APPENDIX I · 2011. 12. 9. · APPENDIX I Water Quality Modeling Report . Scarborough Waterfront Project . Water Quality Modelling . Prepared for . Toronto Region Conservation Authority

E N V I R O N M E N T A L A S S E S S M E N T

SCARBOROUGH WATERFRONT PROJECT T o r o n t o a n d R e g i o n C o n se r va t i o n

APPENDIX I Water Quality Modeling Report

Scarborough Waterfront Project Water Quality Modelling

Prepared for

Toronto Region Conservation Authority

By

Modelling Surface Water Limited

Dr. Ray Dewey

July 2017

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Table of Contents 1 INTRODUCTION ................................................................................................................ 1

2 OBJECTIVES ..................................................................................................................... 2

3 METHODS .......................................................................................................................... 3

3.1 Model Description ........................................................................................................ 3

3.1.1 Hydrodynamics Module ........................................................................................ 3

3.1.2 Advection-Dispersion Module ............................................................................... 3

3.1.3 Lake Hydrodynamics and Heat Exchange ............................................................ 3

3.2 Model Calibration ......................................................................................................... 5

3.2.1 HD Model Calibration ............................................................................................ 5

3.2.2 Calibration Parameters ......................................................................................... 6

3.3 Model Accuracy ..........................................................................................................10

3.3.1 Ministry of the Environment and Climate Change Acoustic Doppler Current Profiler Correlation .........................................................................................................................10

3.3.2 Fourier Norm Scores ............................................................................................12

3.4 Parameters Modeled ...................................................................................................12

3.4.1 Water Quality .......................................................................................................12

3.4.2 Beach Current Speed ..........................................................................................13

3.4.3 Bluffer’s Park Beach Closures .............................................................................13

4 SCOPE ..............................................................................................................................14

5 RESULTS ..........................................................................................................................15

5.1 West Segment ............................................................................................................16

5.1.1 Do Nothing ...........................................................................................................16

5.1.2 Alternative 3A – Island-Bridge, Short Span ..........................................................17

5.1.3 Alternative 3B – Island-Bridge, Long Span ...........................................................19

5.1.4 Alternative 4 – Causeway ....................................................................................20

5.1.5 Alternative 5B – Wide Beach ...............................................................................21

5.2 Central Segment .........................................................................................................23

5.2.1 Do Nothing ...........................................................................................................23

5.2.2 Alternative 1 – Headland-Beach...........................................................................25

5.2.3 Alternative 2 – Revetment ....................................................................................26

5.3 East Segment .............................................................................................................28

5.3.1 Do Nothing ...........................................................................................................28

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5.3.2 Alternative 2A – Bridge with Headland-Beach ......................................................29

5.3.3 Alternative 4B – Headland-Beach to East Point Park ...........................................30

5.4 Preferred Alternative ...................................................................................................31

5.5 Refined Preferred Alternative ......................................................................................33

5.5.1 West Segment .....................................................................................................33

5.5.2 Central Segment ..................................................................................................35

5.5.3 East Segment ......................................................................................................36

6 SUMMARY AND CONCLUSION .......................................................................................38

REFERENCES .........................................................................................................................39

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List of Figures Figure 1 Scarborough Waterfront Project Area and Study Area. ............................................... 1 Figure 2 Lake Ontario thermal processes. ................................................................................. 4 Figure 3 Whole Lake Model with nested grids. .......................................................................... 8 Figure 4 270 m grid with 90 m nested. Ontario Ministry of the Environment and Climate Change ADCP location shown at bottom edge near the 40 m mark. ....................................................... 9 Figure 5 90 m grid with TRCA data. Bluffer’s Park location between 4,000 m and 6,000 m marks. East Point Park on right side at 14,000 m. ...................................................................... 9 Figure 6 Surface layer direction time series. .............................................................................10 Figure 7 Surface layer speed time series. ................................................................................11 Figure 8 Bottom layer temperature time series. ........................................................................11 Figure 9 West Segment existing conditions (i.e., Do Nothing Alternative) at 30 m resolution. ...17 Figure 10 West Segment Alternative 3A at 30 m resolution. .....................................................18 Figure 11 West Segment Alternative 3B at 30 m resolution. .....................................................19 Figure 12 Location of the island-bridge gaps in West Segment Alternative 3A used for the Alternative 4 water exchange calculations. ................................................................................20 Figure 13 West Segment Alternative 5B at 30 m resolution. .....................................................22 Figure 14 Central Segment existing conditions (i.e., Do Nothing Alternative) at 30 m resolution. .................................................................................................................................................24 Figure 15 Central Segment existing conditions (i.e., Do Nothing Alternative) at 10 m resolution. .................................................................................................................................................24 Figure 16 Central Segment Alternative 1 at 30 m resolution (Segment starts at 1,700 m). .......25 Figure 17 Central Segment Alternative 1 at 10 m resolution. ....................................................25 Figure 18 Central Segment Alternative 2 at 30 m resolution. ....................................................27 Figure 19 Central Segment Alternative 2 at 10 m resolution (Segment starts at 1,700 m). .......27 Figure 20 East Segment existing conditions (i.e., Do Nothing Alternative) at 30 m resolution. ..29 Figure 21 East Segment Alternative 2A at 30 m resolution. ......................................................30 Figure 22 East Segment Alternative 4B at 30 m resolution. ......................................................31 Figure 23 Preferred Alternative at 30 m resolution. ..................................................................32 Figure 24 Existing West Segment shoreline with the six water quality parameter "test spots" indicated at a 30 m resolution. ..................................................................................................34 Figure 25 Refined West Segment Preferred Alternative shoreline configuration with the six water quality parameter "test spots" indicated at a 30 m resolution. ..........................................34 Figure 26 Existing East Segment shoreline with the six water quality parameter "test spots" and storm sewer outfall locations indicated at a 30 m resolution. .....................................................36 Figure 27 Refined East Segment Preferred Alternative shoreline configuration with the six water quality parameter "test spots" and storm sewer outfall locations indicated at a 30 m resolution. .................................................................................................................................................37

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List of Tables Table 1 Fourier Norm scores and Root Mean Square error values for the MOECC ADCP location. ....................................................................................................................................12 Table 2 Average predicted water quality parameter concentrations at the F.J. Horgan WTP intake and Rouge Beach, under the Do Nothing/Existing Conditions for West Segment. ..........17 Table 3 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational PWQO of 100 E. coli CFU per 100 mL of water, under the Do Nothing/Existing Conditions for West Segment. ...................................................................................................17 Table 4 Average predicted water quality parameter concentrations at F.J. Horgan WTP intake and Rouge Beach – comparison between Do Nothing/Existing Conditions and West Segment Alternative 3A............................................................................................................................18 Table 5 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational waters PWQO of 100 E. coli CFU per 100 mL of water – comparison between Do Nothing/Existing Conditions and West Segment Alternative 3A. ...............................................18 Table 6 Average predicted water quality parameter concentrations at F.J. Horgan WTP intake and Rouge Beach – comparison between Do Nothing/Existing Conditions and West Segment Alternative 3B............................................................................................................................19 Table 7 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational waters PWQO of 100 E. coli CFU per 100 mL of water – comparison between Do Nothing/Existing Conditions and West Segment Alternative 3B. ...............................................20 Table 8 Volumes of water exchanged through each of the four gaps in West Segment Alternative 3A (m3). ...................................................................................................................21 Table 9 Average predicted water quality parameter concentrations at F.J. Horgan WTP intake and Rouge Beach – comparison between Do Nothing/Existing Conditions and West Segment Alternative 5B............................................................................................................................22 Table 10 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational waters PWQO of 100 E. coli CFU per 100 mL of water – comparison between Do Nothing/Existing Conditions and West Segment Alternative 5B. ...............................................23 Table 11 Average predicted water quality parameter concentrations at the F.J. Horgan WTP intake and Rouge Beach, under the Do Nothing/Existing Conditions for Central Segment. .......24 Table 12 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational PWQO of 100 E. coli CFU per 100 mL of water, under the Do Nothing/Existing Conditions for Central Segment. ...............................................................................................25 Table 13 Average predicted water quality parameter concentrations at F.J. Horgan WTP intake and Rouge Beach – comparison between Do Nothing/Existing Conditions and Central Segment Alternative 1. .............................................................................................................................26 Table 14 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational waters PWQO of 100 E. coli CFU per 100 mL of water – comparison between Do Nothing/Existing Conditions and Central Segment Alternative 1. ..............................................26 Table 15 Average predicted water quality parameter concentrations at F.J. Horgan WTP intake and Rouge Beach – comparison between Do Nothing/Existing Conditions and Central Segment Alternative 2. .............................................................................................................................27

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Table 16 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational waters PWQO of 100 E. coli CFU per 100 mL of water – comparison between Do Nothing/Existing Conditions and Central Segment Alternative 2. ..............................................27 Table 17 Average predicted water quality parameter concentrations at the F.J. Horgan WTP intake and Rouge Beach, under the Do Nothing/Existing Conditions for East Segment. ...........29 Table 18 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational PWQO of 100 E. coli CFU per 100 mL of water, under the Do Nothing/Existing Conditions for East Segment. ....................................................................................................29 Table 19 Average predicted water quality parameter concentrations at F.J. Horgan WTP intake and Rouge Beach – comparison between Do Nothing/Existing Conditions and East Segment Alternative 2A + Sheltered Harbour. ..........................................................................................30 Table 20 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational waters PWQO of 100 E. coli CFU per 100 mL of water – comparison between Do Nothing/Existing Conditions and East Segment Alternative 2A. ................................................30 Table 21 Average predicted water quality parameter concentrations at F.J. Horgan WTP intake and Rouge Beach – comparison between Do Nothing/Existing Conditions and East Segment Alternative 4B............................................................................................................................31 Table 22 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational waters PWQO of 100 E. coli CFU per 100 mL of water – comparison between Do Nothing/Existing Conditions and East Segment Alternative 4B. ................................................31 Table 23 Average predicted water quality parameter concentrations at F.J. Horgan WTP intake and Rouge Beach – comparison between Do Nothing/Existing Conditions and Preferred Alternative. ................................................................................................................................32 Table 24 Average current speeds at Bluffer's Park Beach – comparison between Do Nothing/Existing Conditions and Preferred Alternative. .............................................................33 Table 25 Average predicted water quality parameter concentrations at six locations along the West Segment shoreline – comparison between Do Nothing/Existing Conditions and refined West Segment Preferred Alternative .........................................................................................35 Table 26 Average predicted water quality parameter concentrations at six locations along the East Segment shoreline – comparison between East Segment Preferred Alternative and refined East Segment Preferred Alternative. .........................................................................................37

List of Appendices APPENDIX A ............................................................................................................................40

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1 INTRODUCTION This report describes the results of water quality modeling carried out in support of the Scarborough Waterfront Project (SWP). This modeling exercise was conducted to aid in the evaluation of the Environmental Assessment (EA) Alternative Methods developed for the Project, as per the Individual EA process.

The Project Study Area is located on the north shore of Lake Ontario, between Bluffer’s Park and East Point Park in the City of Toronto (Figure 1). The Project Study Area consists of three Segments. To meet the Project Vision and Objectives, a number of Alternative Methods were developed for each Segment that include various shoreline configurations, the construction of which may have an impact on water quality. Using a defined list of Evaluation Criteria and Indicators, the Alternatives were assessed and evaluated based on their ability to achieve the Project Vision and Objectives. Based on the evaluation, a Preferred Alternative was selected that best meets the overall Vision and Objectives of the Project.

The goal of this modeling exercise is to determine whether any of the EA Alternative Methods have the potential to result in positive or negative impacts to water quality.

Figure 1 Scarborough Waterfront Project Study Area and Regional Study Area.

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2 OBJECTIVES This modeling exercise had the following objectives:

1. Select and develop a dynamic three-dimensional (3-D) hydrodynamic model that accurately simulates the nearshore water currents (in m/s) and water temperature conditions along the north shore of Lake Ontario;

2. Calibrate the model based on observed nearshore water currents and temperature data; 3. Calibrate the model to simulate the bacteria (E.coli) levels from stormwater, combined

sewer outfalls (CSOs) and tributaries, and to simulate levels of Total Suspended Solids (TSS), Total Phosphorus (TP) and Copper (Cu); and

4. Based on the modeling exercise scope, use the calibrated model to: - Assess various shoreline configurations (Alternative Methods as well as the

Preferred Alternative) with respect to their effectiveness in decreasing the Bluffer’s Park beach posting rate (i.e., beach closure rate during the swimming season);

- Determine any local changes in nearshore water current speed; and - Determine any changes in water quality at the F. J. Horgan Water Treatment Plant

water intake and Rouge Beach.

See Sections 3 and 4 for the modeling exercise methodology and scope.

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3 METHODS

3.1 Model Description The modelling software selected for this application was the MIKE-3 package developed by the Danish Hydraulic Institute. MIKE-3 is a professional engineering software package for 3-D free surface flows.

A whole lake model is required to predict the water currents in the nearshore area of interest, such as the Scarborough Waterfront. MIKE-3 uses the full 3-D representation of water motion, including thermodynamics (i.e., the relationship between heat and other forms of energy). It accurately simulates the seasonal thermal conditions and summer stratification (i.e., layering of the lake based on water temperature and subsequent density differences) that affects the circulation pattern in Lake Ontario, which is required for accurate predictions of nearshore water currents.

The model is based on a number of separate software modules which are invoked for various tasks such as hydrodynamic (i.e., the forces acting on or exerted by water) simulation, advection-dispersion (i.e., the transport and mixing) of dissolved substances, and particle tracking for various ecological and biological processes. All advanced modules depend on the basic hydrodynamic module which supplies the information about the lake currents and temperature.

3.1.1 Hydrodynamics Module The Hydrodynamic (HD) module simulates the 3-D incompressible Reynolds averaged Navier-Stokes equations with Boussinesq assumptions. The model is based on continuity of mass, momentum, temperature, density and salinity equations with a turbulence closure scheme. The effects of sources and sinks, river discharges, and surface water elevations are included. The temperature is affected by solar input through air temperature, relative humidity and sky clearness.

3.1.2 Advection-Dispersion Module The HD module is coupled with the Advection-Dispersion (AD) module. The AD module handles transport (advection) of scalar quantities such as temperature, salinity and tracers, as well as dispersion - the spreading, longitudinally, laterally and vertically. Tracers can be conservative or have a first order decay.

3.1.3 Lake Hydrodynamics and Heat Exchange The major forcing function used to drive the currents in the model is wind stress.

The thermal stratification of Lake Ontario begins after the spring thaw. Water throughout the lake eventually reaches a temperature of 4°C, which is uniform with depth. Water near the shoreline warms up first and the zone of warmer water slowly spreads out as the heating from the sun increases. The maximum density of water occurs at 4°C and is the major factor in the formation of the thermal stratification. Cold water at 4°C will sink below warmer water. Wind mixing of the upper water column is only sufficient to keep the top 20 to 35 m or so well mixed

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during the summer period, causing the water below this depth to remain at 4°C. There will be a structured thermal distribution in the water column. Typically the water column would be 20°C from the surface down to approximately 20 m; over the next 10 to 15 m the temperature decreases non-linearly to 4°C and from 35 m downward the water is a constant 4°C. A thermal bar first forms in the spring and slowly extends out into the lake (Figure 2). The spatial distribution of the layers is not even, typically a dome forms in the lake with the warm layer thinnest in the center of the lake and thickest at the shoreline (see “Late June” in Figure 2).

Figure 2 Lake Ontario thermal processes.

When the lake is stratified, wind stress affects the lake differently than when the lake is at a uniform temperature as in the spring and fall. Upwelling and downwelling events occur during stratification, which cause cold deep lake water to flow toward the north shore displacing warmer water with clean fresh cold water (downwelling has the opposite effect). These events are not predicted by two-dimensional (2-D) models, which is why 3-D models such as MIKE-3 need to be used.

In order to cause warming and cooling of the water in the lake, a thermodynamic balance is required. The heat balance is controlled by latent heat loss by thermal radiation to outer space

HaltonHalton--Hamilton Source Protection RegionHamilton Source Protection RegionCTC Source Protection RegionCTC Source Protection RegionTrent Conservation Coalition Source Protection RegionTrent Conservation Coalition Source Protection Region

Lake Ontario Workshop Dec. 9, 201112

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and evaporation and heat gain by solar radiation (long wave and short wave) and conduction from surface air.

3.2 Model Calibration

3.2.1 HD Model Calibration The MIKE-3 model is based on a mathematical formulation known as the finite difference (FD) method. The lake is represented by a grid of squares with vertical layers. The whole lake is divided up into squares with edges 2,430 m long. Equal length vertical layers are used to represent the water depth. The vertical distribution of depths is known as the Z-coordinate system. Other models use a FD grid with a constant distance between layers, such as the Sigma-coordinate system with variable layer thickness, and there are others based on variations of this method. Other models are based on a triangular grid known as a Finite Mesh method and can have either a Z, Sigma-coordinate system, or mixed.

The method MIKE-3 uses for nesting (in order to obtain fine scale resolution of the Study Area) consists of a whole lake model based on a resolution of 2,430 m, in this case, and nested grids at a ratio of 3:1 – or 810 m, 270 m, 90 m, respectively. The nested grids are computed simultaneously along with the whole lake grid. This provides a top-down, bottom-up feedback system so that fine details in the smaller grids can influence the larger grids calculations, and similarly large scale motions are felt by the finer grids. Tributaries can be fed into the computations at any scale of the nesting grids. For example, the Niagara River flows into the large whole lake model, and the water levels at Kingston are used to control the whole lake elevation. Smaller tributaries and other discharges are usually released into the smallest grid. Sometimes it is necessary to use the outer nested grid to discharge tributaries that are remote to the Study Area but may have an effect on the inner area. This helps to keep the simulation times short as larger fine grids vastly increase computer times.

Other models, such as Princeton Ocean Model (POM), Estuary, Lake and Coastal Ocean Model (ELCOM), and Canadian Version of Diecast Model (CANDIE), do not have this flexibility. Their method would be to run a whole lake model, with the velocities, temperature and other pertinent variables stored along boundary lines that form the edges of a nested grid. The nested grid would then be run with the stored data providing the forcing at the boundaries of the finer grid. The finer grid would "feel" the impact of the Niagara River, but it cannot feed back to the whole lake model any influences it may have on the whole lake circulation. For example, the Toronto Inner Harbour, the East Headland, Humber Bay, and other finer resolution shoreline features would not be represented in a whole lake model – the East Headland and Toronto Islands may be just a blip on the shoreline. The flows in and out of the eastern and western gaps of the Inner Harbour would not be felt by the whole lake mode. In the MIKE-3 world, all of these features would be modelled at each time step.

Another significant benefit of simultaneous nested grids is that a plume that moves beyond the finest scale grid is still within the computational domain, and is therefore still in the model. In a two-mode model, like POM, a plume that moves beyond the boundaries of the fine grid is lost. In other words, a plume that moves out the model domain, and then is brought back into the fine

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grid via a current reversal is not accounted for in the non-nested approach of models like POM. The MIKE-3 system can model plumes that move outside of all three sub-nests, into the 2,430 m whole lake model, and then back into 90 m grid, for example, although there will be some loss of definition when going from the coarse to fine grids, but conservation of mass will occur.

A disadvantage of a nested grid model, run in a finite difference format, is the computation time step; the time step of the lake wide model is set by the grid size of the smallest mesh. In the 2,430 m grid, a time step of 600 seconds is possible; however, when the nested grids are used, the time step has to decrease to about 30 seconds for a 90 m grid and 90 seconds for the 270 m grid.

Boegman and Yerubandi (2010) showed 2 km resolution was insufficient to resolve some of the fine scale processes, such as topographic and Kelvin waves, for example, and that grid resolutions smaller than 1 km are required. The grid used here (2,430 m) is a compromise, as computational time increases with smaller grid sizes.

3.2.2 Calibration Parameters The calibration process involves selecting the appropriate grid sizing, time step, vertical resolution, wind source and other driving forces, and then adjusting the model parameters (i.e., fine tuning) to make the model predictions agree with observed data. Typically, current data collected with instruments deployed in the lake are used to calibrate the hydrodynamic module. Temperature data collected at water intakes are also valuable in this process.

3.2.2.1 Turbulence Models MIKE-3 has six optional turbulence models, though the user can select only one. They are:

- the very simple "no eddy viscosity" - "constant eddy viscosity” - Smagorinsky formulation - κ model formulation - κ-ε model formulation - highest order accuracy - Mixed κ-ε/Smagorinsky

As the simple models do not develop a thermal stratification, the Mixed κ-ε/Smagorinsky model was used in all simulations as it is the highest order accuracy scheme and produces better correlations with the observed data.

3.2.2.2 Bathymetry The bathymetry data were obtained from the National Ocean and Atmospheric Administration (NOAA) Lake Ontario CD at a resolution of 3 arcseconds (NOAA, 1999). This grid was interpolated to a 30 or 10 m resolution with the MIKE-3 bathymetry editor. The resolution varied by shoreline segment. The whole lake resolution was therefore 2,430 m.

As the whole lake model resolution of 2,430 m is too coarse to study the near-shore dynamics of the lake, a method of nesting was used to provide currents and plume travel information in greater detail (Figure 3).

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3.2.2.3 Nested Grids The MIKE-3 model uses a 3:1 nesting with smaller grids based on 810 m, 270 m, 90 m, 30 m, and so on. Most of the nested models used in this exercise were based on the 90 and 30 m grids; however, some 10 m grid sizes were used where the additional resolution was required. As the computational time increases with smaller grid sizes, it is important to economize grid layout.

3.2.2.4 Vertical Resolution The choice of vertical resolution is as important as grid size due to computation time. Lake Ontario is over 250 m deep, with the thermocline extending down to about 60 m at the time of fall turnover. Therefore, adequate representation is required of the upper 60 m while the area below the thermocline can be simulated as a single layer of water. This is one limitation of the Z-coordinate system. Many trials have shown that the optimal number of vertical layers lies between 20 and 40 layers with thickness of 4 to 2 m, respectively, or a vertical coverage to approximately 80 m. Previous experience with MIKE-3 in studies such as the City of Toronto’s Wet Weather Flow Master Plan (2003) waterfront modelling study tested the number of layers and found similar results.

3.2.2.5 Scarborough Shoreline Lake Model The model is based on nested grids of Lake Ontario, rotated -45 degrees to orient the Scarborough shoreline on a west to east line, which is more computationally efficient. The nesting is a 3:1 ratio, going from 2,430 m for the whole lake to 810 m, 270 m, 90 m, 30m, 10m, and so on. Examples of the grids are shown below in Figure 4 and Figure 5.

3.2.2.6 Scarborough Shoreline Lake Model Input Data The stormwater and CSO input data for the water quality parameters modeled (see Section 3.4.1) were obtained from watershed models from other City of Toronto studies. The time series of flow and concentration of each water quality parameter were produced for the period of April to October 1991. These data were obtained from the Wet Weather Flow Master Plan study, and represent a reference condition year that has been used in more current studies, such as the Don and Waterfront Trunk Sewers and Combined Sewer Overflow (CSO) Control Strategy (MMM Group Ltd., 2012).

Unfortunately, the NOAA wind data were not available for 1991 (available data were collected starting in the early 2000s). Therefore, Pearson Airport wind speed and direction data were used. There are no current meter data available to check the correlation for 1991. However, Pearson data has been found to produce reasonable correlations in other years so we have to assume the model is preforming similarly (Dewey, 2012).

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Figure 3 Whole Lake Model with nested grids.

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Figure 4 270 m grid with 90 m nested. Ontario Ministry of the Environment and Climate Change ADCP location shown at bottom edge near the 40 m mark.

Figure 5 90 m grid with TRCA data. Bluffer’s Park location between 4,000 m and 6,000 m marks. East Point Park on right side at 14,000 m.

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3.3 Model Accuracy

3.3.1 Ministry of the Environment and Climate Change Acoustic Doppler Current Profiler Correlation

Model accuracy was verified using the Acoustic Doppler Current Profiler (ADCP) data collected by the Ministry of the Environment and Climate Change along the Toronto Waterfront in 2008. See Figure 4 for the ACDP location.

The model was setup for this period using the appropriate meteorological data: wind data were provided by NOAA as a 2-D wind field derived from the North American Meso-Scale Weather model at a resolution of 5 km, and other data were available from Pearson Airport data archives.

Figure 6 shows the direction time series for the surface layer at the ADCP location for both the observed and predicted currents. Figure 7 shows the surface layer speed time series and Figure 8 shows the temperature correlation at the bottom layer.

Figure 6 Surface layer direction time series.

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Figure 7 Surface layer speed time series.

Figure 8 Bottom layer temperature time series.

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3.3.2 Fourier Norm Scores The method used to measure model accuracy is based on a vector average that uses both speed and direction called the Fourier Norm (FN, or Fnorm). The calculation involves the average difference between the two vector components of velocity. In model terms, the velocity is computed as a V component in the onshore-offshore (north-south) direction and the U component in the alongshore (east-west) direction. Equation 1 describes the FN as follows:

0,

,

o

co

N

v

vvF

r

rr

= where 21

2

1

1, ∑∆

=

−=tN

tcoco vv

Nvv rrrr

Where vo = observed data and vc = computed data.

Equation 1 Fourier Norm Equation.

Typical Fnorm values of 0.4-1.2 are reported in the Great Lakes (Beletsky et al., 2006). Fnorm scores below 0.85 are considered to be very good.

The other measure of model accuracy used in this exercise was the Root Mean Square error (RMS) for each vector component. Small RMS values indicate higher accuracy.

The Fnorm scores and RMS values for the MOECC ADCP monitoring location are presented in Table 1. Based on the Fnorm scores and RMS values obtained, the model for 2008 was considered to be well correlated with the observed data.

Table 1 Fourier Norm scores and Root Mean Square error values for the MOECC ADCP location.

Layer Fnorm U RMS (m/s) V RMS (m/s) Surface 1.07 0.12 0.11

Mid-depth 0.86 0.08 0.076 Bottom 0.84 0.066 0.067

3.4 Parameters Modeled

3.4.1 Water Quality The water quality constituents considered in this modeling exercise included Total Phosphorus (TP), Total Suspended Solids (TSS), Total Copper (Cu) and Escherichia coli (E. coli).

TP concentrations typically serve as an indicator of nutrient levels, or eutrophication; TSS levels provide a measure of turbidity; Copper (considered a heavy metal) provides a measure of aquatic toxicity; and E. coli serves as an indicator of faecal pollution or recreational water quality.

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TP, Cu and E. coli Provincial Water Quality Objectives (PWQOs) were used as benchmarks, where TP PWQO is 0.02 mg/L, Copper PWQO is 0.001 mg/L and E. coli PWQO for recreational waters is 100 Colony Forming Units (CFU) per 100 mL of water. While TSS does not have a PWQO value, TSS level of 10 mg/L constitutes the upper limit of turbidity in source water used by the City of Toronto water treatment plants.

The water quality parameters for the Do Nothing/existing conditions, and each Alternative Method and the Preferred Alternative were measured at two environmental end-point locations (EELs): the F.J. Horgan Water Treatment Plant (WTP) intake (closest water treatment plant) and Rouge Beach (closest public beach other than Bluffer’s Park Beach). The F.J. Horgan WTP intake is sensitive to water quality changes as they may impact the ability of the treatment plant to perform to its highest standard. Rouge Beach, while not currently a Blue Flag beach, does meet the recreational waters PWQO and could be compromised by a change in water quality conditions (particularly, E. coli levels increase). Rouge Beach was used as the eastern-most point to assess the potential for regional impacts to water quality.

3.4.2 Beach Current Speed Beach current speeds were used as a metric to indirectly measure potential impacts to water quality associated with a particular Alternative.

Beach current speed was measured for predicted impacts at three points along Bluffer’s Park Beach (west, mid and east), as shown in Figure 9 (see Section 5.1.1). Current speeds were measured at Bluffer’s Park Beach only, as this is the only public beach in the Project Study Area.

A significant decrease in beach current speed could indicate potential water stagnation, creating conditions conducive to algal blooms. However, the changes observed in beach current speed were found to be insignificant for all Alternatives modeled in all three Segments, and are therefore not further discussed below.

3.4.3 Bluffer’s Park Beach Closures Blue Flag status for water quality is achieved at a beach when it is posted (closed) less than 20% of the swimming season (TRCA, 2013). Simulated hourly values of E.coli were used to determine the percentage of the swimming season that Bluffer’s Park Beach, a Blue Flag beach, would exceed the recreational waters PWQO of 100 CFU/100 mL (i.e., the percent of time E. coli levels would exceed the recreational waters PWQO), potentially resulting in a beach posting (i.e., closure).

The typical City of Toronto beach/swimming season of June 1 to September 1 was used. Therefore, the beach posting rate was based on the modeling results from June 1 to September 1.

As there are no observed hourly E. coli values for Bluffer’s Park Beach, the existing model prediction was used as Do Nothing/Existing Conditions scenario.

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As Rouge Beach is not designated as a Blue Flag beach, beach posting rates were not evaluated as there is no Blue Flag status to maintain or be affected.

4 SCOPE Parameters modeled, applicable guidelines and standards, and EELs are previously described in Section 3.4.

The model was run from May 15 to September 5, 1991. The beach posting (i.e., closure) rate was based on data from June 1 to September 1, a typical City of Toronto beach/swimming season.

The modeling exercise scope is outlined below.

STEP 1: MODELING OF THE SEGMENT-LEVEL ALTERNATIVES

Only the Segment-level Alternatives that included shoreline structures/modifications with the greatest potential for impact to local or regional water quality were modeled. The modeled Alternatives included:

Segment Alternative Rationale

West Alternative 3A – Island-Bridge, Short Span

This Alternative was anticipated to have a potential impact on local water quality conditions, with possible reductions in water circulation and resultant water retention behind the island formations.

Alternative 3B – Island-Bridge, Long Span

This Alternative was anticipated to have a potential impact on local water quality conditions, with possible reductions in water circulation and resultant water retention behind the island formations.

Alternative 4 – Causeway As the MIKE-3 model is unable to represent underwater culverts, only circulation was modeled for this Alternative. This Alternative was anticipated to have a potential impact on local water quality conditions, resulting from reduced water circulation through the culverts and resultant water retention between Bluffer’s Park sand beach and the causeway structure.

Alternative 5B – Wide Beach This Alternative was assumed to have the greatest potential for impact on regional flow patterns due to the extent of the Bluffer’s Park headland expansion into Lake Ontario.

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Segment Alternative Rationale

Central Alternative 1 – Headland-Beach

As there were only two Alternatives for Central Segment, both were modeled.

Alternative 2 - Revetment

East Alternative 2A – Bridge with Headland-Beach

This Alternative was anticipated to have the greatest impact on location water quality conditions, as the bridge structure had the potential to impede water circulation and result in some water retention behind the bridge piers.

Alternative 4B – Headland-Beach to East Point Park

This Alternative was anticipated to have the greatest impact on regional water quality conditions due to the extent of the headlands out into Lake Ontario. There was also the increased potential for impact to the F.J. Horgan WTP intake pipe due to the length of the shoreline works, which would extend past the intake.

Note that the existing shoreline represents the Do Nothing/Existing Conditions modeling scenario.

STEP 2: CONFIRMATORY MODELING OF THE PREFERRED ALTERNATIVE

Once the preferred Segment-level Alternatives had been determined, the Preferred Alternative was modeled to evaluate the potential for positive or negative impacts to water quality resulting from implementation of the SWP as a whole.

STEP 3: CONFIRMATORY TESTING OF THE REFINED PREFERRED ALTERNATIVE

Following public, stakeholder and agency review, refinements to the Preferred Alternative were made (see Section 5.5). As the refinements involved scaling back of the proposed shoreline protection works through reductions in lakefill, it was determined that the impacts to regional water quality conditions would be less than those of the original Preferred Alternative. Therefore, the full model was not re-run – however, a “spot testing” method for changes in water quality was employed to evaluate changes in local water quality conditions between existing conditions and the refined Preferred Alternative.

5 RESULTS The modeling results obtained for the West, Central and East Segment Alternatives are presented in Sections 5.1 to 5.3. The results were used in the evaluation of the Segment-level Alternatives to identify a Preferred Alternative that was subsequently refined. The modeling results obtained for the Preferred Alternative are presented in Section 5.4.

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5.1 West Segment The modeling results obtained for the West Segment Alternatives are presented in Sections 5.1.1 to 5.1.5.

Given the scale of the West Segment Alternatives being modeled, a 30 m resolution could be used to evaluate the Alternatives’ effect on local water quality conditions.

All West Segment Alternatives, including the Do Nothing Alternative (i.e., Existing Conditions), were run with a 30 m resolution. However, it should be noted that the average predicted water quality parameters for both the F.J. Horgan WTP intake and Rouge Beach were extracted from the 270 m grid (within which the 30 m grid was nested) for all West Segment Alternatives, as the finer grids (i.e., 30 m and 90 m) did not extend all the way to Rouge Beach.

5.1.1 Do Nothing Figure 9 shows the modeled Do Nothing Alternative (i.e., Existing Conditions) for the West Segment of the SWP. Results are provided in Table 2 and Table 3.

All water quality parameters were well within the applicable guidelines (see Section 3.4.1).

Beach posting/closure rates varied from 13.1% at the East point, 13.4% at the Mid point, and 13.5% at the West point, with an average beach posting/closure rate of 13.3% of the season determined under the Do Nothing/Existing Conditions. These values are consistent with the requirements of a beach with Blue Flag status (posting/closure rate of less than 20%).

Note that the marina configuration differs slightly between the West Segment Alternatives, resulting from the model’s ability to interpolate and express each Alternative’s shoreline configuration input data. As the inner marina does not have any impact on the lake currents, the modeling results are not affected.

For ease of interpretation, the Do Nothing/Existing Conditions scenario modeling results are also presented together with modeling results obtained for other West Segment Alternatives modeled.

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Figure 9 West Segment existing conditions (i.e., Do Nothing Alternative) at 30 m resolution.

Table 2 Average predicted water quality parameter concentrations at the F.J. Horgan WTP intake and Rouge Beach, under the Do Nothing/Existing Conditions for West Segment.

Water Quality Parameter F.J. Horgan WTP Intake Rouge Beach TSS (mg/L) 0.105 8.53 TP (mg/L) 0.00011 0.0086 Cu (mg/L) 7.5E-6 0.00068 E. coli (CFU/100mL) 0.183 93 *data extracted from 270 m grid

Table 3 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational PWQO of 100 E. coli CFU per 100 mL of water, under the Do Nothing/Existing Conditions for West Segment.

Beach Point Modeling Location West Mid East Beach Postings (% of swimming season) 13.5 13.4 13.1

*data extracted from 30 m grid

5.1.2 Alternative 3A – Island-Bridge, Short Span The modeling results for the West Segment 3A Alternative (Figure 10) are shown in Table 4 and Table 5.

No significant differences in TSS, TP, Cu and E. coli concentrations were predicted to occur at either the F.J. Horgan WTP intake or Rouge Beach, and all predicted values met applicable water quality guidelines (Table 4). Therefore, West Segment Alternative 3A is not anticipated to impact TSS, TP, Cu and E. coli levels at the F.J. Horgan WTP intake or Rouge Beach.

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No significant change in beach posting frequency was predicted at the West, Mid and East points along the Bluffer’s Park Beach (Table 5). Beach posting rates varied from 11.6% at the East point, 12.4% at the Mid point, and 12.5% at the West point, with an average beach posting rate of 12.2% of the swimming season. Therefore, West Segment 3A Alternative would not impact the beach’s Blue Flag status.

Figure 10 West Segment Alternative 3A at 30 m resolution.

Table 4 Average predicted water quality parameter concentrations at F.J. Horgan WTP intake and Rouge Beach – comparison between Do Nothing/Existing Conditions and West Segment Alternative 3A.

Water Quality Parameter F.J. Horgan WTP Intake Rouge Beach Do Nothing/

Existing Conditions West 3A Do Nothing/ Existing Conditions West 3A

TSS (mg/L) 0.105 0.105 8.53 8.57 TP (mg/L) 0.00011 0.00011 0.0086 0.0087 Cu (mg/L) 7.5E-6 7.7E-6 0.00068 0.00066 E. coli (CFU/100mL) 0.183 0.191 93 92.7 *data extracted from 270 m grid

Table 5 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational waters PWQO of 100 E. coli CFU per 100 mL of water – comparison between Do Nothing/Existing Conditions and West Segment Alternative 3A.

Beach Postings (% of swimming season) West Mid East Do Nothing/ Existing Conditions 13.5 13.4 13.1

West 3A 12.5 12.4 11.6 *data extracted from 30 m grid

Location of proposed shoreline protection works

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5.1.3 Alternative 3B – Island-Bridge, Long Span The modeling results for the West Segment 3B Alternative (Figure 11) are shown in Table 6 and Table 7.

Table 6 lists the average predicted concentrations of the four water quality parameters at the F.J. Horgan WTP intake and Rouge Beach. Overall, there are no predicted changes of significance in water quality parameters at either location, and all parameters met applicable guidelines. Therefore, West Segment Alternative 3B is not anticipated to impact TSS, TP, Cu and E. coli levels at either the F.J. Horgan WTP intake or Rouge Beach sites.

No significant changes in beach posting frequency were predicted at each of the three locations along Bluffer’s Park Beach (Table 7). Beach posting rates varied from 11.6% at the East point, 12.4% at the Mid point, and 12.5% at the West point, with an average beach posting rate of 12.2% of the swimming season. Therefore, the ability of the Bluffer’s Park Beach to meet the Blue Flag water quality criteria would not be compromised by West Segment Alternative 3B.

Figure 11 West Segment Alternative 3B at 30 m resolution.

Table 6 Average predicted water quality parameter concentrations at F.J. Horgan WTP intake and Rouge Beach – comparison between Do Nothing/Existing Conditions and West Segment Alternative 3B.


Existing Conditions West 3B Do Nothing/ Existing Conditions West 3B

TSS (mg/L) 0.105 0.107 8.53 8.54 TP (mg/L) 0.00011 0.00014 0.0086 0.0087 Cu (mg/L) 7.5E-6 7.7E-6 0.0006 0.0006 E. coli (CFU/100mL) 0.183 0.214 93 92.6 *data extracted from 270 m grid


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Table 7 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational waters PWQO of 100 E. coli CFU per 100 mL of water – comparison between Do Nothing/Existing Conditions and West Segment Alternative 3B.

Beach Postings (% of swimming season) West Mid East Existing 13.5 13.4 13.1 West 3B 12.5 12.4 11.6 *data extracted from 30 m grid

5.1.4 Alternative 4 – Causeway West Segment Alternative 4 has five to six culverts distributed along the length of the causeway landform to facilitate water exchange between the lake and the basin formed by the landform (refer to Chapter 5 in the Environmental Assessment document for a more detailed description of the Alternative). As the lake model cannot represent underwater culverts, another method was employed to determine the exchange with the lake and the potential impact to water quality.

It was assumed that Alternative 4 has six culverts. West Segment Alternative 3A (Island Bridge, Short Span) is the Alternative most similar in configuration to Alternative 4, and was therefore used to calculate the water exchange that would occur for Alternative 4. The flux (water exchange) through each gap in Alternative 3A (Figure 12), labelled #1 through #4, was calculated by the model as a flow into or out of each gap.

Figure 12 Location of the island-bridge gaps in West Segment Alternative 3A used for the Alternative 4 water exchange calculations.

The total volumes of water exchanged between the basin and the lake through each gap from May 15 to September 5 (the model run period) are shown in Table 8. The model calculated the volume averaged over an hour, with the cross-sectional area of the gap multiplied by the speed of water through the gap. The resulting volumes were then sorted into “in” (volume of water entering the basin from the lake) and “out” (volume of water exiting the basin to the lake) and

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summed to produce a net volume (net exchange). While the excursion method is typically used when long distances are involved, the distance (length of each culvert, or the distance between the basin and the lake) was only 30 m for Alternative 3A, therefore a simpler method was used. Method and calculations are further described below.

Table 8 Volumes of water exchanged through each of the four gaps in West Segment Alternative 3A (m3).

Gap #1 Gap #2 In Out Net In Out Net

-1.102E+07 1.170E+07 6.772E+05 -9.333E+06 6.578E+05 -8.676E+06 Gap #3 Gap #4

In Out Net In Out Net -4.885E+06 1.100E+07 6.111E+06 -7.237E+06 9.275E+06 2.038E+06

A net exchange of 150,200 m3 was determined for the model run period. The internal (basin) volume is approximately 72,000 m3. Therefore, the water is exchanged 2.08 times, or approximately twice, in the season (May 15 to September 5).

The approximate depth at each gap and corresponding cross-sectional area, based on the triangular distribution approximation method, are as follows:

Gap Depth (m) Cross-Sectional Area (m2) #1 1.83 27.45 #2 2.20 33.00 #3 0.94 14.10 #4 1.38 20.70

The total cross-sectional area of the four gaps in Alternative 3A is 95.20 m2. Assuming each culvert’s cross-sectional area is 1 m2, the total cross-sectional area of the six culverts in Alternative 4 would be equal to 6 m2, and the ratio of gaps to culverts would be 1/15.8.

Extrapolating the net exchange through the four gaps to the six culverts, there would be 0.13 exchanges through the culverts per season. With the value so small, the exchange rate is essentially water stagnation. Therefore, Alternative 4 is predicted to have the potential to impact water quality in the basin between the beach and the causeway due to poor water circulation.

As the MIKE-3 lake model cannot represent underwater culverts, Shoreplan Engineering Limited employed a culvert flow calculation method and prepared a memorandum (Appendix A) to outline the flows and indicating that although the MIKE-3 model was run at approximately 11 times the culvert area, the results are still scalable by the ratio of the areas.

5.1.5 Alternative 5B – Wide Beach The modeling results for the West Segment Alternative 5B (Figure 13) are shown in Table 9 and Table 10.

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No significant differences in water quality parameter concentrations were observed at either the F.J. Horgan WTP intake or Rouge Beach, and all parameters met applicable water quality guidelines (Table 9). Therefore, West Segment Alternative 5B is not anticipated to impact TSS, TP, Cu and E. coli levels at either the F.J. Horgan WTP intake or Rouge Beach sites.

No significant changes in beach posting frequency were predicted at each of the three locations along Bluffer’s Park Beach (Table 7). Beach posting rates varied from 10.6% at the East point, 11.1% at the Mid point, and 11.2% at the West point, with an average beach posting rate of 11.0% of the swimming season. Therefore, the ability of the Bluffer’s Park Beach to meet the Blue Flag water quality criteria would not be compromised by West Segment Alternative 5B.

Figure 13 West Segment Alternative 5B at 30 m resolution.

Table 9 Average predicted water quality parameter concentrations at F.J. Horgan WTP intake and Rouge Beach – comparison between Do Nothing/Existing Conditions and West Segment Alternative 5B.


Existing Conditions West 5B Do Nothing/ Existing Conditions West 5B

TSS (mg/L) 0.105 0.104 8.53 8.9 TP (mg/L) 0.00011 0.0012 0.0086 0.0090 Cu (mg/L) 7.5E-6 7.6E-5 0.00068 0.00063 E. coli (CFU/100mL) 0.183 0.186 93 97 *data extracted from 270 m grid


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Table 10 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational waters PWQO of 100 E. coli CFU per 100 mL of water – comparison between Do Nothing/Existing Conditions and West Segment Alternative 5B.


West 5B 11.2 11.1 10.6 *data extracted from 30 m grid

5.2 Central Segment The modeling results obtained for the Central Segment Alternatives are presented in Sections 5.2.1 to 5.2.3.

The Central Segment Alternatives had small scale shoreline modifications, necessitating 10 m resolution (10 m grid) in order to capture any difference in the grids. The 10 m resolution model required much longer simulation runs - up to 10 days of clock time. All Central Segment Alternatives, including the Do Nothing (i.e., Existing Conditions), were run with a 10 m resolution.

It should be noted that the average predicted water quality parameters for both the F.J. Horgan WTP intake and Rouge Beach were extracted from the 270 m grid (within which the 10 m grid was nested) for all Central Segment Alternatives, as the finer grids (i.e., 10 m, 30 m and 90 m) did not extend all the way to Rouge Beach.

A new Do Nothing/Existing Conditions grid was also created for Central Segment to more accurately reflect the depths along the Central Segment shoreline that were not captured in the West Segment Do Nothing/Existing Conditions grid.

5.2.1 Do Nothing Figure 14 and Figure 15 show the modeled Do Nothing Alternative (i.e., Existing Conditions) for the Central Segment of the SWP. Results are provided in Table 11 and Table 12.

All water quality parameter concentrations predicted for the F.J. Horgan WTP intake were well within the applicable water quality guidelines (see Section 3.4.1). TP and Cu measured for Rouge Beach were also well within the applicable guidelines; however, both TSS and E. coli were found to exceed the guidelines.

The slight variation in the Do Nothing/Existing Conditions water quality parameter concentrations for the F.J. Horgan WTP intake and larger variations in concentrations at Rouge Beach between West and Central Segments is related to differences in the nested grid size and position, and their resultant effects on dilution. The finer nested grids used to model Central Segment extend farther east than those used to model West Segment. As a result, storm sewers along the shoreline will discharge into a finer grid for Central Segment (e.g., 10 m or 30 m), and into a coarser grid for West Segment (e.g., 90 m or 270 m). Storm sewer discharges

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into the coarser grids result in a higher dilution factor, and therefore lower water quality parameter concentrations are observed.


For ease of Alternatives comparison and results interpretation, the Do Nothing scenario modeling results are also presented together with modeling results obtained for other Central Segment Alternatives modeled.

Figure 14 Central Segment existing conditions (i.e., Do Nothing Alternative) at 30 m resolution.

Figure 15 Central Segment existing conditions (i.e., Do Nothing Alternative) at 10 m resolution.

Table 11 Average predicted water quality parameter concentrations at the F.J. Horgan WTP intake and Rouge Beach, under the Do Nothing/Existing Conditions for Central Segment.


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Table 12 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational PWQO of 100 E. coli CFU per 100 mL of water, under the Do Nothing/Existing Conditions for Central Segment.



5.2.2 Alternative 1 – Headland-Beach Central Segment Alternative 1 is shown in Figure 16 (30 m grid) and Figure 17 (10 m grid), and the results are presented in Table 13 and Table 14.

Table 13 lists the average predicted concentrations of the four water quality parameters at the F.J. Horgan WTP intake and Rouge Beach. Overall, there are no predicted changes of significance in water quality parameters at either location; therefore, Central Segment Alternative 1 is not anticipated to impact TSS, TP, Cu and E. coli levels at either the F.J. Horgan WTP intake or Rouge Beach sites.

No significant changes in beach posting frequency were predicted at each of the three locations along Bluffer’s Park Beach (Table 14). Beach posting rates varied from 9.8% at the East point, 10.5% at the Mid point, and 11.2% at the West point, with an average beach posting rate of 10.5% of the swimming season. Therefore, the ability of the Bluffer’s Park Beach to meet the Blue Flag water quality criteria would not be compromised by Central Segment Alternative 1.

Figure 16 Central Segment Alternative 1 at 30 m resolution (Segment starts at 1,700 m).

Figure 17 Central Segment Alternative 1 at 10 m resolution.


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Table 13 Average predicted water quality parameter concentrations at F.J. Horgan WTP intake and Rouge Beach – comparison between Do Nothing/Existing Conditions and Central Segment Alternative 1.


Existing Conditions Central 1 Do Nothing/ Existing Conditions Central 1


Table 14 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational waters PWQO of 100 E. coli CFU per 100 mL of water – comparison between Do Nothing/Existing Conditions and Central Segment Alternative 1.


Central 1 11.2 10.5 9.8 *data extracted from 10 m grid

5.2.3 Alternative 2 – Revetment Figure 18 and Figure 19 show Central Segment Alternative 2 in 30 m and 10 m nested grids, respectively, and the modeling results are presented in Table 15 and Table 16.

No significant differences in water quality parameter concentrations were observed at either the F.J. Horgan WTP intake or Rouge Beach (Table 15). Therefore, Central Segment Alternative 2 is not anticipated to impact TSS, TP, Cu and E. coli levels at either the F.J. Horgan WTP intake or Rouge Beach sites.

No significant changes in beach posting frequency were predicted at each of the three locations along Bluffer’s Park Beach (Table 16). Beach posting rates varied from 9.8% at the East point, 10.5% at the Mid point, and 11.2% at the West point, with an average beach posting rate of 10.5% of the swimming season. Therefore, the ability of the Bluffer’s Park Beach to meet the Blue Flag water quality criteria would not be compromised by Central Segment Alternative 1.

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Figure 18 Central Segment Alternative 2 at 30 m resolution.

Figure 19 Central Segment Alternative 2 at 10 m resolution (Segment starts at 1,700 m).

Table 15 Average predicted water quality parameter concentrations at F.J. Horgan WTP intake and Rouge Beach – comparison between Do Nothing/Existing Conditions and Central Segment Alternative 2.


Existing Conditions Central 2 Do Nothing/ Existing Conditions Central 2


Table 16 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational waters PWQO of 100 E. coli CFU per 100 mL of water – comparison between Do Nothing/Existing Conditions and Central Segment Alternative 2.


Central 2 11.2 10.5 9.8 *data extracted from 10 m grid


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5.3 East Segment The modeling results obtained for the East Segment Alternatives are presented in Sections 5.3.1 to 5.3.3.

Given the scale of the East Segment Alternatives being modeled, a 30 m resolution could be used to evaluate the Alternatives’ effect on local water quality conditions.

All East Segment Alternatives, including the Do Nothing Alternative (i.e., Existing Conditions), were run with a 30 m resolution. As with the West and Central Segments, it should be noted that the average predicted water quality parameters for both the F.J. Horgan WTP intake and Rouge Beach were extracted from the 270 m grid (within which the 30 m grid was nested) for all East Segment Alternatives, as the finer grids (i.e., 30 m and 90 m) did not extend all the way to Rouge Beach.

A new Do Nothing/Existing Conditions grid was created for East Segment to more accurately reflect the depths along the East Segment shoreline that were not captured in the West or Central Segment Do Nothing/Existing Conditions grids.

5.3.1 Do Nothing Figure 20 shows the modeled Do Nothing Alternative (i.e., Existing Conditions) for the East Segment of the SWP. Results are provided in Table 17 and Table 18.

All water quality parameter concentrations predicted for the F.J. Horgan WTP intake were well within the applicable water quality guidelines (see Section 3.4.1). TP and Cu measured for Rouge Beach were also well within the applicable guidelines; however, similar to Central Segment, both TSS and E. coli were found to exceed the guidelines.

As discussed in Section 5.2.1, the variation in the Do Nothing/Existing Conditions water quality parameter concentrations for the F.J. Horgan WTP intake and Rouge Beach relative to West and Central Segments is related to differences in nested grid size and position, and their resultant effects on dilution of storm sewer discharges.


For ease of Alternatives comparison and results interpretation, the Do Nothing scenario modeling results are also presented together with modeling results obtained for other Central Segment Alternatives modeled.

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Figure 20 East Segment existing conditions (i.e., Do Nothing Alternative) at 30 m resolution.

Table 17 Average predicted water quality parameter concentrations at the F.J. Horgan WTP intake and Rouge Beach, under the Do Nothing/Existing Conditions for East Segment.


Table 18 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational PWQO of 100 E. coli CFU per 100 mL of water, under the Do Nothing/Existing Conditions for East Segment.



5.3.2 Alternative 2A – Bridge with Headland-Beach The modeling results for the East Segment Alternative 2A (Figure 21) are shown in Table 19 and Table 20.

Table 19 lists the average predicted concentrations of the four water quality parameters at the F.J. Horgan WTP intake and Rouge Beach. Overall, no predicted changes of significance in water quality parameters at either location were observed. Therefore, East Segment Alternative 2A is not anticipated to impact TSS, TP, Cu and E. coli levels at either the F.J. Horgan WTP intake or Rouge Beach sites.

No significant changes in beach posting frequency were predicted at each of the three locations along Bluffer’s Park Beach (Table 20). Beach posting/closure rates varied from 12.0% at the East point, 12.8% at the Mid point, and 13.8% at the West point, with an average beach posting/closure rate of 12.9% of the season. Therefore, the East Segment Alternative 2A would not affect the ability of Bluffer’s Park Beach to maintain Blue Flag beach status.

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Figure 21 East Segment Alternative 2A at 30 m resolution.

Table 19 Average predicted water quality parameter concentrations at F.J. Horgan WTP intake and Rouge Beach – comparison between Do Nothing/Existing Conditions and East Segment Alternative 2A + Sheltered Harbour.


Existing Conditions East 2A Do Nothing/ Existing Conditions East 2A


Table 20 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational waters PWQO of 100 E. coli CFU per 100 mL of water – comparison between Do Nothing/Existing Conditions and East Segment Alternative 2A.


East 2A 13.8 12.8 12.0 *data extracted from 30 m grid

5.3.3 Alternative 4B – Headland-Beach to East Point Park The modeling results for the East Segment Alternative 4B (Figure 22) are shown in Table 21 and Table 22.

No predicted changes of significance in water quality parameter concentrations at either location were observed (Table 21). Therefore, East Segment Alternative 2A is not anticipated to impact TSS, TP, Cu and E. coli levels at either the F.J. Horgan WTP intake or Rouge Beach sites.

No significant changes in beach posting frequency were predicted at each of the three locations along Bluffer’s Park Beach (Table 22). As with Alternative 2A, beach posting/closure rates varied from 12.0% at the East point, 12.8% at the Mid point, and 13.8% at the West point, with an average beach posting/closure rate of 12.9% of the season. Therefore, the East Segment Alternative 4B would not affect the ability of Bluffer’s Park Beach to maintain Blue Flag beach status.


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Figure 22 East Segment Alternative 4B at 30 m resolution.

Table 21 Average predicted water quality parameter concentrations at F.J. Horgan WTP intake and Rouge Beach – comparison between Do Nothing/Existing Conditions and East Segment Alternative 4B.


Existing Conditions East 4B Do Nothing/ Existing Conditions East 4B


Table 22 Percent of swimming season that Bluffer's Park Beach is posted based on the recreational waters PWQO of 100 E. coli CFU per 100 mL of water – comparison between Do Nothing/Existing Conditions and East Segment Alternative 4B.


East 4B 13.8 12.9 12.0 *data extracted from 30 m grid

5.4 Preferred Alternative In order to determine the cumulative effects of the combined segment-level Preferred Alternatives, the model was run for the Preferred Alternative (Figure 23). Please see Chapter 5 of the EA document the evaluation of Alternatives process and results.

The Preferred Alternative is comprised of:

• West Segment Alternative 5B - Wide Beach Expansion with Headland Extensions;

• Central Segment Alternative 1 - Headland Beach; and • East Segment Alternative 4B - Headland Beach.


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Since Central Segment Alternative 1 did not cause any significant changes at 10 m resolution (Section 5.2.2), it was modelled at a 30 m resolution in this scenario, along with West Segment Alternative 5B and East Segment Alternative 4B.The results of this modeling exercise are presented in Table 23 and Table 24.

It should be noted that the same Do Nothing/Existing Conditions grid used for East Segment was also used to model the Preferred Alternative existing conditions, as it most accurately reflected variations in depth along the shoreline for the Project Study Area as a whole.

Figure 23 Preferred Alternative at 30 m resolution.

No significant changes were observed for any of the predicted water quality parameter concentrations at the F.J. Horgan WTP intake or Rouge Beach (Table 23). Therefore, the Preferred Alternative is not anticipated to impact TSS, TP, Cu and E. coli levels at either site.

No significant changes in beach posting frequency were predicted at each of the three locations along Bluffer’s Park Beach as a result of the Preferred Alternative (Table 24). Beach posting/closure rates varied from 12.0% at the East point, 12.8% at the Mid point, and 13.8% at the West point, with an average beach posting/closure rate of 7.6% of the season. Therefore, the Preferred Alternative would not affect the ability of Bluffer’s Park Beach to maintain Blue Flag beach status.

Table 23 Average predicted water quality parameter concentrations at F.J. Horgan WTP intake and Rouge Beach – comparison between Do Nothing/Existing Conditions and Preferred Alternative.

Water Quality Parameter F.J. Horgan WTP Intake Rouge Beach

Do Nothing/ Existing Conditions

Preferred Alternative

Do Nothing/ Existing Conditions

Preferred Alternative


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Table 24 Average current speeds at Bluffer's Park Beach – comparison between Do Nothing/Existing Conditions and Preferred Alternative.


Preferred Alternative 8.1 7.7 6.9 *data extracted from 30 m grid

5.5 Refined Preferred Alternative After the completion of the Alternatives evaluation documented in Chapter 5 of the Environmental Assessment document, the results were presented to the public for review and comment and were also reviewed with other stakeholders including various City of Toronto departments, interest groups, and government agencies. A number of meetings with community groups and neighbourhood groups were held to discuss proposed refinements and try to create understanding around various components of the Preferred Alternative (see Chapter 10 of the EA document). Through the input received from these additional consultations the Preferred Alternative was further refined.

As all of the refinements involved reductions in lakefill, it was anticipated that the impact of the refined Preferred Alternative on regional water quality conditions would be equal to or less than that predicted for the Preferred Alternative (see Section 5.4). Potential impacts to local water quality conditions were evaluated using a “spot testing” method to compare predicted water quality parameter values at six locations within West and Central Segment.

5.5.1 West Segment One minor refinement was made to the shape of the Bluffer’s Park headland, which was modified to include a small cobble beach on the west side to provide access to the water by park users and better opportunities for fish habitat enhancement. The overall size of the headland was not substantially changed.

Surface water quality parameter values (see Section 3.4.1) were modeled at six “test spots” at a 30 m resolution along the West Segment shoreline, to compare differences between the Do Nothing/Existing Conditions Alternative and the refined West Segment Preferred Alternative. Both scenarios, and the associated predicted water quality parameter “test spots”, are presented in Figure 24 and Figure 25.

The average concentrations over the simulation period (May 15 to September 5) for TSS, TP, Cu, and E. coli were used for comparison. The average predicted concentration results for each water quality parameter, along with location and depth, are shown in Table 25.

Overall, no significant differences in predicted water quality parameter concentrations were observed for TSS, TP and Cu between the Existing Conditions and the refined West Segment Preferred Alternative. Some notable decreases in E. coli levels were observed at test spots 3, 4 and 5 for the Preferred Alternative (relative to the reductions predicted for test spots 2 and 6),

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with decreases of up to 61.1 CFU/100 mL of water predicted. This may be a result of a sheltering effect provided by the expanded headlands on either side of the beach. All parameters met applicable water quality guidelines.

Therefore, no negative impacts to local water quality conditions along the West Segment shoreline are anticipated as a result of the refined Preferred Alternative.

Figure 24 Existing West Segment shoreline with the six water quality parameter "test spots" indicated at a 30 m resolution.

Figure 25 Refined West Segment Preferred Alternative shoreline configuration with the six water quality parameter "test spots" indicated at a 30 m resolution.

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Table 25 Average predicted water quality parameter concentrations at six locations along the West Segment shoreline – comparison between Do Nothing/Existing Conditions and refined West Segment Preferred Alternative

Scenario Modeling Location

Depth (m)

TSS (mg/L)

TP (mg/L)

Cu (mg/L)

E. coli (CFU/100mL)

Existing Conditions

1 8.1 0.82 0.0009 6.7E-5 24.7

Refined Preferred Alternative 8.05 1.26 0.0014 0.00011 33.3

Existing Conditions

2 6.4 0.97 0.0010 8.2E-5 33.1


Existing Conditions

3 1.5 3.9 0.0042 0.00038 70.4


Existing Conditions

4 0.76 4.9 0.0052 0.00040 64.4


Existing Conditions

5 1.06 5.0 0.0052 0.00040 58.1


Existing Conditions

6 3.88 2.0 0.0021 0.00017 34.9


5.5.2 Central Segment Two refinements to the Central Segment Preferred Alternative were proposed:

1. The eastern headland of the headland-beach system at the base of Doris McCarthy Trail/Bellamy Ravine was scaled back; and,

2. The headland-beach system originally proposed along the Guild Park and Gardens section of shorelines will be replaced with a veneer of rock/stone material on top of the existing revetment.

Please see Chapter 6 of the EA document for the rationale for refinement of these sections.

Given the similarity of the refined Central Segment Preferred Alternative to Central Segment Alternative 2, where no impacts to local or regional water quality conditions were predicted, further evaluation of the refined Central Segment Preferred Alternative was not deemed necessary.

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5.5.3 East Segment Refinements to the East Segment Preferred Alternative involved shortening the headland- beach system to the east side of Grey Abbey Ravine and transitioning the trail up from the toe to the top of the bluffs at this location.

Surface water quality parameter concentrations (see Section 3.4.1) were modeled at six “test spots” at a 30 m resolution along the East Segment shoreline, to compare differences between the existing East Segment shoreline and the refined Preferred Alternative. Both scenarios, and the associated predicted water quality parameter “test spots” are presented in Figure 26 and Figure 27.

The average concentrations over the simulation period (May 15 to September 5) for TSS, TP, Cu, and E. coli were used for comparison. The average predicted concentration results for each water quality parameter, along with location and depth, are shown in Table 26.

Overall, no significant differences in predicted water quality parameter concentrations were observed for TSS, TP and Cu between the Existing Conditions and the refined East Segment Preferred Alternative. Decreases in E. coli levels were observed at all test spots for the refined Preferred Alternative, with the most notable decrease at test spot 5 (484 CFU/100 mL of water). These decreases in E. coli are likely a result of the sheltering effect provided by the headlands of the proposed headland-beach system.

No negative impacts to local water quality conditions are anticipated along the East Segment shoreline as a result of the refined Preferred Alternative.

Figure 26 Existing East Segment shoreline with the six water quality parameter "test spots" and storm sewer outfall locations indicated at a 30 m resolution.

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Figure 27 Refined East Segment Preferred Alternative shoreline configuration with the six water quality parameter "test spots" and storm sewer outfall locations indicated at a 30 m resolution.

Table 26 Average predicted water quality parameter concentrations at six locations along the East Segment shoreline – comparison between East Segment Preferred Alternative and refined East Segment Preferred Alternative.

Scenario Modeling Location

Depth (m)

TSS (mg/L)

TP (mg/L)

Cu (mg/L)

E. coli (CFU/100 mL)

Existing Conditions 1

1.8 13.1 0.034 0.0009 268 Refined Preferred Alternative 1.8 12.7 0.013 0.0009 241











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6 SUMMARY AND CONCLUSION All Objectives of this modeling exercise were fulfilled.

No significant differences in predicated water quality parameter concentrations were observed at the F.J Horgan WTP intake and Rouge Beach for any of the Segment-level Alternatives or the Preferred Alternative, relative to the Do Nothing Alternative (i.e., Existing Conditions). Therefore, none of the Segment-level Alternatives or the Preferred Alternative are anticipated to have an impact on water quality at either site.

As previously discussed in Section 3.4.2, the changes observed in beach current speed were found to be insignificant for all Segment-level Alternatives and the Preferred Alternative. Therefore, none of the Segment-level Alternatives or the Preferred Alternative are anticipated to result in water stagnation (and subsequent potential algal blooms) at the local level, with the exception of West Segment Alternative 4 (Causeway) where water circulation is expected to be inhibited by the culverts.

No significant differences in beach posting rates at Bluffer’s Park Beach were observed for any of the Segment-level Alternatives or the Preferred Alternative, relative to the Do Nothing/Existing Conditions scenario. Therefore, none of the Segment-level Alternatives or the Preferred Alternative are anticipated to impact the Bluffer’s Park Beach Blue Flag status.

Spot testing of local water quality conditions resulting from the refined Preferred Alternative, relative to existing conditions, revealed no significant differences in predicted TSS, TP or Cu concentrations along the West and East Segment shorelines. Some notable decreases in predicted E. coli levels were observed for the refined Preferred Alternative, which may be a result of a sheltering effect provided by the expanded headlands in West Segment and the headlands of the headland-beach system in East Segment. Overall, the refined Preferred Alternative is not anticipated to have a negative impact on local water quality conditions along the Project Study Area shoreline.

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REFERENCES Beletsky, D., Schwab, D. J., and McCormick, M. 2006. Modeling the 1998–2003 summer circulation and thermal structure in Lake Michigan. Journal of Geophysical Research, 111(10), C10010, doi:10.1029/2005JC003222.

Boegman, L. and Yerubandi, R. Rao. 2010. Process oriented modeling of Lake Ontario hydrodynamics. Proceedings 6th International Symposium on Environmental Hydraulics, June 23-25, Athens, Greece, 6 pp.

City of Toronto. 2003. Wet Weather Flow Master Plan (WWFMP).

Dewey, R. 2003. Hydrodynamic and Pollutant Transport Model - Toronto Waterfront. Prepared for the City of Toronto’s Wet Weather Flow Master Plan (WWFMP).

Dewey. 2011. Spill Scenario Modelling for Lake Ontario Intakes, Assessment Report for Five Source Water Protection Areas - Lake Ontario Collaborative.

Dewey, R. 2012. Toronto Inner Harbour Water Quality Modelling Report. Prepared for City of Toronto and MMM Group - In Support of the “Assessment of Receiving Water Response to Alternative Wet Weather Flow Control Options” for the City of Toronto’s Don River and Central Waterfront Project - Class Environmental Assessment Study Report.

Dewey, R. 2013a. Coatsworth Cut Erosion Control - Lake Model. Prepared for Toronto Region Conservation Authority.

Dewey, R. 2013b. Ashbridges Bay Lake Model - Calibration (Draft). Prepared for CH2MHill Canada.

Golders Associates. 2009. Surface Water Environment Assessment of Environmental Effects Technical Support Document New Nuclear- Darlington Environmental Assessment NK054-REP-07730-00012 Rev000. Prepared for Ontario Power Generation.

MMM Group Ltd. 2012. Don River and Central Waterfront Class EA Study Report. Prepared for the City of Toronto.

National Ocean and Atmospheric Administration (NOAA). 1999. Bathymetry of Lake Ontario (Vol. G2).

Toronto and Region Conservation Authority. 2013. Waterfront Report Card 2013. Retrieved June 15, 2017 from https://trca.ca/wp-content/uploads/2016/04/2173_WatershedReportCards_Waterfront_rev7_forWeb.pdf.

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APPENDIX A Culvert Exchange Memorandum, prepared by Shoreplan Engineering Ltd.

Shoreplan Engineering Limited 20 Holly Street, Suite 202 Toronto, ON Canada M4S 3B1 T) 416.487.4756 F) 416.487.5129 E) [email protected]

Memorandum To: File 14-2127 Date: July 20, 2016

Re: Scarborough Waterfront Project Water exchange through culverts for causeway option east of

Bluffers Park Culvert flux estimates based on the scaling of Mike3 modeling results were checked using a simple culvert flow calculation method. Water level output from the Mike3 model was used to calculate flows through the culverts assuming that the flow was driven by the difference in water level between two successive records. Water levels were provided at 225 second intervals for the period from May 15 to September 5, 1991. Flows were calculated through an idealized culvert assuming the head difference across the culvert equalled the sum of the entrance losses, the friction losses, and the velocity head within the culvert. It was assumed the water level on either end of the culvert was identical at the start of each day (i.e. calculations were carried through from one day to the next). The time between two water level records was divided into three 75 second intervals. If there was a head difference across the culvert (caused by a change of water level on the lakeward side) the flow equation was solved to determine the velocity in the culvert, and hence the flow volume. That flow volume was used to adjust the water level in the embayment on the landward side of the culvert. With each flow reversal the volume of water within the culvert was subtracted from the calculated flow volume as that represented water that did not pass all the way through the culvert, and therefore did not contribute to the overall water exchange. For a total of five 135m long, 1.5m diameter CSP culverts, the total flow volumes for the period modeled were calculated to be 8.5 x 105 m3 into the “basin”, and 8.8 x 105 m3 out of the basin. The Mike3 model results (Dewey, 2016) for the West 4 alternative summed to 3.2 x 107 m3 into the basin and 3.3 x 107 m3 out of the basin, or approximately 38 times the values calculated using the culvert flow method. The cross sectional area of the gaps in the West 4 alternative, as modeled with Mike3, is approximately 11 times that of the total culvert area. If it is assumed that the Mike 3 results can be scaled down by the ratio of the areas, the scaled Mike3 results are approximately 3.5 times higher than the culvert flow calculation results. Considering the differences in the methods used and the assumptions made for the culvert

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method, this should be considered to be within an acceptable limit. It can therefore be concluded that the West 4 alternative results from the Mike3 modeling can be scaled to approximate the flows expected through the culverts.

Documents

APPENDIX I · 2011. 12. 9. · APPENDIX I Water Quality Modeling Report . Scarborough Waterfront Project . Water Quality Modelling . Prepared for . Toronto Region Conservation Authority