Draft Technical Support Document: Recommended Estimates for Missing Water Quality Parameters for Application in EPA's Biotic Ligand Model

The Environmental Protection Agency (EPA) is announcing availability of the draft technical support document: Recommended Estimates for Missing Water Quality Parameters for Application in EPA's Biotic Ligand Model for public comment. In 2007, EPA published updated criteria for freshwater copper using the Biotic Ligand Model (BLM), a bioavailability model that relies on ten water quality input parameters to estimate copper criteria protective of aquatic life in freshwater. This draft technical support document summarizes data analysis approaches EPA used to develop recommendations for default values for water quality parameters used in the Freshwater Copper BLM when data are lacking. These default values may also be used to fill in missing water quality input parameters in the application of other metal BLM models as well, when data are lacking. Following closure of this 30 day public comment period, EPA will consider the comments, revise the document, as appropriate, and then publish a final technical support document that will serve as a source of information for states, tribes, territories, and other stakeholders.