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Water: Copper

2003 Draft Updated Aquatic Life Copper Criteria

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

Fact Sheet; November 2003

EPA has published a draft document, 2003 Draft Update of Ambient Water Quality Criteria for Copper (EPA-822-R-03-026), containing updated freshwater and saltwater aquatic life criteria for copper. These criteria revisions are based in part on new data that have become available since EPA's last comprehensive criteria updates for copper. In addition to incorporating new data, the freshwater criteria also incorporate the use of the biotic ligand model (BLM) in the criteria derivation procedures.


Background

EPA periodically publishes updated ambient water quality criteria that ". . . accurately reflect the latest scientific knowledge . . ." Under section 304(a) of the CWA, water quality criteria are based solely on data and scientific judgments about the relationship between pollutant concentrations and environmental and human health effects: they do not consider economic or social impacts. EPA's national recommended water quality criteria are guidance to states and authorized tribes in adopting water quality standards in support of the CWA. They are not regulations in themselves and do not impose legally binding requirements on EPA, states, authorized tribes or the public.

New data on the toxicity of copper to aquatic organisms in fresh and salt waters have become available since EPA last published criteria recommendations for copper. Thus, EPA updated its national recommended aquatic life criteria for copper to include this new data and also to incorporate a more advanced modeling approach for developing water quality-dependent criteria.

EPA used the biotic ligand model (BLM), a metal ‘bioavailability' model, to update its freshwater criteria. Previously, freshwater aquatic life criteria for copper were developed by relating toxic effect concentrations with water hardness. The resulting hardness-dependent criteria, however, represented the combined effects of various water quality variables (e.g., pH and alkalinity) correlated with hardness. Unlike the hardness-dependent criteria, the BLM explicitly accounts for individual water quality variables that effect toxicity and can address variables that were not factored into the hardness-dependent criteria relationship. With these scientific and technical revisions the criteria will provide improved guidance on the concentrations of copper that will be protective of aquatic life. The BLM is not used in the saltwater criteria derivation because further development is required before it will be suitable for use to evaluate saltwater data.

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What are the draft updated criteria?

Freshwater
The procedures described in the Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses indicate that, except where a locally important species is very sensitive, freshwater aquatic organisms an their uses should not be affected unacceptably if the 4-day average concentration of dissolved copper does not exceed the BLM-derived site-water LC50 (i.e., Final Acute Value (FAV)) divided by the final acute-chronic ratio more than once every 3 years on the average (i.e., the CCC); and if the 24-hour average dissolved copper concentration does not exceed the BLM-derived site-LC50 (or FAV) divided by two, more than once every 3 years on the average (i.e., the CMC).

Saltwater
The procedures described in the Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses indicate that, except where a locally important species is very sensitive, saltwater aquatic organisms an their uses should not be affected unacceptably if the 4-day average concentration of dissolved copper does not exceed 1.9 µg/L more than once every 3 years on the average (i.e., the CCC); and if the 24-hour average dissolved copper concentration does not exceed 3.1 µg/L more than once every 3 years on the average (i.e., the CMC).

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How to Get Additional Information

For additional information, contact Luis Cruz (cruz.luis@epa.gov), Health and Ecological Criteria Division (4304T), U.S. EPA, Ariel Rios Building, 1200 Pennsylvania Ave., N.W., Washington, D.C., 20460; (202) 566-1095.

You may view the draft copper document and get a copy of the BLM at: http://www.epa.gov/waterscience/criteria/copper. You can also get copies of the draft criteria document from EPA's Water Resource by calling (202) 566-1729 or sending an e-mail to center.water-resouce@epa.gov.

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