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Water: Current Water Quality Criteria

Revision of National Recommended Water Quality Criteria

Fact Sheet; 2002

EPA has revised its national recommended water quality criteria for 83 chemical criteria to protect human health. These updated criteria supercede any published in EPA's previous criteria compilations including the "Blue Book," "Red Book," "Gold Book" and EPA's last compilation published in April 1999.


The Clean Water Act (CWA) requires EPA to publish and periodically update ambient water quality criteria. These criteria are intended to ". . . accurately reflect the latest scientific knowledge . . . on the kind and extent of all identifiable effects on health and welfare including, but not limited to, plankton, fish, shellfish, wildlife, plant life . . . which may be expected from the presence of pollutants in any body of water . . ."

Water quality criteria developed under section 304(a) of the Clean Water Act are based solely on data and scientific judgments on the relationship between pollutant concentrations and environmental and human health effects. EPA's national recommended water quality criteria are guidance for states and tribes in adopting water quality standards under section 303(c) of the CWA. These water quality criteria are not regulations and do not impose legally binding requirements on EPA, states, authorized tribes or the public.

The revised national recommended water quality criteria may, however, be superceded by the publication of 304(a) criteria after the publication of this update.

What's new in the updated compilation?

The 83 revised human health criteria have been recalculated based on EPA's new methodology entitled, Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health (2000) (EPA-822-B-00-004). This is a partial update based on a comprehensive revision of components of the 304(a) criteria. Partial updates represent a way of increasing the frequency of scientific improvements to the nationally recommended criteria. The revised human health criteria specifically integrate the new fish consumption rate of 17.5 grams/day, relative source contribution (RSC) factors obtained from primary drinking water standards, and any new cancer potency factors (q1*s) or reference doses (RfDs) in the Agency's Integrated Risk Information System (IRIS).

The criteria do not incorporate bioaccumulation factors (BAFs), a component of the new methodology. Rather, the criteria rely on bioconcentration factors (BCFs). EPA intends to focus resources on developing BAFs for pollutants that the Agency considers of high priority and national importance, due to the comparative complexity of developing this component. The revised human health criteria are more stringent than those previously published, however, they are consistent with the criteria updates in the recently published compilation.
EPA is separately publishing partial updates for 15 criteria in the Federal Register because the revisions significantly change the numerical values. EPA will accept scientific views on these 15 criteria. This is consistent with the process for publishing criteria previously described in the April 1999 compilation.

Additional Information

EPA's updated national recommended water quality criteria compilation, including the 83 revisions, is available in a report, National Recommended Water Quality Criteria: 2002 (EPA-822-R-02-047). Contact NSCEP's web site for copies.

Find the most current national recommended water quality criteria table

For additional information about EPA's compilation of national recommended water quality criteria, contact us.

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