By Michael S. Feeley, John C. Heintz, Julia E. Stein and Bobbi-Jo Dobush
On August 23, 2013, the California Department of Public Health (CDPH) released a draft Maximum Contaminant Level (MCL) of 10 parts per billion (ppb) for hexavalent chromium (Cr-6).[1] The Clean Water Act is a federal law, which regulates water pollution.[2] It authorizes the states to develop water quality standards, such as MCLs, that police water contamination.[3] These state standards must be at least as strict as those adopted by the EPA, but states can elect to maintain stricter regulations.[4] Where the EPA has not adopted a standard for a particular contaminant, a state may adopt its own based on appropriate scientific evidence.[5]