
Technical reference material:
Causal Assessment Evaluation and Guidance for California (PDF) (44 pp, 5 MB)