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Human Health Criteria - Methylmercury

The 2001 methylmercury human health criterion is a concentration of methylmercury in fish that EPA calculated to protect human health. States and tribes may use the criterion as the basis for establishing their water quality standards.

Final Implementation Guidance

This implementing guidance provides technical guidance to states and authorized tribes on how they may want to use Water Quality Criterion for the Protection of Human Health: Methylmercury in their surface water protection programs (e.g., TMDLs, NPDES permitting). The guidance addresses questions related to water quality standards adoption (e.g., site-specific criteria, variances), assessments, monitoring, TMDLs, and NPDES permitting. The guidance consolidates existing EPA guidance where relevant to mercury.


EPA's Mercury homepage provides a broad range of information about mercury.