United States Environmental       Office of Water         CDA 000 ,- n. nno
                      Protection Agency             4304T               S 2004

                      FACT SHEET	

                      Notice of Intent to Re-evaluate the

                      Aquatic Life Ambient Water Quality

                      Criteria for Ammonia; Request for Data
	and Information	


EPA intends to re-evaluate the current aquatic life ambient water quality criteria for ammonia to
determine whether they should be revised based on new toxicity data for aquatic organisms.  The
Agency also seeks additional pertinent toxicity data on the acute or chronic toxicity of ammonia to
aquatic life and scientific views on the interpretation of data that may help us in re-evaluating the
ammonia criteria.

Background

The Clean Water Act requires EPA publish and periodically update ambient water quality criteria to
reflect the latest scientific knowledge on the effects of water pollutants on public health and welfare,
aquatic life, and recreation. EPA published "Ambient Water Quality Criteria for Ammonia - 1984."
Since that time, results of additional toxicity tests on ammonia have been published that could affect
the freshwater criterion for ammonia.  The Agency published a 1998 Update to revise the 1984/1985
ammonia criteria document by addressing important issues to the extent possible in a short-term
effort without additional research. EPA obtained public comment on the 1998 Update. In response to
those comments EPA modified its criteria recommendations and prepared an 1999 Update. The 1999
Update differed from the 1998 Update primarily in the handling of the temperature-dependency for
the chronic criterion (criterion continuous concentration or CCC) and, therefore, the formulation of
the CCC and the expression of this national criterion.

Ammonia Criteria Re-Evaluation and Request for Data and Information

EPA notified the public in the Federal Register of its intent to re-evaluate, based on new toxicity data
on aquatic organisms, the current aquatic life criteria for ammonia to determine if they should be
revised.  In particular, recent studies on freshwater mussels suggest that some freshwater mussel
species may be more sensitive to ammonia exposure than the aquatic organisms considered in
deriving the current ammonia criteria.

EPA recently completed a comprehensive review of the available toxicity data for ammonia and now
seeks additional pertinent toxicity data or information,  hi particular, EPA is interested in new data on
the acute or chronic toxicity of ammonia to aquatic life and scientific views on how to interpret the
data, specifically new data on the toxicity of ammonia to freshwater mussels. Persons wishing to
submit data should assure that it is adequately documented and contains supporting information
indicating that acceptable test procedures were used.

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How to Get Additional Information
The full text of the Federal Register notice is available at
www. epa. gov/waterscience/standards/ammonial on the Internet. The bibliography of pertinent
references identified by the Agency for ammonia is available from EPA’s electronic public docket at
www.epa.gov/edocket under Docket ID No. OW-2004-0012. You can also get additional
information by contacting Arnie Howell, U.S. Environmental Protection Agency, Office of Water,
Health and Ecological Criteria Division (4304T), 1200 Pennsylvania Avenue, NW, Washington, DC
20460. (202) 566-1143. howell.amie(2i epa.gov .
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