Water: Water Quality Standards Academy
Getting Started: Prioritizing Chemicals for Criteria Development
- Listing Impaired Waters and Developing TMDLs
- Monitoring & Assessment
- NPDES Permit Program
- Human Health Ambient Water Quality Criteria
- Aquatic Life Criteria
- EPA's Role
- Two Concentration-Related Criteria
- Steps in Deriving the Criteria
- Prioritizing Chemicals
- Collecting Effects Data
- Assessing Acute Effects Data
- Calculate the GMAVs
- Rank the GMAVs
- Calculate the FAV
- From FAV to CMC
- Factoring in Water Characteristics
- CCC Approach Based on Available Data
- Assessing Chronic Effects Data
- CCC Calculation of the FCV
- FCV to CCC
- Criteria Review Process
- Site-Specific Criteria
Basic Course: Supplemental Topics
EPA follows an established, risk-based process for determining which chemicals should be given priority for developing aquatic life criteria. The process involves identifying candidate chemicals, assessing the availability of data, and then ranking the chemicals based on risk. Essentially the same process is used for selecting chemicals with criteria that are due for reevaluation.
To identify candidate chemicals, the Agency solicits and reviews suggestions from EPA Regions, States, Tribes, and stakeholders. EPA then compiles a list of chemicals that have been proposed by two or more of these submitters.
Next, EPA narrows down the list based on the availability of toxicity data. At a minimum, the 1985 Guidelines call for acute data on eight families and chronic data on three species (i.e., for chronic, at least need acute-chronic studies from which the chronic criterion can be derived as a ratio of the final acute value).
The chemicals with the necessary data are then scored and ranked according to risk based on:
- Occurrence. Frequency at which a chemical is found in ambient water and/or fish tissue.
- Toxicity. Relative potential to have an adverse effect on aquatic life.