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To:

Members, Affiliates, and Water Quality Committee

From:

National Office

Date:

August 31, 1998

Reference:

RA 98-18

Action Please By: December 1, 1998

Draft Water Quality Criteria Methodology

On August 14, EPA's published "Draft Revisions to the Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health" in the Federal Register. Among the changes presented in the proposal from the 1980 AWQC National Guidelines that may result in more restrictive water quality criteria include:
  • Replacing bioconcentration factors (BCFs) with bioaccumulation factors (BAFs);
  • Replacing the default fish intake rate of 6.5 grams/day to 17.8 grams/day (for protection of the general adult population and sport anglers) and 86.3 grams/day (for protection of subsistence fishers);
  • When the product of the uncertainty factors (UFs) and the modifying factor (MF) used to derive a reference dose (RfD) is 100 or less, there is to be no consideration of an RfD range allowing a value higher than the point estimate RfD. The product of the UFs and the MF used to derive the 1995 methylmercury RfD of 0.0001 mg/kg/day is 10; and,
  • The addition of an incidental exposure rate of 0.01/liters/day to account for long-term incidental recreational ingestion where recreational waters are not used as drinking water sources.
When finalized, the revised methodology will provide guidance to States that they may use in developing human health criteria as part of their water quality standards. In addition to the draft Federal Register notice, EPA has developed a Technical Support Document (TSD). The TSD includes more technical detail and is supplemented by three proposed criteria developed using the new methodology.

If you would like contribute to AMSA's comment response, please send your comments to Mark Hoeke, AMSA at mhoeke@amsa-cleanwater.org or fax at: 202/833-4657, no later than December 1, 1998.

ATTACHMENT:
- August 1998 EPA "1998 Update of Ambient Water Quality Criteria for Ammonia"

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- August 1998 EPA "Draft Water Quality Criteria Methodology Revisions: Human Health; Notice"