United States
Environmental Protection
Agency
Environmental Research
Laboratory
Duluth MN 55804
Research and Development
EPA-600/S3-84-064 June 1984
&EPA Project Summary
Chemical and Biological Studies
Related to the Water Quality
of St. Louis Bay of Lake Superior
Anthony R. Carlson and Nelson Thomas
This study was a cooperative effort
among the University of Wisconsin-
Superior, University of Minnesota-
Duluth, and U.S. EPA Environmental
Research Laboratory-Duluth to develop
and evaluate effluent toxicity screening
methods and test methods and
protocols for deriving site-specific
water quality criteria. The principal
components of the study were to
include: (1) a chemical characterization
of the main discharges to the St. Louis
River and Harbor, (2) persistence of
toxic pollutants in the St. Louis River
and Harbor, (3) a description of the
exposure times for various components
of the ecosystem, (4) bioassays with St.
Louis River water ad resident species,
(5) an assessment as to the degradation
of the biologic community of St. Louis
Harbor, and (6) a modeling framework
to address items 1 through 5.
Because persistent toxic pollutant
concentrations were not found in the
Western Lake Superior Sanitary District
(WLSSD) effluent and no persistent
open water pollutant problems were
apparent, this study was ended.
Following are a series of reports on
work completed.
This Project Summary was developed
by EPA's Environmental Research
Laboratory, Duluth. MN. to announce
ke y findings of the research project that
is fully documented in a separate report
of the same title (see Project Report
ordering information at back).
Introduction
St. Louis Bay of Lake Superior provides
a unique opportunity to study a natural
ecosystem and related observed
response to pollutants to laboratory
testing effect endpoints and
observations. To understand a pollutant's
cause and effect relationship in such a
system, it must be studied in sufficient
depth to understand the controlling
factors To this end, several on site (field)
and laboratory studies were undertaken
to quantify possible pollutant impacts and
resulting biotic responses of the bay
ecosystem
Such research is needed to provide a
basis for the U.S Environmental
Protection Agency's (EPA) Office of Water
to provide guidance to the states on the
modification of national water quality
criteria to site-specific situations, and the
control of complex effluents through the
National Pollution Discharge System. The
EPA Great Lakes National Program Office
also needs information on the causes of
pollution of St. Louis Bay and the impact
of the bay on western Lake Superior
The primary objectives of this research
project were: (1) field test the EPA
guidelines for deriving site-specific water
quality criteria, (2) obtain data on the
relationship between toxicity testing of a
complex effluent and receiving water
biotic response, and (3) evaluate the
usefulness of water quality criteria to
protect a Great Lakes ecosystem.
To meet the above objectives, three
conditions must have existed. The first is
that a point source discharge to the bay
had to be at least chronically toxic, the
toxic components of the effluent had to be
identified, and the bay biota had to be
impacted by the effluent. Because the
Western Lake Superior Sanitary District
(WLSSD) discharge, containing both
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treated domestic and industrial wastes,
appeared to meet the above conditions, it
was selected for initial study. It is the
largest single point discharger to the bay,
its final effluents had exhibited toxicity in
the past and some fish kills had occurred
in the embayment near its discharge pipe
During 1982 studies to chemically char-
acterize the WLSSD effluent, determine
its toxicity and trace its movement in and
out of the bay were initiated Other
studies were initiated to provide a water
chemistry and biological baseline for the
bay from which present and future
pollutant impacts on the bay, and the
bay's impact on Lake Superior, could be
determined A literature search of all
studies relevant to St. Louis Bay was also
begun. Information gained from these
first-year efforts were necessary to
determine if the primary objectives of this
research project were achievable and, if
achievable, to plan subsequent studies.
This project was undertaken as a coop-
erative effort of the U.S. EPA Environ-
mental Research Laboratory-Duluth,
University of Minnesota-Duluth, and
University of Wisconsin-Superior.
Following are reports on individual
research tasks undertaken in 1982.
Results and Conclusions--
St. Louis Bay
Water Chemistry Surveys
At the six sites, in the small embayment
near the WLSSD wastewater treatment
plant, ammonia, alkalinity, total phos-
phorus, and chloride were higher than in
the control embayments.
The fraction of WLSSD effluent,
estimated from chloride concentration
was 0.20-0.25 in the three sites closest to
the discharge pipe and 0.05-0 10 in the
three sites farthest from the discharge
pipe. Ammonia and total phosphorus
appear to have a substantial sediment
source m the small embayment near
WLSSD.
Nutrient input budgets for St. Louis Bay
revealed that 90% of the alkalinity,
ammonia and total phosphorus loadings
were derived from the St. Louis River with
the remainder originating from WLSSD.
However, high chloride concentrations in
the WLSSD effluent contribute 43% of
the Cl loading to St. Louis Bay, compared
to 57% from the St. Louis River.
Comparison of the total phosphorus
input budget for 1982 with a similar
budget for 1972 revealed that the WLSSD
sewage treatment plant released one-
fifth the total phosphorus that was
released by the nine sewage treatment
plants operating in 1972
Phenol concentrations decreased from
8 to 9 fjg L'1 in the mid-1970s to 3//g L '
in 1982.
The mean total phosphorus at site L
(downstream from the present WLSSD
plant) decreased from 110 /ug LH between
1972 to 1979 to 75 fjg L ' for 1979 to 1982.
The mean ammonia concentration at
site L decreased from 0.259 mg L~1 (pre-
1979) to 0.116 mg L'1 after 1979.
Benthic Invertebrate Surveys
The benthic invertebrate surveys
demonstrated noticeable differences
between the WLSSD discharge bay and
two bays (controls) upstream. The
discharge bay contained fewer types of
organisms and these are considered
more tolerant of domestic effluents. The
differences between the bays were less
noticeable in October than in June or
August.
Phytoplankton andZooplankton
Surveys
The Duluth-Supenor Harbor is a
complex system for pelagic sampling. Not
only is the bathymetry complex, with the
extensive shallows plus the deep
dredged ship channels, but the
interactive flows of the St. Louis River
and seiche currents from Lake Superior
make point samples a function of many
variables. In the shallows, particularly,
the range of seasonal change can be
extreme Within this context, examina-
tion of the plankton data from Summer
1982 shows no adverse influence of the
effluent from the WLSSD plant.
WLSSD Effluent Toxicity and
Characterization
Effluent Toxicity
The effluent was intermittently acutely
toxic to aquatic organisms (fish and
invertebrates) in toxicity tests. Behavioral
monitoring of fish continuously exposed
to the plant effluent was used to identify
periods of effluent toxicity.
Increases in fish locomotor and respir-
atory activity correlate with fish mortality
in bioassays of grab samples Some
possible causes of observed toxicity were
thought to be related to elevated total
residual chlorine or carbon dioxide
concentrations resulting from changes in
wastewater treatment in response to
changes in influent conditions
It is recommended that any future
bioassays of WLSSD effluent, or the
effluent from other treatment plants, be
complemented with chemical analyses ol
total chlorine, pH (immediate and after
extended aeration), carbon dioxide,
alkalinity, and hardness. If possible,
these tests should be coupled with
sensitive aquatic organism behavioral
monitoring to identify episodic periods ol
toxicity.
Effluent Characterization
A comparative qualitative analysis was
made of the WLSSD effluent and influent,
and a similar analysis was made of the
effluent from the largest single contribu-
tor of industrial type organics (a pulp and
paper industry) to the WLSSD influent
The isolation and concentrations in com-
posite samples were done in threes tc
reflect the acidic, neutral, and basic
functionalities m the components
analyzed using mass spectroscopy. The
mass of data is presently being incorpora-
ted into a three x three matrix (3 analyses
and 3 sample sites) based on functional-
ity. When completed, an interpretation ol
the meaning and significance of the data
will be made.
Because chlorophenols originating
from WLSSD had been previously tracec
within the bay and into Lake Superior, E
gas chromatography with electror
capture detection procedure aimed a
sensitivity and a second procedure with
liquid chromatography with a variable
wavelength that would aid the identifica
tion of chlorophenols in comple)
mixtures were developed.
A detailed report containing the
methods used in effluent characteriza-
tion and raw data, and chlorophenol
analysis procedures are available on
request.
Conclusions
1. The water quality of the St. Louis
Harbor has improved. Much of the
improvement can be attributed tc
the onset of the operation of the
present WLSSD wastewater
treatment plant.
2. There was only a slight impact or
the benthic invertebrate community
from the WLSSD outfall.
3. Survey data indicate that phyto-
plankton and zooplankton were no(
demonstrably impacted by the
WLSSD effluent.
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4. The WLSSD plant is currently treat-
ing its waste to a higher degree than
the 1 mg/L phosphorus limit. The
concentration in the main channel
opposite the plant has decreased by
a factor of three since 1973.
5. The WLSSD discharge was occa-
sionally acutely toxic. It appears that
some toxic discharges are related to
changes in treatment processes and
plant operations in response to
special waste treatment needs
resulting in high residual chlorineor
carbon dioxide concentrations in the
effluent. Data indicate that at times
the mixtures of the WLSSD plant
effluent and bay would be acutely
toxic in the immediate vicinity of the
discharge pipe but not impact the
rest of the bay because of a high
dilution ratio.
6. The primary objectives of this
research project were not attainable
at this site because persistent toxic
pollutants were not found in the
WLSSD effluent and no persistent
open water pollutant problems were
apparent.
Bibliography
Devore, P. 1983. An Annotated
Bibliography of Environmental Research
Conducted Within the St Louis River
Estuary 1903-1982. [Order No NTIS
PB83-261 -693] (EPA-600/S3-83-092).
This report is intended as a tool for people
to locate specific types of studies con-
ducted within St. Louis Bay and was an
attempt to compile and review all the
physical, biological, and chemical studies
related to the bay.
R. B. Cook, J. A meet, J. R. Hargis, and R. Caple are with the University of
Minnesota, Duluth, MN 55812; D. J. Call, L T. Brook. C.Northcott, and D. E.
Hammermeister are with the University of Wisconsin, Superior, Wl 54880; the
EPA authors A. R. Carlson, N. A. Thomas (also the EPA Project Officers, see
below), 7. H. Roush, and R. A. Drummond are with the Environmental
Research Labortory, Duluth, MN 55804.
The complete report, entitled "Chemical and Biological Studies Related to the
Water Quality of St. Louis Bay of Lake Superior," (Order No. PB 84-195 379;
Cost: $14.50, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Research Laboratory
U.S. Environmental Protection Agency
6201 Congdon Blvd.
Duluth, MN 55804
U S GOVERNMENT PRINTING OFFICE, 1984 — 759-015/7734
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Environmental Protection
Agency
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