HomeMy Public PortalAboutFox Point Lake Water Quality Monitoring Report 2017
Fox Point Lake
2017 Water Quality Monitoring Report
Prepared for
Municipality of the District of Chester
Water Quality Monitoring Committee (Mill Cove)
By
Bluenose Coastal Action Foundation
37 Tannery Road, PO Box 730
Lunenburg, N.S.
B0J 2C0
February 2018
Table of Contents Page
1. Introduction………………………………………………………………………………………………………………………………………… 1
1.1 Project Background………………………………………………………………………………………………………………………… 1
1.2 Review of the 2016 Fox Point Lake Water Quality Monitoring Report……………………………………………. 4
1.3 Changes to the 2017 Fox Point Lake Water Quality Monitoring Program……………………………………….. 4
1.4 Aspotogan Ridge Golf Course Visit…………………………………………………………………………………………………. 5
2. Water Quality Monitoring Results……………………………………………………………………………………………………….. 5
2.1 Algae Bloom in Fox Point Lake……………………………………………………………………………………………………….. 5
2.2 Trophic State of Fox Point Lake………………………………………………………………………………………………………. 6
2.3 Thermal Stratification of Fox Point Lake…………………………………………………………………………………………. 8
2.4 Sediment Sampling in Fox Point Lake (southwest cove) and the South Inlet Stream………………………. 12
2.5 Water Temperature……………………………………………………………………………………………………………………….. 14
2.6 Dissolved Oxygen…………………………………………………………………………………………………………………………… 16
2.7 pH………………………………………………………………………………………………………………………………………………….. 17
2.8 Total Dissolved Solids…………………………………………………………………………………………………………………….. 19
2.9 Total Suspended Solids…………………………………………………………………………………………………………………… 20
2.10 Total Phosphorus…………………………………………………………………………………………………………………………. 21
2.11 Total Nitrogen……………………………………………………………………………………………………………………………… 23
2.12 Fecal Coliform Bacteria………………………………………………………………………………………………………………… 24
2.13 Precipitation and Lake Water Level………………………………………………………………………………………………. 25
2.14 Stream Discharge…………………………………………………………………………………………………………………………. 26
3. Time Series Data from 2015 to 2017……………………………………………………………………………………………………. 28
4. Discussion……………………………………………………………………………………………………………………………………………. 30
5. Recommendations………………………………………………………………………………………………………………………………. 32
References………………………………………………………………………………………………………………………………………………. 33
List of Figures
Figure 1 – Map of the Fox Point Lake drainage basin and four water quality monitoring sites…………………. 3
Figure 2 – Formulas used for the calculation of three Trophic State Indices and the TSI scores
for 2017……………………………………………………………………………………………………………………………………… 7
Figure 3 – Thermal stratification of a water column with three layers of varying densities
and temperatures………………………………………………………………………………………………………………………. 8
Figure 4 – Thermal stratification represented by dissolved oxygen/water temperature depth
profile curves……………………………………………………………………………………………………………………………… 9
Figure 5 – Common dissolved oxygen depth profiles observed in thermally stratified lakes……………………. 10
Figure 6 – Dissolved oxygen/water temperature depth profiles in Fox Point Lake in 2017………………………. 11
Figure 7 – Water temperature at four FPL sample sites from May to October 2017………………………………… 15
Figure 8 – Dissolved oxygen concentrations at four FPL sample sites from May to October 2017……………. 17
Figure 9 – pH results at four FPL sample sites from May to October 2017……………………………………………….. 18
Figure 10 – Total dissolved solids at four FPL sample sites from May to October 2017……………………………. 20
Figure 11 – Total phosphorus concentrations at four FPL sample sites from May to September 2017…….. 22
Figure 12 – Total nitrogen concentrations at four FPL sample sites from May to September 2017………….. 24
Figure 13 – Precipitation and water level at Fox Point Lake from June to October 2017………………………….. 26
Figure 14 – Stream discharge rates at three FPL sample sites from May to October 2017……………………….. 27
Figure 15 – Time series data for key water quality parameters at four FPL sample sites from
2015 to 2017………………………………………………………………………………………………………………………………. 29
List of Tables
Table 1 – Mean and range values for key parameters from the Lake sample site in Fox Point Lake
from May to October 2017…………………………………………………………………………………………………………. 6
Table 2 – Mean and range values associated with trophic levels in lakes…………………………………………………. 7
Table 3 – TSI scores for Secchi disk (SD), chlorophyll a (CHL), and total phosphorus (TP) for the Lake
sample site in Fox Point Lake from 2015 to 2017……………………………………………………………………….. 7
Table 4 – Orthophosphate and phosphorus in sediment at the South Inlet sample site and the
Southwest Cove sample site on October 31, 2017……………………………………………………………………… 13
Table 5 – Metals in sediment at the South Inlet sample site on October 31, 2017, and Nova Scotia
Environmental Quality Standards for Sediments………………………………………………………………………… 14
Table 6 – Mean and minimum summer dissolved oxygen concentrations from July to September
2017, with 2015 and 2016 results for comparison……………………………………………………………………… 16
Table 7 – Mean and minimum pH results from May to October 2017, with 2015 and 2016 results for
comparison………………………………………………………………………………………………………………………………… 18
Table 8 – Total dissolved solids from May to October 2017, with 2015 and 2016 results for
comparison………………………………………………………………………………………………………………………………… 19
Table 9 – Total suspended solids (mg/L) from May to October 2017……………………………………………………….. 21
Table 10 – Mean and maximum total phosphorus concentrations from May to September 2017,
with 2015 and 2016 results for comparison……………………………………………………………………………….. 22
Table 11 – Mean and maximum total nitrogen concentrations from May to September 2017,
with 2015 and 2016 results for comparison……………………………………………………………………………….. 23
Table 12 – Fecal coliform (cfu/100 mL) results at four FPL sample sites from May to October 2017……….. 25
Table 13 – Mean and range stream discharge rates from May to October, with 2015 and 2016
results for comparison……………………………………………………………………………………………………………….. 27
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1. Introduction
1.1 Project Background
In 2014, the Municipality of the District of Chester created the Fox Point Lake Water Quality
Monitoring Committee to monitor the health of Fox Point Lake (FPL). Residents of the lake have
expressed concerns about the potential water quality impacts from a large development
project within the lake’s catchment area. The development, Aspotogan Ridge, is a 550-acre
family lifestyle community which includes over 350 residential units and an 18-hole golf course.
At the onset of golf course construction, the residents of FPL observed several sedimentation
plumes entering the lake through the southern inlet stream following periods of rainfall and
overland run-off, leading to concerns over the impacts of the development project on the
health of the lake and its drainage basin.
In 2015, Coastal Action was contracted by the Municipality of the District of Chester to work
with the Fox Point Lake Water Quality Monitoring Committee on the development of a
monitoring program which would document water quality conditions and track any changes in
the health of the lake over the course of the development project. Coastal Action has trained a
small, dedicated group of volunteers to conduct various monitoring activities at the lake with
the support of the Coastal Action Project Manager. A description of the monitoring program
can be found in the Fox Point Lake Water Quality Monitoring Program (2015) and results from
the first two years of monitoring can be found in the Fox Point Lake Water Quality Monitoring
Report (2015) and in the Fox Point Lake 2016 Water Quality Monitoring Report, all available on
request from the Municipality of the District of Chester.
The goals and objectives of the monitoring program remain unchanged from those stated in
2015 and are as follows:
Program Goals:
1. Establish a baseline of the water quality conditions and trophic status of Fox Point Lake
based on an initial monitoring period of May-October 2015, with the understanding that
conditions may already be degraded to a certain degree as a result of development
activities.
2. Monitor the water quality conditions and trophic status of Fox Point Lake throughout the
course of the multi-year Aspotogan Ridge development project.
Program Objectives:
a) Monitor various biological, chemical, and physical water quality parameters in Fox
Point Lake to establish a baseline of these indicators and track any changes as a result of
development.
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b) Determine the current trophic status of Fox Point Lake based on results of the initial
monitoring period (May-October 2015), using the following key parameters: total
phosphorus, total nitrogen, chlorophyll a, and Secchi disk depths.
c) Monitor the trophic status of Fox Point Lake throughout the course of development for
signs of cultural eutrophication.
d) Monitor the water depth of Fox Point Lake throughout the course of development as
an indicator of sediment in-filling or altered drainage basin hydrology.
e) Monitor precipitation amounts throughout the course of development to track local
rainfall patterns and the severity of associated siltation events in Fox Point Lake.
f) Monitor stream flow discharge in two inlet streams and one outlet stream of Fox Point
Lake throughout the course of development as an indicator of altered hydrology within
the drainage basin.
g) Monitor and document siltation events and algal blooms occurring in Fox Point Lake
throughout the course of development.
h) Monitor thermal stratification of Fox Point Lake by conducting temperature/
dissolved oxygen profiles to track the influence of increased nutrient loading on the
algal and dissolved oxygen conditions of the lake.
Fox Point Lake, the largest lake on the Aspotogan Peninsula at 1.4 km², is long and shallow with
11 small islands and an average depth of 4.9 m (Beanlands, 1980). The lake has a drainage area
of 8 km², with two inlet streams and one outlet. The northern inlet drains a heavily forested
area and flows through a wetland before entering FPL, while the southern inlet flows through
the Aspotogan Ridge development site draining the southern end of the lake’s drainage basin. A
single outlet stream flows out of the southeast corner of the lake draining directly into St.
Margaret’s Bay.
The Fox Point Lake Water Quality Monitoring Program was designed to be carried out primarily
by volunteer lake residents, with the assistance of the Coastal Action Project Manager. Easily
accessible sample sites were chosen which would allow volunteers to monitor the conditions of
the north and south inlet streams, the outlet stream, and within the lake itself. A monitoring
station was established on a volunteer’s property where water level and rainfall amounts were
recorded daily (see Fig. 1).
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Figure 1 – Map of the Fox Point Lake drainage basin and four water quality monitoring sites.
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1.2 Review of the 2016 Fox Point Lake Water Quality Monitoring Report
Residents of Fox Point Lake reported that the water clarity was better than they had seen for
many years during the summer of 2016. Nova Scotia, in particular the southwestern region of
the province, experienced a severe drought during the summer of 2016, which meant there
were very few rainfall events carrying run-off (as well as sediment, nutrients, bacteria, and
other contaminants) into streams and lakes. No construction activity took place at the
Aspotogan Ridge development site during the 2016 monitoring period and the golf course was
not active.
The trophic status of FPL was determined to be oligotrophic and approaching mesotrophic in
both 2015 and 2016, meaning that there had not been any major change in the biological
productivity of the lake between 2015 and 2016.
Thermal stratification was monitored at two locations in the lake in 2016, with both sites
displaying dissolved oxygen depletion at concentrations < 3 mg/L in the bottom waters of the
lake.
An algae bloom occurred in June of 2016 and water sample analysis confirmed the presence of
microcystin-LR, which is a toxin produced by cyanobacteria. The confirmation of cyanobacterial
toxins in FPL highlights the need for residents to be aware of the risks associated with algae
blooms and informed as to the proper precautions to take during a bloom.
Nutrients (phosphorus and nitrogen) were found to exceed water quality guidelines at the
South Inlet sample site only, which is consistent with the 2015 monitoring results. The south
inlet stream appears to be suffering from excessive nutrient loading.
1.3 Changes to the 2017 Fox Point Lake Water Quality Monitoring Program
In 2016, two lake sites were monitored for thermal stratification. Results indicated that there
was little variation between these two sites and the monitoring of this second lake site added a
significant amount of sampling time for volunteers; therefore, the second lake site was
removed from the program for the 2017 monitoring season.
Phosphorus and nitrogen concentrations in the south inlet stream have indicated that this
stream suffers from anthropogenic sources of excessive nutrient loading. Additional monitoring
activities were recommended for this stream, which included the collection of a sediment
sample from the stream bottom and an assessment of stream conditions along the entire
length of the stream. This assessment included a visit to the Aspotogan Ridge Golf Course.
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1.4 Aspotogan Ridge Golf Course Visit
On October 4, 2017, two Coastal Action staff members were given a tour of the golf course
grounds by Ged Stonehouse, owner of the Stonehouse Golf Group and Project Coordinator for
the new owners of the Aspogotan Ridge development project. The purpose of this visit was to
investigate the conditions of the stream that flows through the development site and into the
southwest cove of Fox Point Lake. A full stream assessment, including in-stream and riparian
health assessments and habitat measurements, was not performed; however, in-situ water
quality parameters were assessed at several locations along the stream using a YSI Professional
Plus water meter. Results of these spot-tests were consistent with the water quality conditions
observed downstream of the golf course at the South Inlet sample site, with the most notable
result being low dissolved oxygen concentrations in many spots.
The majority of the stream’s riparian habitat, as it runs through the golf course property, has
been maintained as a good quality buffer zone between the golf course greens and the stream
itself. Several sediment control measures were noted in areas of potential overland run-off,
which is important for the protection of the stream from sedimentation issues in the future as
development continues.
2. Water Quality Monitoring Results
The following section provides an analysis of the 2017 monitoring program. Several water
quality parameters will be compared to guidelines which have been established by the
Canadian Council of Ministers of the Environment (CCME), Health Canada, or through other
research bodies.
As in the summer of 2016, the Aspotogan Ridge development project was not active during the
2017 monitoring period and residents of FPL did not report any visible impacts on water quality
in the lake (sedimentation plumes) near the south inlet stream or any other locations in the
lake. The 2017 monitoring period began on May 25 and ended on October 31, comprising a
total of 10 sampling days.
2.1 Algae Bloom in Fox Point Lake
An algae bloom was observed in Fox Point Lake on June 13, 2017. A water sample was collected
in a laboratory-certified bottle by a member of the FPL volunteer group, delivered to Maxxam
Analytics laboratory in Bedford, then shipped to Nautilus Environmental laboratory in Calgary,
Alberta for analysis of microcystin-LR, a cyanobacteria (blue-green algae) toxin.
Analysis of this sample indicated a concentration of microcystin-LR of 0.71 µg/L. This
concentration is lower than that found in the sample collected last year on June 22, 2016 during
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an algae bloom (microcystin-LR of 1.25 µg/L). Both samples displayed concentrations which fell
below the drinking water guideline for microcystin-LR which is 1.5 µg/L (Health Canada, 2010).
There is no simple method to distinguish a toxic bloom from a non-toxic bloom; therefore,
every algal bloom which occurs in a waterbody should be treated with caution. Cyanobacteria
toxins can persist in a waterbody for several weeks after a visible bloom has dissipated.
Exposure to these toxins occurs most often through the consumption of drinking water;
however, minor exposure can occur through recreational activities and domestic water uses.
Inadvertent ingestion of water or skin contact through recreational activities can, in rare cases,
result in headache, fever, vomiting, skin and eye irritation, muscle pain, and weakness (WHO,
2003; Federal-Provincial-Territorial Committee on Drinking Water, 2002).
2.2 Trophic State of Fox Point Lake
Trophic state describes the biological productivity of a waterbody and can be used as a
benchmark from which to assess changes in the health of a lake due to anthropogenic activities
within the lake and its drainage basin. Oligotrophic lakes have low productivity and relatively
pristine conditions, mesotrophic lakes display moderate biological productivity, while eutrophic
lakes exhibit high densities of plant biomass and high productivity. The natural, long-term
process of waterbodies progressing from lower trophic states to higher ones is termed
eutrophication; whereas, cultural eutrophication refers to an acceleration of this process
towards higher trophic states due to anthropogenic activities within the drainage basin of a
waterbody. Symptoms of cultural eutrophication include excessive nutrient loading, increased
growth of rooted aquatic plants and algae, and low dissolved oxygen (Brown & Simpson, 1998;
Brylinsky, 2004).
Trophic state is determined through the analysis of key water quality parameters: total
phosphorus, total nitrogen, chlorophyll a, and Secchi disk depth. Results for these parameters
are compared to means and ranges established by Vollenweider and Kerekes (1982) as well as
entered into formulas for the calculation of the Carlson Trophic State Index (TSI) (Carlson,
1977).
Table 1 – Mean and range values for key parameters from the Lake sample site in Fox Point Lake from
May to October 2017.
Total Phosphorus
(µg/L)
Total Nitrogen
(µg/L)
Chlorophyll a
(µg/L)
Secchi Disk Depth
(m)
Mean 7.0 236.2 1.97 2.71
Range 5.0 – 10.0 213.0 – 276.0 0.98 – 3.31 2.03 – 3.72
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Table 2 – Mean and range values associated with trophic levels in lakes (Brown & Simpson, 1998).
Comparing the means and ranges for these key parameters from FPL in 2017 (see Table 1) to
those established by Vollenweider and Kerekes (1982) (see Table 2) identifies the trophic state
of FPL as oligotrophic and approaching mesotrophic. Further analysis using the Carlson Trophic
State Index will provide numerical scores which can be compared from one year to the next.
Secchi disk: TSI(SD) = 60 – 14.41 ln(SD) TSI(SD) = 45.5
Chlorophyll a: TSI(CHL) = 9.81 ln(CHL) + 30.6 TSI(CHL) = 37.3
Total phosphorus: TSI(TP) = 14.42 ln(TP) + 4.15 TSI(TP) = 32.2
(ln = natural log)
Figure 2 – Formulas used for the calculation of three Trophic State Indices and the TSI scores for 2017.
Table 3 – TSI scores for Secchi disk (SD), chlorophyll a (CHL), and total phosphorus (TP) for the Lake
sample site in Fox Point Lake from 2015 to 2017.
2015 2016 2017
TSI (SD) 49 45.7 45.5
TSI (CHL) 34 41.5 37.3
TSI (TP) 37 31.8 32.2
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TSI scores less than 40 indicate an oligotrophic lake, while mesotrophic lakes display TSI scores
between 40 and 50, and eutrophic lakes have TSI scores greater than 50. Priority is often given
to the TSI score for chlorophyll a as it provides the most accurate prediction of algal biomass
and biological productivity (Brown & Simpson, 1998).
Using the TSI scores for both chlorophyll a and total phosphorus, Fox Point Lake is classified as
an oligotrophic lake. The TSI scores for Secchi disk depth fall within the mesotrophic range;
however, Secchi depths can be influenced by more than just biological productivity levels, such
as sediment, silt, and other suspended particles in the water column (NSSA 2014; EPA 2002).
The trophic state of Fox Point Lake has held steady from 2015 to 2017 in the range of
oligotrophic approaching mesotrophic, meaning that the lake displays low to moderate
biological productivity.
2.3 Thermal Stratification of Fox Point Lake
Thermal stratification of a waterbody involves the separation of the water column into layers of
different densities based on changing water temperatures. Spring turnover occurs when water
temperatures are consistent from top to bottom, and wind and currents draw dissolved oxygen
into bottom waters and pull nutrients to the surface. As surface water warms in early summer,
three density layers begin to form in the water column. The epilimnion is the warm surface
layer where wind circulates water, adding dissolved oxygen. The metalimnion, or thermocline,
displays rapid changes in water temperature with depth. The hypolimnion is the bottom layer
consisting of the coldest, densest water (see Fig. 3).
Figure 3 – Thermal stratification of a water column with three layers of varying densities and
temperatures (Chowdhury et al., 2014).
There is little to no mixing between these layers of water, which means that the hypolimnion
no longer receives dissolved oxygen from the surface once stratification is established. This
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finite supply of oxygen can be depleted over the course of the summer as organic material sinks
to the bottom and microbial decomposition uses the available oxygen to break this material
down. This can lead to hypoxic (<2 mg/L dissolved oxygen) or anoxic (<1 mg/L dissolved oxygen)
conditions in the bottom waters and a decreased ability to support aquatic life (USGS 2014;
Brylinsky, 2004).
Thermal stratification breaks down with fall turnover, when water temperatures once again
become uniform from top to bottom. This allows water to mix and replenish the bottom waters
with dissolved oxygen (see Fig. 4).
Figure 4 – Thermal stratification represented by dissolved oxygen/water temperature depth profile
curves (Wetzel, 2001).
There are four types of dissolved oxygen depth profile curves that can be observed during
thermal stratification, depending on the trophic state of a waterbody (see Fig. 5). Orthograde
profiles occur in oligotrophic lakes when dissolved oxygen concentrations increase in the
hypolimnion (bottom layer). Clinograde profiles occur in mesotrophic and eutrophic lakes when
dissolved oxygen concentrations decrease in the hypolimnion due to microbial decomposition.
Heterograde profiles occur when dissolved oxygen concentrations change at unlikely depths.
Negative heterograde profiles display low dissolved oxygen concentrations in the thermocline
due to an accumulation of decomposing organic material caught in the density boundary.
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Positive heterograde profiles display high dissolved oxygen concentrations in the thermocline,
usually due to a high concentration of photosynthesizers at that depth (Mackie, 2004).
Figure 5 – Common dissolved oxygen depth profiles observed in thermally stratified lakes (Mackie,
2004).
Depth profiles were conducted at the Lake sample site from May 25 to October 31 in 2017 (see
Fig. 6). Thermal stratification was established in the lake at some point between the June 11
and June 28 sampling days, with an initial thermocline depth of approximately 4 m. Throughout
the months of July and August, dissolved oxygen concentrations displayed negative
heterograde profiles, meaning there was likely an accumulation of organic material in the
thermocline and microbial decomposition was consuming dissolved oxygen at that depth.
Dissolved oxygen concentrations in the hypolimnion consistently fell below the CCME Guideline
for the Protection of Aquatic Life for cold-water species (≥ 6.5 mg/L) from July until October.
There appears to have been a partial breakdown of stratification around September 13 with
both the water temperature and dissolved oxygen curves staying consistent from the surface to
a depth of 14 m. This partial breakdown of stratification was not enough to cause mixing with
the bottom hypolimnion layer as dissolved oxygen concentrations remained very low in
September and October. Dissolved oxygen concentrations dropped as low as 1.3 mg/L in
September and October; whereas, the lowest concentration observed in 2016 was 2.7 mg/L.
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Figure 6 – Dissolved oxygen/water temperature depth profiles in Fox Point Lake in 2017.
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2.4 Sediment Sampling in Fox Point Lake (southwest cove) and the South Inlet Stream
Sediment samples were collected from the stream bottom at the South Inlet sample site and
from the lake bottom in the southwest cove of Fox Point Lake (UTM Zone 20T 414024 E,
4938846 N) on October 31, 2017 using an Ekman dredge sampling device. This sampling device
collected sediment to a depth of 10-15 cm. The sediment sample collected from the South Inlet
sample site was analyzed for a full suite of metals, as well as phosphorus and orthophosphate,
while the sediment from the Southwest Cove sample site was analyzed for phosphorus and
orthophosphate only (see Table 4). Due to laboratory error, phosphorus concentrations in the
overlying water column were not analyzed on October 31, 2017.
Sediment sampling was recommended for these sites due to the severe sedimentation run-off
events that occurred during the initial construction activities at the Aspotogan Ridge
development site, which coincided with large sediment plumes flowing through the south inlet
stream and into Fox Point Lake. The south inlet stream suffers from excessive nutrient loading
and a significant degree of sedimentation. The southwest cove of FPL is the location where the
south inlet stream enters the lake and where sedimentation plumes were most severe. This
cove is likely the area where much of this sediment would have settled to the lake bottom.
Determining phosphorus concentrations in these bottom sediments is necessary to understand
the potential for internal phosphorus loading (phosphorus release from sediment) in the south
inlet stream and FPL, which can contribute to eutrophication, anoxic conditions, and algae
blooms.
When phosphorus enters an aquatic environment, it undergoes several complex
transformations which are influenced by the physical, biological, and chemical conditions of
that aquatic system. This process is called phosphorus cycling and involves the uptake and
release of phosphorus from sediments and the continuous conversion of phosphorus between
inorganic, organic, dissolved, and particulate forms (Howell, 2010; Brylinsky, 2004). Phosphorus
occurs in four forms in an aquatic environment: dissolved inorganic phosphorus (DIP), dissolved
organic phosphorus (DOP), particulate inorganic phosphorus (PIP), and particulate organic
phosphorus (POP) (Reddy et al., 1999). The dissolved inorganic form of phosphorus (DIP), also
called orthophosphate, is the bioavailable form and the only form which plants are able to
assimilate. Because orthophosphate is taken up by plants so quickly, it tends to be present in
lower concentrations compared to other forms. Once assimilated by plants, orthophosphate
transforms into the particulate phosphorus form, which constitutes the largest proportion of
total phosphorus in an aquatic environment. When this plant material dies and decomposes,
phosphorus is released back into the environment as the bioavailable orthophosphate form
(CCME, 2004; Howell, 2010).
The retention capacity of a stream refers to its ability to remove phosphorus from the water
column and transform it into non-bioavailable forms, thus decreasing the phosphorus loading
of downstream waterbodies. Retention depends on many factors including stream velocity,
water depth, the assimilation of phosphorus into vegetation, microorganisms, and sediment,
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and the concentration of elements with the capacity to bind and release phosphorus (Abu-
Hmeidan et al., 2018). Anoxic conditions can facilitate the release of sediment-bound
phosphorus from complexes with metals such as iron, aluminum, and magnesium through
oxidation reduction processes (Hayes et al., 1985). In addition, phosphorus can be rapidly
released from sediment and transported downstream during high-flow storm events (Reddy et
al., 1999; Brylinsky, 2004).
The South Inlet sample site displayed a phosphorus concentration of 460 mg/kg and an
orthophosphate concentration of 0.51 mg/kg, meaning that orthophosphate constitutes just
0.11 % of the total phosphorus load in the stream sediment. Elevated concentrations of
aluminum and iron in the sediment from the South Inlet sample site suggest that a significant
proportion of the non-bioavailable phosphorus may be complexed with metals (see Table 5).
The Southwest Cove sample site displayed a phosphorus concentration of 850 mg/kg and an
orthophosphate concentration of 0.17 mg/kg, with orthophosphate constituting 0.02% of the
total phosphorus load in the lake sediment. This indicates that orthophosphate is being rapidly
assimilated by aquatic plants and that the majority of the phosphorus load in the sediment is
comprised of other non-bioavailable forms.
Ontario’s Provincial Sediment Quality Guidelines have established a guideline for total
phosphorus in sediment for the protection of the aquatic environment. This guideline is set at a
‘lowest effect level’ of 600 mg/kg, and a ‘severe effect level’ of 2,000 mg/kg. Lowest effect level
represents clean to marginally polluted sediment which can be tolerated by sediment-dwelling
aquatic organisms, while the severe effect level represents heavily contaminated sediment
which is detrimental to most sediment-dwelling aquatic organisms (Ontario MOE, 2008).
The total phosphorus concentration in the South Inlet sample site sediment falls below the
lowest effect level of 600 mg/kg, while the Southwest Cove sample site sediment falls within
the range of 600-2000 mg/kg, closer to the lowest effect level end of the guideline spectrum.
Table 4 – Orthophosphate and phosphorus in sediment at the South Inlet sample site and Southwest
Cove sample site on October 31, 2017.
South Inlet site Southwest Cove
Fox Point Lake
Orthophosphate in sediment
(mg/kg)
0.51 0.17
Acid extractable phosphorus in
sediment (mg/kg)
460 850
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Table 5 – Metals in sediment at the South Inlet sample site on October 31, 2017, and Nova Scotia
Environmental Quality Standards for Sediments (NSE, 2014).
Metals (in soil) Units South Inlet site N.S. Freshwater Sediment
Quality Standards (mg/kg)
RDL (mg/kg)
Acid Extractable Aluminum (Al) mg/kg 4400 - 10
Acid Extractable Antimony (Sb) mg/kg ND 25 2.0
Acid Extractable Arsenic (As) mg/kg 7.9 17 2.0
Acid Extractable Barium (Ba) mg/kg 30 - 5.0
Acid Extractable Beryllium (Be) mg/kg ND - 2.0
Acid Extractable Bismuth (Bi) mg/kg ND - 2.0
Acid Extractable Boron (B) mg/kg ND - 50
Acid Extractable Cadmium (Cd) mg/kg ND 3.5 0.30
Acid Extractable Chromium (Cr) mg/kg 3.2 90 2.0
Acid Extractable Cobalt (Co) mg/kg 1.9 - 1.0
Acid Extractable Copper (Cu) mg/kg 7.4 197 2.0
Acid Extractable Iron (Fe) mg/kg 5900 43,766 50
Acid Extractable Lead (Pb) mg/kg 17 91.3 0.50
Acid Extractable Lithium (Li) mg/kg 6.8 - 2.0
Acid Extractable Manganese (Mn) mg/kg 330 1100 2.0
Acid Extractable Mercury (Hg) mg/kg 0.12 0.486 0.10
Acid Extractable Molybdenum (Mo) mg/kg ND - 2.0
Acid Extractable Nickel (Ni) mg/kg 2.7 75 2.0
Acid Extractable Phosphorus (P) mg/kg 460 - 100
Acid Extractable Rubidium (Rb) mg/kg 7.1 - 2.0
Acid Extractable Selenium (Se) mg/kg ND 2 1.0
Acid Extractable Silver (Ag) mg/kg ND 1 0.50
Acid Extractable Strontium (Sr) mg/kg 12 - 5.0
Acid Extractable Thallium (Tl) mg/kg ND - 0.10
Acid Extractable Tin (Sn) mg/kg ND - 2.0
Acid Extractable Uranium (U) mg/kg 6.9 - 0.10
Acid Extractable Vanadium (V) mg/kg 6.1 - 2.0
Acid Extractable Zinc (Zn) mg/kg 30 315 5.0
RDL = Reportable Detection Limit
ND = Not Detected
2.5 Water Temperature
Water temperature is one of the most important indicators of water quality and plays a
significant role in the health and productivity of aquatic ecosystems, effecting many physical,
biological, and chemical factors within a waterbody. Water temperature influences dissolved
oxygen concentrations, another critical parameter in aquatic ecosystem health, as cold water
holds more oxygen than warm water.
Aquatic organisms have varying levels of sensitivity to temperature as well as optimal
temperature ranges. Extreme temperature fluctuations outside of those optimal ranges, both
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acute and chronic, can cause physiological stress, relocation, or death (NSSA, 2014). Salmonids,
such as Atlantic salmon (Salmo salar) and brook trout (Salvelinus fontinalis), require cold water
for survival. Brook trout, known to populate Fox Point Lake, are one of the most temperature-
sensitive salmonid species, and will begin to experience physiological stress if water
temperatures exceed 20°C. In response to high temperatures, fish will seek out areas of
thermal refugia, such as spring/groundwater-fed streams and streams with deep cold-water
pools (MacMillan et al., 2005).
Water temperature was monitored bi-weekly at all four sample sites from May 25 to October
31 2017. Surface water temperatures exceeded the 20°C threshold for cold-water fish species
at the Lake sample site from June 28 to August 24 and again on September 26. The Outlet
sample site displayed water temperatures very close to the 20°C threshold and exceeded this
temperature on July 14 and August 24. Both the North Inlet and South Inlet sample sites did not
exceed this threshold at any time throughout the monitoring period (see Fig. 7)
Figure 7 – Water temperature at four FPL sample sites from May to October 2017.
16
2.6 Dissolved Oxygen
Dissolved oxygen is one of the most important indicators of water quality and aquatic
ecosystem health. Oxygen enters water through wind and wave action, rainfall, cascading
water, and photosynthesis by aquatic vegetation. Dissolved oxygen concentrations in a
waterbody can be influenced by several factors including thermal stratification, water
temperature, algae and aquatic plant growth, and the oxygen content of inlet streams (EPA,
2002).
The CCME Guideline for the Protection of Aquatic Life for dissolved oxygen is ≥ 6.5 mg/L for
cold-water species and ≥ 5.5 mg/L for warm-water species (CCME, 1999).
Both the Lake and Outlet sample sites maintained dissolved oxygen concentrations above the
CCME Guideline for the Protection of Aquatic Life (for cold-water species) throughout the entire
monitoring period (see Fig. 8). The North Inlet sample site fell below this guideline from June 28
to September 26, which is similar to the previous monitoring period, with this site falling below
the guideline from July 4 to September 30 in 2016.
In 2016, dissolved oxygen concentrations fell below the guideline at the South Inlet sample site
from July 4 to September 9, and displayed a seasonal (July-September) mean concentration of
5.63 mg/L. In 2017, the dissolved oxygen conditions at the South Inlet sample site showed a
slight improvement, with concentrations falling below the guideline on two sampling dates,
August 24 and September 26, and the seasonal (July-September) mean increased to 6.70 mg/L
(see Table 6).
Statistical analysis, using paired t-tests with a significance threshold of 95%, determined that
there are no significant differences between dissolved oxygen concentrations in 2015 and 2017
for all four sample sites (North Inlet p-value = 0.814, South Inlet p-value = 0.878, Lake p-value =
0.673, Outlet p-value = 0.918).
Table 6 – Mean and minimum summer dissolved oxygen concentrations from July to September 2017,
with 2015 and 2016 results for comparison.
North Inlet South Inlet Lake Outlet
Mean summer dissolved
oxygen (mg/L)
(2015/2016)
3.59
(2.25/3.36)
6.70
(6.31/5.63)
8.21
(7.88/8.02)
7.66
(7.05/6.97)
Minimum summer
dissolved oxygen (mg/L)
(2015/2016)
1.93
(1.38/2.31)
5.38
(5.86/3.92)
7.75
(7.33/7.43)
6.80
(5.75/5.61)
17
Figure 8 – Dissolved oxygen concentrations at four FPL sample sites from May to October 2017.
2.7 pH
pH is a measurement of the hydrogen-ion concentration in water which is expressed on a
logarithmic scale from 0 to 14. A pH of 0 is the most acidic, pH of 7 is neutral, and a pH of 14 is
the most basic. The CCME Guideline for the Protection of Aquatic Life for pH is within the range
of 6.5-9.0 (CCME, 2002). Natural variation in pH occurs as a result of soil and bedrock
composition, drainage from coniferous forests, and aquatic vegetation and organic material
biomass. Anthropogenic influences on pH include wastewater discharge, increased atmospheric
carbon dioxide, and acid precipitation (B.C. MOE, 1998).
Nova Scotia has lost the greatest percentage of fish habitat due to acid precipitation in all of
North America. The province is positioned directly downwind from high emission-polluting
areas of central Canada and the Midwestern United States. Southwestern Nova Scotia suffers
significantly from the effects of acid precipitation due to the poor buffering capacity of the soils
in this region, which are unable to neutralize the effects of the acids (NSSA, 2015). Fish and
other aquatic organisms experience negative physiological impacts in water with pH < 5.0.
Salmon can withstand pH as low as 5.0, and trout species are slightly hardier and can withstand
pH as low as 4.7 (NSSA, 2014).
18
The North Inlet, South Inlet, and Outlet sample sites all fell below the CCME Guideline for the
Protection of Aquatic Life throughout the entire monitoring period, which is consistent with the
2015 and 2016 monitoring periods (see Fig. 9). The Lake sample site maintained pH levels
within the CCME guideline range for most of the monitoring period, falling below the guideline
on two sampling days (August 24 and September 26). Statistical analysis, using paired t-tests
with a significance threshold of 95%, confirmed that the Lake sample site has shown a
significant increase in pH from 2015 to 2017 (p-value = 0.0001727).
Table 7 – Mean and minimum pH results from May to October 2017, with 2015 and 2016 results for
comparison.
North Inlet South Inlet Lake Outlet
Mean pH
(2015/2016)
4.98
(4.56/5.17)
5.23
(5.08/5.64)
6.95
(6.11/6.39)
5.49
(5.45/5.74)
Minimum pH
(2015/2016)
4.49
(3.88/4.36)
4.78
(4.10/4.85)
6.10
(5.66/6.08)
5.08
(5.04/5.59)
Figure 9 – pH results at four FPL sample sites from May to October 2017.
19
2.8 Total Dissolved Solids
Total dissolved solids is a measure of dissolved materials in water such as calcium, magnesium,
chloride, sodium, sulphate, nitrate, and bicarbonate. Sources of dissolved solids include natural
sources in the environment, sewage effluent, urban and agricultural run-off, industrial
wastewater, and road salts. High concentrations of dissolved solids can influence the taste,
color, and clarity of water (B.C. MOE, 1998; NSSA, 2014). There is no CCME guideline for
dissolved solids in terms of the protection of aquatic life; however, Health Canada has
established a drinking water guideline of ≤ 500 mg/L (Health Canada, 1991), and the average
total dissolved solids concentration for pristine lakes in Nova Scotia is 20 mg/L (Hinch &
Underwood, 1985).
The Lake sample site displayed a mean total dissolved solids concentration of 30.62 mg/L in
2017 (see Table 8). The Lake and Outlet sample sites display very similar total dissolved solids
concentrations throughout the monitoring period. The North Inlet sample site displays the
highest total dissolved solids levels of the four sites, with a mean concentration of 49.29 mg/L,
while the South Inlet sample site displays the lowest mean concentration of 25.91 mg/L (see
Fig. 10).
Table 8 – Total dissolved solids from May to October 2017, with 2015 and 2016 results for comparison.
North Inlet South Inlet Lake Outlet
Mean total dissolved solids
(mg/L)
(2015/2016)
49.29
(43.36/46.73)
25.91
(25.16/28.93)
30.62
(27.50/29.74)
30.88
(27.82/30.14)
Maximum total dissolved solids
(mg/L)
(2015/2016)
58.50
(52.65/52.65)
31.20
(37.05/37.05)
31.85
(27.95/30.55)
31.85
(28.60/31.20)
20
Figure 10 – Total dissolved solids at four FPL sample sites from May to October 2017.
2.9 Total Suspended Solids
Total suspended solids is a measure of the solids suspended in a water column which do not
pass through a 45µm glass fiber filter. These solids include silt, clay, plankton, microscopic
organisms, and fine organic and inorganic particles. Total suspended solids is one of the most
visible indicators of water quality, as it provides a measure of water clarity and sedimentation,
and it is strongly influenced by precipitation and overland run-off. Sources of suspended solids
include natural geological erosion, agriculture, forestry, construction, and wastewater
discharge. High concentrations of suspended solids can cause an increase in surface water
temperatures as particles in the water column absorb solar radiation, as well as a decrease in
dissolved oxygen as particles decrease light penetration and photosynthesis rates (CCME,
2002).
The average background concentration in Nova Scotia lakes is 3.0 mg/L (Hinch & Underwood,
1985). The CCME Guideline for the Protection of Aquatic Life is dependent on the baseline
concentrations of suspended solids in each individual waterbody. When baseline
concentrations are ≤ 100 mg/L, the maximum allowable increase is 10 mg/L above baseline
levels. When baseline concentrations are > 100 mg/L, the maximum allowable increase is 10%
of baseline levels (CCME, 2002).
21
Total suspended solids concentrations at the Lake sample site did not exceed the average
background concentration in Nova Scotia lakes (3.0 mg/L) throughout the entire monitoring
period in 2017, which is consistent with the 2015 and 2016 monitoring periods (see Table 9).
A spike in total suspended solids was observed at the South Inlet sample site on October 31,
with a concentration of 21 mg/L. The validity of this sample was confirmed by a laboratory
duplicate as part of Maxxam Analytics’ quality control procedures.
Table 9 – Total suspended solids (mg/L) from May to October 2017.
North Inlet South Inlet Lake Outlet
May 25, 2017 1.4 1.6 1.8 2.2
June 28, 2017 3.6 2.2 1.6 2.0
July 26, 2017 2.5 2.4 1.0 1.2
August 24, 2017 4.4 1.8 1.4 1.0
September 26, 2017 2.0 1.8 ND (RDL = 1.0) ND (RDL = 1.0)
October 31, 2017 1.0 21 ND (RDL = 1.0) 2.0
* ND = Not Detected, RDL = Reportable Detection Limit
2.10 Total Phosphorus
Total phosphorus is a measure of both organic and inorganic forms of phosphorus. Phosphorus
is an essential nutrient for plant growth, and is usually the limiting factor for the growth of
algae and aquatic plants in freshwater systems. Phosphorus has few natural sources in the
environment, meaning that elevated concentrations in a waterbody are likely caused by
anthropogenic activities. Natural sources of phosphorus include the weathering and erosion of
rocks and the decomposition of organic matter. Anthropogenic sources of phosphorus include
industrial effluent, sewage effluent, and run-off from urban, agricultural, or forestry land-use
activities (B.C. MOE, 1998).
Lakes that are not significantly impacted by anthropogenic activities typically display total
phosphorus concentrations of < 0.01 mg/L (B.C. MOE, 1998). CCME has not established a
guideline for total phosphorus because it is not a ‘toxic substance’, but rather it has secondary
effects in the environment such as eutrophication and dissolved oxygen depletion (CCME,
2004). Provincial guidelines have been established in some provinces, but not in Nova Scotia.
Ontario’s Ministry of Environment and Climate Change (MOECC) have established widely-
recognized guidelines for both stream and lake habitats. The total phosphorus guideline for
lakes is ≤ 0.02 mg/L, while the guideline for rivers and streams is ≤ 0.03 mg/L (MOECC, 1979).
Total phosphorus concentrations at the Lake sample site did not exceed the MOECC lake
guideline of ≤ 0.02 mg/L throughout the entire monitoring period. The Outlet sample site did
not exceed the MOECC stream guideline of ≤ 0.03 mg/L throughout the entire monitoring
22
period, while the North Inlet sample site narrowly exceeded this guideline on one sample date
(July 26, 2017) with a concentration of 0.034 mg/L (see Fig. 11).
The South Inlet sample site exceeded the MOECC stream guideline throughout the entire
monitoring period with a mean concentration of 0.088 mg/L (see Table 10). This sample site has
exceeded the MOECC stream guideline for total phosphorus on every sampling occasion in
2015, 2016, and 2017. The mean total phosphorus concentrations have decreased over the
three years, with a mean of 0.164 mg/L in 2015, 0.149 mg/L in 2016, and 0.088 mg/L in 2017;
however, this decrease is not statistically significant (p-value = 0.1208).
Table 10 – Mean and maximum total phosphorus concentrations from May to September 2017, with
2015 and 2016 results for comparison.
North Inlet South Inlet Lake Outlet
Mean total
phosphorus (mg/L)
(2015/2016)
0.021
(0.020/0.018)
0.088
(0.164/0.149)
0.007
(0.010/0.007)
0.007
(0.008/0.012)
Maximum total
phosphorus (mg/L)
(2015/2016)
0.034
(0.030/0.031)
0.120
(0.240/0.320)
0.010
(0.014/0.008)
0.008
(0.008/0.027)
Figure 11 – Total phosphorus concentrations at four FPL sites from May to September 2017.
23
2.11 Total Nitrogen
Total nitrogen is a measure of all forms of organic and inorganic nitrogen. Nitrogen, like
phosphorus, is an essential nutrient for plant growth, and is usually the limiting factor for the
growth of aquatic plants and algae in marine environments. Anthropogenic sources include
sewage effluent, urban and agricultural run-off, and industrial effluent (B.C. MOE, 1998). As
with total phosphorus, CCME has not established a guideline for total nitrogen, as it is not
considered to be a ‘toxic substance’, rather one that has secondary effects on the environment
such as eutrophication and dissolved oxygen depletion (CCME, 2004). Recommended guidelines
have emerged through extensive research on the fate of nitrogen in freshwater environments.
Dodds and Welch (2000) have established a total nitrogen guideline of ≤ 0.9 mg/L for
freshwater environments in which excessive nutrient loading and eutrophication are likely to
occur. Underwood and Josselyn (1979) have reported a total nitrogen concentration guideline
of ≤ 0.3 mg/L for oligotrophic waterbodies.
All four sample sites fell below the Dodds and Welch (2000) guideline of ≤ 0.9 mg/L for the
entire monitoring period (see Fig. 12). The Lake sample site has fallen below the Underwood
and Josselyn (1979) guideline of ≤ 0.3 mg/L for all sampling events from 2015 to 2017,
supporting the trophic state classification of Fox Point Lake as oligotrophic (see Table 11).
Statistical analysis, using paired t-tests with a significance threshold of 95%, has shown a
significant decrease in total nitrogen concentrations at the South Inlet sample site from 2015 to
2017 (p-value = 0.01228).
Table 11 – Mean and maximum total nitrogen concentrations from May to September 2017, with 2015
and 2016 for comparison.
North Inlet South Inlet Lake Outlet
Mean total
nitrogen (mg/L)
(2015/2016)
0.478
(0.530/0.481)
0.595
(1.22/0.612)
0.236
(0.234/0.214)
0.244
(0.365/0.236)
Maximum total
nitrogen (mg/L)
(2015/2016)
0.605
(0.624/0.584)
0.683
(2.01/0.763)
0.276
(0.266/0.266)
0.264
(0.696/0.298)
24
Figure 12 – Total nitrogen concentrations at four FPL sample sites from May to September 2017.
2.12 Fecal Coliform Bacteria
Fecal coliform bacteria are found in the waste of warm-blooded animals and are used as an
indicator of fecal contamination in the environment. With hundreds of types of pathogenic
bacteria, viruses, protozoa and other harmful microorganisms, it is not practical to test for all of
them in the environment. Non-pathogenic bacteria species are used as indicators of the
possible presence of pathogenic organisms.
Sources of fecal bacteria include stormwater run-off, straight pipe septic systems,
malfunctioning septic systems, livestock, wildlife, domestic animals, and agricultural run-off.
Exposure to water contaminated with fecal bacteria poses a significant risk to public health and
can cause illnesses such as gastroenteritis, hepatitis, respiratory infections, as well as eye, skin,
and ear infections (B.C. MOE, 1998; Health Canada, 2012).
Health Canada has established guidelines for the protection of human health during water-
based recreation activities. Separate guidelines have been developed, depending on the level of
water contact and the likelihood of ingesting water during certain types of water-based
activities.
25
Primary contact: Activities in which the whole body or the face and trunk are frequently immersed, or the
face is frequently wetted by spray, and where it is likely that some water will be swallowed (e.g.,
swimming, surfing, waterskiing, whitewater canoeing/rafting/kayaking, windsurfing, subsurface diving).
Secondary contact: Activities in which only the limbs are regularly wetted and in which greater contact
(including swallowing water) is unusual (e.g., rowing, sailing, canoe touring, fishing).
(Health Canada, 2012)
The primary contact guideline for E. coli is ≤ 400 cfu/100 mL, and the secondary contact
guideline for E. coli is ≤ 1,000 cfu/100 mL. Fecal coliforms are used as a proxy measurement for
E. coli, as the majority of a fecal coliform sample is comprised of E. coli bacteria; therefore, the
fecal coliform results from FPL will be compared to the Health Canada E. coli guidelines.
All four sample sites fell below the Health Canada guideline for primary contact throughout the
entire monitoring period. The South Inlet sample site displayed an elevated fecal bacteria
concentration of 380 cfu/100 mL on June 28 but did not exceed the primary contact guideline
of ≤ 400 cfu/100 mL (see Table 12).
Table 12 – Fecal coliform (cfu/100 mL) results at four FPL sample sites from May to October 2017.
North Inlet South Inlet Lake Outlet
May 25, 2017 ND (RDL = 10) 40 ND (RDL = 10) ND (RDL = 10)
June 28, 2017 90 380 ND (RDL = 10) 60
July 26, 2017 100 20 ND (RDL = 10) 30
August 24, 2017 100 30 ND (RDL = 10) 20
September 26, 2017 ND (RDL = 10) 10 ND (RDL = 10) ND (RDL = 10)
October 31, 2017 60 10 ND (RDL = 10) 130
* ND = Not Detected, RDL = Reportable Detection Limit
2.13 Precipitation and Lake Water Level
Precipitation and the water level of FPL were monitored daily from June 10 to October 30
during the 2017 monitoring period. A record of precipitation events is important for the
interpretation of water quality data, as many parameters are strongly influenced by rainfall and
overland run-off. Daily monitoring of lake water level captures the natural variability and
seasonal fluctuations of the lake and creates an important baseline for the identification of
significant changes which may be attributable to anthropogenic activities such as watercourse
and wetland alterations, irrigation water usage, vegetation removal, or topographic alterations
(Fisheries and Oceans Canada, 2006).
26
The total precipitation amount at Fox Point Lake from June 10 to October 30 was 483.6 mm.
Over the course of the 2016 monitoring period, as southwest Nova Scotia suffered from a
significant drought, the precipitation amount totalled just 163 mm from June 22 to October 21.
Water level was recorded from a fixed-elevation staff gauge on a shoreline dock structure. The
water level of FPL fluctuated between 0.58 m – 0.78 m, which is consistent with the fluctuation
range of 0.63 m – 0.78 m measured in 2016, and 0.61 m – 0.80 m in 2015 (see Fig. 13).
Figure 13 – Precipitation and water level at Fox Point Lake from June to October 2017.
2.14 Stream Discharge
Stream discharge rates were monitored at the North Inlet, South Inlet, and Outlet sample sites
on a bi-weekly basis from May to October in 2017. Stream discharge is a product of water
velocity times the depth and width of the water flowing in a stream. Anthropogenic activities
within a drainage basin which effect hydrologic conditions may result in altered stream
discharge rates (Meals & Dressing, 2008).
The Outlet sample site displayed the most variability in discharge rates as well as the highest
mean discharge rate of 0.608 m³/s, as this is the only outlet stream draining Fox Point Lake (see
Fig. 14). The South Inlet sample site displayed a mean discharge rate of 0.060 m³/s, which is
27
more than double the mean discharge rate observed at this site in 2016 (0.027 m³/s). The North
Inlet sample site displayed a mean discharge rate of 0.157 m³/s, a lower rate than that
observed in 2016 (0.213 m³/s) (see Table 13).
Table 13 – Mean and range stream discharge rates from May to October, with 2015 and 2016 results for
comparison.
North Inlet South Inlet Outlet
Mean stream
discharge rate (m³/s)
(2015/2016)
0.157
(0.428/0.213)
0.060
(0.036/0.027)
0.608
(0.235/0.178)
Range of stream
discharge rate (m³/s)
(2015/2016)
0.104-0.195
(0.202-0.701/0.161-0.271)
0.015-0.106
(0.021-0.058/0.012-0.035)
0.254-0.930
(0.052-0.749/0.032-0.540)
Figure 14 – Stream discharge rates at three FPL sample sites from May to October 2017.
28
3. Time Series Data from 2015 to 2017
Several important water quality parameters have been plotted as a time series, representing
the data from the Fox Point Lake Water Quality Monitoring Program from 2015 to 2017. With
three years of water quality data collected, important changes in parameters and relationships
between sample sites can be identified through statistical analysis.
As seen in Figure 15, the pH of the Lake sample site has been consistently higher than the pH
levels of the inlet and outlet streams. The Lake sample site has shown a statistically significant
increase in pH from 2015 to 2017 (p-value = 0.0001727).
Total phosphorus concentrations have been consistently higher at the South Inlet sample site
compared to the other three sample sites. Total phosphorus concentrations have decreased at
the South Inlet sample site from 2015 to 2017; however, this decrease is not statistically
significant. Total nitrogen concentrations have shown a statistically significant decrease at the
South Inlet sample site from 2015 to 2017 (p-value = 0.01228). Nutrient levels between the
South Inlet sample site and the North Inlet sample site have shown statistically significant
differences for both total phosphorus (p-value = 0.000065) and total nitrogen (p-value = 0.014)
for 2015, 2016, and 2017.
The South Inlet sample site has been found to be significantly different from the Lake sample
site for all parameters tested in 2015, 2016, and 2017.
29
Figure 15 – Time series data for key water quality parameters at four FPL sample sites from 2015 to
2017.
30
4. Discussion
Fox Point Lake has experienced an algal bloom during the month of June in both 2016 and
2017. Analysis of water samples from both blooms has confirmed the presence of a
cyanobacterial toxin, microcystin-LR, at a concentration of 1.25 µg/L in 2016 and 0.71 µg/L in
2017. Both microcystin-LR concentrations fall below the Health Canada drinking water guideline
of 1.5 µg/L (Health Canada, 2010). Cyanobacteria blooms tend to recur in the same waterbody
year after year, thus highlighting the importance of limiting external inputs of nutrients into Fox
Point Lake as well as maintaining adequate dissolved oxygen concentrations in the hypolimnion
layer in order to prevent an increase in the frequency and severity of algae blooms in the lake.
Exposure to cyanobacteria toxins through the consumption of water, and in rare cases,
recreational skin contact with water, does pose a risk of illnesses such as fever, vomiting,
stomach cramps, and eye or skin irritation (WHO, 2003; Federal-Provincial-Territorial
Committee on Drinking Water, 2002). As such, the residents of Fox Point Lake should be
provided with educational materials about algal blooms and the associated risks and
appropriate preventative measures. In addition, all lake residents should be notified in the case
of a confirmed algal bloom, as the bloom may not be visible in all parts of the lake and
cyanobacterial toxins can persist in the water for several weeks after a visible bloom has
dissipated.
Fox Point Lake has not experienced any measurable increase in trophic state from 2015 to
2017, with the classification holding steady at oligotrophic approaching mesotrophic
throughout each annual monitoring period. In 2017, the chlorophyll a and total phosphorus TSI
scores indicated an oligotrophic state, meaning the lake has low biological productivity. The TSI
score for Secchi disk depth indicated a mesotrophic state, which suggests that the Secchi disk
depths may be more strongly influenced by the presence of suspended particles, such as
sediment or silt, than by algal biomass.
Thermal stratification was established in the deepest part of the lake by mid-June in 2017, with
a thermocline depth of 4-6 m. Dissolved oxygen concentrations were severely depleted in the
hypolimnion layer, with hypoxic conditions (< 2 mg/L) being observed in September and
October. Dissolved oxygen concentrations in the hypolimnion reached a minimum of 1.3 mg/L
in 2017, compared to a low of 2.7 mg/L in 2016. This oxygen depletion is indicative of the level
of microbial decomposition of organic material, which consumes the available oxygen and can
lead to the release of the bioavailable form of phosphorus. In addition, the low dissolved
oxygen conditions in the stratified parts of the lake pose a risk of internal phosphorus loading
through the release of phosphorus from bottom sediments where it is bound to metals such as
aluminum and iron (Brylinsky, 2004).
Fox Point Lake has displayed a reduction in acidification over the three annual monitoring
periods. The Lake sample site has shown a statistically significant increase in pH from 2015 to
2017 (p-value = 0.0001727). Several studies have shown that lakes are recovering from
31
acidification as a result of stricter sulphur dioxide emission regulations. Research on Nova
Scotia lakes has shown an increase in pH, as well as biodiversity and dissolved organic carbon,
without an associated increase in nutrients, which suggests that N.S. lakes are experiencing
some level of recovery from acidification (Anderson et al., 2017).
The South Inlet sample site displayed an unusually high concentration of total suspended solids
(21 mg/L) on October 31, 2017. The analysis of a laboratory duplicate confirmed the validity of
this result. A rainfall amount of 16 mm was measured on October 30; however, rainfall is likely
not the cause of this spike in suspended solids as similar rainfall amounts have occurred prior to
other sampling days without a corresponding spike in total suspended solids. It is possible that
some form of wildlife caused an upstream disturbance of bottom sediments prior to the
collection of water samples.
As in 2015 and 2016, nutrient concentrations exceeded guidelines at only one site: the South
Inlet sample site. This site exceeded total phosphorus guidelines throughout the entire
monitoring period in 2017. Mean annual total phosphorus concentrations have shown a
decrease from 2015 to 2017; however, this decrease is not statistically significant. The South
Inlet site has shown a significant decrease in total nitrogen concentrations from 2015 to 2017
(p-value = 0.01228).
While the south inlet stream does suffer from excessive nutrient loading, the Lake sample site
has not exceeded nutrient guidelines. Lakes which are not significantly impacted by
anthropogenic activities normally display total phosphorus concentrations of < 0.01 mg/L (B.C.
MOE, 1998). Annual mean total phosphorus concentrations at the Lake sample site have not
exceeded 0.01 mg/L. Underwood and Josselyn (1979) have reported a total nitrogen guideline
of ≤ 0.3 mg/L for oligotrophic lakes. The Lake sample site has never exceeded this guideline,
supporting the classification of Fox Point Lake as predominantly oligotrophic.
Sediment from the stream bottom at the South Inlet sample site displayed a total phosphorus
concentration of 460 mg/kg on October 31, 2017. A median total phosphorus concentration of
360 mg/kg was reported by McDaniel et al. (2009) for 105 streams in agricultural-dominated
watersheds across Illinois, while McDowell and Sharpley (2001) reported an average total
phosphorus concentration of 281 mg/kg in sediment from four agricultural streams in
Pennsylvania. In comparison to streams in agricultural watersheds, which are likely to receive
external nutrient loading, the total phosphorus in the sediment at the South Inlet sample site
suggests that this stream does receive an external source of nutrient loading, much of which is
being retained within the bottom sediments. The total phosphorus concentration at this site
does not exceed Ontario’s Ministry of the Environment guideline for lowest effect level of 600
mg/kg, which indicates that the phosphorus load in the sediment at this location is not having a
detrimental effect on the aquatic environment (Ontario MOE, 2008).
The Southwest Cove sample site revealed a total phosphorus concentration of 850 mg/kg in the
bottom sediments. Lake sediments normally contain much higher concentrations of
32
phosphorus than the overlying waters (CCME, 2004), and this internal load can contribute to
eutrophication and algal blooms when stratification and hypolimnial anoxic conditions facilitate
the release of phosphorus from sediment (Hickey & Gibbs, 2009). The total phosphorus
concentration at this location falls within the range of lowest effect level to severe effect level
(600-2,000 mg/kg) according to Ontario’s Ministry of the Environment Sediment Quality
Guidelines, closer to the lowest effect level guideline, which suggests the sediment is clean to
marginally polluted in terms of phosphorus loading (Ontario MOE, 2008).
5. Recommendations
The following recommendations are suggested for the Fox Point Lake Water Quality Monitoring
Program:
• The Fox Point Lake Water Quality Monitoring Program should continue in 2018 and
beyond, as construction at the Aspotogan Ridge development project is slated to
continue into future years and this program was developed to track changes in the
health of Fox Point Lake throughout the development of this site.
• Consider amending the frequency of the sampling program (i.e. reducing sampling to
monthly rather than bi-weekly) to reduce volunteer time and commitments to the
program.
• Continue to collect sediment samples from the South Inlet sample site and the
southwest cove of Fox Point Lake once per year for the analysis of phosphorus and
orthophosphate.
• Water samples should be collected at the Lake sample site from below the hypolimnion
layer during thermal stratification for the analysis of total nitrogen and total phosphorus
to determine if dissolved oxygen depletion in the bottom waters of the lake are
resulting in the release of nutrients from lake sediments.
• Field replicates and blank samples should be added to the Quality Assurance/Quality
Control plan to ensure the validity of field sampling procedures.
• Residents of Fox Point Lake should continue to be supplied with laboratory-certified
bottles and sampling procedures for the collection of water samples during an algae
bloom.
33
References
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In Current and Geologic Utah Lake Sediments: Implications for Water Quality
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Anderson, L.E., Krkosek, W.H., Stoddart, A.K., Trueman, B.F. & Gagnon, G.A. 2017. Lake
Recovery Through Reduced Sulphate Deposition: A New Paradigm for Drinking Water
Treatment. Environ. Sci. Technol. 51, 1414-1422.
Beanlands, D.I. 1980. Surveys of Ten Lakes in Guysborough, Halifax, Hants, and Lunenburg
Counties, Nova Scotia, 1978. Freshwater and Anadromous Division Resource Branch.
Canadian Data Report of Fisheries and Aquatic Sciences No. 192.
British Columbia Ministry of Environment (B.C. MoE). 1998. Guidelines for Interpreting Water
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