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Water: Methodology

Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health

We published revisions to the 1980 Ambient Water Quality Criteria National Guidelines to better protect human health. The 1980 Ambient Water Quality Criteria National Guidelines outline the methodology used by states and tribes to develop human health water quality criteria. Revisions to the 1980 guidelines incorporate significant scientific advances in key areas such as cancer and non-cancer risk assessments, exposure assessments, and bioaccumulation in fish. The revised methodology will provide more flexibility for decision-making at the state, tribal and EPA regional levels. It is most likely that the methodology will result in more stringent criteria for bioaccumulatives and generally similar values of nonbioaccumulatives.

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Final Document

This document presents our recommended methodology for developing human health ambient water quality criteria as required under the Clean Water Act. The methodology is guidance for scientific human health assessments used by us to develop, publish, and from time to time revise, recommended criteria for water quality accurately reflecting the latest scientific knowledge. The recommended criteria serve states and tribes' needs in their development of water quality standards.

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