Water: Water Quality Standards Academy
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Education & TrainingTraining ProgramsWater Quality Standards AcademyDeriving the CMC: From FAV to CMC
Education & TrainingTraining ProgramsWater Quality Standards AcademyDeriving the CMC: From FAV to CMCDeriving the CMC: From FAV to CMC
Course Navigation
- 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
- Summary
- Quiz
Basic Course: Supplemental Topics
After the FAV is calculated, it is divided by two (a safety factor to avoid lethality) to arrive at the recommended acute criterion—that is, the Criterion Maximum Concentration. The CMC is set equal to half of the FAV to represent a low level of effect for the fifth percentile genus, rather than a 50 percent effect.
Key Point. An acute criterion is applied as a limit on the short-term average concentration in the environment. Both the acute and chronic criteria are values that are not to be exceeded more than once in 3 years. In other words, the criteria specify a magnitude, duration, and frequency to be met in order to provide protection of aquatic life.
