Comox Lake and Puntledge River Temperature Modelling Study

Fisheries and Oceans Canada

COMOX LAKE AND PUNTLEDGE RIVER TEMPERATURE MODELLING STUDY

FISH.073

July 2004

HAY & COMPANY CONSULTANTS INC. One West 7th Avenue Vancouver, BC V5Y 1L4 www.hayco.com Comox Lake and Puntledge River Temperature Modelling Study July 2004

EXECUTIVE SUMMARY

The Puntledge River flows from Comox Lake to Comox Harbour on the east coast of Vancouver Island, BC, and provides important spawning and rearing habitat for salmon. A storage dam at the outlet of the lake and a diversion dam on the river are used to control lake levels and river flows. Fisheries and Oceans Canada (DFO) is considering cold lake water withdrawal from Comox Lake as an option to reduce water temperature in the Puntledge River in the summer months, since high temperatures experienced in the river are a negative stressor for fish. This report presents a modelling study of lake and river temperatures. A prediction system, consisting of three numerical models, has been developed for the simulations of water level, velocity and temperature in both Comox Lake and the Puntledge River.

Circulation within Comox Lake was simulated using Hay & Company’s proprietary three-dimensional hydrodynamic model H3D. The model is able to capture the important processes of the development of thermal stratification over the course of the year as it evolves from the uniform conditions of winter, through the stratified conditions of summer, to the turnover during fall. The model is driven by heat exchange at the lake surface, wind forcing and river inflows. The outflow from the lake was modelled in two ways. For the existing condition, outflow was through shallow submerged gates in the Comox Dam; the deep-water withdrawal was modelled as an extraction from a depth of 35 m. Withdrawing the colder deep water results in a warming of the lake water down to about 40 m depth over the summer and fall, with a maximum temperature difference of over 5 degrees compared to the surface withdrawal simulation. The outflow from the lake model for the two runs was used to create two series of inflow temperatures for the Puntledge River model.

The river temperature model is an implementation of H3D, which simulates changes in river temperatures due to meteorological forcing and mixing of tributary waters. A major modification for the Puntledge River implementation was the provision for heat flux into and out of the rock bed of the river. Another major change was ‘flattening’ the river. If the entire 125 m elevation drop over the river’s length were to be modelled, the grid would be computationally expensive. Instead, the one-dimensional model MIKE 11 was used to generate the mean geodetic water surface elevation, which was then used to calculate the gravity force in the three-dimensional model. This accounts for the true surface slope while conducting calculations on a flattened grid with no elevation drop. The river bathymetry was generated from a topographic survey of the Puntledge River conducted in 2002. Water levels from the same survey were used to calibrate the river model.

Water temperatures have been collected at seven sites on the Puntledge River since 1999. The temperatures were used as input temperatures for the river model as well as to validate the river model. Two simulations were performed, one with the existing surface water supply, and the second with the deep lake withdrawal, to evaluate the impact of the cold water withdrawal on river temperatures. Supplying water from the deep withdrawal in the lake results in much cooler river temperatures. The

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Comox Lake and Puntledge River Temperature Modelling Study July 2004 average temperatures along the river, based on a reach-by-reach comparison, decreased by as much as 5.5 degrees in the hottest month of August, compared to the surface supply. The maximum river water temperature in August was about 16 degrees with the deep withdrawal, compared to a maximum of over 20 degrees with the current surface withdrawal. These cooler temperatures would be beneficial for fish migrating up the Puntledge River during the warm months.

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Comox Lake and Puntledge River Temperature Modelling Study July 2004

TABLE OF CONTENTS

1 INTRODUCTION ...... 1 1.1 Background...... 1 1.2 Context...... 2 1.3 Technical overview...... 2 2 LAKE MODEL...... 3 2.1 Model description ...... 3 2.2 Input data ...... 4 2.3 Calibration...... 5 2.4 Comparison of surface and deep water withdrawal ...... 6 3 RIVER MODEL ...... 7 3.1 Field Survey...... 7 3.2 1-D Hydrodynamic River Model ...... 9 3.3 3-D River Temperature Model...... 10 3.3.1 Description...... 10 3.3.2 Water level calibration...... 11 3.3.3 Temperature calibration ...... 12 3.3.4 Deep water withdrawal simulation...... 13 4 CONCLUSIONS AND RECOMMENDATIONS ...... 15 5 REFERENCES ...... 16

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Comox Lake and Puntledge River Temperature Modelling Study July 2004

LIST OF FIGURES

Fig. 1.1 Map of Comox Lake and Puntledge River, with 1999 average annual flows Fig. 2.1 Lake-headpond model 100-m grid Fig. 2.2 Measured and modelled lake temperature profiles Fig. 2.3 Comox Lake temperatures: spring, summer, fall 1998 Fig. 2.4 Lake-headpond model vs. measured water temperature, 1999 Fig. 2.5 Drawdown of warm water with surface withdrawal Fig. 2.6 Lake profiles, deep vs. surface withdrawal Fig. 2.7 Difference in lake temperature (May, June, July 1999) Fig. 2.8 Difference in lake temperature (August, September, October 1999) Fig. 2.9 Heat in lake-headpond model, deep vs. surface withdrawal Fig. 2.10 Change in sluicegate temperature, deep vs. surface withdrawal Fig. 3.1 River survey key plan Fig. 3.2 River survey longitudinal profile Fig. 3.3 Headpond contours Fig. 3.4 Headpond cross-sections Fig. 3.5 Surveyed cross-sections 1, 2, and 3 Fig. 3.6 Surveyed cross-sections 4, 5, and 6 Fig. 3.7 Surveyed cross-sections 7, 8, and 9 Fig. 3.8 Surveyed cross-sections 10, 11, and 12 Fig. 3.9 Surveyed cross-sections 13, 14, and 15 Fig. 3.10 Surveyed cross-sections 16, 17, and 18 Fig. 3.11 Surveyed cross-sections 19, 20, and 21 Fig. 3.12 Surveyed cross-sections 22, 23, and 24 Fig. 3.14 Surveyed cross-sections 25, 26, and 27 Fig. 3.15 Surveyed cross-sections 28, 29, and 30 Fig. 3.16 Surveyed cross-sections 31, 32, and 33 Fig. 3.17 Surveyed cross-sections 37 and 38 Fig. 3.18 Surveyed cross-sections 27a and 28a Fig. 3.19 Surveyed cross-sections 29a and 30a Fig. 3.20 Puntledge River MIKE 11 implementation Fig. 3.21 Surveyed and modelled water levels along Puntledge River

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Comox Lake and Puntledge River Temperature Modelling Study July 2004

Fig. 3.22 Modelled and surveyed water levels and bathymetry in Puntledge River (chain 16465 to 15066) Fig. 3.23 Modelled and surveyed water levels and bathymetry in Puntledge River (chain 14401 to 12870) Fig. 3.24 Modelled and surveyed water levels and bathymetry in Puntledge River (chain 12128 to 10034) Fig. 3.25 Modelled and surveyed water levels and bathymetry in Puntledge River (chain 9439 to 8535) Fig. 3.26 Modelled and surveyed water levels and bathymetry in Puntledge River (chain 8043 to 6618) Fig. 3.27 Modelled and surveyed water levels and bathymetry in Puntledge River (chain 6414 to 4246) Fig. 3.28 Predicted tide, surveyed levels and modelled water level at mouth Fig. 3.29 Temperature sensor locations Fig. 3.30 Puntledge River modelled and measured water temperature, 1999 Fig. 3.31 August river temperature, surface vs. deep input Fig. 3.32 Division of Puntledge River model into reaches Fig. 3.33 River temperature model results – deep vs. surface supply – July 1999 Fig. 3.34 River temperature model results – deep vs. surface supply – August 1999 Fig. 3.35 River temperature model results – deep vs. surface supply – September 1999 Fig. 3.36 River temperature model results – deep vs. surface supply – October 1999

LIST OF TABLES

Table 3.1 Surveying Methods Table 3.2 Cooling due to deep-water withdrawal: decrease in mean monthly temperature compared to surface withdrawal

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Comox Lake and Puntledge River Temperature Modelling Study July 2004

LIST OF ANIMATIONS

(Note: Animations are included on accompanying CD)

Animation 2.1 Comparison of surface and deep withdrawal – lake temperatures Animation 3.1 July river temperature, surface vs. deep input (July 1 to 15, 1999) Animation 3.2 July river temperature, surface vs. deep input (July 16 to 31, 1999) Animation 3.3 August river temperature, surface vs. deep input (Aug. 1 to 15, 1999) Animation 3.4 August river temperature, surface vs. deep input (Aug. 16 to 31, 1999) Animation 3.5 September river temperature, surface vs. deep input (Sept. 1 to 15, 1999) Animation 3.6 September river temperature, surface vs. deep input (Sept. 16 to 30, 1999)

LIST OF APPENDICES

Appendix A 2002 Addendum

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Comox Lake and Puntledge River Temperature Modelling Study July 2004

1 INTRODUCTION

The Puntledge River flows from Comox Lake to Comox Harbour on the east coast of Vancouver Island, BC, and provides important spawning and rearing habitat for salmon. Figure 1.1 shows a map of the Comox Lake and Puntledge River system along with 1999 flows. A storage dam at the outlet of the lake and a diversion dam on the river are used to control lake levels and river flows. A large percentage of the historical river flow is diverted through a penstock for power generation. The river has pool/riffle sequences, is generally 40 m wide with flow depths of 0.1 to 1.0 m, with a bed of primarily exposed bedrock and cobbles. During summer months, river temperatures approach dangerous levels for salmon (20oC to 25oC) due to both high temperature inflows from the surface of Comox Lake and warming of shallow flow over bedrock.

Fisheries and Oceans Canada (DFO) is considering cold lake water withdrawal from Comox Lake as an option to reduce water temperature in the Puntledge River in the summer months. Evaluating this proposed option requires an understanding of the lake dynamics and the impacts associated with cold water withdrawal at depth, the possible result of mixing cold lake water with BC Hydro flow releases and the attenuation of mixed water temperatures downstream in the Puntledge River. This report presents a lake and river temperature model that has been developed to assist in evaluating the feasibility of the proposed cold water withdrawal project. In this first phase, the model is used to assess, evaluate and confirm that the cold water withdrawal is feasible for reducing Puntledge River summer temperatures. Subsequently, the working model can be used in the development, assessment and evaluation of cold water withdrawal delivery options and alternatives.

1.1 Background

Comox Lake is located approximately 10 km west of Courtenay, BC. The lake has an area of 20.9 km2, a volume of 1370 million m3, a maximum depth of 128 m and an average depth of 65 m. The lake is oligotrophic (Hirst, 1991) and is fed primarily by two creeks, the Upper Puntledge and Cruickshank Rivers. Comox Lake forms the reservoir for power generation on the Puntledge River.

The lake is drained by the Puntledge River, with the flow regulated by gates at the Comox Lake Storage Dam. This dam forms the upstream boundary of the Puntledge River headpond, with the Puntledge River Diversion Dam at the downstream end of the headpond, 5 km along the river length. The year 1999 experienced high flows, however in this year flow data was available at other sites in the river system and therefore was chosen as the model calibration year. In 1999, an average 43 m3/s flowed through the headpond, of which 23 m3/s was diverted through the 5 km long penstock for power generation. In general, the penstock flow is kept constant at 26 m3/s, although it is lowered when necessary. The remaining 20 m3/s of the flow out of the lake was spilled over the Diversion Dam and through the upper diversion reach of the Puntledge River. The diversion reach flow had a minimum of approximately 6 m3/s and a maximum of 123 m3/s in 1999. Pools, riffles and cascades exist throughout the diversion reach

1 Comox Lake and Puntledge River Temperature Modelling Study July 2004 and flow patterns are controlled by the bedrock bottom features. Flow is added to the Puntledge River by two major tributaries, Brown’s River (8 m3/s average in 1999) and the Tsolum River (15 m3/s average in 1999), in addition to the flow through the penstock which re-enters the Puntledge River at the powerhouse. Minimum flow conditions above and below the powerhouse are specified and vary seasonally, to provide adequate spawning and rearing habitat for salmon. The river flows into Comox Harbour, an estuary on the Strait of Georgia, at Courtenay.

1.2 Context

In 1993, DFO prepared a preliminary draft report (McElhanney Consulting Inc., February 2000) that investigated the feasibility of a cold water withdrawal. Initial thoughts were to design and construct a deep water intake at a depth of greater than 30 m at an approximate distance of 300 m from the current BC Hydro (BCH) dam at the outlet of Comox Lake. The preferred option was a gravity water supply discharging just downstream of the existing Comox Lake Dam into the headpond. The intent of the project was to supply cold water for specific periods of time (primarily summer months) for mixing with BCH flow releases downstream of the Comox Dam. This would benefit the Puntledge River by reducing the high water temperatures experienced, which are at times in excess of 20°C during sensitive fisheries periods. Such high temperatures, especially during the summer periods, negatively impact fish migration and are extreme stressors to fish in the river system.

Concurrent to this proposal, DFO was aware that the Regional District of Comox-Strathcona (RDC-S) was also in the process of investigating additional potable water sources for the projected doubling of the service population by the year 2012. The RDC-S currently extracts their potable water supply (maximum sustained daily withdrawal of 0.921 m3/s or 17,500,000 gallons/day) from the BCH penstock, just upstream of the BCH generating station. One proposed possible source was a deep water intake and siphon line as the water quality and temperature would be more desirable. This option proposed an independent potable water supply line that would commence in Comox Lake and follow the alignment of the BCH penstock to the RDC-S metering station. This would remove their reliance on BCH’s operation and would satisfy future demands, which may not be available under the current arrangements with BCH.

1.3 Technical overview

The present study involves numerical prediction of lake and river temperatures to assess the option of reducing Puntledge River temperatures in the summer months by withdrawing cold water from deep in Comox Lake. It is assumed that all outflow being drawn from the lake, currently from shallow submerged gates in the Comox Dam, will instead be drawn from a depth of 35 m. A prediction system, consisting of three numerical models, has been developed for the simulations of water level, velocity and temperature in both Comox Lake and the Puntledge River. These models are described in following sections. A three-dimensional, baroclinic numerical model was used to determine the thermal structure of Comox Lake as it evolves from the uniform conditions of winter, through the stratified conditions of

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Comox Lake and Puntledge River Temperature Modelling Study July 2004 summer, to the turnover during fall. The model is driven by heat exchange at the lake surface, wind forcing and river inflows. The one-dimensional MIKE11 model was used to simulate the mean water level in the Puntledge River, which in turn is used as input to calculate the gravity force in a three- dimensional model of the Puntledge River. The three-dimensional model simulates changes in river temperatures due to input sources and meteorological forcing.

2 LAKE MODEL

2.1 Model description

Circulation within Comox Lake was simulated using Hay & Company’s proprietary three-dimensional hydrodynamic model H3D. H3D is derived from GF8 (Stronach, Backhaus and Murty, 1993), developed for Fisheries and Oceans. It is a three-dimensional time-stepping numerical model, and computes the three components of velocity (u,v,w) on a regular grid in three dimensions (x,y,z), as well as scalar fields such as temperature and contaminant concentrations. The spatial grid can be visualized as a number of interconnecting computational cells, which collectively represent the body of water. Velocities are determined on the faces of the cells, and non-vector variables, such as temperature, are situated in the centre of the cells. All cells have the same x and y dimensions. To accommodate full spatial coverage of Comox Lake and to allow an efficient computational time, a grid size of 100 m was chosen for the model.

In the vertical, the cells near the surface are closely spaced, with thickness of 1 m for this study, and are thicker at depth, so that the bottommost cell extends from 100 m to 125 m in the deepest part of the lake. The differences in horizontal and vertical geometry are required because of the large aspect ratio characterizing the lake, and because much of the variability (stratification, wind mixing, inputs from streams and land drainage) is concentrated near the surface, and requires better vertical resolution there. In addition, the model is capable of dealing with large excursions in overall water level as the lake rises and falls in response to varying inflows and outflows, by allowing the surface layers to appear and disappear as the water level varies.

The model is able to capture the important processes of the development of thermal stratification over the course of the year, and the response, in terms of enhanced currents and vertical mixing, to wind-driven events. This is achieved by applying atmospheric forcing to each surface grid point on each time step, including wind stress on the lake surface and radiant and turbulent heat fluxes through the lake surface. For the Comox Lake implementation, H3D was driven by the following forcing mechanisms:

Wind stress acting at the water surface: winds for the entire lake were based on data from Comox Airport. The drag coefficient, which relates wind stress on the lake to the square of wind speed, was taken to be 1.5 x 10-3 .

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Comox Lake and Puntledge River Temperature Modelling Study July 2004

River inflows: the Puntledge River and the Cruickshank River flow into the lake at specified boundary cells. Each river enters the lake at the plunge point, i.e. in the model layer where the river temperature matches the lake temperature so that their densities match. This phenomenon is observed whenever a denser river enters a lake or reservoir, and is readily simulated in H3D.

Outflow: the flow out of the lake was modelled in two ways. For the existing shallow withdrawal at the Comox Dam, discharge was drawn from the two layers in the grid cell corresponding to the dam gate location (the bottom depth in that cell corresponded to the sluicegate bottom elevation). The deep water withdrawal was modelled as an extraction from the bottom layer at a point corresponding to a proposed location (McElhanney, 2000), at a depth of 35 m.

Heat fluxes across the water surface: data from Comox Airport for wind speed, dry bulb air temperature, wet bulb air temperature and cloud cover, along with water surface temperature from the model, are used to compute the heat flux at the lake surface. Bulk transfer coefficients were taken from Friehe and Schmitt (1976) and albedo variables from Kondratyev (1972).

The model includes a penetrative convection mechanism: whenever a cell becomes more dense than the cell immediately below it, through surface cooling at night for instance, the two cells are assumed to mix instantaneously, thus removing the static instability. This procedure leads to vertical mixing of lake water, especially in the fall cooling period.

Turbulence modelling is important in determining the correct distribution of velocity and scalars such as contaminants. The diffusion coefficients for momentum and scalars at each computational cell are dependent on the level of turbulence at that point. H3D used a shear-dependent turbulence formulation in the horizontal, and a shear and stratification dependent formulation in the vertical for momentum. For scalars, a constant horizontal eddy diffusivity was used, and the vertical diffusivity was similar to the vertical eddy viscosity, but scaled by a fixed ratio. These parameters were shown to work well when simulating the annual cycle of temperature in Comox Lake, as shown below.

The model operated in a time-stepping mode over the period of simulation. The 100 m grid model used a 60 second timestep. During each time step, values of velocity and temperature were updated in each cell. Typically, data were archived (saved to disk) on an hourly or daily basis, so that a manageable amount of data was generated for subsequent analysis.

2.2 Input data

The lake bathymetry was generated from a 1990 survey provided by DFO. The entire lake has been included in the model, with river flow input and output specified at the boundaries. The model grid and river inflow and outflow locations are shown in Figure 2.1. As the river model domain starts below the diversion dam, the headpond was included in the lake model grid. The headpond was defined as a

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Comox Lake and Puntledge River Temperature Modelling Study July 2004 winding channel 4.1 km long, 60 m wide and 1.5 m deep, with a deep pool corresponding to the surveyed area described in Section 3.1 below.

River flow data for flow into and out of Comox Lake was obtained from BC Hydro, in addition to lake water levels. Examination of the data showed a discrepancy between the changes in water level predicted by summing the inflows and outflows, and the actual measured water levels. Both the inflow and outflow data provided by BC Hydro are synthetic, calculated from downstream gauge differentials. As well, the inflow showed a data gap in August 1998 that had been replaced by interpolated values. A corrected data series was generated to better model the impact of the flows on the lake dynamics and to ensure that the modelled lake water levels, based on the prescribed flows, matched the measured levels.

The Upper Puntledge River upstream of the lake is ungauged while the Cruickshank River has a Water Survey of Canada gauge near its mouth (08HB074). BC Hydro / Water Survey of Canada maintains a gauge on the Puntledge River in the diversion reach (08HB006). BC Hydro also records flow at the powerhouse, i.e. flow in the penstock. The outflow from the lake was taken to be the sum of the flow in the diversion reach and the flow in the penstock. The Puntledge River flow into the lake was then calculated from changes in the measured water levels and the difference between the outflow and the Cruickshank inflow. At times this calculation produced negative inflow values; these values were replaced by positive values and the artificially introduced flow was subtracted from the data series over several days, so that the total volume of the inflow was conserved and the lake water levels matched the measured values over the course of the year.

Wind and climate data (wet and dry bulb temperatures, cloud amounts) from the Comox Airport were used as model inputs. Although this is the nearest meteorological station to the lake, the climate can vary substantially from the actual conditions at the lake, due to sheltering effects of the surrounding topography. In calibrating the model, it was necessary to modify the wind data slightly in order to achieve temperatures within the lake that matched observations (see Sections 2.3 and 2.4 below).

2.3 Calibration

Water column stratification is reproduced in the model through the transport and dispersion of temperature, and its effect on the local water density. The temperature field is determined through a heat flux balance at each grid point. Stratification and the formation of a thermocline are dependent on the heat flux balance internally and the energy flux at the water surface. Internal waves due to perturbations in the baroclinic pressure field are set up in a stratified water body and can also affect the stratification. H3D has been shown to reproduce these phenomena well, for instance, in Okanagan Lake.

Model calibration is based on adjusting the model such that it reproduces the lake temperature stratification throughout the annual cycle. Six lake temperature profiles were measured in Comox Lake in

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Comox Lake and Puntledge River Temperature Modelling Study July 2004

1998 by Enkon Environmental Ltd. Comparison of modelled and observed profiles in Figure 2.2 for conditions on May 28, July 30 and September 8, shows that the model simulates the lake temperatures very closely during the warmer months. Calibration is usually performed by adjusting the vertical eddy diffusivity and other model parameters to match measured surface temperatures, location of the thermocline and lake temperatures at depth. A major improvement in this model was achieved by reducing the wind speeds based on observations at Comox Airport by 25 percent from June onwards, reflecting lower wind speeds at the inland location of the lake. In fact, this was the only adjustment necessary.

Figure 2.3 shows three cross-sections of temperature along the lake centreline, from the south end to the east end. These plots show development of stratification and deepening of the thermocline throughout the lake through the spring, summer and fall of 1998. Outflow from the lake for this run used the shallow withdrawal procedure at the Comox Dam, as described in Section 2.1.

2.4 Comparison of surface and deep water withdrawal

After calibration of the model with the 1998 temperature profiles, the model was run for the year 1999 to compare the relative impacts of the existing near-surface withdrawal with the impacts of the proposed deep water withdrawal. The two goals of these runs were to examine the effect of the withdrawal on the lake temperature structure, and to produce lake outflow temperatures to be used as input to the river temperature model.

Temperature observations at the upstream and downstream ends of the headpond were available for validation of the lake-headpond model for 1999. The observed water temperatures in the headpond were somewhat low compared to the modelled temperatures, even after reducing solar input by 10%. Even with this change, the modelled temperature in the headpond for the surface withdrawal was somewhat higher than observed (Figure 2.4). Since local meteorological data is unavailable, it is unreasonable to expect perfect agreement. The temperatures from this lake-headpond model run with surface withdrawal will be used as the base case for comparison with the deep water withdrawal, assuming that both models have similar errors and that differences will cancel when comparisons are made.

When the water is discharged through the sluicegates, warmer surface water tends to be drawn down to the outlet at times (Figure 2.5). When the deep withdrawal is used instead as the only outlet from the lake, drawdown no longer occurs. A comparison of the evolution of the lake’s thermal structure with the two withdrawal methods is presented in animated form in Animation 2.1, included on the CD that accompanies this report. In this animation, the plots for both surface and deep withdrawal show the same section along the midline of the lake.

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Comox Lake and Puntledge River Temperature Modelling Study July 2004

Withdrawing the colder deep water results in a warming of the lake water down to about 40 m depth over the course of the summer and fall. Profiles of lake temperature for the two simulations show the warming and deepening of the thermocline due to the deep-water withdrawal (Figure 2.6). The difference between the two runs is shown for a section along the lake in Figures 2.7 and 2.8. In mid-May, the difference in lake temperature for the two simulations is less than 0.5 degrees. By mid-June, temperatures between 20 and 30 m depth are up to 2.75 degrees warmer for the deep-withdrawal simulation than the surface- withdrawal case. In mid-July, the area affected grows to encompass depths from 10 to 40 m, with a warming of up to 3.5 degrees. Through August and September, the affected area does not grow in depth, but the temperature difference increases to 5.5 degrees. By mid-October, the temperature difference is greatest between 25 and 35 m depth, with a maximum difference of 6.8 degrees. The waters above 25 m depth are around 3 degrees warmer compared to the surface-withdrawal simulation in mid-October.

The warming of the lake water with the deep-water withdrawal compared to the surface withdrawal reflects the change in the heat flux out of the lake when colder water is withdrawn. The heat flux into the lake via the Puntledge and Cruickshank rivers is identical for the two simulations. The flux between the lake and the atmosphere remains roughly the same for the two runs. The major difference between the two runs is the heat flux out of the lake-headpond model, due only to the difference in the temperature of the outflow, since the flowrate is the same for the two runs. When colder water is extracted via the deep withdrawal, less heat leaves the lake, hence the heat content in the lake is higher as the season progresses (Figure 2.9).

Warmer lake water temperatures may have implications for the aquatic life in the lake, a topic that is beyond the scope of the present study. In addition, the warming of the upper portion of the lake with the deep-water withdrawal has implications downstream in the Puntledge River if water is to be discharged through the Comox Dam sluice gate. The water introduced to the headpond would be warmer than normal, by up to 2 degrees (Figure 2.10). However this warmer water would be mixed with the cold deep water, which can be as much as 5 degrees cooler compared to the current surface withdrawal (see Figure 2.9). The overall mixed temperature would still likely be cooler than the existing conditions, depending on the proportions of flow from the deep intake and the dam. The benefits of cooler water for fish downstream in the Puntledge River would not be as great if surface discharge were mixed with the deep withdrawal, compared to the deep withdrawal alone.

3 RIVER MODEL

3.1 Field Survey

A topographic survey of the Puntledge River was conducted over three weeks in August, September and October, 2002. The goal of the survey was two-fold: to meet requirements of fisheries studies conducted by others and to determine the cross-sectional and longitudinal characteristics of the river, such that the

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Comox Lake and Puntledge River Temperature Modelling Study July 2004 data could be used to set up the 1-dimensional MIKE 11 river model for river hydrodynamics and ultimately to implement a 3-dimensional H3D model for river temperature simulations.

The survey combined three methods for data collection: Total Station, Global Positioning System (GPS) and depth sounder. All three were combined to produce a highly accurate topographic description of the river. Table 3.1 lists the uses, benefits and limitations of the three methods.

Table 3.1 Surveying Methods

Method Use Benefit Limitation Total Station In-stream cross-sections High accuracy, data Time consuming to travel collection under tree large distances, shallow canopy water only Global Survey control (to tie High accuracy, easy to For use only where satellite Positioning together all cross-sections), travel large distances coverage exists, limited by System headpond survey location tree canopy Depth Sounder Headpond bathymetric Fast and accurate data For use where depths are survey collection in deep water greater than 0.9 m

Figure 3.1 shows the location of the Puntledge River, which flows eastward from Comox Lake to Comox Harbour in the Strait of Georgia. A longitudinal profile is shown in Figure 3.2, which shows that the river bed elevation drops from geodetic elevation of 120.3 m to –2.9 m over 12.4 km along the channel from cross-section 38 at the upstream end (downstream of the Puntledge River Diversion Dam) to cross-section 1 at the downstream end (near the mouth of the Puntledge River at Comox Harbour).

In total 42 cross-sections were surveyed in the Puntledge River using the Total Station. Of these, 38 were located on the main channel and 4 were located on the side channel downstream of the Island Highway bridge. The cross-section locations are shown in Figure 3.1, and cross-sectional data is presented in Figures 3.5 through 3.19 from the downstream end of the river at Comox Harbour to the upstream end at the Puntledge River Diversion Dam. Data collected in smaller side channels are contained with the data for the main channel, since most side channels were small channels around islands. Cross-sections were measured at areas of biological interest, identified by biologist Dave Burt. Additional cross-sections were measured to fill in the gaps and complete the physical picture of the river. In general, the Puntledge River is wide and shallow, with a relatively uniform cross-section. The longitudinal profile exhibits pools and riffles, and the river bed is composed of bedrock and cobbles with few sediments.

A detailed bathymetric survey of a portion of the headpond was conducted using Real-Time Kinetic GPS system and a depth sounder. The location is shown on Figure 3.1. The channel length of the surveyed

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Comox Lake and Puntledge River Temperature Modelling Study July 2004 section is approximately 500 m. A contour map for this survey is presented in Figure 3.3. This part of the survey was conducted at the request of BC Hydro. Figure 3.4 shows four cross-sections in the headpond, identified by biologists.

3.2 1-D Hydrodynamic River Model

The Puntledge River was modelled using MIKE 11, a dynamic model developed by the Danish Hydraulic Institute. The MIKE 11 hydrodynamic module, used in this study, uses an implicit, finite difference scheme for the computation of unsteady flows in rivers and estuaries. The module can describe subcritical as well as supercritical flow conditions through a numerical scheme that adapts according to the local flow conditions. The computational scheme is applicable for vertically homogeneous flow conditions extending from steep river flows to tidally influenced estuaries. This model is therefore well suited for modelling a tidally influenced river such as the Puntledge River.

MIKE 11 was implemented with available data, including: A river network - a plan of the river and the along-channel river chainage were determined from topographic maps and air photos; Cross sectional data - 42 river topography cross-sections were surveyed to establish the channel geometry; A longitudinal channel profile - determined from the surveyed sections; Flow data at the Puntledge Diversion Dam (upstream boundary condition), Brown’s River (tributary), flow through the BC Hydro Penstock outlet at the powerhouse (treated as a tributary) and the Tsolum River (tributary); Tidal water level data for Comox Harbour (downstream boundary condition).

Figure 3.20 is an air photo of the Puntledge River showing the river network implemented in MIKE11, as well as locations of cross sections and boundary conditions within the one-dimensional model grid.

Originally it was proposed that the outputs of the MIKE 11 model run would be used to prescribe water levels and velocities at each time step in the three-dimensional river temperature model, which would model heat fluxes and temperatures only. The three-dimensional model was subsequently modified so that it could model the water level and flows itself, eliminating the need for a time series from MIKE 11. The MIKE 11 model was then used solely to generate the geodetic water surface profile for calculating the gravity force in the three-dimensional model as described below. The MIKE 11 model interpolates between the input data of the surveyed cross-sections, hence the water surface was extracted at the known cross-section locations and interpolated to the grid of the three-dimensional model.

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Comox Lake and Puntledge River Temperature Modelling Study July 2004

3.3 3-D River Temperature Model

3.3.1 Description

The river temperature model is a version of H3D, as described above in Section 2.1. This model calculates water levels, three components of velocity and transport of scalars such as temperature. The variable number of vertical layers in the model accommodates the fact that average river depths vary between 0.3 m and 3.5 m along the length and also allows heat transfer between layers. A major modification of H3D for the Puntledge River implementation was the provision for heat flux into and out of the rock bed – this is achieved by determining the temperature of the rock bed due to atmospheric heat flux attenuated through the water column. The flux between the deepest water layer and the bed is a function of the temperature, heat capacity, thermal conductivity and density of both the water and the rock.

Another major change in this implementation of H3D was ‘flattening’ the river. If the entire 125 m elevation drop over the river’s length were to be modelled, the grid would be computationally expensive, since the layers must be quite thin to model the water depth – for example, with layers of 0.2 m thickness, 625 vertical layers would be required. Instead, the geodetic water surface elevation at all points on the grid, obtained from MIKE 11, allows computation of a body force due to gravity at each cell, which accounts for the true surface slope while conducting calculations on a flattened grid, i.e. with no elevation drop.

A long, thin grid representing the river channel was generated from the field survey data. The zero datum in the model grid was assumed to be the water level for average flow, determined by MIKE 11. Surveyed water levels were available from 2002; since this was a very low flow year, the surveyed water level was set at -0.2 m. In order to flatten the grid, the measured elevations at each section were dropped by the amount corresponding to setting the surveyed water level at -0.2 m. For sections downstream of the Tsolum River (sections 1 to 7), water level is tidally influenced, hence the geodetic cross-section elevations were used to generate the model grid there. In addition the two most downstream sections required deepening to allow the tidal water level to be specified as a boundary condition.

The grid is 10 cells wide by 641 cells long, where the size of each grid cell is 20 m by 20 m. The river is characterized by a deeper section with shallower banks on one side or both sides. Simple averaging of the survey depths across the river into 20 m cells did not resolve this combination of deep pools and shallows. To better represent the cross-channel bathymetry within the 20 m grid resolution, the survey depths were sorted from deepest to shallowest at each section. Averaging the depths across 20 m cells now produced a river channel with a thalweg on the left bank and gradually shallower steps to the right. Although in reality the shallow banks migrate from side to side, this representation allows the model to better simulate the differences in heating and cooling experienced in shallower and deeper areas. The river channel width ranged between one and four cells; primarily it is two or three cells wide. The bathymetry was interpolated between the surveyed sections to fill in the cells along the grid. A minor amount of smoothing was applied along the channel to reduce abrupt transitions.

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Comox Lake and Puntledge River Temperature Modelling Study July 2004

Other inputs to the model include: Meteorological data including wind, air temperature, and cloud cover from Comox Airport. River flows and water temperatures at the upstream boundary and for tributary rivers. Tidal water levels at the downstream boundary.

The model is operated at a variable time step, calculated from stability criteria. The time step was small (generally around 1.5 s) to ensure numerical stability for time-varying velocities in the 20 m grid.

3.3.2 Water level calibration

The river model was calibrated against the surveyed water levels in 2002. The two factors having the most impact on the water level are the bottom friction and the geodetic water surface elevation used to calculate the body force. The friction factor was assumed to decrease down the river, since the bottom material is larger at the head of the river and finer at the mouth, and there are more regions of riffles and waterfalls characterized by high head loss at the upper end of the river. A number of runs were performed with varying friction to attempt to match the modelled water levels to the measured water levels. When a sufficient accuracy was reached, the model parameters were saved for use in the temperature model. The modelled and surveyed water levels are shown in profile in Figure 3.21, and at individual cross-sections in Figures 3.22 to 3.27.

While the agreement was qualitatively good, in general, the modelled water level was too shallow in the upstream half of the river and too deep in the downstream half of the river. Further changes in friction factor did not improve the overall agreement. The model is limited by the fact that the topography and the geodetic water surface elevation are inferred between the surveyed cross-sections, so that certain features may not be represented. The upper portion of the river is characterized by waterfalls over abrupt drops in bed elevation, which are not resolved in the model grid. These waterfalls dissipate much energy and would serve to raise the water level in those reaches.

In validating the water levels, an interesting phenomenon was discovered. During the field survey, at times when the tide at Comox was rising, the surveyed water level was dropping. It was hypothesized that the tidal flats between the river mouth and Comox Harbour prevent it from draining on the ebb tide. An existing H3D model implementation for the Baynes Sound area was used to confirm this hypothesis. Figure 3.28 shows the time series of the tide along with the modelled water level at the mouth of the Puntledge from the Baynes Sound implementation and the surveyed water levels (note that the survey times are approximate). It is evident that the river cannot drain fully due to the tidal flats and so does not attain the same low water levels as the low tide in the harbour.

To accurately model the water level at the downstream boundary of the Puntledge River, there are two options. The first would be to run the Baynes Sound model for the period of simulation to generate the

FISH.073 11

Comox Lake and Puntledge River Temperature Modelling Study July 2004 boundary condition for the river temperature model, which is beyond the scope of the present project. The second would be to add grid cells to the river model to represent the mud flats, out to the harbour where the tidal boundary condition could be specified, which is computationally expensive. If the model is left as it is, the water levels of the five most downstream sections cannot be validated against the field survey since the current implementation of the Puntledge River model uses the tide as its boundary condition. Using the tidal water levels as the model boundary condition allows the river water level to drop lower than in reality for low tides; this would only affect river properties within the zone of tidal influence, i.e. seaward of chainage 7000.

3.3.3 Temperature calibration

Water temperatures have been collected at seven sites on the Puntledge from spring/summer 1999 onwards (Figure 3.29). The temperatures were used as input temperatures for the model as well as to validate the model. Site 2 at the Diversion Dam was used as the temperature at the upstream boundary of the river model. No temperatures were collected on the tributaries, hence the closest approximation of the tributary temperatures was taken from the sites just downstream of each tributary, which is actually the mixed temperature of the Puntledge and the tributary. The temperature at Site 6 (5th Street Bridge) was taken as the temperature for the Tsolum. The temperature at Site 5 (Main Fence) was used for the Penstock temperature. Although Site 4 (Lower Pink Side Channel) is located downstream of the Brown’s River, recorded temperatures were significantly cooler than other sites on the Puntledge at times and did not fit in with the along-channel trend, so Site 4 could not be used as the input temperature for the Brown’s. In fact Sites 3 and 4 are in a side channel and hence do not reflect the actual temperatures in the river; their temperatures differed significantly from adjacent sites. In a first attempt to provide a realistic temperature for the Brown’s River, it was assumed to have characteristics similar to the Tsolum, and the temperature at Site 6 was used for the Brown’s as well. However, the temperature proved to be too cool as well, according to anecdotal evidence (the Site 6 temperature did not make as much of an impact with the Tsolum inflow due to its much smaller flows). In the final model run, the Brown’s temperature was set to the temperature in the Puntledge just upstream, so that the Brown’s added flow to the Puntledge without a change in temperature.

Sites 3 and 7 were not used as input temperatures for the model and can be used for independent verification of the temperature model. However, Site 3 is in the Upper Pink Side Channel and is noticeably warmer than other river sites, so it cannot be taken as representative of the Puntledge River temperatures. Thus only Site 7 (17th Street Bridge) can be used for independent validation of the temperature modelling. The other sites can also aid in validation of the model: modelled river temperature at their locations should be close to or warmer than their observed values, since those temperatures were used as inputs to the model at the tributary locations somewhat upstream of the actual sensor locations.

Hourly, depth-averaged water temperatures from the model are compared with the measured values in Figure

FISH.073 12

Comox Lake and Puntledge River Temperature Modelling Study July 2004

3.30, for all sites within the Puntledge River (i.e. excluding the side channel sites). The top panel shows the temperature at the Diversion Dam, which was used as the input temperature for the river model, so that the modelled temperature equals the measured temperature. In the remaining panels, the hourly time series of modelled river temperature shows the diurnal variation in the simulated temperature, compared to daily values of measured temperature. The measured temperature at Site 5 was used as the input temperature for the penstock, which is located about 500 m upstream of the site. The penstock has a much higher flow than the Puntledge out of Comox Lake, hence the modelled water temperature at the site matches closely with the measured values. The temperature at Site 6 was used as the input temperature for the Tsolum, roughly 500 m upstream of the sensor location. The Tsolum has a very small flow compared to the main channel at that point, so it does not have a very large impact on the river temperature. Site 6 can be used as essentially an independent check of the model. The predicted temperature is warmer than measured in July, and slightly cooler on average in the hotter months of August and September. The difference between the daily-averaged model temperatures and the daily measured temperatures is at most 0.65 oC.

At Site 7, which was not used as input to the model and can be used for independent validation of the model, the predicted temperature is warmer than measured during the month of July. The modelled temperature is very close to the measured values in the hotter months of concern, August and September. The average difference between the modelled and measured values is less than 0.4 oC in those months. The temperature model performs well based on this validation and can be used to simulate the impact of the deep water withdrawal on river temperatures.

3.3.4 Deep water withdrawal simulation

Two simulations were performed to evaluate the impact of the deep lake withdrawal on river temperatures. Since the lake model surface-withdrawal simulation did not provide a perfect match with the measured temperatures in the headpond, the river model was run with temperatures from the lake surface withdrawal simulation as a base case for comparison with the deep withdrawal case. In both the surface and the deep withdrawal runs, the temperature at the downstream end of the headpond in the lake-headpond model (i.e. at the diversion dam) was used as the input temperature for the Puntledge River and for the penstock in the river temperature model. It was assumed that the temperature in the penstock does not change greatly along its length, since not much surface area is exposed for heat transfer. The temperature of the water supplied for the two cases can be compared in the top panel of Figure 2.9.

FISH.073 13

Comox Lake and Puntledge River Temperature Modelling Study July 2004 and jumps are expected. Hydraulic jumps show as sudden increases in water surface. The persistent jump at around chainage 14,000 is due to an unfortunately abrupt change in friction specified in the model. Other sharp changes in the water surface are found where the tributaries enter the Puntledge, and the extra flow must be accommodated. The more gradual changes in the water surface are simply the response to changes in bathymetry. A very interesting feature to note in the accompanying animations (Animations 3.1 to 3.6) is the intermittent presence of a series of waves that propagate downstream between chainage 14,000 and 13,000 (for example on August 8th and 9th in Animation 3.3). Such roll waves commonly form in steep, shallow flows.

For the deep withdrawal case, the temperature along the river shows two rather abrupt transitions where the Brown’s and the penstock enter the Puntledge (Figure 3.31). On the date shown, the flow in the Brown’s was 8.9 m3/s, flow in the Puntledge was 18.3 m3/s and flow in the penstock was 26 m3/s. The flow of the Brown’s is nearly half that of the Puntledge, so it has an impact on the resulting mixed temperature. The same time series of temperature was used for the Brown’s in both cases in order to isolate the effects of the lake withdrawal on river temperature. The temperature in the Brown’s was set to the temperature in the Puntledge just upstream of the Brown’s from the surface withdrawal run, for both the surface and the deep withdrawal case. Hence, the temperature in the Brown’s is much warmer than the Puntledge for the deep withdrawal run. The penstock enters the Puntledge with a temperature equal to the head of the Puntledge (since no warming was assumed along the penstock) and with higher flow than the combined Puntledge and Brown’s, so it results in a mixed temperature closer to the value at the head of the river. On the date shown, the flow of the Tsolum is only 2 percent of the Puntledge River flow where it enters, thus it has little impact on the river temperature. The rock bed receives heat from the water above it, and transmits some back. The topmost metre or so of rock shows diurnal fluctuations, corresponding to the diurnal variation in the overlying water temperature. In Figure 3.31 it is apparent that supplying water from the deep-water withdrawal in the lake results in much cooler river temperatures compared to the existing surface supply.

To summarize the impact of the deep-water withdrawal on the river water temperatures, the Puntledge River was divided into six reaches (Figure 3.32). In each reach, the monthly minimum, maximum and mean water temperatures were determined for each of the two simulations. Figures 3.33 to 3.36 show the impact of the deep-water withdrawal on the river reach temperatures for July through October, 1999. In the hottest month, August, the maximum temperature decreases from 20.1ºC to 15.5ºC as a result of switching to the deep-water withdrawal. In July, August and September, the maximum temperature in each reach with the deep-water withdrawal is equal to or lower than the mean temperature with the surface withdrawal. The average cooling is more than 3 degrees for all reaches in the months of July, August and September; see Table 3.2 below for a summary of the amount of cooling. In October, the temperature of the deep-water withdrawal is very close to the surface withdrawal temperature, and in fact exceeds it later in the month (see Figure 2.11), so the impact on the river temperature is small. However, river temperatures in October are already low and are not harmful to fish, so loss of cooling from deep extraction should not be a problem.

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Comox Lake and Puntledge River Temperature Modelling Study July 2004

Table 3.2 Cooling due to deep-water withdrawal: decrease in mean monthly temperature compared to surface withdrawal

Headpond Reach 1 Reach 2 Reach 3 Reach 4 Reach 5 Reach 6 July 4.6º 4.4º 4.3º 3.2º 3.4º 3.4º 3.2º August 5.8º 5.5º 4.9º 3.1º 4.6º 4.6º 4.4º September 4.1º 3.8º 3.1º 2.3º 3.4º 3.3º 3.1º October 0.7º 1.1º 1.0º 0.3º 1.2º 1.0º 0.9º

4 CONCLUSIONS AND RECOMMENDATIONS

The lake and river models have demonstrated the impacts of the proposed deep water withdrawal on temperatures in the lake and in the Puntledge River. The lake model replicated the seasonal evolution of the lake temperatures for current conditions. When the deep-water withdrawal was simulated, the top 35 metres of lake warmed considerably compared to the surface withdrawal. The greatest difference between the two withdrawal methods occurred in September and October, with warming at 30 m of more that 5 °C compared to the present withdrawal method. The implications of warmer lake water on the aquatic ecology should be considered. The lake model should also be run over a period of several years to investigate whether the lake would return to its historical conditions after the winter cooling period, or whether long-term warming would persist.

The deep withdrawal from the lake supplied cooler water to the Puntledge River compared to the current withdrawal at the sluicegate. The river model showed the impacts of this change in water temperature along the Puntledge River. The water in the river was 2.3 to 5.8 degrees cooler in the summer months when the deep withdrawal was used compared to the surface withdrawal, based on monthly averages of each reach. The cooling effect persisted over the entire length of the river. The instantaneous difference in the temperature of the deep withdrawal compared to the surface withdrawal reached a maximum of 6.4 degrees in mid-August. The maximum temperature in the river was 16.1 degrees with the deep withdrawal, compared to a maximum of 20.1 degrees with the surface withdrawal. The cooler temperatures would be beneficial for fish migrating up the Puntledge River during the warm months.

The lake and river models could be used to investigate and evaluate other alternatives for cold water withdrawal, for example mixing deep water and surface flow. The lake model could also be used to examine nutrient cycling and the potential for change in the aquatic ecology of the lake driven by the elevated temperatures and deepened thermocline that would result from bottom withdrawal.

FISH.073 15

Comox Lake and Puntledge River Temperature Modelling Study July 2004

For future modelling of the river temperature, it would be beneficial to consider different locations for the temperature loggers. Specifically, temperature loggers should have been installed in the major tributaries, such as the Brown and Tsolum Rivers. Knowing the temperature of the tributaries would improve the model and would also improve the general understanding of processes in the river that control temperature, irrespective of the modelling that was undertaken.

Considerable uncertainty in the lake modelling could have been eliminated by the installation of a meteorological station on the lake, so that the heat fluxes at the lake surface could be parameterized more accurately.

Future studies do not require the use of MIKE 11 as H3D has proved capable of modelling the river flow and could be calibrated to the water elevation on its own.

Considerable effort was expended in developing both the lake and river models. This technology is not tied to the Comox Lake / Puntledge River system. The models could also be applied to other lakes and rivers, simply by changing the bathymetric and input data sets.

5 REFERENCES

Danish Hydraulic Institute. 2000. MIKE 11: A Modelling System for Rivers and Channels, Reference Manual. DHI Software.

Enkon Environmental Limited. 2000. Final Report: Comox Valley Water System, Comox Lake and Watershed Study, for Regional District of Comox-Strathcona. Victoria, BC.

Friehe and Schmitt. 1976. Parameterization of air-sea interface fluxes of sensible heat and moisture by the bulk aerodynamic formulas, J. Phys. Oceanogr. 76:801-805.

Hirst, S.M. 1991. Impacts of the Operation of Existing Hydroelectric Developments on Fishery Resources in British Columbia, Volume II Inland Fisheries. Canadian Manuscript Report of Fisheries and Aquatic Sciences 2093, Fisheries and Oceans Canada, Habitat Management Division, Pacific Region.

Kondratyev, K.Y. 1972. Radiation Processes in the Atmosphere, WMO No. 309.

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Comox Lake and Puntledge River Temperature Modelling Study July 2004

McElhanney Consulting Services. 2000. Regional District of Comox Strathcona: Comox Lake and Watershed Study. Courtenay, BC.

Stronach, J.A., J.O. Backhaus and T.S. Murty. 1993. An update on the numerical simulation of oceanographic processes in the waters between Vancouver Island and the mainland: the GF8 model. Oceanography and Marine Biology Annual Review. 31:1-86.

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FIGURES

HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER MAP OF COMOX LAKE AND PUNTLEDGE RIVER, WITH 1999 AVERAGE ANNUAL FLOWS TEMPERATURE MODELLING 1.1 340000 342000 344000 346000 348000 350000 352000

HEADPOND 5502000 5502000

Surface outflow to Headpond

COMOX LAKE 5500000 5500000 Deep withdrawal 1998 Profiles (to Headpond)

5498000 5498000

5496000 5496000

Cruickshank River Inflow 5494000 5494000

5492000 5492000

Puntledge River Inflow

5490000 5490000

340000 342000 344000 346000 348000 350000 352000 HAYCO HAY & COMPANY CONSULTANTS INC. FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER LAKE-HEADPOND 2.1 TEMPERATURE MODELLING STUDY 100 m MODEL GRID Fri Nov 7 11:28:52 2003:S:\fish-073\jtop_headpond\big_grid M M M 0 M M M M M M M M M M M M M M M 5 M M M M M

M M M

10 M M M

M MM

M M M 15 M M M

MM M DEPTH (m) 20 MM M 28-May-1998

M 30-Jul-1998 M 08-Sep-1998 25 M M Model: 28-May-98

M M Model: 30-Jul-98

M M Model: 08-Sep-98 30

35 5 10 15 20 25 TEMPERATURE (oC) HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA COMOX LAKE AND PUNTLEDGE RIVER MEASURED AND MODELLED FIG. 2.2 TEMPERATURE MODELLING STUDY LAKE TEMPERATURE PROFILES

Z:\fish-073\jtop_lake\profile\report.lpk 09 Oct 2003 10:10:53 1998 05 10 12:00 21 0 20 10 19 18 20 17 30 16 40 15 50 14 60 13

depth 70 12 11 80 10 90 9 100 8 110 7 120 6 0 5000 10000 15000 5 dist 4

1998 07 10 12:00 21 0 20 10 19 18 20 17 30 16

40 15

50 14 60 13

depth 70 12 11 80 10 90 9

100 8 110 7 120 6 0 5000 10000 15000 5 dist 4

1998 09 10 12:00 21 0 20 10 19 18 20 17 30 16 40 15 50 14 60 13

depth 70 12 11 80 10 90 9 100 8 110 7 120 6 0 5000 10000 15000 5 HAYCO dist 4 HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA COMOX LAKE AND PUNTLEDGE RIVER COMOX LAKE TEMPERATURES FIG. 2.3 TEMPERATURE MODELLING STUDY SPRING, SUMMER, FALL 1998

Z:\fish-073\jtop_lake\plots\section\portrait.lay 09 Oct 2003 10:38:04 20 20

modelled 18 18 measured 16 16 [C] 14 14 12 12 Lake outlet / Headpond inlet 10 10 1 4 7 10 13 16 19 22 25 28 1 4 7 10 13 16 19 22 25 28 31 3 6 9 12 15 18 21 24 27 30 2 5 8 11 14 17 20 23 26 29 Jun Jul Aug Sep 20 20 18 18 16 16 [C] 14 14 Headpond outlet 12 12 10 10 1 4 7 10 13 16 19 22 25 28 1 4 7 10 13 16 19 22 25 28 31 3 6 9 12 15 18 21 24 27 30 2 5 8 11 14 17 20 23 26 29 Jun Jul Aug Sep

HAYCO HAY & COMPANY CONSULTANTS INC. FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER LAKE-HEADPOND MODEL VS. 2.4 TEMPERATURE MODELLING STUDY MEASURED WATER TEMPERATURE, 1999 Fri Oct 10 09:48:36 2003:S:\fish-073\jtop_headpond\runs\run8 1999 6 16 12:00 19 0 18 17 10 16 20 15

30 14 OUTLET 40 13

50 12 11 60 10 70 Depth (m) 9

80 8 90 7

100 6 5 110 4 120 0 5000 10000 15000 Distance (m) HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS FIG. COMOX LAKE AND PUNTLEDGE RIVER DRAWDOWN OF WARM WATER 2.5 TEMPERATURE MODELLING STUDY WITH SURFACE WITHDRAWAL

S:\fish-073\jtop_headpond\plots\section\surface\report.lay 09 Oct 2003 17:26:34 0

DEPTH (m) 25

35 Surface Deep 15-Jul-99 15-Aug-99 40 15-Sep-99 15-Oct-99

45 5 10 15 20 TEMPERATURE (oC) HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA COMOX LAKE AND PUNTLEDGE RIVER LAKE PROFILES, DEEP VS FIG. 2.6 TEMPERATURE MODELLING STUDY SURFACE WITHDRAWAL

Z:\fish-073\jtop_headpond\profile\comox_profiles.lpk 05 Nov 2003 10:50:27 1999 5 15 12:00

0 Tdeep -Tsurface 10 7 20 6.5 6 30 5.5 5 40 4.5 50 4 3.5 60 3 2.5 70 2 Depth (m) 1.5 80 1 0.5 90 0 100 -0.5 110 120 0 5000 10000 15000 Distance (m)

1999 6 15 12:00

0 Tdeep -Tsurface 10 7 20 6.5 6 30 5.5 5 40 4.5 50 4 3.5 60 3 2.5 70 2 Depth (m) 1.5 80 1 0.5 90 0 100 -0.5 110 120 0 5000 10000 15000 Distance (m)

1999 7 15 12:00

0 Tdeep -Tsurface 10 7 20 6.5 6 30 5.5 5 40 4.5 50 4 3.5 60 3 2.5 70 2 Depth (m) 1.5 80 1 0.5 90 0 100 -0.5 110 120 0 5000 10000 15000 Distance (m) HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA COMOX LAKE AND PUNTLEDGE RIVER DIFFERENCE IN LAKE FIG. 2.7 TEMPERATURE MODELLING STUDY TEMPERATURE

Z:\fish-073\jtop_headpond\plots\section\diff-1.lay 14 Nov 2003 17:52:31 1999 8 15 12:00

0 Tdeep -Tsurface 10 7 20 6.5 6 30 5.5 5 40 4.5 50 4 3.5 60 3 2.5 70 2 Depth (m) 1.5 80 1 0.5 90 0 100 -0.5 110 120 0 5000 10000 15000 Distance (m)

1999 9 15 12:00

0 Tdeep -Tsurface 10 7 20 6.5 6 30 5.5 5 40 4.5 50 4 3.5 60 3 2.5 70 2 Depth (m) 1.5 80 1 0.5 90 0 100 -0.5 110 120 0 5000 10000 15000 Distance (m)

1999 10 15 12:00

0 Tdeep -Tsurface 10 7 20 6.5 6 30 5.5 5 40 4.5 50 4 3.5 60 3 2.5 70 2 Depth (m) 1.5 80 1 0.5 90 0 100 -0.5 110 120 0 5000 10000 15000 Distance (m) HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA COMOX LAKE AND PUNTLEDGE RIVER DIFFERENCE IN LAKE FIG. 2.8 TEMPERATURE MODELLING STUDY TEMPERATURE

Z:\fish-073\jtop_headpond\plots\section\diff-2.lay 14 Nov 2003 17:53:12 surface withdrawal deep withdrawal 20 20 15 15 T [C] 10 10 TEMPERATURE OUT OF LAKE 5 5 1 6 11 16 21 26 31 5 10 15 20 25 30 5 10 15 20 25 30 4 9 14 19 24 29 3 8 13 18 23 28 3 8 13 18 23 28 May Jun Jul Aug Sep Oct 400 400 300 300 200 200 Q/1e9 100 100 HEAT FLUX OUT OF LAKE 0 0 1 6 11 16 21 26 31 5 10 15 20 25 30 5 10 15 20 25 30 4 9 14 19 24 29 3 8 13 18 23 28 3 8 13 18 23 28 May Jun Jul Aug Sep Oct 70 70 60 60 50 50 H/1e15 40 40 HEAT CONTENT IN LAKE 30 30 1 6 11 16 21 26 31 5 10 15 20 25 30 5 10 15 20 25 30 4 9 14 19 24 29 3 8 13 18 23 28 3 8 13 18 23 28 May Jun Jul Aug Sep Oct

HAYCO HAY & COMPANY CONSULTANTS INC. FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER HEAT IN LAKE-HEADPOND MODEL, 2.9 TEMPERATURE MODELLING STUDY DEEP VS. SURFACE WITHDRAWAL Tue Nov 4 12:45:52 2003:Z:\fish-073\jtop_headpond\plots\ts 22 22

deep withdrawal

surface withdrawal 20 20 18 18 16 16 T [C] 14 14 TEMPERATURE AT SLUICEGATE 12 12 10 10 8 8 1 6 11 16 21 26 31 5 10 15 20 25 30 5 10 15 20 25 30 4 9 14 19 24 29 3 8 13 18 23 28 3 8 13 18 23 28 May Jun Jul Aug Sep Oct

HAYCO HAY & COMPANY CONSULTANTS INC. FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER CHANGE IN SLUICEGATE TEMPERATURE 2.10 TEMPERATURE MODELLING STUDY WITH DEEP VS. SURFACE WITHDRAWAL Tue Nov 4 13:50:49 2003:Z:\fish-073\jtop_headpond\runs

HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER PUNTLEDGE RIVER MIKE 11 IMPLEMENTATION TEMPERATURE MODELLING 3.20 120

110 Model 100 Survey 90 80 70 60 50 40

water level (masl) 30 20 10 0 -10 15000 10000 5000 chainage (m) HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER SURVEYED AND MODELLED WATER LEVELS 3.21 TEMPERATURE MODELLING STUDY ALONG PUNTLEDGE RIVER

D:\Projects\fish-073\jtop_2002\validation\7ds\xs-val\longitud-report.lay 04 Nov 2003 10:54:57 Survey bottom Survey water surface Model bottom Model water surface

2002 08 12 14:00, CHAIN = 16465 2002 08 12 16:00, CHAIN = 16354 2002 08 13 11:00, CHAIN = 16026

1 1 1

0 0 0

-1 -1 -1 elevation w.r.t. model datum (m) elevation w.r.t. model datum (m) elevation w.r.t. model datum (m) -2 -2 -2 0 1020304050607080 0 1020304050607080 0 1020304050607080 cross-channel distance (m) cross-channel distance (m) cross-channel distance (m)

2002 08 13 12:00, CHAIN = 15817 2002 08 14 09:00, CHAIN = 15112 2002 08 14 10:00, CHAIN = 15066

1 1 1

0 0 0

HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER MODELLED AND SURVEYED WATER LEVELS 3.22 TEMPERATURE MODELLING STUDY AND BATHYMETRY IN PUNTLEDGE RIVER

D:\Projects\fish-073\jtop_2002\validation\7ds\xs-val\validation-report-1.lay 04 Nov 2003 11:26:28 Survey bottom Survey water surface Model bottom Model water surface

2002 08 14 16:00, CHAIN = 14401 2002 08 14 15:00, CHAIN = 14018 2002 08 14 15:00, CHAIN = 13983

1 1 1

0 0 0

2002 08 14 18:00, CHAIN = 13702 2002 08 14 18:00, CHAIN = 13632 2002 08 15 10:00, CHAIN = 12870

1 1 1

0 0 0

HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER MODELLED AND SURVEYED WATER LEVELS 3.23 TEMPERATURE MODELLING STUDY AND BATHYMETRY IN PUNTLEDGE RIVER

D:\Projects\fish-073\jtop_2002\validation\7ds\xs-val\validation-report-2.lay 04 Nov 2003 11:28:09 Survey bottom Survey water surface Model bottom Model water surface

2002 08 15 12:00, CHAIN = 12128 2002 08 15 13:00, CHAIN = 11998 2002 08 15 15:00, CHAIN = 11520

1 1 1

0 0 0

2002 08 15 17:00, CHAIN = 10969 2002 08 15 18:00, CHAIN = 10183 2002 09 05 11:00, CHAIN = 10034

1 1 1

0 0 0

HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER MODELLED AND SURVEYED WATER LEVELS 3.24 TEMPERATURE MODELLING STUDY AND BATHYMETRY IN PUNTLEDGE RIVER

D:\Projects\fish-073\jtop_2002\validation\7ds\xs-val\validation-report-3.lay 04 Nov 2003 11:27:51 Survey bottom Survey water surface Model bottom Model water surface

2002 09 03 13:00, CHAIN = 9439 2002 09 05 14:00, CHAIN = 9058 2002 09 05 13:00, CHAIN = 9017

1 1 1

0 0 0

2002 09 03 16:00, CHAIN = 8766 2002 09 03 17:00, CHAIN = 8643 2002 09 05 14:00, CHAIN = 8535

1 1 1

0 0 0

HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER MODELLED AND SURVEYED WATER LEVELS 3.25 TEMPERATURE MODELLING STUDY AND BATHYMETRY IN PUNTLEDGE RIVER

D:\Projects\fish-073\jtop_2002\validation\7ds\xs-val\validation-report-4.lay 04 Nov 2003 11:27:13 Survey bottom Survey water surface Model bottom Model water surface

2002 09 05 17:00, CHAIN = 8043 2002 09 05 16:00, CHAIN = 7515 2002 09 04 17:00, CHAIN = 7219

1 1 1

0 0 0

2002 09 04 16:00, CHAIN = 6969 2002 09 04 14:00, CHAIN = 6887 2002 09 05 08:00, CHAIN = 6618

1 1 1

0 0 0

HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER MODELLED AND SURVEYED WATER LEVELS 3.26 TEMPERATURE MODELLING STUDY AND BATHYMETRY IN PUNTLEDGE RIVER

D:\Projects\fish-073\jtop_2002\validation\7ds\xs-val\validation-report-5.lay 04 Nov 2003 11:26:58 Survey bottom Survey water surface Model bottom Model water surface

2002 09 05 10:00, CHAIN = 6414 2002 09 04 13:00, CHAIN = 6223 2002 09 04 08:00, CHAIN = 5693

1 1 1

0 0 0

2002 09 04 09:00, CHAIN = 5044 2002 09 04 10:00, CHAIN = 4925 2002 09 04 11:00, CHAIN = 4246

1 1 1 Note: model channel has been deepened compared to survey (to allow for low tide) 0 0 0

-1 -1 -1

-2 -2 -2

-3 -3 -3 elevation w.r.t. model datum (m) elevation w.r.t. model datum (m) elevation w.r.t. model datum (m)

-4 -4 -4 0 1020304050607080 0 1020304050607080 0 1020304050607080 cross-channel distance (m) cross-channel distance (m) cross-channel distance (m)

HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER MODELLED AND SURVEYED WATER LEVELS 3.27 TEMPERATURE MODELLING STUDY AND BATHYMETRY IN PUNTLEDGE RIVER

D:\Projects\fish-073\jtop_2002\validation\7ds\xs-val\validation-report-6.lay 07 Nov 2003 11:35:54 66 66 00 06 12 18 00 06 12 18 00 06 12 18

modelled predicted surveyed 55 55 44 44 33 33 WATER LEVELWATER LEVEL [m above chart datum] 22 22 11 11

00 06 12 18 00 06 12 18 00 06 12 18 00 00 3 4 Sep 2002

HAYCO HAY & COMPANY CONSULTANTS INC. FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER PREDICTED TIDE, SURVEYED LEVELS 3.28 TEMPERATURE MODELLING STUDY & MODELLED WATER LEVEL AT MOUTH Mon Nov 3 16:22:18 2003:D:\Projects\fish-073\jtop_2002\plots\ts\tide LAZ

SANDWICK 4 6 3 1 – Comox Lake

5 COURTENA Y COMOX 2 – Diversion Dam 7 3 – Upper Pink Side Channel 4 – Lower Pink Side Channel BEVAN 2 BAL 5 – Hatchery Main Fence 6 – 5th Street Bridge 7 – 17th Street Bridge ROY STON 1

CUMB ERLA ND

HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER TEMPERATURE SENSOR LOCATIONS TEMPERATURE MODELLING STUDY 3.29 measured modelled 20 20 16 16 SITE 2 12 12 DIV. DAM 8 8 1 5 9 13 17 21 25 29 2 6 10 14 18 22 26 30 3 7 11 15 19 23 27 1 5 9 13 17 21 25 29 Jul Aug Sep Oct 20 20 16 16 SITE 5 12 12 HATCHERY 8 8 1 5 9 13 17 21 25 29 2 6 10 14 18 22 26 30 3 7 11 15 19 23 27 1 5 9 13 17 21 25 29 Jul Aug Sep Oct 20 20 16 16 SITE 6 12 12 5TH STREET 8 8 1 5 9 13 17 21 25 29 2 6 10 14 18 22 26 30 3 7 11 15 19 23 27 1 5 9 13 17 21 25 29 Jul Aug Sep Oct 20 20 16 16 SITE 7 12 12 17TH STREET 8 8 1 5 9 13 17 21 25 29 2 6 10 14 18 22 26 30 3 7 11 15 19 23 27 1 5 9 13 17 21 25 29 Jul Aug Sep Oct

HAYCO HAY & COMPANY CONSULTANTS INC. FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER MODELLED AND MEASURED 3.30 TEMPERATURE MODELLING STUDY WATER TEMPERATURE, 1999 Wed Jun 16 11:22:35 2004:D:\Projects\fish-073\jtop_temp\plots\T-validation\run26 o 1999 8 1 15:00 Temperature ( C) 20.5 -2 20.0

-1 Surface withdrawal from lake 19.5

feeding Puntledge and Penstock Brown's Penstock Tsolum 19.0 0 18.5 Water 1 18.0 17.5 Rock 2 17.0 elevation (m) 3 16.5 16.0 4 15.5

5 15.0 15000 10000 5000 14.5 -2 Deep withdrawal from lake 14.0 -1 feeding Puntledge and Penstock 13.5 Brown's Penstock Tsolum 13.0 0 12.5 Water 1 12.0 11.5 2 Rock 11.0 lvto (m) elevation 3 10.5 10.0 4 9.5 5 9.0 15000 10000 5000 8.5 HAYCO chainage (m) HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER AUGUST RIVER TEMPERATURE 3.31 TEMPERATURE MODELLING STUDY SURFACE VS. DEEP INPUT

D:\Projects\fish-073\jtop_temp\plots\section\run27\aug1.lay 16 Jun 2004 10:33:15 Tsolum River

N Reach5

R e Reach4 a c h Brown’s River 3

Reach2 Reach6

Reach1 D nstock e P Comox Harbour C

Headpond Note: B, C, D are B BC Hydro designations

Comox Lake

HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER DIVISION OF PUNTLEDGE RIVER MODEL INTO REACHES TEMPERATURE MODELLING 3.32 JULY Model run:Surface withdrawal Deep withdrawal

18 C) o 16

14 Temperature (

8 Headpond Reach 1 Reach 2Reach3 Reach 4 Reach5 Reach6

HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER RIVER TEMPERATURE MODEL RESULTS 3.33 TEMPERATURE MODELLING STUDY COMPARISON OF RUNS - JULY 1999

D:\Projects\fish-073\jtop_temp\plots\ave-max\run27\jul.lay 15 Jun 2004 17:41:07 AUGUST Model run:Surface withdrawal Deep withdrawal

18 C) o 16

14 Temperature (

8 Headpond Reach 1 Reach 2Reach3 Reach 4 Reach5 Reach6

HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER RIVER TEMPERATURE MODEL RESULTS 3.34 TEMPERATURE MODELLING STUDY COMPARISON OF RUNS - AUGUST 1999

D:\Projects\fish-073\jtop_temp\plots\ave-max\run27\aug.lay 15 Jun 2004 17:48:56 SEPTEMBER Model run:Surface withdrawal Deep withdrawal

18 C) o 16

14 Temperature (

8 Headpond Reach 1 Reach 2Reach3 Reach 4 Reach5 Reach6

HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER RIVER TEMPERATURE MODEL RESULTS 3.35 TEMPERATURE MODELLING STUDY COMPARISON OF RUNS - SEPTEMBER 1999

D:\Projects\fish-073\jtop_temp\plots\ave-max\run27\sep.lay 15 Jun 2004 17:43:22 OCTOBER Model run:Surface withdrawal Deep withdrawal

18 C) o 16

14 Temperature (

8 Headpond Reach 1 Reach 2Reach3 Reach 4 Reach5 Reach6

HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER RIVER TEMPERATURE MODEL RESULTS 3.36 TEMPERATURE MODELLING STUDY COMPARISON OF RUNS - OCTOBER 1999

D:\Projects\fish-073\jtop_temp\plots\ave-max\run27\oct.lay 15 Jun 2004 17:44:02

APPENDIX A 2002 MODELLING ADDENDUM

Fisheries and Oceans Canada

COMOX LAKE AND PUNTLEDGE RIVER TEMPERATURE MODELLING STUDY 2002 ADDENDUM

FISH.073

July 2004

HAY & COMPANY CONSULTANTS INC. One West 7th Avenue Vancouver, BC V5Y 1L4 www.hayco.com Comox Lake and Puntledge River Temperature Modelling Study – 2002 Addendum July 2004

EXECUTIVE SUMMARY

This addendum presents a modelling study of temperatures in Comox Lake and Puntledge River for the months of July, August and September 2002. The modelling follows the approach for the 1999 study described in the accompanying report. The effects of surface and deep lake withdrawals on temperatures in the lake and river are compared.

Supplying water from a deep withdrawal in the lake results in much cooler river temperatures. The monthly average temperatures along the river, based on a reach-by-reach comparison, decreased by as much as 7.2 degrees, compared to a simulation using surface supply. The maximum river water temperature of 22.4 degrees occurred in July with the current surface withdrawal. With the deep withdrawal, the maximum temperature in July decreased to 16.7 degrees. These cooler temperatures would be beneficial for fish migrating up the Puntledge River during the warm months.

FISH.073 A-i

Comox Lake and Puntledge River Temperature Modelling Study – 2002 Addendum July 2004

TABLE OF CONTENTS

A-1 INTRODUCTION ...... 1 A-1.1 Background...... 1 A-1.2 Technical overview...... 1 A-2 LAKE MODEL...... 2 A-2.1 Comparison of surface and deep water withdrawal ...... 2 A-3 RIVER MODEL ...... 3 A-3.1 Surface and deep withdrawal simulations...... 3 A-4 CONCLUSIONS...... 6

FISH.073 A-ii

Comox Lake and Puntledge River Temperature Modelling Study – 2002 Addendum July 2004

LIST OF FIGURES

Fig. A-2.1 Lake-headpond model vs. measured water temperature, 2002 Fig. A-2.2 Lake profiles, deep vs. surface withdrawal Fig. A-2.3 Difference in lake temperature (May, June, July 2002) Fig. A-2.4 Difference in lake temperature (August, September, October 2002) Fig. A-2.5 Heat in lake-headpond model, deep vs. surface withdrawal Fig. A-3.1 Temperature sensor locations, 2002 sampling program Fig. A-3.2 Puntledge River modelled and measured water temperature, 2002 Fig. A-3.3 July river temperature, surface vs. deep input Fig. A-3.4 River temperature model results – deep vs. surface supply – July 2002 Fig. A-3.5 River temperature model results – deep vs. surface supply – August 2002 Fig. A-3.6 River temperature model results – deep vs. surface supply – September 2002 Fig. A-3.7 Lake model temperatures and flows, 1999 vs. 2002

LIST OF TABLES

Table A-3.1 Cooling due to deep-water withdrawal: decrease in mean monthly temperature compared to surface withdrawal

LIST OF ANIMATIONS

(Note: Animations are included on accompanying CD)

Animation A-2.1 Comparison of surface and deep withdrawal – lake temperatures Animation A-3.1 July river temperature, surface vs. deep input (July 1 to 15, 2002) Animation A-3.2 July river temperature, surface vs. deep input (July 16 to 31, 2002) Animation A-3.3 August river temperature, surface vs. deep input (Aug. 1 to 15, 2002) Animation A-3.4 August river temperature, surface vs. deep input (Aug. 16 to 31, 2002) Animation A-3.5 September river temperature, surface vs. deep input (Sept. 1 to 15, 2002) Animation A-3.6 September river temperature, surface vs. deep input (Sept. 16 to 30, 2002)

FISH.073 A-iii

Comox Lake and Puntledge River Temperature Modelling Study July 2004

A-1 INTRODUCTION

The Puntledge River flows from Comox Lake to Comox Harbour on the east coast of Vancouver Island, BC, and provides important spawning and rearing habitat for salmon. A storage dam at the outlet of the lake and a diversion dam on the river are used to control lake levels and river flows. A large percentage of the historical river flow is diverted through a penstock for power generation. During summer months, river temperatures approach dangerous levels for salmon (20 oC to 25 oC) due to both high temperature inflows from the surface of Comox Lake and warming of shallow flow over bedrock.

Fisheries and Oceans Canada (DFO) is considering cold lake water withdrawal from Comox Lake as an option to reduce water temperature in the Puntledge River in the summer months. Evaluating this proposed option requires an understanding of the lake dynamics and the impacts associated with cold water withdrawal at depth, the possible result of mixing cold lake water with BC Hydro flow releases and the attenuation of mixed water temperatures downstream in the Puntledge River. This addendum presents the results of the lake and river temperature model developed in the accompanying report. The model is used to evaluate the reduction of Puntledge River summer temperatures with the cold water withdrawal for the year 2002.

A-1.1 Background

Comox Lake is drained by the Puntledge River. The river experienced low flows in 2002. For the months of July through September 2002, an average 15.8 m3/s flowed through the headpond, of which an average 8.4 m3/s was diverted through the 5 km long penstock for power generation. The remaining 7.5 m3/s of the flow out of the lake was spilled over the Diversion Dam and through the upper diversion reach of the Puntledge River. The diversion reach flow had a minimum of approximately 3.8 m3/s and a maximum of 17 m3/s in summer 2002. Flow is added to the Puntledge River by two major tributaries, Brown’s River (0.5 m3/s average in summer 2002) and the Tsolum River (0.7 m3/s average in summer 2002), in addition to the flow through the penstock which re-enters the Puntledge River at the powerhouse.

A-1.2 Technical overview

The present study involves numerical prediction of lake and river temperatures to assess the option of reducing Puntledge River temperatures in the summer months by withdrawing cold water from deep in Comox Lake. It is assumed that all outflow being drawn from the lake, currently from shallow submerged gates in the Comox Dam, will instead be drawn from a depth of 35 m. A prediction system, consisting of three numerical models, has been developed for the simulations of water level, velocity and temperature in both Comox Lake and the Puntledge River. These models are described in the accompanying report. A three-dimensional, baroclinic numerical model was used to determine the thermal structure of Comox Lake as it evolves from the uniform conditions of winter, through the

A-1 Comox Lake and Puntledge River Temperature Modelling Study – 2002 Addendum July 2004 stratified conditions of summer, to the turnover during fall. The model is driven by heat exchange at the lake surface, wind forcing and river inflows. The lake surface outflow or deep withdrawal in turn feeds a three-dimensional model of the Puntledge River. The three-dimensional model simulates changes in river temperatures due to input sources and meteorological forcing.

A-2 LAKE MODEL

Circulation within Comox Lake was simulated using Hay & Company’s proprietary three-dimensional hydrodynamic model H3D, as described in the accompanying report. The model was previously validated against 1998 temperature profiles.

A-2.1 Comparison of surface and deep water withdrawal

The model was run for April to October 2002 to compare the relative impacts of the existing near-surface withdrawal with the impacts of the proposed deep water withdrawal. The two goals of these runs were to examine the effect of the withdrawal on the lake temperature structure, and to produce lake outflow temperatures to be used as input to the river temperature model.

Temperature observations at the upstream and downstream ends of the headpond were available for validation of the lake-headpond model for 2002. The observed water temperatures in the headpond were somewhat high compared to the modelled temperatures (Figure A-2.1). However, a perfect match between observed and modelled temperatures is not necessary as the same approach is followed as in the 1999 report. The temperatures from this lake-headpond model simulation with surface withdrawal will be used as the base case for comparison with the deep water withdrawal case. Assuming that both models have similar errors, the differences will cancel when comparisons are made.

A comparison of the evolution of the lake’s thermal structure with the two withdrawal methods is presented in animated form in Animation A-2.1, included on the CD that accompanies this report. In this animation, the plots for both surface and deep withdrawal show the same section along the midline of the lake. Withdrawing the colder deep water results in a warming of the lake water down to about 40 m depth over the course of the summer and fall. The warming in 2002 is not as pronounced as it was in 1999, likely due to the lower flows in the Puntledge River (i.e. less water withdrawn from Comox Lake). Profiles of lake temperature for the two 2002 simulations show the warming and deepening of the thermocline due to the deep-water withdrawal compared to the surface withdrawal (Figure A-2.2). The difference between the two runs is shown for a section along the lake in Figures A-2.3 and A-2.4. In May, the difference is negligible. In mid-June, the difference in lake temperature for the two simulations is less than 0.5 degrees. By mid-July, temperatures between 5 and 30 m depth are up to 1.2 degrees warmer for the deep-withdrawal simulation than for the surface-withdrawal case. In mid-August, the affected area is between 10 and 35 m depth, with warming up to 3.2 degrees. Through August and

FISH.073 A-2

Comox Lake and Puntledge River Temperature Modelling Study – 2002 Addendum July 2004

September, while the affected area does not grow in depth or extent, the temperature difference increases to a maximum of 4.1 degrees. By mid-October, the temperature difference is greatest between 25 and 35 m depth, with a maximum difference of 2.8 degrees. The waters above 25 m depth are around 0.6 degrees warmer compared to the surface-withdrawal simulation in mid-October.

The warming of the lake water with the deep-water withdrawal compared to the surface withdrawal reflects the change in the heat flux out of the lake when colder water is withdrawn. The heat flux into the lake via the Puntledge River and Cruickshank River is identical for the two simulations. The flux between the lake and the atmosphere remains roughly the same for the two runs. The major difference between the two runs is the heat flux out of the lake-headpond model, due only to the difference in the temperature of the outflow, since the flowrate is the same for the two runs. When colder water is extracted via the deep withdrawal, less heat leaves the lake, hence the heat content in the lake is higher as the season progresses (Figure A-2.5).

A-3 RIVER MODEL

A three-dimensional model of flows and temperatures in the Puntledge River was developed as described in the accompanying report and previously validated against 2002 water levels. The model was used to simulate the months of July through September, 2002. October was not included in the 2002 modelling since the river temperatures tend to be cool enough not to be a problem for fish, and since the lake outlet temperatures are very similar for both the surface and deep withdrawals at that point in the season (see Figure A-2.5).

A-3.1 Surface and deep withdrawal simulations

Two simulations were performed to evaluate the impact of the deep lake withdrawal on river temperatures. Since the surface-withdrawal simulation of the lake model did not provide a perfect match with the measured temperatures in the headpond, the river model was run with temperatures from the lake surface withdrawal simulation as a base case for comparison with the deep withdrawal case. In both the surface and the deep withdrawal runs, the temperature at the downstream end of the headpond in the lake- headpond model (i.e. at the diversion dam) was used as the input temperature for the Puntledge River and for the penstock in the river temperature model. It was assumed that the temperature in the penstock does not change greatly along its length, since not much surface area is exposed for heat transfer.

Water temperatures were collected at nine sites on the Puntledge River in 2002 (Figure A-3.1). In the 2002 runs, none of these observed temperatures were used as input temperatures for the model. The same methodology used in 1999 was followed for the Brown’s River, since no representative temperatures were recorded: the temperature in the Brown’s River was set to the model temperature just upstream in the Puntledge River, so that the Brown’s River added flow but did not modify the mixed temperature.

FISH.073 A-3

Comox Lake and Puntledge River Temperature Modelling Study – 2002 Addendum July 2004

The temperature modelled in the surface withdrawal run was also applied to the Brown’s River in the deep withdrawal run, to isolate the effects of the lake deep withdrawal. For the Tsolum River, the temperature at the 5th Street Bridge was used in the 1999 run. In 2002, no data was available at that site after July 7 (nearly the entire modelling period), so it could not be used as the Tsolum River temperature. As with the Brown’s River, the Tsolum River added flow to the model but did not change the temperature.

Since the lake model did not replicate exactly the temperatures at the headpond inlet and outlet (Figure A- 2.1), the modelled river temperature will not match the measured values either. In addition, most of the observed temperatures were measured in side channels that are not representative of the main river, and so cannot be used for validation. However, we can compare the modelled temperatures with observations in order to assess whether the model results are warmer or cooler than actual river temperatures in summer 2002. Figure A-3.2 shows hourly, depth-averaged water temperatures from the model (low-pass filtered for plotting purposes), compared with the daily measured values, for observation sites with a complete data set over the modelling period. Note that the Upper and Lower Pink sites are in side channels. For the main channel sites, the modelled temperatures are cooler than the observed temperatures by, on average, 1.3 degrees (Site 2) to 1.6 degrees (Site 7) over the modelling period.

The temperature along the river for the both the deep feed and surface feed, along with the temperature in the upper portion of the underlying bedrock, are shown for a selected timestep in Figure A-3.3. The results are portrayed along the flattened grid; for the true elevation of the river, refer to the accompanying report. For the deep withdrawal case, the temperature along the river shows two rather abrupt transitions where the Brown’s River and the penstock enter the Puntledge River (Figure A-3.3). On the date shown, flow in the Puntledge River was 6.3 m3/s, flow in the Brown’s River was 0.25 m3/s and flow in the penstock was 7.9 m3/s. The flow of the Brown’s River is small compared to the Puntledge River, so it has a small impact on the resulting mixed temperature. The same time series of temperature was used for the Brown’s River in both the surface and deep feed cases in order to isolate the effects of the lake withdrawal on river temperature. The temperature in the Brown’s River was set to the temperature in the Puntledge River just upstream of the Brown’s River from the surface withdrawal run, for both the surface and the deep withdrawal case. Hence, the temperature in the Brown’s River is much warmer than the Puntledge River for the deep withdrawal run. The penstock enters the Puntledge River with a temperature equal to that at the head of the Puntledge River (since no warming was assumed along the penstock) and with flow roughly equal to the combined Puntledge River and Brown’s River, so it results in a mixed temperature closer to the value at the head of the river. On the date shown, the flow of the Tsolum River is only 0.15 m3/s, thus it has little impact on the river temperature. The rock bed receives heat from the water above it, and transmits some back. The topmost metre or so of rock shows diurnal fluctuations, corresponding to the diurnal variation in the overlying water temperature. In Figure A-3.3 it is apparent that supplying water from the deep-water withdrawal in the lake results in much cooler river temperatures compared to the existing surface supply.

FISH.073 A-4

Comox Lake and Puntledge River Temperature Modelling Study – 2002 Addendum July 2004

To summarize the impact of the deep-water withdrawal on the river water temperatures, the Puntledge River was divided into six reaches (see accompanying report for reach locations). In each reach, the monthly minimum, maximum and mean water temperatures were determined for each of the two simulations, and are shown in Figures A-3.4 to A-3.6. Note that the actual temperatures may be 1.3 to 1.6 degrees warmer based on the comparison with observations in Figure A-3.2. Figures A-3.4 to A-3.6 show the impact of the deep- water withdrawal on the river reach temperatures for July through September, 2002. The hottest month on average was August, while the highest maximums were predicted in July. The maximum temperature in July decreases from 22.4ºC to 16.7ºC (Reach 2) as a result of switching to the deep-water withdrawal. In each month, the maximum temperature in each reach with the deep-water withdrawal is noticeably lower than the mean temperature with the surface withdrawal. The average cooling is more than 3 degrees for all reaches in each month, up to a cooling of 7.2 degrees, attained in Reach 1 in July. A summary of the amount of cooling for each reach and each month is presented in Table A-3.1. The 1999 results are also presented for comparison.

Table A-3.1 Cooling due to deep-water withdrawal: decrease in mean monthly temperature compared to surface withdrawal

Headpond Reach 1 Reach 2 Reach 3 Reach 4 Reach 5 Reach 6 July 1999 4.6º 4.4º 4.3º 3.2º 3.4º 3.4º 3.2º July 2002 6.2º 7.2º 6.5º 5.4º 6.2º 6.0º 5.7º August 1999 5.8º 5.5º 4.9º 3.1º 4.6º 4.6º 4.4º August 2002 6.4º 7.1º 6.7º 6.2º 6.7º 6.5º 6.1º September 1999 4.1º 3.8º 3.1º 2.3º 3.4º 3.3º 3.1º September 2002 4.3º 4.9º 4.6º 4.2º 4.2º 4.0º 3.6º

The cooling achieved in 2002 is greater than that in 1999, mainly due to differences in lake stratification caused by the large difference in river flows between the two years. The river flows into and out of the lake were much larger in 1999 (following a winter of record snowfalls) than in 2002 (Figure A-3.7). Withdrawing large amounts of water reduces the stratification in the lake, so that surface and deep temperatures approach each other (Figure A-3.7). The temperature of the surface withdrawal from Comox Lake supplied to the Puntledge River was especially warmer in July 2002 compared to July 1999, when the difference in flows between the two years was greatest. In addition, the deep water in the lake stayed cooler throughout summer 2002 compared to summer 1999.

FISH.073 A-5

Comox Lake and Puntledge River Temperature Modelling Study – 2002 Addendum July 2004

A-4 CONCLUSIONS

The lake and river models have demonstrated the impacts of the proposed deep-water withdrawal on temperatures in the lake and in the Puntledge River for 2002. When the deep-water withdrawal was simulated, the top 35 metres of lake warmed considerably (up to 4.1 degrees) compared to the surface withdrawal, since cooler water is withdrawn from the lake, leaving a higher heat content in the upper portion of the lake.

The deep withdrawal from the lake supplied cooler water to the Puntledge River compared to the surface withdrawal at the sluicegate (the method presently used). The river model showed the impacts of this change on water temperature along the Puntledge River. The water in the river was 3.6 to 7.2 degrees cooler, based on monthly averages of each reach, when the deep withdrawal was used, compared to the surface withdrawal. The cooling effect persisted over the entire length of the river. For comparison, in 1999 the cooling ranged from 2.3 to 5.8 degrees, on reach-by-reach monthly averages. The cooling in the river was greater in 2002 than in 1999 due to smaller flows through the lake and enhanced stratification in the lake in 2002 compared to 1999.

The maximum temperature in the river was 16.7 degrees with the deep withdrawal, compared to a maximum of 22.4 degrees with the surface withdrawal. The cooler temperatures would be beneficial for fish migrating up the Puntledge River during the warm months.

FISH.073 A-6

FIGURES

modelled measured 30 30 25 25 20 20 15 15 10 10 Model: Lake outlet Site 1: Lake Outlet 5 5 0 0 1 7 13 19 25 1 7 13 19 25 31 6 12 18 24 30 6 12 18 24 30 5 11 17 23 29 4 10 16 22 28 4 10 16 22 28 Apr May Jun Jul Aug Sep Oct 30 30 25 25 20 20 15 15 10 10 Site 2: Hatchery Model: Headpond outlet 5 5 0 0 1 7 13 19 25 1 7 13 19 25 31 6 12 18 24 30 6 12 18 24 30 5 11 17 23 29 4 10 16 22 28 4 10 16 22 28 Apr May Jun Jul Aug Sep Oct

HAYCO HAY & COMPANY CONSULTANTS INC. FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER LAKE-HEADPOND MODEL VS. A-2.1 TEMPERATURE MODELLING STUDY MEASURED WATER TEMPERATURE, 2002 Wed Jun 23 11:45:54 2004:D:\Projects\fish-073-2002\lake-surf\runs 0

DEPTH (m) 25

35 Surface Deep 15-Jul-02 15-Aug-02 40 15-Sep-02 15-Oct-02

45 5 10 15 20 TEMPERATURE (oC) HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA COMOX LAKE AND PUNTLEDGE RIVER LAKE PROFILES, DEEP VS FIG. A-2.2 TEMPERATURE MODELLING STUDY SURFACE WITHDRAWAL

D:\Projects\fish-073-2002\lake-surf\plots\profile\comox_profiles.lpk 13 Jul 2004 14:24:12 2002 5 15 12:00

0 Tdeep -Tsurface 10 3 20 30 2.5

40 2 50 1.5 60 1 70 Depth (m) 80 0.5

90 0 100 110 120 0 5000 10000 15000 Distance (m)

2002 6 15 12:00

0 Tdeep -Tsurface 10 3 20 30 2.5

40 2 50 1.5 60 1 70 Depth (m) 80 0.5

90 0 100 110 120 0 5000 10000 15000 Distance (m)

2002 7 15 12:00

0 Tdeep -Tsurface 10 3 20 30 2.5

40 2 50 1.5 60 1 70 Depth (m) 80 0.5

90 0 100 110 120 0 5000 10000 15000 Distance (m) HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA COMOX LAKE AND PUNTLEDGE RIVER DIFFERENCE IN FIG. A-2.3 TEMPERATURE MODELLING STUDY LAKE TEMPERATURE

D:\Projects\fish-073-2002\lake-surf\plots\compare\may-jun-jul.lay 13 Jul 2004 14:59:31 2002 8 15 12:00

0 Tdeep -Tsurface 10 3 20 30 2.5

40 2 50 1.5 60 1 70 Depth (m) 80 0.5

90 0 100 110 120 0 5000 10000 15000 Distance (m)

2002 9 15 12:00

0 Tdeep -Tsurface 10 3 20 30 2.5

40 2 50 1.5 60 1 70 Depth (m) 80 0.5

90 0 100 110 120 0 5000 10000 15000 Distance (m)

2002 10 15 12:00

0 Tdeep -Tsurface 10 3 20 30 2.5

40 2 50 1.5 60 1 70 Depth (m) 80 0.5

90 0 100 110 120 0 5000 10000 15000 Distance (m) HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA COMOX LAKE AND PUNTLEDGE RIVER DIFFERENCE IN FIG. A-2.4 TEMPERATURE MODELLING STUDY LAKE TEMPERATURE

D:\Projects\fish-073-2002\lake-surf\plots\compare\aug-sep-oct.lay 13 Jul 2004 15:01:57 surface withdrawal deep withdrawal 20 20 15 15 T [C] 10 10 TEMPERATURE OUT OF LAKE 5 5 1 6 11 16 21 26 31 5 10 15 20 25 30 5 10 15 20 25 30 4 9 14 19 24 29 3 8 13 18 23 28 3 8 13 18 23 28 May Jun Jul Aug Sep Oct 100 100 75 75 50 50 Q/1e9 25 25 HEAT FLUX OUT OF LAKE 0 0 1 6 11 16 21 26 31 5 10 15 20 25 30 5 10 15 20 25 30 4 9 14 19 24 29 3 8 13 18 23 28 3 8 13 18 23 28 May Jun Jul Aug Sep Oct 70 70 60 60 50 50 H/1e15 40 40 HEAT CONTENT IN LAKE 30 30 1 6 11 16 21 26 31 5 10 15 20 25 30 5 10 15 20 25 30 4 9 14 19 24 29 3 8 13 18 23 28 3 8 13 18 23 28 May Jun Jul Aug Sep Oct

HAYCO HAY & COMPANY CONSULTANTS INC. FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER HEAT IN LAKE-HEADPOND MODEL A-2.5 TEMPERATURE MODELLING STUDY SURFACE VS. DEEP WITHDRAWAL Tue Jul 13 15:15:54 2004:D:\Projects\fish-073-2002\lake-surf\plots\ts LAZO

4 SANDWICK 5,6 3 1 – Comox Lake

7 COURTENAY COMOX 2 – Diversion Dam 8 3 – Upper Pink Side Channel 4 – Lower Pink Side Channel BEVAN 2 5 – Power House Pool 6 – Hatchery Pump House 7 – Hatchery Main Fence ROYSTON 1 8 – 5th Street Bridge

CUMBERLAND

HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER TEMPERATURE SENSOR LOCATIONS 2002 SAMPLING PROGRAM TEMPERATURE MODELLING STUDY A-3.1 measured modelled 22 22 20 20 18 18 16 16 SITE 2 DIV. DAM 14 14 12 12 1 4 7 10 13 16 19 22 25 28 31 3 6 9 12 15 18 21 24 27 30 2 5 8 11 14 17 20 23 26 29 Jul Aug Sep Oct 22 22 20 20 18 18 16 16 SITE 3 UPPER PINK 14 14 12 12 1 4 7 10 13 16 19 22 25 28 31 3 6 9 12 15 18 21 24 27 30 2 5 8 11 14 17 20 23 26 29 Jul Aug Sep Oct 22 22 20 20 18 18 16 16 SITE 4 LOWER PINK 14 14 12 12 1 4 7 10 13 16 19 22 25 28 31 3 6 9 12 15 18 21 24 27 30 2 5 8 11 14 17 20 23 26 29 Jul Aug Sep Oct 22 22 20 20 18 18 16 16 SITE 7 HATCHERY 14 14 12 12 1 4 7 10 13 16 19 22 25 28 31 3 6 9 12 15 18 21 24 27 30 2 5 8 11 14 17 20 23 26 29 Jul Aug Sep Oct

HAYCO HAY & COMPANY CONSULTANTS INC. FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER MODELLED AND MEASURED A-3.2 TEMPERATURE MODELLING STUDY WATER TEMPERATURE, 2002 Wed Jun 23 14:19:24 2004:Q:\FISH-073\2002\river-surf\plots\ts o 2002 7 29 14:00 Temperature ( C) -2 20.5 20.0 -1 Surface withdrawal from lake 19.5

feeding Puntledge and Penstock Brown's Penstock Tsolum 0 19.0 Water 18.5 1 18.0

2 Rock 17.5 17.0 elevation (m) 3 16.5

4 16.0 15.5 5 15000 10000 5000 15.0 -2 14.5 Deep withdrawal from lake 14.0 -1 feeding Puntledge and Penstock

Brown's Penstock Tsolum 13.5 0 13.0 Water 12.5 1 12.0 Rock 2 11.5

lvto (m) elevation 11.0 3 10.5 4 10.0 9.5 5 15000 10000 5000 9.0 HAYCO chainage (m) HAY & COMPANY CONSULTANTS INC. 8.5

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER JULY RIVER TEMPERATURE A-3.3 TEMPERATURE MODELLING STUDY SURFACE VS. DEEP INPUT

Q:\FISH-073\2002\river-surf\plots\section\jul.lay 13 Jul 2004 12:06:36 JULY Model run : Surface withdrawal D eep withdrawal

C) 18 o

14 Temperature (

8 H e a dpond Reach 1 Reach 2Reach3 Reach 4 Reach5 Reach6

HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER R IVER TEM PER ATU R E M OD EL R ESU LTS A-3.4 TEMPERATURE MODELLING STUDY DEEP VS. SURFACE SUPPLY - JU LY 2002

Q:\FISH-073\2002\river-surf\plots\ave-max\jul.lay 07 Jul 2004 17:15:47 AUGUST Model run:Surface withdrawal Deep withdrawal

C) 18 o

14 Temperature (

8 Headpond Reach 1 Reach 2Reach3 Reach 4 Reach5 Reach6

HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER RIVER TEMPERATURE MODEL RESULTS A-3.5 TEMPERATURE MODELLING STUDY DEEP VS. SURFACE SUPPLY - AU GU ST 2002

Q:\FISH-073\2002\river-surf\plots\ave-max\aug.lay 07 Jul 2004 17:15:59 SEPTEMBER Model run:Surface withdrawal Deep withdrawal

C) 18 o

14 Temperature (

8 Headpond Reach 1 Reach 2Reach3 Reach 4 Reach5 Reach6

HAYCO HAY & COMPANY CONSULTANTS INC.

FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER RIVER TEMPERATURE MODEL RESULTS A-3.6 TEMPERATURE MODELLING STUDY DEEP VS. SURFACE SUPPLY - SEPTEM BER 2002

Q:\FISH-073\2002\river-surf\plots\ave-max\sep.lay 07 Jul 2004 17:16:14 2002 1999 80 80 60 60 40 40 [m3/s] 20 20 FLOW OUT OF LAKE 0 0 1 4 7 10 13 16 19 22 25 28 31 3 6 9 12 15 18 21 24 27 30 2 5 8 11 14 17 20 23 26 29 Jul Aug Sep 20 20 18 18 [C] 16 16 SURFACE WITHDRAWAL TEMP. 14 14 1 4 7 10 13 16 19 22 25 28 31 3 6 9 12 15 18 21 24 27 30 2 5 8 11 14 17 20 23 26 29 Jul Aug Sep 14 14 12 12 [C] 10 10 DEEP WITHDRAWAL TEMP. 8 8 1 4 7 10 13 16 19 22 25 28 31 3 6 9 12 15 18 21 24 27 30 2 5 8 11 14 17 20 23 26 29 Jul Aug Sep

HAYCO HAY & COMPANY CONSULTANTS INC. FISHERIES AND OCEANS CANADA FIG. COMOX LAKE AND PUNTLEDGE RIVER LAKE MODEL TEMPERATURES A-3.7 TEMPERATURE MODELLING STUDY AND FLOWS, 1999 VS. 2002 Wed Aug 18 15:20:47 2004:D:\Projects\fish-073-2002\lake-surf\plots\ts\compare_yrs