Water: Water Quality Standards Academy
Introduction: Steps in Deriving the Criteria
- 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’s process for deriving estimates for ALC threshold concentrations involves the steps listed below, which are summarized in the following pages of the module.
- Select the chemical of concern for criteria development (or the chemical in need of reevaluation).
Deriving the Criterion Maximum Concentration
- Collect and assess effects data (i.e., on median lethal and median effective concentrations).
- Calculate the Final Acute Value.
- Assess any effects from water characteristics (e.g., hardness) on the chemical’s toxicity.
- Derive the CMC.
Deriving the Criterion Continuous Concentration
- Collect and assess effects data (i.e., on species growth, reproduction, survival).
- Calculate the Acute/Chronic Ratio, when—as typically is the case—sufficient chronic toxicity test data are not available to meet the minimum requirement.
- Calculate the Final Chronic Value/CCC.
Illustration. View graphic showing overview of ALC derivation. Proceed to the Illustration. » (Note: This link launches a pop-up window.)
Once EPA has developed draft versions of the recommended criteria for a given chemical, the criteria undergo internal and external review before they are released as final.