Appendix 2 

Assessment of the Degradation of Phytoplankton and
Zooplankton Populations Beneficial Use Impairment
Thunder Bay Area of Concern

Tara K. George
Great Lakes Unit
Water Monitoring Section
Environmental Monitoring and Reporting Branch
Ontario Ministry of the Environment and Climate Change

February 8, 2016

  

Table of Contents
Executive Summary…………………………………………………………....................... iii
List of Tables…………………………………………………………………………….….v
List of Figures……………………………………………………………………………....vi
1.0

Introduction………………………………………………………………………….. 1
1.1 Beneficial Use Workshops…………………………………………………. 1
1.1.1 2004 BUI Monitoring Workshop………………………………. 1
1.1.2 2010 Phyto/Zooplankton Workshop……………………............ 2
1.1.3 2014 Remedial Action Plan Implementation Workshop………. 2

2.0

Plankton Population and Nutrient Assessments ……………………………………. 3
2.1 Phytoplankton Monitoring Program ………………………………………. 3
2.2 Water Quality Assessment of Ten Lake Superior Embayments, Spring
1983 ……………………………………………………….…….................. 4
2.3 Thunder Bay Nearshore Water Quality Assessment ………………............. 4
2.4 Water and Sediment Quality in the Kaministiquia River Delta and
Nearshore Area of Lake Superior …………………………………………..4
2.5 Great Lakes Reconnaissance Survey ………………………………….……4
2.6 Assessment of Total Phosphorus and Chlorophyll in Thunder Bay, 2005… 4
2.7 Great Lakes Nearshore Index Station Network……………………………. 5
2.7.1 Plankton Assessment ………………………………………….. 5

3.0

Remediation and Delisting ………………………………………………………….. 5
3.1 Guidelines …………………………………………………………………. 5
3.2 Delisting Guidelines ………………………………………………………..6
3.3 Remedial Strategies ………………………………………………………...6

4.0

Lines of Evidence …………………………………………………………………… 7
4.1 Top-Down and Bottom-Up Approach …………………………………….. 7
4.1.1 Introduction ……………………………………………………. 7
4.1.2 Bottom-Up ……………………………………………………...8
4.1.3 Top-Down ……………………………………………………... 9
4.1.4 Conclusions ……………………………………………………. 9
4.2 Effluent Monitoring and Effluent Limit Regulations……………………… 10
4.2.1 Toxicity Testing ……………………………………………….. 11
4.2.1.1 Resolute Forest Products …………………...............11

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4.3
4.4
4.5

4.2.1.2 Ontario Power Generation, TBTGS ……….. ………14
4.2.2 Loadings……………………………………………………….. 14
4.2.2.1 Resolute Forest Products……………………………14
4.2.2.2 Ontario Power Generation, TBTGS………............... 14
4.2.3 Treatment Upgrades and Process Changes……………………. 17
4.2.3.1 Resolute Forest Products……………………………17
4.2.3.2 Ontario Power Generation, TBTGS………... ………18
Thunder Bay Water Pollution Control Plant Treatment Upgrades…............ 18
Industrial Closures…………………………………………………………. 19
Invasive Species Strategies………………………………………………….21

5.0

Conclusions………………………………………………………………………….. 22

6.0

References…………………………………………………………………................ 25

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Executive Summary
For decades practitioners working on Great Lakes Areas of Concern (AOCs) have been
discussing how to best address the ‘Degradation of Phytoplankton and Zooplankton
Populations’ beneficial use impairment (BUI). Not only is there considerable variation in
defining the issue of the identified AOCs, but there are also inconsistencies in the approaches for
monitoring and reporting the BUI. Thunder Bay is one of five AOCs that have the plankton BUI
listed as ‘requiring further assessment.’ The initial identification of the BUI in Thunder Bay was
based on the assumption of eutrophication and the introduction of invasive species altering
plankton populations; however the claim of an altered population was not substantiated by a
baseline study. The intention of this report was to assess the current status of the plankton BUI
by using an approach that deviates from the approaches previously taken. Different lines of
evidence, with emphasis on the issues originally identified, were examined in a pragmatic
manner, and a determination of status was made based on available information and data as it
pertains to the health of plankton in the Thunder Bay AOC. Examined lines of evidence
included past and current nutrient assessments; a top-down, bottom-up approach (assessment of
water quality indicators and fish health); toxicity of industrial effluents; industrial and municipal
loading levels; industrial and municipal treatment upgrades and process changes; industrial
closures; and invasive species.
There have been several studies which have characterized the nearshore and offshore zones of
Thunder Bay (Hopkins 1986, Simpson 1987, Anderson 1986, Boyd 1990, Richman 2004, Benoit
et al. 2012, George 2012). This assessment focused mainly on the nearshore zone of the
Thunder Bay AOC, as the plankton would be most likely influenced by anthropogenic inputs in
this area. Generally the studies found the nutrient levels to be highest in the deltic area of the
Kaministiquia River, where in most cases, the total phosphorus (TP) levels exceed the TPProvincial Water Quality Objectives (PWQO - 20 µg/L in lakes and 30 µg/L in rivers). Despite
the elevated levels of TP, nuisance algae has not been reported during the monitoring surveys,
which is likely due to the capacity of the Lake to dilute concentrations of TP below the level that
would cause algal blooms.
The industrial landscape of the AOC shoreline has changed substantially in the past decades.
Several industries, that contributed high loadings of nutrients, BOD5, and other contaminants,
have closed and thereby lessened the load to the receiving environment. The three remaining
point sources of nutrients and contaminants to the Thunder Bay AOC include Resolute Forest
Products, Ontario Power Generation – Thunder Bay Thermal Generating Station, and the
Thunder Bay Water Pollution Control Plant. Treatment upgrades and/or process changes at
these facilities have significantly improved effluent quality. The improvement in effluent has
been observed in the outcome of acute and chronic toxicity tests that are regulated through
Ontario’s Effluent Monitoring and Effluent Limit Regulations. There have been no acute toxicity
violations since 2006 at Ontario Power Generation, and very seldom are the potential for chronic
effects observed at concentrations less than 100% effluent. There has been minimal acute

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toxicity over the sampling period of 2002 to 2015 at Resolute Forest Products. Where acute
violations (failures) did occur, they were most often due to a specific operational change (e.g.,
shutdown). Recent chronic toxicity tests (past 1.5 years) from Resolute Forest Products have
shown minimal to no chronic toxicity to zooplankton and phytoplankton, respectively. Prior
tests from the combined-mill outfall had demonstrated the potential for chronic impairment to
plankton.
To obtain a broader view of the AOC, a top-down and bottom-up approach was adopted using
water quality data (Benoit et al. 2012) and fish community index data (Foster 2012, Marshall
2015) to determine the status of the plankton trophic level. In addition, the approach was used as
a screening level assessment to determine if further investigation was warranted for the plankton
BUI. From the bottom-up, it was shown that the study area was not phosphorus limited, and that
chlorophyll-a concentrations were not likely to result in undesirable levels of algae (Benoit et al.
2012). From the top-down, current data suggests that the Thunder Bay AOC supports a more
diverse fish community than adjacent areas. Generally, it was determined that there was no basis
to continue with a full plankton assessment.
A concern that was originally identified was the introduction of aquatic invasive species,
specifically the zebra mussel and the spiny water flea (Thunder Bay RAP 1991, 2004).
Dreissenid mussels (which include zebra mussels) are not wide-spread through Lake Superior
due to the cold water temperatures; however they are present in specific nearshore areas,
including Thunder Bay. Fish communities in Lake Superior, both nearshore and offshore, are
primarily supported by a diet of Mysis and Diporeia. In the lower Great Lakes, populations of
these macroinvertebrates have declined as a result of the abundance of Dreissenid mussels, but
this has not been the case in Lake Superior. With respect to the spiny water flea (Bythotrephes),
limited studies have been conducted in Lake Superior and further research is required to fully
understand this invasive species. Trophic food web studies (Gamble et al. 2011a, Gamble et al.
2011b, Keeler et al. 2015) have shown that some fish species, predominantly Cisco, have
incorporated Bythotrephes into their diet; in this case the adopted feeding behaviour may serve
as a top-down control of the invasive population (Keeler et al. 2015). Overall, based on the food
web configuration at a low level of prey diversity, there is system stability (Gamble et al.
2011b). Regardless of the indications of adaption to the invasive species, the issue is a priority
and there are a number of provincial, federal, and binational initiatives that focus on monitoring
and prevention.
The assessment of the key factors that influence the health of the plankton population has
demonstrated that there is little basis to continue the assessment of this BUI. The industrial
landscape of the Thunder Bay AOC has changed substantially since the inception of the RAP
program, and nutrient and contaminant loading have declined from original levels. The
assimilative capacity of the large Kaministiquia River and receiving oligotrophic Lake Superior
have provided an environment that is not prone to algal blooms, and which supports a healthy
fish population. At this time, it is recommended that the ‘requires further assessment’ status of
the Degradation of Phytoplankton and Zooplankton Populations BUI be removed. The lower

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food web of the lake, as a whole, will continue to be assessed through the Lake Superior
Partnership by way of the Coordinated Science and Monitoring Initiative.

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List of Tables
Table 1

Changes to Resolute Forest Product, and former companies, mill
components (1990-2014)…………………………………………………….. 18

Table 2

Environmental Compliance Approval effluent objectives and limits, and
effluent concentrations pre- and post-treatment upgrade for the Atlantic
Avenue Water Pollution Control Plant……………………............................. 19

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List of Figures
Figure 1

Resolute Forest Products acute toxicity test results for A) Ceriodaphnia
dubia and B) Pimephales promelas (1994 – 2015)……………………………12

Figure 2

Resolute Forest Products chronic toxicity test results for A) Ceriodapnia
dubia, B) Selenastrum capricornutum, and C) Pimephales promelas
(1997 – 2015)…………………………………………………………………..13

Figure 3

Ontario Power Generation, Thunder Bay Thermal Generating Station
acute toxicity test results for A) Ceriodaphnia dubia and B) Pimephales
promelas (2006 – 2015)……………..................................................................15

Figure 4

Loading levels (annual average) of regulated parameters (A) BOD5,
TSS, flow; B) TP, DOC, AOX; and C) toluene, phenol, and chloroform)
at Resolute Forest Products (1994-2015)………………………………………16

Figure 5

Loading levels (annual average) of regulated parameters Al, Fe, TSS, SE, and
flow at Ontario Power Generation, Thunder Bay Thermal Generating Station
(1994-2015)……………………………………………………………………. 17

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1.0

INTRODUCTION

Biological assemblages are complex and respond in unpredictable ways to a wide range of
physical and biological conditions. As such, setting qualitative and quantitative targets to assess
the status of these assemblages can be difficult. For decades, practitioners working on the Great
Lake Areas of Concern (AOCs) have been discussing how to best address the ‘Degradation of
Phytoplankton and Zooplankton Populations’ beneficial use impairment (BUI). Not only is
there considerable variation in defining the issue of the identified AOCs, but there are also
inconsistencies in the approaches for monitoring and reporting the BUI. Further to that, there is
often disagreement as to the validity of one approach over another. In the last decade there has
been much discussion, in the form of workshops (section 1.1), meetings, and articles/reports
(George and Boyd 2007, Benoit et al. 2012), regarding challenges associated with the plankton
BUI.
Thunder Bay is one of five AOCs with the plankton BUI listed as ‘requiring further assessment.’
In many cases, this status designation is a result of the beneficial use not being properly assessed
initially by community and population analysis. In the case of Thunder Bay, the initial
identification of the BUI was based on the assumption of eutrophication and the introduction of
invasive species altering plankton populations. Generally, there has been no clear consensus on
the best approach to collecting further information to address this BUI; a scenario that exists for
most other AOCs dealing with this BUI. The intention of this paper is to assess the status of the
plankton BUI by investigating the issues that resulted in the BUI being listed originally, as well
as available data that both directly and indirectly addresses the status of the BUI. Different lines
of evidence will be examined in a pragmatic manner, and a determination of status will be made
based on available information and data as it pertains to the health of plankton in the Thunder
Bay AOC.
1.1
Beneficial Use Workshops
Since 2004 there have been several collective efforts, in the form of workshops, to address
challenges related to the BUIs. Specifically, experts have been brought together to discuss the
plankton BUI and derive solutions to effectively monitor and report on this indicator within the
AOC program. A common denominator of the various discussions is the lack of guidance in
assessing the plankton BUI. Although many approaches have been proposed, a clear consensus
was rarely achieved both within and among workshops. However, the lastest workshop in 2014
suggested that a pragmatic lines of evidence approach was the favoured amongst AOC and RAP
practioners.
1.1.1 2004 BUI Monitoring Workshop
In 2004, the Ontario Ministry of the Environment hosted a BUI Monitoring Workshop in
Guelph, ON. Experts from different agencies were invited to attend with the purpose of
achieving consensus on the type and quantity of information required to report progress towards
delisting (George et al. 2004). In addition, the intention was to establish agreement on survey
design principles of the BUI-focused monitoring plan as a template for agencies who agreed to
undertake various components of the plan. There was an expectation that following the

1
 

  

workshop the generic recommendations would be used in the development of specific
monitoring plans for each AOC.
A break-out session was held for each BUI, with special emphasis on those within the mandate
of the MOE. With respect to the degradation of phytoplankton/zooplankton populations BUI,
participants generally agreed that there was not enough guidance on what was intended by this
beneficial use and how it should be measured. Group discussions concluded that several of the
issues under the plankton BUI could be dealt with under the Eutrophication and Undesirable
Algae BUI. In terms of assessing the relevance of this BUI on an ecological basis, it was
suggested that a decline in fish populations or degradation of aesthetics (e.g., algae blooms)
might be a more effective way of describing rapid shifts in plankton populations; the suggestion
of a top-down, bottom-up approach ensued from this discussion. Overall it was agreed that
sharing information between the AOCs was essential.
1.1.2 2010 Phyto/Zooplakton Workshop
The 2010 Phyto/Zooplankton Expert Workshop was held in Burlington, ON and experts from
several provincial and federal government agencies, academia, and consulting were invited to
attend. The purpose of the workshop was to determine how the degradation of phytoplankton
and zooplankton BUI could be assessed in AOCs where data was poor or lacking within a two
year timeframe. The ultimate goal of the workshop was to enable Great Lakes managers to
determine the status of the BUI so that decisions could be made on delisting targets. A practical
and scientifically defensible approach to assessing the lower trophic levels at all AOCs is a
valuable tool in the creation of a management framework for future decision making.
There were several highlights and conclusions drawn from the two-day workshop. Overall, it
was agreed that the current definition of the plankton BUI is not clear, and that a consistent
unified approach for assessing the BUI amongst all the applicable AOCs would be desirable.
The approach to be taken would be to assess plankton in terms of both structure and function
across a gradient of environmental conditions or using a reference condition for comparison.
The primary action to manage the plankton BUI, in most AOCs, is nutrient loading control.
However, it was also expressed that other BUIs such as eutrophication and undesirable algae,
and fish community structure, while related, are not necessarily direct indicators of the health of
the plankton population. Other novel techniques such as mapping energy flow patterns using
isotopes and zooplankton fatty acid measurements were flagged as being worth consideration. It
was recognized that analysis of samples requires human, analytical, and taxonomic resources,
which can be costly. As such, it was suggested that a steering committee be formed, comprised
of both scientists and management, to coordinate the approach and ensure optimal use of
resources; currently knowledge suggests the formation of this committee did not occur.
1.1.3 2014 Remedial Action Plan Implementation Workshop
The 2014 Remedial Action Plan Implementation Workshop, held in Burlington, ON, was
intended to build on discussions from earlier workshops to reflect on progress and discuss
practical strategies for some of the continuing challenges with the AOC program. Once again, it

2
 

  

was highlighted that even at the data rich Bay of Quinte AOC, there remained challenges and a
series of debateable questions.
The AOCs with the “requires further information” designation for the plankton BUI were
highlighted at this Workshop, and the most current approach implemented at the respective areas
were presented: Thunder Bay AOC “top-down, bottom-up” approach (described in section 4.1);
lines of evidence approach for Toronto AOC; and an upstream, midstream, and downstream
comparison approach for the Detroit River AOC. For the most part, workshop participants were
in favour of a line of evidence approach for addressing the plankton BUI. The functionality
aspect of approaches that use lines of evidence (the top-down, bottom-up approach included)
was noted as useful. It was from discussions at this workshop that it was determined that the
lines of evidence approach that incorporated both direct and indirect measures of biotic health
would be implemented as a means to redesignate the plankton BUI in Thunder Bay.

2.0

PLANKTON POPULATION AND NUTRIENT ASSESSMENTS

There has been few plankton studies conducted in the Thunder Bay AOC. Generally, where
plankton sampling has been undertaken, it has been part of a bigger sampling effort where the
overall quality of the system was being assessed. Outlined below are Ontario Ministry of the
Environment studies, conducted since the 1980s, that have measured plankton abundance and/or
levels of nutrients (specifically TP) in surface water.
Off-shore water quality and plankton studies have been conducted by other government and
academic institutions (Reavie et al. 2013, Kelly et al. 2015). Although the results do not speak
specifically to the status of the BUI, they do provide an indication of the diversity and density of
plankton populations in Lake Superior, as well as a background nutrient profile of the surface
water.
 

2.1 Phytoplankton Monitoring Program
In 1972, a phytoplankton monitoring program was implemented at the drinking water intake at
Bare Point; general water quality parameters were added to the program in 1979 (Hopkins 1986).
The main purpose of the program was to assess the nearshore water quality over time with
emphasis on tropic indices. Untreated water samples were collected weekly, year-round and
analyzed for chlorophyll, phosphorus, nitrogen, silica and chloride. For phytoplankton, weekly
samples were combined and analyzed as monthly composites.
Over the period of 1980 to 2013, the mean annual total phosphorus concentration was 4.85 ±
1.73 µg/L and did not change monotonically. Mean annual chlorophyll-a also did not change
over time (0.97 ± 0.27 µg/L), although concentrations steadily decreased between 2000 and
2013. Between 1983-2013, mean annual algal density was relatively low and in most years was
dominated by diatoms, followed by cryptophytes and chrysophytes. Total algal density tended to
be higher in years with higher total phosphorus concentrations, and nutrients were an important

3
 

  

predictor of phytoplankton community composition over time (Palmer and Winter, unpublished
data).
2.2 Water Quality Assessment of Ten Lake Superior Embayments, Spring 1983
In the spring of 1983, ten embayments were investigated in Lake Superior, one of which
included Thunder Bay (Simpson 1987). Thirty-two stations within the whole of Thunder Bay
were sampled, with the majority located on the western shore. Total phosphorus concentrations
were highest and exceeded the TP-PWQO in the nearshore area of the McIntyre River (26 µg/L),
Neebing River (34 µg/L), and Kaministiquia River (39 µg/L); concentrations gradually declined
into the off-shore waters. The remainder of the stations in the whole of the Bay had TP
concentrations that ranged from 5 to 18 µg/L.
2.3
Thunder Bay Nearshore Water Quality Assessment
In 1983, nearshore water quality study was conducted to define the nature and extent of water
quality impairment in Thunder Bay (Anderson 1986). Sixty stations were sampled and it was
determined that the mean TP concentration was 15 µg/L ± 18 SD. Twenty-five percent of the
stations sampled had an average TP concentration > 20 µg/L; the provincial guideline required to
avoid nuisance concentrations of algae. Most of these sites of concern were located in the
Kaministiquia River delta and near Bare Point. No nuisance algae growths were identified at
these sites.
2.4

Water and Sediment Quality in the Kaministiquia River Delta and Nearshore Area of
Lake Superior
Water quality at stations located in the Kaministiquia delta and offshore waters were measured in
the late spring and summer of 1985 and 1986 (Boyd 1990). Generally it was determined that the
TP-PWQO (20 µg/L) was exceeded in the delta area, with mean concentrations ranging from 36
to 100 µg/L at the depth of maximum turbidity, and 12.5 to 31 µg/L at the depth of minimum
turbidity. However, it was noted that nuisance algae was not an issue in this study area, stating
the oligotrophic nature of the receiving water ensures the elevated concentrations are diluted to
less than the PWQO.
2.5
Great Lakes Reconnaissance Survey
As part of the Great Lakes Nearshore Monitoring and Assessment Program, data was collected
on Lake Superior under the Great Lakes Reconnaissance Surveys and the Great Lakes Nearshore
Index Station Network (Richman 2004). Eleven stations, located mainly in the delta area of the
Kaministiquia River, the north end of the harbour and bare point, and a station at the Welcome
Island were sampled in 1999. Results showed the highest levels of TP were detected at the
mouths of the Kaministiquia and Mission Rivers (ranging from 32 to 72 µg/L over three
surveys).
2.6
Assessment of Total Phosphorus and Chlorophyll in Thunder Bay, 2005
In 2005, the Ministry of the Environment undertook a study measuring TP and chlorophyll-a
concentrations as water quality indicators of trophic status (Benoit et al. 2012). The survey was
intended as a screening level survey to determine the need for a more direct and quantitative

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evaluation of plankton populations to assess the degradation of plankton BUI. Stations were
located in the Kaministiquia delta, harbour area, and offshore towards the Welcome Island.
More details of this study are provided in section 4.1.
2.7
Great Lakes Nearshore Index Station Network
The Ministry of Environment and Climate Change undertakes a comprehensive survey of
eighteen stations on Lake Superior (including the St. Marys River) under the Great Lakes
Nearshore Index Station Network (MOECC, unpublished). This program was implemented in
1999 and the surveys are conducted every six years (2005 and 2011). Phyto/zooplankton
samples are collected, along with water, sediment, and benthos samples.
2.7.1 Plankton Assessment
The Freshwater Ecosystem Research section of the Great Lakes Laboratory for Fisheries and
Aquatic Sciences at Fisheries and Oceans Canada has summarized the available plankton data
from Thunder Bay and has reported separately (Currie et al. 2015). Since data on plankton
communities within the AOC are very limited, data sets from the general area of Thunder Bay
were assessed and presented. The Ministry of the Environment and Climate Change provided
plankton samples from index stations 283 (Flatland Island), 284 (Welcome Island), and 285
(Sturgeon Bay) collected in each season over 3 years (1999, 2005, and 2011 in spring, summer,
and fall). Additional samples were provided to Fisheries and Oceans Canada by Environment
Canada, Ontario Ministry of Natural Resources and Forestry, and the United States Geological
Survey.
3.0

REMEDIATION AND DELISTING

3.1
Guidelines
In 1991, the International Joint Commission (IJC) provided listing and delisting guidelines to
serve as indicators for use impairments in the Great Lakes, as well as to assist in identifying new
AOCs, and reviewing all stages of remedial action plans (RAPs). The listing/delisting guidelines
for the ‘Degradation of Phytoplankton and Zooplankton Populations’ beneficial use impairment
(BUI) reads as follows:
Listing – when phytoplankton or zooplankton community structure significantly diverges from
unimpacted control sites of comparable physical and chemical characteristics. In addition, this
use will be considered impaired when relevant, field- validated, phytoplankton or zooplankton
bioassays (e.g. Ceriodaphnia; algal fractionation bioassays) with appropriate quality
assurance/quality controls confirm toxicity in ambient waters.
Delisting – when phytoplankton and zooplankton community structure does not significantly
diverge from unimpacted control sites of comparable physical and chemical characteristics.
Further, in the absence of community structure data, this use will be considered restored when
phytoplankton and zooplankton bioassays confirm no significant toxicity in ambient waters.

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3.2
Delisting Criteria
Prior to the designation of this BUI as impaired, the Great Lakes Water Quality Board prepared a
report on the water quality of the Great Lakes for the IJC (Great Lakes Water Quality Board
1987). Appendix A of the report provided a summary of the environmental assessment of the
area and the RAP development process for each AOC. The area of focus in Thunder Bay was
the Kaministiquia River and the following was provided with regard to the plankton BUI:
“Recent assessments of nutrient concentrations in Thunder Bay indicate that
although total phosphorus concentrations remain high in the lower Kaministikwia
River, eutrophication is not a problem. Trend analyses based on weekly sampling
of intake waters from the Bare Point pumping station in the northern part of
Thunder Bay harbour showed no significant increases in total phosphorus or total
Kjeldahl nitrogen from 1980-1984 and, as expected, no apparent increases in
phytoplankton biomass. In general, phytoplankton production in Thunder Bay
waters is low and does not represent a nuisance condition.”
The status of the plankton BUI in Thunder Bay was deemed impaired in 1991, with the condition
of the plankton populations in Thunder Bay “…assumed to be degraded in the Kaministiquia
River and in the Harbour, within the breakwall” (Thunder Bay Remedial Action Plan Team
1991). Based on the documented impairment of both water quality and benthic communities, it
was assumed that the plankton populations were also impaired. The accidental introduction of
exotics, such as the spiny water flea (Bythotrephes cederstroemi), was also of concern; the
predacious exotic zooplankton was introduced in the harbour in 1988 (Thunder Bay Remedial
Action Plan Team 1991).
In the Stage 2 RAP (Thunder Bay Remedial Action Plan Team 2004), the status of the plankton
BUI continued to be deemed impaired. Specifically, it was stated that populations were assumed
to be degraded in the vicinity of industrial outfalls; however, there were no assessment studies
conducted. It was recognized in the Stage 2 RAP (Thunder Bay Remedial Action Plan Team
2004) that process effluent from Bowater, the pulp and paper mill on the Kaministiquia River,
was not acutely toxic to Ceriodaphnia. In addition, secondary treatment at Abitibi (at the mouth
of the Mission River) was implemented, and effluent toxicity decreased (Thunder Bay Remedial
Action Plan Team 2004).
The status of the BUI, as well as the key actions completed and remaining, were outlined in 2010
by the provincial and federal governments (EC/MOE 2010). The status of the ‘degradation of
phytoplankton and zooplankton populations’ was changed to ‘requires further assessment’ since
it was acknowledged that the BUI was assumed to be impaired, but not assessed prior to that
determination. As such, there are no formal delisting criteria for the degradation of plankton
BUI given the current status.
3.3
Remedial Strategies
The intention of the Stage 2 RAP report (2004) was to outline remedial strategies to restore the
impaired beneficial uses for the Thunder Bay AOC. Since there were no studies to verify the

6
 

  

assumption of degradation, the Stage 2 report recommended that studies be carried out to obtain
a baseline measurement of the plankton communities, as well as to collect any information
necessary to determine suitable remediation measures. Once the baseline and investigative
studies were completed, then appropriate delisting criteria, a remediation strategy, and a
monitoring program would be developed under the three Management Actions in the RAP report
(Stage 2 RAP 2004).
The alternative strategy in the Stage 2 RAP report (2004) was to gather the opinion of an expert
panel to determine if the studies verify the impairment. If no impairment was apparent, then the
BUI status would be changed accordingly.
Despite the recommendations made in the Stage 2 RAP, plankton studies were not completed. In
the time that had lapsed since that recommendation, the issues that were originally identified as
causing the impairment had improved. It was discussed at the 2014 Remedial Action Plan
Workshop that, where insufficient data exists, it must be decided whether the cost of collecting
and analyzing the data is justified given the implications of the BUI. In light of the current
priorities for the Thunder Bay AOC, a full plankton survey could not be justified at this point.
These factors, in addition to the support shown for a pragmatic lines of evidence approach at the
2014 Remedial Action Plan Implementation Workshop (section 1.1.3), prompted this rationale
document which reviews the lines of evidence that directly and indirectly relate to the plankton
BUI. This approach to determine the current status of the plankton BUI was supported by the
Remedial Action Plan Team.
4.0

LINES OF EVIDENCE

Ideally, the degradation of phytoplankton and zooplankton populations BUI would have been
assessed using plankton data collected prior to the status determination, and at several time
intervals afterwards. Adequate replicates of plankton samples would have been collected on a
temporal (seasonal) basis from representative sampling locations within and outside the AOC.
Given that this did not occur, this assessment report will use the same reasoning that was used to
list the BUI to both determine the current status of the BUI and the progress towards delisting. A
lines of evidence approach can be used to indirectly assess or infer the health of the plankton
population in the most heavily impacted areas of the Thunder Bay AOC.
4.1

Top-Down and Bottom-Up Approach

4.1.1 Introduction
The top-down and bottom-up approach was introduced at the 2004 COA Monitoring Workshop.
The basis of the approach was that the plankton trophic level would be assumed to be healthy
and sustainable if the trophic levels above (predators; fish community health) and below
(plankton food; water quality indicators) were healthy.

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It is recognized that trophic interactions are very complex, and that the top-down and bottom-up
approach offers only a high-level generalized view of the status of the target trophic level, in this
case plankton. However, this pragmatic recommendation, generated from the workshop, served
as a screening level assessment that would be used to determine further action, if necessary.
4.1.2 Bottom-Up
In 2005, the MOE measured total phosphorus and chlorophyll-a (as well as other water quality
parameters) in the nearshore area of Thunder Bay in order to provide a ‘bottom-up’ assessment
of plankton in the AOC (Benoit et al. 2012). The approach taken in this study, herein referred to
as the TP/chlorophyll study, was supported by studies (Shuter and Ing 1997, Stemberger et al.
2001) were it has been shown that chemical and physical indicators, such as chlorophyll
concentrations and total phosphorus, can serve as sensitive indicators of biological status.
The stations examined in the 2005 TP/chlorophyll study were separated into three main blocks:
the Kaministiquia delta and river (including Mission and McKellar Rivers); the Harbour; and the
off-shore areas. As expected, concentrations of measured water quality parameters were highest
in the nearshore area, especially in the Kaministiquia delta, and decreased to offshore station
locations. The concentrations of TP were highest, and elevated above the TP-PWQO, at the
convergence in the Kaministiquia River and at the mouths of the Kaministiquia, McKellar, and
Mission Rivers, with average concentrations ranging from 38.2 to 57.3 µg/L. The median
concentrations of chlorophyll-a were low, ranging from 1.1 to 2.7 µg/L, and representative of a
typical oligotrophic system.
The consistently low concentrations of chlorophyll-a at the stations sampled in this study suggest
that the algal populations were likely limited by light and temperature, rather than TP (Hopkins
1986); Benoit et al. (2012) further supported this conclusion by use of a biomass-based trophic
state index (TSI). Large variations in TP and chlorophyll relationships do exist and are
associated with regional, biogeographical, morphometrical, and physico-chemical features of the
body of water (Stemberger et al. 2001). The TSI suggested that the potential prevalence of
phosphorus bond to particulate matter in the river water did not influence chlorophyll
concentrations. The TSI for offshore stations was consistent with the oligotrophic nature of the
open lake.
Overall it was determined that: (1) the elevated TP concentrations at some sites were not
indicative of negative effects; (2) chlorophyll-a concentrations do not suggest high algal
biomass; and (3) the TSI (as determined by the interplay of TP, chlorophyll, and secchi depth)
showed that other parameters such as DOC and turbidity/suspended solids (as inferred by
conductivity) were somewhat responsible for the shallow water column transparency at the more
impacted nearshore stations. Benoit et al. (2012) concluded that the TP-chlorophyll-a
relationship suggested that the AOC is not phosphorus limited, and that the overall chlorophyll-a
concentrations would not likely result in undesirable algae. The deltic area water chemistry
differed from the open water chemistry; however, that was simply due to the urban and
industrialized characteristics of the waterfront.

8
 

  

4.1.3 Top-Down
Assessments of more recent fish community data in Thunder Bay have been used to fulfill the
‘top-down’ portion of the overall top-down, bottom-up approach (Foster 2012, Marshall 2015).
Generally, the status of the Thunder Bay fish community is evaluated against the BUI delisting
criteria which states that: fish populations will no longer be impaired when the species
composition and relative abundance of the fish community within the AOC is similar to the
nearshore (0-80 m deep) community located adjacent to the AOC for three consecutive years.
Further to this, there are specific requirements (age, length, maximum mortality rates, etc.) of
self-sustaining populations of native species, such as Lake Trout, Lake Whitefish, Lake
Sturgeon, Walleye, and Brook Trout.
Marshall (2015) assessed the status of fish populations, and their habitat, using data collected
from the MNRF’s Fish Community Index Netting program, spanning from 2009-2014. The
assessment determined that although the fish community has changed substantially in
comparison to historical observations, Thunder Bay supports a more diverse fish community
than adjacent areas. In a separate review of a number of studies, Foster (2012) confirmed fiftyfive species in an area that included the Thunder Bay North Harbour, Current River, Thunder
Bay Harbour, and Thunder Bay as a whole. The catch per unit effort of fish was the same within
and outside the AOC; however differences were noted in the contribution of individual species
(Marshall 2015). The increased abundance inside the AOC, and the variation in species
abundance was likely due to differences in physical habitat.
There were several reasons cited to account for the changes to the populations and community
over time, including habitat modification due to industrial, residential, and recreational
development; commercial and recreational over-exploitation; introduction of exotic species; and
dredging, channelization, and the release of pollutants. Remedial and restoration activities, and
monitoring initiatives that have been implemented to address these issues and the Stage 2 RAP
recommendations (Marshall 2015).
The abundance and biomass of native and non-native planktivorous fish, specifically, in the
Thunder Bay AOC mirrors the results from a lake-wide study conducted by the USGS in 2014
(Vinson et al. 2014). Measurements of these two indicators have shown a lake-wide decline at
all trophic levels of fish. Preliminary results from the Ministry of Natural Resources and
Forestry Community Index Netting Survey (2009-2014) showed the highest catch per unit effort
to be in 2012, with a decrease in the following two years. It was noted that 2012 was a warm
summer, which lead to an increased success in fish capture; by comparison 2013 and 2014 had
much cooler sampling seasons. Despite low abundance and biomass, other indicators such as
periodic recruitment and survival suggested that the populations in the AOC are healthy (E.
Berglund, personal communication 2015).
4.1.4 Conclusion
The top-down/bottom-up approach was not supported by all technical experts at the 2010 COA
Expert Workshop. However, given that there was no generally accepted standard for

9
 

  

establishing plankton restoration objectives at the time, especially in dynamic areas such as
tributary mouths, the Remedial Action Plan Team supported the implementation of this
approach. The intention behind the 2005 chlorophyll and TP study was to take a pragmatic
approach to the issue and to conduct a screening level assessment, which could then be used to
determine whether additional sampling efforts were warranted.
From the perspective of the bottom-up, the TP-chlorophyll-a relationship has shown that the
study area is not phosphorus limited, and that chlorophyll-a concentrations are not likely to result
in undesirable algae; temperature and light are thought to be the limiting factors. In addition,
there is little evidence that of nutrient-driven eutrophication in the AOC, and the offshore areas
remain oligotrophic.
From the ‘top-down’, current data suggested that the Thunder Bay AOC supports a more diverse
fish community than the adjacent areas. It has been noted that the biomass and abundance of
fish within the AOC has decreased over recent years; however, this trend is also being observed
lakewide. In general, pelagic and transient fish prefer the open lake waters where the
temperatures are cooler, and as such, their presence in the nearshore waters of the AOC suggests
habitable conditions and an adequate food source.
Using the combination of data collected from the bottom-up and top-down approaches, it was
determined that there was little need to continue the assessment of the degradation of plankton
and zooplankton populations BUI.
4.2

Effluent Monitoring and Effluent Limits Regulations

The Municipal-Industrial Strategy for Abatement (MISA) was the backbone of nine Effluent
Monitoring and Effluent Limit Regulations (EMEL) (one for each industrial sector type)
developed under Ontario’s Environmental Protection Act in the early 1990s. The legislation
regulates the industrial discharges of contaminants into surface waters through setting loading
limitations for certain toxic substances, parameter and lethality limits, and monitoring schedules.
Within the areas originally identified as potentially being impacted (Kaministiquia River and the
inner Harbour) there are two industry sectors that fall under EMEL: pulp and paper sector, and
electric power generation sector. The effluent monitoring and effluent limits for the pulp and
paper sector are regulated under Ontario Regulation 760/93, and in this case include(d): Resolute
Forest Products (formerly Bowater Pulp and Paper Canada Inc.), Abitibi-Consolidated Inc., Fort
William Division (now closed), and Superior Fine Papers (formerly Cascades Fine Paper Group
Inc. – now closed). The electric power generation sector effluent monitoring and effluent limits
are regulated under Ontario Regulation 215/95 and captures Ontario Power Generation, Thunder
Bay Thermal Generating Station. The focus of this discussion will be on the active facilities:
Resolute Forest Products and Ontario Power Generation.

10
 

  

4.2.1 Toxicity Testing
According to the effluent monitoring and effluent limit regulations, the discharger shall control
the quality of the monitoring stream from the plant to ensure that the mortality that may result
from acute toxicity tests conducted on Daphnia magna and Rainbow Trout does not exceed 50%
in 100% effluent. Acute toxicity tests are conducted monthly, until which time twelve
consecutive passes (test not exceeding 50% mortality) is achieved; at this point acute toxicity
monitoring is conducted quarterly. In this assessment, data from all effluent control pipes were
consolidated on a monthly basis. Therefore, if a violation (fail) occurred at only one pipe, a
violation was still noted for that month.
Chronic toxicity tests are conducted semi-annually on Pimephales promelas (fathead minnow),
the zooplankton Ceriodaphnia dubia, and the phytoplankton Selenastrum capricornutum.
Growth inhibition is used as the measurement endpoint in the 7-day Fathead Minnow tests,
reproduction inhibition and survivability is used in the 7-day C. dubia test, and growth inhibition
is used as the endpoint in the 72-hr S. capricornutum toxicity test. The potential for impairment
is demonstrated by the IC25, which is defined as the concentration (% effluent) which causes a
25% inhibition of a specified endpoint. Chronic toxicity tests are only conducted when twelve
consecutive acute toxicity testing passes have been achieved.
4.2.1.1 Resolute Forest Products
Resolute Forest Products (and former companies) have had minimal acute toxicity
exceedences for Daphnia magna and Rainbow Trout for the sampling period of 2002 to
2015 (not all data before that time was readily available) (Figure 1A and 1B). In the past
three years there have been no toxicity failures in any of the monthly effluent samples.
Acute toxicity failures in previous years have been intermittent and generally have had a
specific reason (e.g., shutdown) (M. Holenstein, personal communication 2015). The
Environmental Officer at the Ministry of the Environment and Climate Change is advised
of all adverse test results and conducts an investigative follow-up.
At certain times, effluent from the combined-mill outfall has posed a potential for chronic
impairment to plankton. While the biannual results prove to be variable since 1997, the
last 1.5 years have shown very minimal to no risk of sub-lethal effects to plankton
populations (Figure 2A and 2B). There are no measureable chronic effects (growth)
observed with Pimephales promelas (fathead minnows) exposed to 100% effluent in the
laboratory (Figure 2C). The Aquatic Toxicology Unit with the Laboratory Services
Branch at the Ontario Ministry of the Environment and Climate Change will be reviewing
the chronic toxicity data in the near future.
Although the end-of-pipe effluent has been shown to have the potential to cause chronic
toxicity to C. dubia, it is noted that the Kaministiquia River has an assimilative capacity
that is capable of diluting the effluent to concentrations that do not inhibit growth or
reproduction (as measured by IC25) in the laboratory. XCG Consultants Ltd. (2005) ran
a CORMIX model showed that at average flow rates, the mill effluent was diluted to 7%
of the initial concentration in the near-field (13.5 m downstream of diffuser) and 4% at

11
 

  

A)

B)

Figure 1. Resolute Forest Products acute toxicity test results for A) Rainbow Trout
and B) Daphnia magna (1994 – 2015).

12
 

  

(A)

(B)

(C)

Figure 2. Resolute Forest Products chronic toxicity test results for A)
Ceriodapnia dubia, B) Selenastrum capricornutum, and C) Pimephales
promelas (1997 – 2015).

13
 

  

the river mouth. As such, based on available toxicity data (IC25 and confidence intervals) from
1997 to present day, it would be expected that there would be no inhibition of reproduction to C.
dubia in the near-field and beyond. The effluent has been proven to be more toxic to S.
capricornutum at times; however the IC25 has remained above 7% effluent since the latter half
of 2010.
4.2.1.2

Ontario Power Generation, Thunder Bay Thermal Generating Station
Two test control points are sampled at OPG to collect effluent for the assessment of
acute and chronic toxicity under EMEL regulation: the ash transport water treatment
plant (ATWTP - 200) and the oily water separator (OWS - 1100).
Acute toxicity tests on Daphnia magna and Rainbow Trout have been conducted on a
quarterly basis since 2007. Toxicity failures were noted in the early 1990s; however
there have been no violations reported in the past decade (data was scarce prior to
2006).
In the past decade there have been minimal incidences of chronic impairment to the
zooplankton Ceriodaphnia dubia and fathead minnows (Pimephales promelas) when
exposed to effluent from the two streams (Figure 3A and 3B). The chronic
impairments could not be explained; however where impairment was evident, there
was no impact on survival of the exposed organisms.

4.2.2
Loadings
Loading limits for each industrial sector were originally established in the respective EMEL
regulation. As per the regulation, the limits can be amended based on the reference production
rate. The company reports quarterly through the Ministry of the Environment Wastewater
System (MEWS) on specific parameters at different control points. In addition, an
Environmental Compliance Approval may establish stricter, receiver-based discharge and
loading limits; however the reporting requirements differ from the EMEL regulations.
4.2.2.1

Resolute Forest Products
Resolute Forest Products (and former companies) is (was) required to report on
loading values for adsorbable organic halides (AOX), toluene, biological oxygen
demand (BOD5), flow, phenol, total suspended solids (TSS), and chloroform. The
company also reported on dioxins and furans until 2006. Figures 4A, 4B, and 4C
show that generally the annual average loadings have decreased over the past decade
as a result of closures of certain components of the mill, namely a number of paper
machines, and one of the market kraft pulp mills. There have been no monthly
violations of the effluent loading limits since 2005.

4.2.2.2

Ontario Power Generation, Thunder Bay Thermal Generating Station
The Thunder Bay Generating Station is required, under the EMEL regulation, to
report on loading values for aluminum (Al), iron (Fe), TSS, solvent extractables (SE),
and flow. Figure 5 shows the annual average of loading levels of the reportable

14
 

  

(A) 

(B) 

Figure 3. Ontario Power Generation, Thunder Bay Thermal Generating Station
acute toxicity test results for A) Ceriodaphnia dubia and B) Pimephales promelas
(2006 – 2015).

15
 

  

A)

B)

C)

Figure 4. Loading levels (annual average) of regulated parameters (A) BOD5, TSS,
flow; B) TP, DOC, AOX; and C) toluene, phenol, and chloroform) at Resolute Forest
Products (1994-2015).
16
 

  

parameters from a plant level. There has been a decrease in the loadings of reportable
parameters (from a plant level) since the mid-1990s; a trend that can be mainly attributed
to decreased production rates over the past decade. There have been no monthly violations
of the effluent loading limits since 2006.

Figure 5. Loading levels (annual average) of regulated parameters Al, Fe, TSS, SE,
and flow at Ontario Power Generation, Thunder Bay Thermal Generating Station
(1994-2015).
4.2.3

Treatment Upgrades and Process Changes

4.2.3.1

Resolute Forest Products
The operation of Resolute Forest Products has changed substantially since the 1990s
(Table 1). In regards to effluent quality, the most significant treatment changes has been:
the installation of secondary treatment (kraft mill in 1993 and newsprint mill in 1995), the
switch to elemental chlorine free bleaching (100% chlorine dioxide) in 1994, and the
elimination of the sulphite mill, with the replacement of the thermo-mechanical pulp mill,
which is a cleaner technology.
Operational declines in the past decade, namely the reduction to one paper machine and
one market kraft pulp mill, has also been a major contributor to the improved effluent in
terms of both quality and quantity.

17
 

  

Table 1. Changes to Resolute Forest Product, and former companies, mill components
(1990-2014).
Mill Component
1990s
2000-2009
2010-2014
Paper machine

4 (no. 1 - 4)1,2
@ 1300 mt/day

3 (no. 3 – 5)3
@1500 mt/day

1 (no. 5)
@ 615 mt/day

Market Kraft pulp mill

2 (A and B)
@ 1600 mt/day

2 (A and B)4
@ 1600 mt/day

1 (B)
@1000 mt/day

Recycle plant

15

1

06

Thermo-mechanical pulp mill

17

1

1

1

no. 1 and 2 shut down in 1991
no. 5 started in 1991
3
no. 3 and 4 shut down in 2003 and 2009, respectively
4
mill A shut down in 2006
5
started in 1992
6
shut down in 2011
7
started in 1991
2

4.2.3.2

Ontario Power Generation, Thunder Bay Thermal Generating Station
Current knowledge suggests that there have been no treatment upgrades, or none of
significance, to either the ash transport water treatment plant or the oily water separator.
The most significant operational change to the plant was in 2014 when they ceased burning
coal.

4.3

Thunder Bay Water Pollution Control Plant Treatment Upgrades

The Atlantic Avenue Water Pollution Control Plant (WPCP) was expanded and retrofitted in 2005 to
become a secondary sewage treatment plant. The upgrade, which was a part of the City’s 1999
Pollution Prevention and Control Plan, included secondary treatment, phosphorus removal, sludge
digestion and dewatering, and a nitrification process to eliminate wastewater (City of Thunder Bay
2015). As shown in Table 2, the upgrade to the plant substantially improved the quality of the
effluent, with the biochemical oxygen demand (CBOD5) and total suspended solids (TSS) decreasing
by more than an order of magnitude. The 2015 annual average (based on data from the first half of
the year) concentrations of CBOD5, TSS, and TP were all below the effluent objectives outlined in
the WPCP’s Environmental Compliance Approval (Table 2). Effluent objectives are set for total
ammonia (NH3); however no effluent compliance limits are set for this parameter. The WPCP
reports on TKN, which decreased from an annual average of 21.3 mg/L in 2004 to 3.5 mg/L in 2015.

18
 

  

Table 2. Environmental Compliance Approval effluent objectives and limits, and effluent
concentrations pre- and post-treatment upgrade for the Atlantic Avenue Water Pollution
Control Plant.
Pre-upgrade
Effluent Objectives1
Effluent Limits2
2015 (1st half)3
(2004)3
Parameter
(mg/L)
(mg/L)
(mg/L)
(mg/L)
CBOD5
15.0
25.0
74.2
7.8
TSS
15.0
25.0
39.9
8.7
TP
0.5
1.0
0.96
0.4
1

the Owner shall use the best efforts to design, construct and operate the Works with the objective that the
concentrations do not exceed the specified value.
2
the Owner shall operate and maintain the Works such that the concentrations specified are not exceeded.
3
annual average

4.4

Industrial Closures

Since the designation of the AOC, there have been many changes to the industrial landscape of the
Kaministiquia River and inner Harbour. In the past, there were several significant industrial point
sources of contaminants and BOD loads into the receiving waters of this area of interest. The closure
of many of these industries has contributed to the improvement of the surface water and sediment in
the lower Kaministiquia River and inner Harbour (George 2012, Clerk et al. 2012). The most
significant point source dischargers on the Kaministiquia River that have ceased operation are:
Riverside Grain Products Inc. (formerly Olgilvie Mills Ltd.), Arclin Canada Ltd. (formerly Reichhold
Limited), and Abitibi Consolidated Inc. - Fort William Division (located at the mouth of the Mission
River). Within the inner Harbour, Northern Wood Preservers Inc., and Superior Fine Papers have
closed.
Riverside Grain Products Inc. (formerly Olgilvie Mills Ltd.), was located on the shore of the
Kaministiquia River, and produced wheat gluten and starch. Under the ownership of Olgilvie, the
mill operated from 1912 to 1996 (Turner and Francesca) and discharged via a bank outfall to the
river. Riverside Grain Products Inc. reopened the mill in 1998 and operated until its closure in 2000
(Turner and Francesca). The Certificate of Approval for the mill (dated 1985) allowed for a
discharge of 900 kg of BOD5/day. A study of the water quality of the lower Kaministiquia River in
1986 (Klose 1988) showed the effluent loads from the mill to have a high levels of BOD (478 mg/L),
suspended solids (1310 mg/L), and total phosphorus (117 mg/L). Additionally, three 24-hour
composites of effluent was collected and analyzed for over 120 organic and inorganic parameters.
Analysis results showed that 27 parameters exceeded the detection limits, and of that, 11 parameters
exceeded the applicable Ontario Provincial Water Quality Objectives. The 11 parameters that were
noted for further analysis included: heptachlor (12 - 42 ng/L); pp-DDE (120 ng/L); pp-DDD (25
ng/L); endosulfan II (58 ng/L); dieldrin (4 - 46 ng/L); endrin (22 ng/L); dehydroabietic acid (28
µg/L); iron (1.50 - 4.10 mg/L); manganese (0.33 – 0.71 mg/L); copper (0.15 – 0.34 mg/L); and zinc
(0.36 – 1.10 mg/L). According to 1986 measurements, the average effluent flow rate of the grain
mill (0.008 m3/s) was three orders of magnitude less than the upstream pulp and paper mill and the
WPCP; however the levels of BOD5, suspended solids, and TP were significantly higher.

19
 

  

Arclin Canada Ltd. produced adhesive resins that were used mainly in the manufacturing of
particleboard and oriented strandboard. Formerly Reichhold Limited, Neste Canada Inc. (19992001), and Dynea Canada Ltd. (2001-2007), the plant ceased operation in October 2009. Although
Reichhold was no longer discharging directly into the Kaministiquia River when the AOCs were
formed, it was recognized as one of the significant point sources in the 1986 study conducted by
Klose (1988). The average flow rate was low (0.004 m3/s) relative to the other point sources;
however inputs of BOD5 (29.4 mg/L), suspended solids (157 mg/L), and TP (2.05 mg/L) were
elevated.
The Fort William Division of AbitibiBowater Inc. (legal name Abitibi Consolidated Company of
Canada) was a pulp and paper mill that operated at the mouth of the Mission River. In 2000, the
allowable daily plant process effluent loading limits were: 4530 kg/day BOD5, 127 kg/day TP, and
6070 kg/day TSS. A 2005 study conducted by George (2012) measured the concentrations of TP and
TKN in the surface water at the mouth of the Mission River to be 0.047 mg/L and 0.41 mg/L,
respectively; the TP value exceeded the TP-PWQO. The mill was permanently closed in November
2007.
Northern Wood Preservers Inc. is located on the shore of the inner Harbour. For over 50 years,
creosoted wood products such as railway ties, telephone poles, and pentachlorophenol treated lumber
were produced at the site (Jaagumagi et al. 1998). Over time, elevated levels of polycyclic aromatic
hydrocarbons (PAHs), chlorophenols (CPs), and dioxins and furans (PCDD/Fs) accumulated in the
sediment adjacent to the plant (Santiago 2003). From 1997 to 2003 the contaminated sediments were
addressed through the Northern Wood Preservers Alternative Remediation Concept (NOWPARC).
The main objectives of NOWPARC were to isolate the contaminant source, remediate the
contaminated sediment, and to enhance fish habitat through the use of dredging, a rockfill
containment berm, contaminant isolation structures, storm water and groundwater control and
treatment, and fish habitat enhancements (Santiago et al. 2003). The end result of the remediation
effort was the removal, treatment, and reuse of 11 000 m3 of highly contaminated sediment;
containment of 21 000 m3 of contaminated sediment; isolation of the contaminated site; and the
creation of 5 ha of fish habitat (Inch and Santiago 2005). A long term monitoring plan was put in
place to measure natural recovery in the harbour area outside of the rockfill containment berm (Inch
and Santiago 2005).
Superior Fine Papers, a pulp and paper mill, was located on the shore of the inner north Harbour.
The mill was built in 1918 by Abitibi Price Inc, and operated for almost 90 years under different
owners. The mill changed hands three times since 2007, but has not been operational since then
(with the exception of four months in 2007). The current owner, Reliance Development Corporation,
is in the process of decommissioning the site. Canada and Ontario have committed to developing a
sediment management strategy for the North Harbour site under the 2014 Canada-Ontario
Agreement on Great Lakes Water Quality and Ecosystem Health. A significant amount of work has
been completed towards this strategy, including a risk assessment which concludes that the site poses
risks to human health and the environment. The risk assessment recommends a 9.9 hectare area for
active remediation, such as dredging or isolation capping, and a 15.8 hectare area for passive
remediation, such as thin-layer capping (Franz Environmental Inc. 2013). The final sediment
management options report recommends dredging and disposal at an existing confined disposal
facility as the preferred option (Cole Engineering Group Ltd. 2015). The federal government is the

20
 

  

lead for the project because the majority of the contaminated water lot is federally-owned (Transport
Canada), and administered by the Thunder Bay Port Authority.
4.5

Invasive Species Strategies

The Stage 1 and 2 Thunder Bay RAP documents (Thunder Bay Remedial Action Plan Team 1991,
2004) expressed concerns regarding the presence of the spiny water flea and zebra mussels. With
regard to invertebrates, the Lake Superior Aquatic Invasive Species Guide (Ontario Federation of
Anglers and Hunters 2014) has listed the spiny waterflea (Bythotrephes longimanus) as the only
invasive plankton identified in lake-wide in Lake Superior to-date. It was first identified in 1987
(Lake Superior Binational Program 2014) and was introduced via ballast water.
Fish communities in Lake Superior, both nearshore and offshore, have a diet primarily of the
macroinvertebrates Mysis and Diporeia (Gamble et al. 2011a, 2011b). In the lower lakes, Diporeia
populations have decreased as a result of the increased abundance of dreissenid mussels (Dermott
and Kerec 1997; Nalepa et al. 2007, Watkins et al. 2007); however this has not been the case in Lake
Superior due to the low biomass of dreissenids (Grigorovich et al. 2003). In Lake Superior, the
presence of dreissenids is confined to near shore areas, as the off-shore surface water is too cold to
support a viable population. As such, the populations of diet items such as Mysis and Diporeia are
not presently at risk.
The spiny water flea is predacious, feeding on native crustacean zooplankton such as Daphnia, and
therefore reducing food for other native zooplankton and small fishes (Lake Superior Binational
Program 2014). In terms of being prey, Bythotrephes is consumed mostly by larger juvenile and
adult fish (Keeler et al. 2015). Gamble et al. (2011a) found that presence of Bythotrephes in Lake
Superior has resulted in the incorporation of this species into the diet of some fish. In Gamble’s
study (2011a), it was determined, via stomach content, that an important component of the diet of
Cisco and Lake Whitefish in the late summer and fall was Bythotrephes. Offshore of Stockton Island
in the Apostle Islands Lakeshore in Lake Superior, Keeler et al. (2015) found that between
September and November, 1.4% and 839% of Bythotrephes production was consumed by small
Cisco and large Cisco, respectively, in the intermediate and offshore sites. Small Bloater and large
Lake Whitefish also consumed Bythotrephes (at a production rate) of 8% and 8.1%, respectively. In
the offshore area, the consumption rate exceeded the production rate in all observed instances;
however this ratio decreased towards shore where consumption was not observed. It was noted that
no Cisco were present in the nearshore area, and that consumption was observed at the nearshore site
in Lake Michigan (Keeler et al. 2015). From the perspective of controlling the Bythotrephes
populations, it would appear that Cisco could serve as a top-down control in some instances. That
being said, there are thought to be several factors that influence the dynamics of Bythotrephes –
depth, temperature, prey resources – and further research is required to fully understand this invasive
species (Keeler et al. 2015).
The food web configurations determined by Gamble et al. (2011a 2011b) were similar to other large,
stable oligotrophic systems. Based on the indications that food web complexity is positively
associated with community-level stability, it was assumed that the community-level stability of Lake
Superior was low given the low levels of food web complexity present (Gamble et al. 2011b).
However, Gamble et al. (2011b) applied the Quirk-Rupert sign-matrix for system stability to the
Lake Superior data and found that the organization of the food web was stable at the lower levels.
21
 

  

Schmidt et al. (2009) found that over the last century the food web of the native Lake Superior fish
community has remained stable and has been able to accommodate the introduction of non-native
fish species.
There are a number of programs, both provincially and federally, that address the prevention and
management of aquatic invasive species (AIS): Ontario Ministry of Natural Resources and Forestry Invasive Species Plan; federal – Invasive Alien Species Strategy for Canada; Canadian Council of
fisheries and Aquaculture Ministers – Canadian Action Plan to Address the Threat of Aquatic
Invasive Species. Specific to Lake Superior, the Lake Superior Partnership Working Group
developed the binational Lake Superior Aquatic Invasive Species Complete Prevention Plan (Lake
Superior Binational Program 2014) under the Lake Superior Lakewide Action and Management Plan.
In general the plan outlines recommendations for new actions, as well as promoting existing efforts,
to prevent invasive species from both entering and establishing in Lake Superior. Steps have been
taken towards fulfilling the actions outlined in the Complete Prevention Plan, specifically with regard
to early detection monitoring and prevention education.
5.0

Conclusions

The assessment of plankton populations and communities is complex. The complexity is magnified
when assessed within the confines of the AOC model, which uses a limited number of indicators
(BUIs) to define a plethora of issues, and Remedial Action Plans to direct remediation and/or
restoration. The limitations of this approach are clear in the Thunder Bay AOC, where issues such as
eutrophication and the introduction of invasive species were originally identified through the RAP
process. These issues must be addressed in some manner, and therefore the Degradation of
Phytoplankton and Zooplankton Populations BUI box gets checked at the onset of the program.
However, practioners do not always support a common assessment approach with regard to the
Degradation of Phytoplankton and Zooplankton Populations. Inconsistencies across AOCs existed
with the description of impairment, and have continued for two decades in both monitoring and
reporting efforts. The lack of consensus on the proper assessment of these issues, as well as the
absence of a defensible baseline prior to determination of BUI status, has made it difficult to properly
assess the status of this BUI.
This report deviated from the approaches previously taken to assess the plankton BUI and
investigated the current status of the issues that were originally identified as cause for the plankton
population degradation. Different lines of evidence were examined in depth to provide a status
determination on this BUI. Currently the status of the BUI is requires further assessment.
The nearshore of the Thunder Bay AOC, which includes the Kaministiquia River, is industrialized
and urbanized, and there are many possible sources of nutrients and contaminants. To add to the
complexity of this environment, the receiving Lake Superior is oligotrophic and cold, which makes it
physically and chemically different from the other select lower Great Lake AOCs that have the
plankton BUI listed as impaired or requiring further assessment. There have been several studies
which have characterized the nearshore and offshore zones of Thunder Bay (Hopkins 1986, Simpson
1987, Anderson 1986, Boyd 1990, Richman 2004, Benoit et al. 2012, George 2012). This assessment
focused mainly on the nearshore zone of the Thunder Bay AOC, as the plankton would be most likely
influenced by anthropogenic inputs in this area. Generally the aforementioned studies found the
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nutrient levels to be highest in the delta area of the Kaministiquia River, where in most cases, the TP
levels exceed the TP-PWQO (20 µg/L in lakes and 30 µg/L in rivers). Despite the elevated levels of
TP, nuisance algae has not been reported during the monitoring surveys, which is likely due to the
capacity of the Lake to dilute concentrations of TP below the level that would cause algal blooms.
There continues to be three main point sources of nutrients and contaminants to the Thunder Bay
AOC: Resolute Forest Products and Ontario Power Generation, Thunder Bay Thermal Generating
Station, and the Thunder Bay Water Pollution Control Plant. The inputs from Resolute Forest
Products and Ontario Power Generation, which are regulated through the Municipal-Industrial
Strategy Abatement regulations and Environmental Compliance Approvals, have had no monthly
violoations of loading limits since the mid-2000s. In fact, treatment upgrades and/or decreased
production rates over time have resulted in a significant decrease in loading levels. Secondary
treatment upgrades to the Thunder Bay Water Pollution Control Plant, which is regulated through
Environmental Compliance Approvals, have substantially improved the quality of effluent. In
addition to the decrease in loading from operating industries, there have been several significant point
source contributors that have closed in the past decade and beyond, further improving the quality of
the receiving environment.
Toxicity is an indicator that is often used to assess the quality of the effluent. Resolute Forest
Products and Ontario Power Generation are both required, under MISA regulations, to conduct acute
and chronic toxicity tests at identified control points on a specified schedule (dependent upon
previous results). Currently, there is minimal cause for concern with respect to the effluent streams at
Ontario Power Generation. There have been no acute toxicity violations since 2006, and very seldom
are the potential for chronic effects observed at concentrations less than 100% effluent. With respect
to Resolute Forest Products, there has been minimal acute toxicity over the sampling period of 2002
to 2015. Where violations (failures) did occur, they were most often due to a specific operational
change (e.g., shutdown). Prior to the past year and a half, effluent from the combined-mill outfall has
posed a potential for chronic impairment to plankton; current data does not indicate a potential for
chronic toxicity. It is noted that the assimilative capacity of the Kaministiquia River (XCG
Consultants Ltd. 2005) is such that, based on available present day chronic toxicity data, there would
be no chronic impact to plankton at a distance in excess of 13.5 m downstream from the diffuser.
A high-level generalized view of the status of the planktonic trophic level employed a top-down and
bottom-up approach (Benoit et al. 2012). Although the approach was not uniformly supported by all
technical experts, it provided a pragmatic screening level assessment of the issue. From the bottomup, it was shown that the study area was not phosphorus limited, and that chlorophyll-a
concentrations were not likely to result in undesirable levels of algae (Benoit et al. 2012). From the
top-down, current data (Foster 2012, Marshall 2015) suggests that the Thunder Bay AOC supports a
more diverse fish community than adjacent areas. This screening level top-down, bottom-up
approach concluded that there was no basis to recommend a full plankton assessment.
One of the primary issues of concern with regard to this BUI was the introduction of aquatic invasive
species, specifically the zebra mussel and the spiny water flea (Thunder Bay RAP 1991, 2004).
Dreissenid mussels (which include zebra mussels) are not wide-spread through Lake Superior due to
the cold water temperatures; however they are present in specific nearshore areas, including Thunder
Bay. Fish communities in Lake Superior, both nearshore and offshore, are primarily supported by a
diet of Mysis and Diporeia. In the lower Great Lakes, these populations of these macroinvertebrates
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have declined as a result of the abundance of dreissenid mussels; given the physical constrictions this
has not been the case in Lake Superior. With respect to the spiny water flea (Bythotrephes), there are
limited studies that have been conducted in Lake Superior and further research is required to fully
understand this invasive species. Trophic food web studies (Gamble et al. 2011a, Gamble et al.
2011b, Keeler et al. 2015) have shown that some fish species, predominantly Cisco, have
incorporated Bythotrephes into their diet. In specific cases, this adopted feeding behaviour may serve
as a top-down control of the invasive population (Keeler et al. 2015). Overall, based on the food web
configuration at a low level of prey diversity, there is system stability (Gamble et al. 2011b).
Regardless of the indications of adaption to the invasive species, the issue is a top priority and there
are a number of provincial, federal, and binational initiatives that focus on monitoring and prevention.
In conclusion, the assessment of the key factors that influence the health of the plankton population
has demonstrated that there is no reason to suspect impairment of the plankton community within the
AOC. The industrial landscape of the Thunder Bay AOC has changed substantially since the
inception of the RAP program, and concerns of nutrient and contaminant loading are no longer as
significant an issue they once were. The assimilative capacity of the large Kaministiquia River and
receiving oligotrophic Lake Superior have provided an environment that is not prone to algal blooms,
and which supports a healthy fish population. At this time, it is recommended that the ‘requires
further assessment’ status of the Degradation of Phytoplankton and Zooplankton Populations BUI be
removed from the Thunder Bay AOC. The lower food web of the lake, as a whole, will continue to
be assessed through the Lake Superior Partnership by way of the Coordinated Science and
Monitoring Initiative.

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6.0

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