United States
Environmental Protection
\r ^1	Agency
Office of Water
EPA 822-F-18-003
December 2018
Fact Sheet: Final 2018 Aquatic Life Ambient Water
Quality Criteria for Aluminum in Freshwaters
The EPA has published final updated aquatic life
ambient water quality criteria recommendations for
aluminum in freshwater under Section 304(a)(1) of
the Clean Water Act to reflect the latest scientific
knowledge. There are not enough data to support
the development of estuarine/marine aluminum
criteria at this time. Aluminum can inhibit an aquatic
organism's ability to regulate salt concentrations and
clog fish gills, potentially resulting in death or
affecting growth and reproduction.
States and authorized tribes can adopt these criteria
into their water quality standards or can adopt other
aluminum criteria that is scientifically defensible
based on local or site-specific conditions. These final
criteria are not a regulation, nor do they impose a
legally-binding requirement. These criteria provide
information for states to develop science-based
standards that reflect site-specific factors and are
protective against the effects of aluminum on
aquatic life.
The EPA first published criteria for aluminum in
1988. The updated aluminum criteria better reflect
the latest science. Studies have shown that three
water chemistry parameters - pH, total hardness,
and dissolved organic carbon (DOC) -can affect the
toxicity of aluminum by affecting the bioavailability
of aluminum in the water to aquatic species. Unlike
the fixed acute and chronic values found in the 1988
criteria recommendation, these final 2018
recommended criteria provide users the flexibility to
develop site-specific criteria based on local water
The EPA released a draft of this criteria in 2017 for
public comment and has reviewed the comments
and updated the document.
What is Aluminum and How Does It Enter
the Water?
Aluminum is found in most soils and rocks. It is the
third most abundant element and the most common
metal in the earth's crust. Aluminum can enter the
water via natural processes, like weathering of rocks.
Aluminum is also released to water by mining,
industrial processes using aluminum, and in waste
water and drinking water treated with alum, an
aluminum compound.
How Does Aluminum Affect Aquatic Life?
Aluminum is considered a non-essential metal
because fish and other aquatic life do not need it to
function. Elevated levels of aluminum can affect
some species' ability to regulate ions, like salts, and
inhibit respiratory functions, like breathing.
Aluminum can accumulate on the surface of a fish's
gill, leading to respiratory dysfunction, and possibly
death. Aquatic plants are generally less sensitive to
aluminum than fish and other aquatic life.
What is a Water Chemistry Parameter and
Why is it Important?
Bioavailability is the measure of whether a substance
in the environment is available to affect living
organisms, like fish. The bioavailability of aluminum
is dependent on the chemistry of the water. The
more bioavailable the aluminum is, the more likely it
is to cause a toxic effect. The water chemistry
parameters that have the greatest impact on
aluminum's bioavailability are pH, total hardness,
and DOC.
	pH: a low pH generally makes it easier for
aluminum to be dissolved, and therefore more
bioavailable. At higher pH, aluminum speciation
changes make it more bioavailable.
	Hardness: generally, higher hardness values
mean there are more ions present. These ions

compete with aluminum and make aluminum
less bioavailable.
 DOC: higher dissolved organic carbon reduces
bioavailability. Aluminum is bound to DOC,
making the aluminum less bioavailable to aquatic
What are the Recommended Criteria for
Aluminum in Freshwater for the Protection
of Aquatic Life?
The recommended aquatic life criteria for aluminum
in freshwater depend on a site's water chemistry
parameters. Unlike the fixed values found in the
1988 criteria document, these criteria use Multiple
Linear Regression (MLR) models to normalize the
toxicity data and provide a range of acceptable
values. The criteria are calculated based on a site's
pH, total hardness, and DOC. See Table 1 for a
comparison of 2018 and 1988 criteria values.
For freshwater criteria, users can enter their site's
water quality parameters into the Aluminum Criteria
Calculator V.2.0.xlsm or use the lookup tables in the
criteria document's appendix. The resulting acute
criterion indicates that freshwater organisms would
be protected if the one-hour average concentration
is not exceeded more than once every three years
on average. The chronic criterion indicates that
freshwater organisms would be protected if the
four-day average concentration is not exceeded
more than once every three years on average.
Where can I find more information?
For more information and to view the aluminum
criteria document and the criteria calculator, please
visit EPA's website at www.epa.gov/wqc/aquatic-
life-criteria-aluminum or email Diana Eignorat
Table 1: Comparison of the EPA's 2018 and 1988 National Recommended Aquatic Life Criteria for
Freshwater Acute3
(1 hour,
total recoverable aluminum)
Freshwater Chronic3
total recoverable aluminum)
2018 Criteria
(vary as a function of a site's pH, total hardness, and DOC)
1 - 4,800 ng/Lb
0.63 - 3,200 ng/Lb
1988 Criteria
(pH 6.5 - 9.0, across all total hardness and DOC ranges)
750 ng/L
87 ixg/l
a Values are recommended not to be exceeded more than once every three years on average.
b Values will be different under differing water chemistry conditions.