Uunder the Clean Water Act, the U.S. EPA is issuing its first water quality criterion for methylmercury to be used by states in determining levels in fish tissue.

To help protect human health for methylmercury, the form of mercury that is found in contaminated fish, the U.S. EPA is issuing under the Clean Water Act its first water quality criterion for methylmercury to be used by states in determining levels in fish tissue. Both the new criteria and the new reference dose are based on updated scientific data on environmental fate and human health effects of methylmercury.