How are the updated national freshwater copper criteria expressed?
The revised national recommendations are contained in EPA’s Aquatic Life Ambient Freshwater Quality Criteria Copper 2007 Revision (EPA-822-R-07-001). The freshwater acute and chronic criteria recommendations for copper are expressed differently than traditional criteria, in that the criteria maximum concentration (CMC) and the criteria continuous concentration (CCC) are expressed as outputs of a computer model, the BLM, rather than as regression-based hardness formulas (see Question 1.2 for a definition of the BLM). The BLM utilizes acute toxicity data for copper and calculates chronic criteria using the final acute-chronic ratio (FACR).
