United States
Environmental Protection
Agency
Environmental Research
Laboratory
Duluth MN 55804
Research and Development
EPA-600/S3-84-029 Mar. 1984
Project Summary
Derivation of Site-Specific
Water Quality Criteria for
Cadmium and the St. Louis River
Basin, Duluth, Minnesota
R. L. Spehar and A. R. Carlson
Several freshwater aquatic species
were exposed to cadmium in site and
laboratory water to evaluate an "organ-
ism testing" protocol proposed by the
U.S. Environmental Protection Agency
for deriving site-specific, water quality
criteria. The procedures of recalcula-
tion, indicator species, and resident
species were used in this protocol to
modify the national maximum 30-day
average cadmium criteria. These
procedures were used to account for
differences in species sensitivity and in
the biological availability and/or
toxicity of cadmium due to physical
and/or chemical characteristics of the
site water.
The site-specific, maximum concen-
tration derived from the recalculation
procedure was slightly lower (1.3 as
compared to 2.2 /ug/l) than the national
criterion value. The maximum
concentration derived from the
indicator species procedure was 7.0
jug/I and was calculated by using a
water effect ratio from tests conducted
in both site and laboratory water. Acute
tests with several species demonstrated
that cadmium was less toxic in site
water than in laboratory water. The site-
specific, maximum concentration
derived from the resident species
procedure (from eight species exposed
to cadmium in site water) was 1.9 /ug/l.
The 30-day average concentrations
were the same as the maximum con-
centrations in all procedures where the
national acute-chronic ratio was used in
the calculation. These concentrations
were much lower when the site-specific,
acute-chronic ratio was applied.
Acute tests conducted monthly in site
water showed that cadmium toxicity
varied by more than a factor of three
over the year. This indicates the need
for considering seasonal changes in
physical and chemical characteristics of
the site water when deriving criteria to
protect aquatic life.
This Project Summary was developed
by EPA's Environmental Research Lab-
oratory. Duluth, MN, to announce key
findings of the research project that is
fully documented in a separate report of
the same title (see Project Report order-
ing information at back).
Introduction
Under the Clean Water Act of 1977
[Sec. 304(a)(1)], the U.S. Environmental
Protection Agency (EPA) is required to
review and publish criteria for water
quality necessary to protect public water
supplies and the propagation of shellfish,
fish and wildlife. Criteria present scien-
tific data and guidance on the
environmental effects of pollutants that
can be useful to derive water quality-
based regulatory requirements such as
effluent limitations, water quality
standards or toxic pollutant effluent
standards.
National water quality criteria have
been derived by applying a set of
guidelines to data for certain pollutants
designated as toxic under Section
307(a)(1) of the Clean Water Act of 1977,
pursuant to an agreement in the case of
Natural Resources Defense Council et al.
vs. Train, 1976. These guidelines specify
that criteria should be based on an array
of data from species, both plant and
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animal, occupying various trophic
levels Based on these data, criteria can
be derived which should adequately
protect the type of species necessary to
support an aquatic community. Although
criteria represent a reasonable estimate
of pollutant concentrations consistent
with the maintenance of designated
uses, each state may appropriately
modify these values to reflect local
conditions.
Since national criteria may be either
underprotective or overprotective, the
Office of Research and Development and
the Office of Water Regulations and
Standards of the EPA are currently
developing guidelines for modifying
national water quality criteria to local
conditions or to site-specific criteria
National criteria are based on information
obtained from toxicity and bioconcentra-
tion tests conducted in laboratory sources
of water. However, lexicological
information obtained for laboratory
tested aquatic species, however, may not
be applicable to species in specific water
bodies because: 1) the species at a
particular site may be more or less
sensitive than those included in the
national criteria data base, or 2) the
physical and/or chemical characteristics
of the water at the site may alter the bio-
logical availability and/or toxicity of the
material.
The main purpose of this research was
to test procedures that might be useful for
deriving site-specific water quality
criteria. The specific objective of the study
was to conduct tests to evaluate an
"organism testing" protocol for deriving
site-specific criteria utilizing toxicity tests
with several species of aquatic organisms
in site and laboratory water. The type of
tests and/or exercises that were per-
formed in this study were designed to
correlate with the site-specific guidelines
as they are now proposed. This study was
designed to help identify problems that
one might encounter when using the
guidelines and to provide an example for
a site-specific criteria derivation for a
chemical at an actual site.
Tests were conducted with cadmium
because this chemical is highly toxic to
aquatic organisms, and is commonly
found in the environment due to its
presence in treated municipal wastes. Its
chemistry in water is such that it may be
influenced by changes in water quality,
which would be a major consideration for
modifying the present national criteria.
Overall Assessment
Although all of the above procedures
were tested in this study, only one
approach would most likely be used in an
actual site criteria modification. If species
sensitivity was the important factor, the
recalculation procedure would be the
least costly approach because it would
require no testing. When water quality at
a site may mitigate the toxicity of a
chemical, the indicator species procedure
is encouraged. This is especially true for
metals like cadmium where biological
availability and/or toxicity are signifi-
cantly affected by variations in water
quality characteristics of the site water.
When both species sensitivity and water
quality are important considerations for a
particular site, the resident species
procedure would be the best approach
because it is designed to account for
differences due to both of these factors.
This approach, however, would be the
most costly because at least eight acute
tests are required to be conducted in site
water.
The above procedures were designed
for deriving site-specific water quality
criteria by allowing substantial flexibility
with respect to the methodology used
This should perm it regulatory agencies to
choose the most efficient means of ob-
taining the information needed to modify
national criteria for each particular site.
Site-specific water quality criteria for
cadmium and the St Louis River obtained
from the site specific guidelines appear to
be logical, taking into account the
national cadmium criteria and physical,
chemical and biological characteristics of
this site water Using these procedures to
derive site-specific, water quality criteria
for toxic materials at different sites
should provide additional input to the
development of effective, site-specific
guidelines
The EPA authors R. L. Spehar and A. R. Carlson are with the Environmental
Research Laboratory, Duluth, MN 55804.
The complete report, entitled "Derivation of Site-Specific Water Quality Criteria
for Cadmium and the St Louis River Basin, Duluth, Minnesota," (Order No. PB
84-153 196; Cost: $10.00, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
For information contact the authors at:
Environmental Research Laboratory
U.S. Environmental Protection Agency
6201 Congdon Blvd.
Duluth, MN 55804
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