PHA United States	°f^e_r
Environmental Protection
\f hI	Agency	July 2017
Fact Sheet: Draft Aquatic Life Ambient Water
Quality Criteria for Aluminum in Freshwaters
Summary
EPA published a draft update of aluminum aquatic
life ambient water quality criteria for freshwaters
under Section 304(a)(1) of the Clean Water Act to
reflect the latest scientific knowledge. EPA will
accept public comment on the draft criteria for 60
days upon publication of the Federal Register notice.
Once final, the criteria will serve as
recommendations to states and tribes by defining
the concentration of aluminum in water that will
protect against harmful effects to aquatic life.
Background
EPA first published criteria for aluminum in 1988 to
protect aquatic life from harmful effects of
aluminum toxicity in freshwaters. 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. EPA is updating the aluminum criteria
to better reflect the latest science. Unfortunately,
there are not enough data to support the
development of estuarine/marine criteria at this
time.
Unlike the fixed acute and chronic values found in
the 1988 document, this draft document provides
users the flexibility to develop site-specific criteria
based on a site's water chemistry using the
Aluminum Criteria Calculator V.l.O.xIsx or by using
the lookup tables provided in the criteria appendix.
Studies have shown that three water chemistry
parameters, pH, dissolved organic carbon (DOC), and
hardness, can affect the toxicity of aluminum by
affecting the bioavailability of aluminum in the water
to aquatic species.
What is Aluminum and How Does it Enter
the Water?
Aluminum is found in most soils and rocks and 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 waste
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 don't 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 Quality Parameter and
Why is it Important?
Bioavailability is the measure whether a substance in
the environment is available to enter living
organisms, like fish. The bioavailability of aluminum
is dependent on the chemical properties of water,
otherwise known as water quality parameters. The
more bioavailable the aluminum is, the more likely it
is to cause a toxic effect. The water quality
parameters that have the greatest impact on
aluminum's bioavailability are pH, DOC, and
hardness.
¦ 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.

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¦	DOC: higher dissolved organic carbon reduces
the bioavailability of aluminum because it binds
to form aluminum complexes.
¦	Hardness: higher hardness values mean there are
more ions present that compete with aluminum.
This makes aluminum less bioavailable.
What is the Recommended Level of
Aluminum in Freshwater for the Protection
of Aquatic Life?
The recommended level of aluminum in freshwater
depends on a site's water quality parameters. Unlike
the fixed values found in the 1988 criteria document,
these criteria use a Multiple Linear Regression (MLR)
model to normalize the data, and the criteria are
based on a site's pH, DOC, and hardness. See Table 1
for a comparison of existing and draft criteria values.
For freshwater criteria, users can put their site's
water quality parameters into the Aluminum Criteria
Calculator V.l.O.xIsx or use the lookup tables in the
document's appendix. The resulting acute criterion
would have an appropriate level of protection if the
one-hour average concentration is not exceeded
more than once every three years on average. If the
four-day average concentration is not exceeded
more than once every three years on average, the
chronic criterion is protective.
Where can I find more information?
For more information please visit EPA's website at
www.epa.gov/wqc/aquatic-life-criteria-aluminum or
contact Diana Eignorat Eignor.Diana@epa.gov.
Table 1: 2017 Draft Aluminum Aquatic Life Criteria Compared to Current 1988 Criteria3
Version
Freshwater
Acute
(1 day, total
aluminum)
Freshwater
Chronic
(4-day, total
aluminum)
2017 Draft AWQC Criteria
(MLR normalized to pH = 7, hardness = 100 mg/L, DOC = 1 mg/L)
1,400 ng/L
390 ng/L
1988 AWQC Criteria
(pH 6.5 - 9.0, across all 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.
Note: Values will be different under differing water chemistry conditions as identified in this document.

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