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Water: Water Quality Standards Academy

Introduction: Steps in Deriving the Criteria

Aquatic Life Criteria

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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.

Getting Started

  • 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.
illustration2
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.


Disclaimer:
For informational purposes only–Not official statements of EPA policy.


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