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Earth Science Information Systems

Thursday, January 22, 2009

Gayle SooChan, P.Geo. Director – Groundwater Resources Central Lake Ontario Conservation Authority 100 Whiting Avenue Oshawa, Ontario L1H 3T3

RE: Tier 1 Water Budget Study of the Watersheds in the Central Lake Ontario Conservation Authority Area

Dear Gayle:

We have reviewed the additional peer review comments and have made revisions to the text and figures of the report to address the concerns raised. We are pleased to provide this final copy of the Tier 1 assessment of the surface water and groundwater balance within the CLOCA area watersheds.

We trust this final report meets with your satisfaction. We would like to thank you for the opportunity to work on this project. If you have any questions, please call.

Yours truly Earthfx Inc

Dirk Kassenaar, M.Sc., P.Eng.

E.J. Wexler, M.Sc., M.S.E., P.Eng.

Subsequent to revisions completed by Earthfx Inc stated above, this report was further revised in November 2009 to incorporate comments provided by the CTC Source Protection Committee. The final revisions include the finalized Significant Groundwater Recharge mapping and reference changes to reflect requirements in the provincial Director’s Rules versus the earlier released guidelines.

3363 Yonge St., Toronto, Ontario, Canada M4N 2M6 T: 416.410.4260 F: 416.481.6026 www.earthfx.com

CLOCA Tier 1 Water Budget Report January, 2009

Table of Contents

1 EXECUTIVE SUMMARY ...... 10 2 INTRODUCTION ...... 15 2.1 TIER 1 WATER BUDGET AND STRESS ASSESSMENT ...... 16 2.2 WATER BUDGET ELEMENTS ...... 17 2.2.1 Selection of Models ...... 18 2.2.2 Approach to Model Verification ...... 18 2.3 DESCRIPTION OF THE CONCEPTUAL HYDROSTRATIGRAPHIC MODEL ...... 20 2.4 DESCRIPTION OF SURFACE WATER SYSTEM ...... 20 3 WATER SUPPLY ESTIMATION ...... 22 3.1 PRMS CONTINUOUS SURFACE WATER MODEL ...... 22 3.1.1 PRMS Operation ...... 23 3.2 APPLICATION OF THE PRMS MODEL ...... 25 3.2.1 PRMS Data Compilation and Assessment ...... 25 3.2.2 PRMS Model Parameters ...... 25 3.2.3 Data related to Topography ...... 26 3.2.4 Data related to Land Cover ...... 26 3.2.5 Data related to Soil Cover/Surficial Geology ...... 27 3.2.6 Data related to Combinations of Land Use and Soil Cover ...... 28 3.2.7 Data related to Climate ...... 28 3.2.8 Other Parameters ...... 30 3.3 CALIBRATION TARGETS ...... 30 3.4 THREE-DIMENSIONAL GROUNDWATER FLOW MODEL ...... 32 3.4.1 Need for a Groundwater model ...... 32 3.4.2 MODFLOW Model Code ...... 33 3.4.3 Groundwater Flow Model Development ...... 33 3.4.4 MODFLOW Model Parameters ...... 34 3.4.5 Groundwater Flow Model Calibration ...... 34 3.5 PRMS/MODFLOW INTEGRATED RESULTS ...... 35 3.5.1 PRMS Results ...... 35 3.5.2 East Model Results ...... 37 3.6 SURFACE WATER SUPPLY ...... 38 3.7 GROUNDWATER SUPPLY ...... 39 3.8 SIGNIFICANT RECHARGE AREAS ...... 40 4 WATER DEMAND ESTIMATION ...... 44 4.1 OVERVIEW ...... 44 4.2 SOURCES OF DEMAND ESTIMATION DATA ...... 45 4.2.1 PTTW Database ...... 45 4.2.2 Unserviced Population Consumption Estimate ...... 45 4.2.3 Non-Permitted Agricultural Demand ...... 46 4.3 WATER DEMAND CORRECTIONS ...... 47 4.3.1 Permit Confirmation and Actual Use Estimate ...... 47 4.3.2 Consumption Factor Correction ...... 47 4.3.3 Seasonal Water Use Correction (Monthly Allocation) ...... 47 4.4 WATER DEMAND ESTIMATION RESULTS ...... 48 4.5 WATER DEMAND CONCLUSIONS ...... 48 5 WATER RESERVE ESTIMATION ...... 49 Earthfx Inc. 4

CLOCA Tier 1 Water Budget Report January, 2009

5.1 SURFACE WATER RESERVE ...... 49 5.2 GROUNDWATER RESERVE ...... 50 6 SUBWATERSHED STRESS ASSESSMENT ...... 51 6.1 OVERVIEW ...... 51 6.2 WATER DEMAND CALCULATION METHODOLOGY ...... 52 6.2.1 Groundwater Calculation ...... 52 6.2.1.1 Average Annual Groundwater Supply Calculation Methodology ...... 53 6.2.1.2 Monthly Groundwater Supply Calculation Methodology ...... 53 6.2.2 Surface Water Calculation ...... 53 6.3 STRESS ASSESSMENT CRITERIA ...... 54 6.3.1 Groundwater Stress Assessment ...... 54 6.3.2 Surface Water Stress Assessment...... 54 6.4 TIER 1 STRESS ASSESSMENT RESULTS ...... 55 6.4.1 Groundwater Stress Assessment: Current Conditions ...... 55 6.4.2 Groundwater Stress Assessment: Future Conditions ...... 55 6.4.3 Surface Water: Current and Future Conditions ...... 55 6.5 STRESS ASSESSMENT VALIDATION ...... 56 6.6 MUNICIPAL WELLHEAD AND INTAKE ASSESSMENT ...... 56 7 UNCERTAINTY, DATA AND KNOWLEDGE GAPS ...... 57 8 CONCLUSIONS ...... 59 9 LIMITATIONS ...... 60 10 REFERENCES ...... 61 11 TABLES ...... 64 12 FIGURES ...... 85 13 APPENDIX A: SUMMARY OF CONCEPTUAL UNDERSTANDING ...... 148 13.1 OVERVIEW ...... 148 13.2 TOPOGRAPHY AND PHYSIOGRAPHY ...... 148 13.3 HYDROSTRATIGRAPHY ...... 149 13.3.1 Stratigraphic Framework ...... 149 13.3.2 Bedrock Geology ...... 150 13.3.3 Quaternary Sediments ...... 150 13.3.3.1 Scarborough Formation ...... 151 13.3.3.2 Sunnybrook Drift ...... 151 13.3.3.3 Thorncliffe Formation ...... 151 13.3.3.4 Newmarket Till ...... 151 13.3.3.5 Regional Unconformity (“Tunnel Channels”) ...... 152 13.3.3.6 Oak Ridges Moraine Deposits ...... 152 13.3.3.7 Halton Till ...... 153 13.3.3.8 Surficial Glaciolacustrine Deposits ...... 153 13.3.3.9 Geologic Cross-section ...... 154 13.4 REFERENCES ...... 155 14 FIGURES ...... 157 15 APPENDIX B: PERMIT TO TAKE WATER (PTTW) DETAILS ...... 168 16 APPENDIX C: DETAILED MONTHLY GROUNDWATER AND SURFACE WATER STRESS ASSESSMENTS ...... 172

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CLOCA Tier 1 Water Budget Report January, 2009

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CLOCA Tier 1 Water Budget Report January, 2009

LIST OF FIGURES

Figure 1: Location of the Study Area ...... 86 Figure 2: Watersheds in the CLOCA area...... 87 Figure 3: Water Budget/Water Quantity Risk Assessment framework (from MOE, 2007)...... 88 Figure 4: Components of a steady-state water budget (after MOE, 2007)...... 89 Figure 5: Streams in the CLOCA area classified by Strahler Code...... 90 Figure 6: Flow chart for the PRMS code...... 91 Figure 7: Flowchart for the PRMS snowpack sub-model...... 92 Figure 8: Land surface topography in the CLOCA area from 30-m DEM (data from MNR)...... 93 Figure 9: Areas of hummocky topography (data provided by MNR)...... 94 Figure 10: Slope classification scheme for the CLOCA area classified from 30-m DEM...... 95 Figure 11: Physiography of the CLOCA area (Chapman and Putnam, 1984)...... 96 Figure 12: Land use and ecological land classification for the CLOCA area (data provided by CLOCA). . 97 Figure 13: Surficial geology in the CLOCA area (Sharpe et al., 1997) ...... 98 Figure 14: Example of land-use based input parameter (% imperviousness) for the PRMS model...... 99 Figure 15: Precipitation normals 1971-2000 interpolated using inverse distance squared weighting...... 100 Figure 16: Monthly average precipitation for stations within the CLOCA area...... 101 Figure 17: Sample input data set for the PRMS model...... 102 Figure 18: Location of HYDAT and CLOCA stream gauges...... 103 Figure 19: Average daily flow for the period of record for HYDAT stations in the CLOCA area...... 104 Figure 20: Total flow and separated baseflow (two methods) for Lynde Creek near Whitby (02HC018). 105 Figure 21: Extent of the East Model...... 106 Figure 22: Simulated versus observed annual average total flows at Environment Canada gauges ...... 107 Figure 23: Simulated versus estimated annual average baseflows at Environment Canada gauges ..... 108 Figure 24: Simulated annual average precipitation (POBS) for WY1981 to WY1999...... 109 Figure 25: Simulated annual average net precipitation (PNET)...... 110 Figure 26: Simulated annual average net precipitation after depression storage losses...... 111 Figure 27: Simulated annual average potential evapotranspiration (PET)...... 112 Figure 28: Simulated annual average actual evapotranspiration (AET)...... 113 Figure 29: Simulated annual average total evapotranspiration (AET + Interception)...... 114 Figure 30: Simulated annual average runoff (RO)...... 115 Figure 31: Simulated annual average direct recharge to the saturated zone (UGS)...... 116 Figure 32: Simulated annual average recharge to the unsaturated zone...... 117 Figure 33: Simulated annual average groundwater recharge (QR)...... 118 Figure 34: Simulated monthly average groundwater recharge (UGS+USS) for November...... 119 Figure 35: Simulated monthly average groundwater recharge (UGS+USS) for July...... 120 Figure 36: Applied recharge for the East Model using PRMS results for the CLOCA area...... 121 Figure 37: Simulated and observed heads in model Layer 3 representing the Oak Ridges Aquifer Complex (where present)...... 122 Figure 38: Simulated versus observed ORAC heads in the CLOCA area and local model calibration statistics...... 123 Figure 39: Simulated and observed heads in model Layer 5 representing the Thorncliffe Aquifer Complex...... 124 Figure 40: Simulated groundwater discharge to streams in the CLOCA area...... 125 Figure 41: Ranked-flow curve for Lynde Creek at Whitby (02HC018) showing streamflow statistics (1959 - 2003)...... 126 Figure 42: Median flows for the period of record at each gauge expressed in mm/yr...... 127 3 Figure 43: Annual average groundwater recharge (QR) by watershed (m /s)...... 128 Figure 44: Average annual lateral inflow (QIN) by watershed...... 129 Figure 45: Average annual lateral outflow (QOUT) by watershed ...... 130 Figure 46: Average annual groundwater supply QSUPPLY (QR + QIN) by watershed...... 131 Figure 47: Backward particle tracking from potential seeps and springs in the ORM ...... 132 Figure 48: Reverse particle tracking from high groundwater discharge areas ...... 133 Figure 49: High volume recharge area identified by backward tracking from cells with simulated groundwater discharge to streams greater than 1 L/s ...... 134 Figure 50: High Volume Recharge Areas by Watershed ...... 135 Earthfx Inc. 7

CLOCA Tier 1 Water Budget Report January, 2009

Figure 51: High Volume Recharge Areas by Physiographic Region ...... 136 Figure 52: High Volume Recharge Areas by Jurisdiction ...... 137 Figure 53: Significant Groundwater Recharge Areas (as defined under the Clean Water Act, 2006) ..... 138 Figure 54: Location of surface water Permits to Take Water ...... 139 Figure 55: Location of groundwater Permits to Take Water ...... 140 Figure 56: Pringle Creek Sewage Treatment Plant near Hwy 401 ...... 141 Figure 57: Annual average groundwater reserve by catchment ...... 142 Figure 58: Percent Water Demand by catchment (current conditions) ...... 143 Figure 59: Final groundwater stress levels by catchment ...... 144 Figure 60: Surface water stress levels by catchment ...... 145 Figure 61: Cumulative flow analysis for Lynde Creek at Whitby (1959 to 2003) ...... 146 Figure 62: Cumulative flow analysis for Oshawa Creek (1959 to 2003) ...... 147 Figure 63: Bedrock topography in the CLOCA area ...... 158 Figure 64: Quaternary deposits found within the CLOCA area ...... 159 Figure 65: Interpolated thickness of the Scarborough Formation ...... 160 Figure 66: Interpolated thickness of the Sunnybrook Drift ...... 161 Figure 67: Interpolated thickness of the Thorncliffe Formation ...... 162 Figure 68: Interpolated thickness of the Newmarket Till ...... 163 Figure 69: Deposition of the Oak Ridges Moraine between two ice lobes ...... 164 Figure 70: Interpolated thickness of the Oak Ridges Moraine deposits...... 165 Figure 71: Interpolated thickness of the Halton Till ...... 166 Figure 72: Northeast-Southwest cross section through the CLOCA watersheds ...... 167

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CLOCA Tier 1 Water Budget Report January, 2009

LIST OF TABLES

Table 1: Land use related parameter values (see Leavesley et al., 1983; Chow, 1964; Linsley et al., 1975)...... 65 Table 2: Soil properties related to surficial geology (see Todd, 1980; Linsley et al., 1975; Chow, 1964). . 66 Table 3: Hydrologic soil groups (from Chisholm, 1981)...... 67 Table 4: CN values based on land use classes and soil properties (see Chow, 1964)...... 68 Table 5: Climate normals for 1971 to 2000 from Environment Canada climate stations in the CLOCA area (Data from Environment Canada)...... 69 Table 6: Monthly and annual estimated potential evapotranspiration for the CLOCA area...... 70 Table 7: Total flow and separated baseflow for gauged streams in the CLOCA area...... 70 Table 8: Annual average recharge rates used in the East Model outside the CLOCA area (from Kassenaar and Wexler, 2006)...... 70 Table 9: PRMS outputs stored on a monthly, yearly, average monthly, and average annual basis...... 71 Table 10: Median monthly flows (m3/s) at Environment Canada HYDAT stations in the CLOCA area (see CLOCA 2000b for details on each gauge)...... 72 Table 11: Simulated median monthly flows (m3/s) at the catchment outlets based on the PRMS model. . 72 Table 12: Simulated monthly groundwater recharge (QR) by watershed...... 73 Table 13: Estimates of Lateral Groundwater Flow (QIN) by Catchment. Highlighted watersheds are experiencing a net groundwater inflow...... 74 Table 14: Thresholds for high recharge ...... 74 Table 15: Total Water Demand Summary ...... 75 Table 16: Summary of permitted groundwater usage by permit class ...... 75 Table 17: Summary of permitted surface water usage by permit class ...... 76 Table 18: Un-permitted Current Groundwater Demand ...... 77 Table 19: Total Current Groundwater Demand (QD) by Month ...... 77 Table 20: Future Un-Permitted Groundwater Demand ...... 78 Table 21: Total Future Groundwater Demand (QD) by Month ...... 78 Table 22: Total Current Surface Water Demand (QD) by Month ...... 79 Table 23: Discharge from water pollution control facilities and estimated reserve ...... 80 Table 24: QP90 flows from Environment Canada gauges...... 80 Table 25: Simulated monthly lower decile flows (m3/s) at the catchment outlets based on the PRMS model...... 80 Table 26: Groundwater reserve estimation for the gauged catchments...... 81 Table 27: Groundwater reserve estimation for the CLOCA watersheds...... 81 Table 28: Groundwater stress assessment summary - current conditions ...... 82 Table 29: Monthly groundwater stress threshold assessment - current conditions ...... 82 Table 30: Groundwater stress assessment summary - future conditions ...... 83 Table 31: Monthly groundwater stress threshold assessment - future conditions...... 83 Table 32: Surface water stress assessment - current and future conditions...... 84 Table 33: Permit to Take Water (PTTW) Data Details ...... 169 Table 34: Detailed monthly surface water stress assessment - current and future conditions...... 173 Table 35: Detailed monthly groundwater stress assessment - current conditions...... 176 Table 36: Detailed monthly groundwater stress assessment - future conditions...... 179

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CLOCA Tier 1 Water Budget Report January, 2009

1 EXECUTIVE SUMMARY

The Province of Ontario has introduced new legislation under the Clean Water Act (2006) to protect drinking water by developing watershed-based Source Water Protection (SWP) plans. These plans include a multi-tiered approach to characterizing the hydrologic system and assessing the water supply and water demands in the province. The water budget process, which succeeds the Watershed Characterization and Conceptual Understanding phases, follows a tiered process to screen the areas to identify where there is potential water quantity stress. These potentially stressed areas that are associated with mandated drinking water supplies are then studied in more detail. The process is designed so that each successive tier in the analysis (up to and including Tier 3), becomes more complex, requiring increased sophisticated analysis and data. As a result, with each successive tier the certainty in the findings of the analysis is increased.

This Tier 1 Water Budget Assessment report, which represents first-level “screening”, identifies subwatersheds that may later require more detailed evaluation. Data gathered and the understanding generated will also prove useful for other water management programs carried out by the Conservation Authority.

The report followed the Ontario Ministry of the Environment (MOE) draft guideline entitled “Assessment Report: Draft Guidance Module 7 Water Budget and Water Quantity Risk Assessment” (MOE, March 2007) and complies with Part III requirements of the Clean Water Act Technical Director‟s Rules for the Assessment Report --. The guidance and rules outline the steps required to conduct a Tier 1 water budget analysis. This Tier 1 analysis utilized available data collected within the CLOCA watersheds and relied heavily on the previously developed YPDT-CAMC database and groundwater flow models. Additional data on population, permits to take water (PTTW), and water use were compiled to determine the groundwater and surface water consumptive demand within each catchment.

The water budgets characterize each component of the hydrologic system on a catchment basis and describe, in a quantitative manner, the pathways that water takes through the watersheds. Typically, a Tier 1 level assessment is based on simplified calculations. However, more advanced analysis methods (i.e., numerical models) should be used to determine the water supply component of the water budget if they are available. Two numerical models were available to CLOCA and were applied in an integrated manner for this study. The models provided a quantitative assessment of groundwater recharge, interaction between the groundwater and surface water systems, and groundwater movement across watershed boundaries. The groundwater model extended beyond the CLOCA boundary and was used to estimate inflow from recharge areas external to the CLOCA study area.

The hydrologic model used in this study was based on the U.S. Geological Survey (USGS) Precipitation-Runoff Modelling System (PRMS) (Leavesley et al., 1983). It was modified by Earthfx Incorporated to conduct the water balance on a distributed (i.e., a cell-by-cell) basis. The PRMS model provided estimates of precipitation, interception, evaporation, potential and actual evapotranspiration, snowmelt, runoff, infiltration, interflow, and groundwater recharge. The primary target for PRMS model calibration was to match measured surface water flows and estimated baseflows at Environment Canada surface water gauges with long-term record.

A significant aspect of the PRMS model application was that it used distributed data on soil properties, topography, vegetative cover, and land-use classes. All physical properties, including land-use classes, were represented on a 25-metre cell grid covering the study area.

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CLOCA Tier 1 Water Budget Report January, 2009

Daily rainfall and temperature data from five climate stations in the study area were spatially interpolated using an inverse-distance weighting technique. Another important aspect of this assessment was that consistent model parameters were selected for each land-use/soil- type/vegetation combination across all the watersheds in the CLOCA area. For example, agricultural areas on Halton Till soils were assigned the same properties in the Lynde Creek watershed as in the Soper Creek watershed. In this way, the hydrologic response of each watershed was dependent on the relative coverage and distribution of each land-use/soil-type combination. This also helped to overcome the limitations imposed by having a small number of gauges with long-term record relative to the number of catchments modelled.

As noted in Guidance Module 7 and the Clean Water Act Technical Directors Rules, water budget analysis must consider the link between the surface water and groundwater systems. Hydrologic models are often developed with the implicit assumption that groundwater flow across watershed boundaries is negligible. Preliminary analyses of surface water and groundwater flow indicated that groundwater inflow and outflow across watershed boundaries was likely a significant portion of the water budget in many of the CLOCA catchments. Ignoring the contribution of cross-watershed flows often leads to assigning different (and incorrect) hydrologic properties to each catchment to account for the difference in observed flows.

To better represent the linkage, a second model, based on the U.S. Geological Survey‟s MODFLOW numerical groundwater flow code (MacDonald and Harbaugh, 1988), was applied to represent the groundwater system. The groundwater model which includes the study area was developed as an extension to the previous Oak Ridges Moraine groundwater model development project (Kassenaar and Wexler, 2006). The groundwater model provided estimated groundwater potentials, groundwater budget items (such as the exchange of water between shallow and deeper aquifers), lateral inflows and outflows from the catchments, and groundwater discharge to streams. The groundwater model was also used to identify significant groundwater recharge areas (SGRA). The groundwater model was calibrated to observed groundwater potentials and estimated baseflows.

The hydrologic and groundwater models were linked by using the groundwater recharge output from the PRMS hydrologic model, averaged over a 19-year simulation period, as input to the MODFLOW groundwater model. In turn, net lateral inflows and estimated groundwater discharge to streams from the MODFLOW model were used to constrain the PRMS calibration targets. An iterative calibration procedure was employed in which recharge and baseflow estimates were refined until agreement was reached between the two models. By integrating the surface water and groundwater analysis and accounting for inter-catchment groundwater flow, a better calibration was achieved and a consistent and more insightful assessment of the overall hydrologic system was obtained.

Daily outputs from the hydrologic model were summarized to produce tables and maps (as per the Tier 1 guidance requirements) showing the “Water Supply” component of the water budget. This included estimates of precipitation (P), evapotranspiration (ET), recharge (QR), and runoff (RO) on a monthly and annual basis. Output from the steady-state groundwater model was summarized to produce tables and maps showing lateral groundwater inflow and outflow (QIN and QOUT) and groundwater discharge to streams (GD) on a long-term average basis. The PRMS model indicated that seasonal and year-to-year variation in groundwater recharge is very large, with near zero recharge in the summer months and highly variable recharge throughout the other months of the year, depending on ET processes, snowpack accumulation, and snowmelt events. The sum of the annual average recharge (QR) and the lateral inflow (QIN) were used as the groundwater supply (QSUPPLY) in subsequent groundwater stress assessments.

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CLOCA Tier 1 Water Budget Report January, 2009

This study showed that groundwater inflow across watershed boundaries was a significant component of the water budget. Lateral groundwater inflow ranged from 22 to 69% of QSUPPLY (QR + QIN). In most catchments, QIN was balanced by QOUT. However, Bowmanville and Oshawa Creek watersheds had significant net lateral inflows (i.e., QIN – QOUT). Many of the small watersheds had small net lateral outflows. As expected, the watersheds that include significant portions of the Oak Ridges Moraine exhibit the largest overall QSUPPLY.

The PRMS model results were used to determine the location of significant groundwater recharge areas (SGRA) using one of the two recommended methods stated in the Director‟s Rules Part 5, 44(1) and 44(2). Specifically, Rule 44.1 considers an area as SGRA if it exceeds the annual average recharge rate by a factor of 1.15. Delineation of SGRA was done for the CLOCA study area on a watershed basis using the jurisdictional average to identify relatively high recharge areas. Using the method suggested in 44(1), approximately 30% of the study area was defined.

Further, Rule 45.states that “despite rule 44, an area shall not be delineated as a significant groundwater recharge area unless the area has a hydrological connection to a surface water body or aquifer that is the source of a drinking water for a drinking water system.” This requires the removal of SGRAs that are not connected to drinking water systems (such as Lake Ontario serviced areas). The final clipped maps are entitled SGRAs in this report while the maps prepared under Rule 44 (1) are labelled High Volume Recharge Areas to avoid confusion.

Prior to the release of these Rules, when this report was in preparation, provincial guidance required verification of high volume recharge areas for “significance” by considering the hydrological function that these areas support within each watershed. Two methods were applied to verify that areas of high groundwater discharge were related to the High Volume Recharge Areas identified in the study and are presented in this report. Aerial thermography survey data, which appeared to correlate well with brook trout occurrence data, were used to define significant seepage areas on the south flank of the moraine. Reverse particle tracking, using results of the MODFLOW model, identified where recharge to those significant functional zones occurs. In an alternative approach, stream reaches exhibiting more than 1 L/s of groundwater discharge per 100 m reach (as predicted by the groundwater model), were assessed using particle tracking to determine their associated points of recharge. The recharge points were widely dispersed but their locations were found to be generally consistent with the High Volume Recharge Areas. It is important to note, that while the analyses were restricted to the CLOCA area, the High Volume Recharge Areas include areas outside of the CLOCA watersheds that contribute to streamflow within the study area.

The “Water Demand” component of the water budget analysis was determined from four sources: the MOE Permit to Take Water database (PTTW), estimates of unserviced population water consumption, agricultural water use, and other potential water users identified by CLOCA. There are no groundwater-based municipal water systems presently operating in the CLOCA SWP study area.

Monthly corrections for the consumptive demand were estimated from usage descriptions in the PTTW database. Overall permitted water demand in the CLOCA watersheds was found to be 1.3 times higher in the spring and summer than in the fall and winter months. CLOCA is currently working to confirm permit status and actual water use for permits in the PTTW database. Because that work is still ongoing, maximum permitted rates, as recommended in Guidance Module 7, were used in the Tier 1 demand analysis. Finally, the demand estimates were adjusted, as per Guidance Module 7, to account for water pumped but locally returned to the watershed (consumptive use correction). All analyses were subsequently reviewed against Earthfx Inc. 12

CLOCA Tier 1 Water Budget Report January, 2009 the requirements of the Clean Water Act Technical Director‟s Rules for the Assessment Report to ensure compliance.

The water demand analysis calculated a total groundwater demand equal to18,249 m3/d. Lynde, Oshawa, Bowmanville, Soper and Darlington watersheds have the highest total groundwater demand, with Lynde alone accounting for 39% of the total. Similarly, the Lynde watershed accounts for over 56% of the total surface water consumptive demand (excluding demand from Lake Ontario). Golf course irrigation and snowmaking are the two most significant permitted groundwater uses in the CLOCA watersheds; however un-permitted agricultural demand exceeds both golf course irrigation and snowmaking. Population growth is estimated to increase the overall groundwater demand (for direct human consumption) by about 3% over the next 25 years.

The water reserve components of the groundwater and surface water budgets were first estimated from streamflow data. Because the contributing areas to the gauges do not cover the entire CLOCA area, water reserve was instead computed using the simulated streamflow from the calibrated numerical models. Groundwater reserve (QRESERVE) was estimated as 10% of the groundwater model simulated baseflow (GD). The simulated lower decile flows (QP90) from the hydrologic model were used to estimate the surface water reserve on a monthly basis.

Groundwater stress assessments were conducted to calculate percent water demand on an annual and monthly basis. QSUPPLY and QRESREVE were estimated from the models and values of annual and average monthly demand were determined from the water demand analysis The groundwater stress assessment conducted using annual average demand indicated that, under current conditions, two watersheds have moderate stress levels (Lynde and Darlington Creek watersheds) while the remaining have low stress levels. The assessment using monthly demand indicated that Lynde and Darlington Creek watersheds have elevated stress levels but were below the (higher) monthly threshold values. The maximum stress levels from the two analyses were combined to determine the final stress levels and, again, Lynde and Darlington Creek watersheds were characterized as having moderate stress levels while the remaining catchments had low stress levels. The analyses were repeated using estimates of future demand. No changes to the stress assessment levels resulted from the future conditions scenario. It should be noted that, unless significant land-use changes are anticipated, only increased demand is to be considered in the Tier1 future stress analyses. With development restrictions afforded by the Oak Ridges Moraine Conservation Act and Greenbelt legislation in the study area, future land-use change is not considered to be 'significant'.

A surface water stress assessment was conducted to calculate percent water demand on a monthly basis using simulated median flows (QP50) for QSUPPLY and lower decile flows (QP90) for QRESREVE. Results indicated that Lynde, Goodman, Oshawa, Darlington, and Soper Creek watersheds all had significant stress levels during summer months. This is not uncommon in the smaller watersheds in Southern Ontario given that groundwater recharge occurs primarily in the spring and fall and little recharge occurs in the summer. All other catchments, with the exception of Bowmanville Creek, had low stress levels because they had no surface water demand. Bowmanville Creek had low stress levels because of a relatively high water supply (which included significant lateral groundwater inflow from parts of the Oak Ridges Moraine outside the CLOCA boundaries) and a relatively low surface water demand compared to the other large catchments.

Cumulative flow analyses were used to verify the Tier 1 Stress Assessment results. These analyses, conducted for the two watersheds with long-term data (Lynde and Oshawa Creeks), suggest that there has been a decrease in streamflow since the late 1990s. These changes Earthfx Inc. 13

CLOCA Tier 1 Water Budget Report January, 2009 may indicate an increasing watershed stress although factors, such as climate change, changes in stream hydraulics, and an increase in permitted water demand may also be contributing to the observed decrease in flow. Further investigation, beyond the Tier 1 level of analysis, is recommended. Given that this is not a drinking water concern, these further analyses should be conducted under other CLOCA watershed protection programs.

There are no operating municipal groundwater supply wells in the CLOCA watersheds, therefore, according to the SWP Guidelines, a Tier 2 stress assessment will not be necessary. CLOCA, however, is committed to watershed protection and improving of their understanding of the watersheds, and as such, has developed a list of data and knowledge gaps for their watersheds (CLOCA, 2007). Most significant of these, is a more comprehensive understanding of the QDEMAND component of the water budget, including updating permit data and assessing actual water use. Additional surface water gauges and wells have been installed, and with time, their records will allow an improved assessment and understanding of the watersheds.

On a more general level, this study has demonstrated the benefits of an integrated assessment of groundwater and surface water resources. Lateral groundwater movement between catchments is significant, and in particular, lateral inflows from outside the CLOCA watersheds form an important component of the flow system, both from a water volume and SGRA protection perspective. Particularly notable was that particle tracking suggested that groundwater recharge northeast of CLOCA flows in deep aquifers under Soper Creek before discharging to Bowmanville Creek. Also important is the quantitative insight into the variability in groundwater recharge, both on a yearly and monthly basis. Many of the CLOCA watersheds exhibit a net outflow of water during the summer months, indicating that groundwater storage must play a significant role in the maintaining groundwater supply. Understanding the role of storage, through the use of transient groundwater models, should be considered in conjunction with long-term monitoring of groundwater levels.

Explanatory Note:

This report has been prepared to meet provincial requirements under the Clean Water Act, 2006 and should not be used for other purposes without consultation with the responsible conservation authority. The water budget process follows a tiered process to screen the areas to identify where there is potential water quantity stress. These potentially stressed areas that are associated with mandated drinking water supplies are then studied in more detail. The process is designed so that each successive tier in the analysis (up to and including Tier 3), becomes more complex, requiring increased sophisticated analysis and data. As a result, with each successive tier the certainty in the findings of the analysis is increased.

The analysis used to produce this report was based on best information available at the time. Priority should be given to site specific information collected in accordance with accepted scientific protocols when being used for other decision-making purposes, such as determining the impact of a specific water taking.

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CLOCA Tier 1 Water Budget Report January, 2009

2 INTRODUCTION

The Province of Ontario has introduced new legislation under the Clean Water Act to protect drinking water by developing watershed-based Source Water Protection (SWP) plans. The SWP plan is considered the first step in a multi-barrier approach to ensuring safe drinking water. A SWP plan is based on a technical assessment of the many different sources of drinking water and the potential threats to those drinking water sources. SWP plans are to be developed for all watersheds in Ontario. The Central Lake Ontario Conservation Authority (CLOCA), Credit Valley Conservation (CVC), the Toronto and Region Conservation Authority (TRCA) have joined with municipal partners (including the Regional Municipalities of York, Peel, Durham, and Halton and the City of Toronto) to develop SWP plans for the CTC region.

Developing a SWP plan requires, amongst other things, a quantitative understanding of the surface water and groundwater flow processes that occur within the watershed in order to protect all drinking water resources. The primary means of developing the quantitative understanding is through a detailed water budget assessment. Water budgets developed for SWP plans characterize each component of the hydrologic system on a watershed basis and describe, in a quantitative manner, the pathways that water takes through the watersheds. While water budgets carried out for SWP plans are meant to primarily address drinking water sources, the knowledge gained and tools developed can be used to aid in other areas of water resource and watershed management.

The Ontario Ministry of the Environment (MOE) has prepared a draft guideline entitled “Assessment Report: Draft Guidance Module 7 -- Water Budget and Water Quantity Risk Assessment” (MOE, March 2007) which outlines the steps needed to estimate the quantity of water flowing through a watershed, describe the significant processes that affect flow and the pathways that water follows, and assess the sustainability of drinking water supplies. Guidance Module 7 proposed a staged study approach, building on information included within the watershed characterization report (Module 1). The level of investigation required in the tiered approach depends on the severity of local water quantity issues. In June 2008, MOE released the draft “Technical Rules: Assessment Report, Clean Water Act, 2006” which replaced Guidance Module 7 and other SWP Guidance Modules. The Tier 1 Water Budget Assessment Report was reviewed to ensure compliance with Technical Rules (also known as the Director‟s Rules).

CLOCA has completed a watershed characterization study (CLOCA, 2006) and a conceptual water budget study (CLOCA, 2007) for the watersheds under its jurisdiction. The present study takes the SWP water budget analysis process to the Tier 1 level by employing a set of water resource management tools (i.e., numerical models) to provide a deeper understanding of the physical processes that control the rate of movement of water through the various parts of the hydrologic cycle within the CLOCA watersheds. A map showing the location and extent of the study area is provided in Figure 1. Locations of the major watersheds within the CLOCA jurisdiction are shown on Figure 2. Emphasis was placed on the detailed numerical assessment of groundwater recharge, interaction between the groundwater and surface water systems and on groundwater movement across watershed boundaries. In particular, it was important to determine whether significant quantities of groundwater enter across the CLOCA boundary from high recharge areas on the Oak Ridges Moraine and whether cross-watershed flows are a significant component of the water budget of the individual watersheds.

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CLOCA Tier 1 Water Budget Report January, 2009

Figure 3 shows a general outline of the Water Budget assessment process proposed for the SWP program. It should be noted that a typical Tier 1 analysis uses simple water budgeting tools to estimate surface water and groundwater flow through the subwatershed. However, Guidance Module 7 also recommends that output from numerical models should be utilized in the Tier 1 assessment if these tools already exist. This approach is also sanctioned by the province under the Directors Rules. Such is the case for the CLOCA watersheds. A partnership formed by the Regional Municipalities of Peel, York, and Durham, the City of Toronto, and the nine Conservation Authorities (YPDT-CAMC) located along the Oak Ridges Moraine (ORM) initiated a detailed analysis of the groundwater flow systems associated with the ORM in 2001. As part of this study, all water-related data, including streamflow, climate, borehole, and water well information, and pertinent mapping and reports, were collated into a water resources database (referred to as the YPDT-CAMC database). These data were used in the construction and calibration of a three-dimensional numerical groundwater flow model for the central part of the ORM (referred to as the Core Model) (Kassenaar and Wexler, 2006). This model was recently expanded eastward to include Durham Region and the CLOCA watersheds. In addition, a hydrologic model, based on the U.S. Geological Survey‟s Precipitation-Runoff Modelling System (PRMS) code, was used to help quantify the spatial distribution of the principal components of the water budget including groundwater recharge. The database and numerical models were used extensively in this Tier 1 water budget analysis.

2.1 Tier 1 Water Budget and Stress Assessment

The Tier 1 water budget and stress assessment follows the Watershed Characterization and Conceptual Understanding phases. The primary purpose of the Tier 1 analysis is to describe the movement of water within the various elements (such as soils, aquifers, streams, lakes) that constitute the hydrologic cycle within each watershed in a quantitative manner. A second purpose of the Tier 1 analysis is to estimate the hydrologic stress within each subwatershed in order to screen out areas that are unstressed from a water quantity perspective. Future efforts and resources (Tier 2 and 3) could then be focussed on areas that serve municipal supplies that are found to be under hydrologic stress or likely to be so in the future.

This Tier 1 analysis utilizes available data that have been collected within the CLOCA watersheds. These data represent information that has been collected routinely over the years by CLOCA and other government agencies such as the Ontario Ministry of the Environment and Environment Canada. These data have been analyzed in earlier studies and as part of the Watershed Characterization and Conceptual Water Budget Studies (CLOCA, 2006 and CLOCA, 2007). As noted above, these data were compiled into the YPDT-CAMC database and used to build a conceptual geologic model and a regional scale groundwater model that includes the CLOCA watersheds (Kassenaar and Wexler, 2006). A detailed hydrologic model was also built for the CLOCA area using the available hydrologic data to accurately estimate the water budget for the CLOCA watersheds. Output from the groundwater and hydrologic models formed the basis for the Tier 1 assessment. The models are described briefly within this report in the discussion of the analysis of “available water supply”.

Additional data on population, permits to take water (PTTW), and water use were used to estimate water demand as described further on in this report. Together, the results of the water supply and water use analyses were used to evaluate the cumulative stress within each subwatershed. A screening assessment was completed which included an estimation of the percentage of the water supply that is demanded consumptively by water users. This percentage is referred to as the Percent Water Demand. According to earlier MOE Guidance

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Module 7 during the period when this report was being prepared, subwatersheds with significant consumptive takings may jeopardize the reliability of the well or intake. This concept is similarly understood in the requirements outlined in the Director‟s Rules. As a result, subwatersheds that are estimated to experience a significant-to-moderate degree of stress, and which contain municipal drinking water systems, will move on to the Tier 2 Water Budget and Stress Assessment (Section 4) for refinement of estimates. Subwatersheds that experience a significant-to-moderate degree of stress, and do not contain municipal drinking water systems, will be highlighted but will not automatically move on to Tier 2 unless directed so by the Province. Subwatersheds calculated to have a low degree of stress during this Tier 1 analysis will not be required to undergo any further steps in the Water Budget – Water Quantity Risk Assessment process for Source Water Protection.

As indicated, this Tier 1 analysis utilized a set of existing models to estimate the various water budget fluxes. The hydrologic model, based on the U.S. Geological Survey PRMS code (Leavesley et al., 1983), provided information on precipitation, interception, evaporation, potential and actual evapotranspiration, snowmelt, runoff, infiltration, interflow, and groundwater recharge for all the CLOCA watersheds. As noted in the guidance documents, the Tier 1 analysis must also consider the link between the surface water and groundwater systems. To establish this linkage, a numerical groundwater flow model, based on the USGS MODFLOW code (MacDonald and Harbaugh, 1988), took results of the PRMS model as applied recharge to the groundwater system. The groundwater model provided estimated groundwater potentials, groundwater budget items (such as the exchange of water between shallow and deeper aquifers), lateral groundwater inflow and outflow across catchment boundaries, and groundwater discharge to streams. Results from the groundwater modelling, described later on, established that significant volumes of groundwater were entering the CLOCA watersheds from high recharge areas to the northeast and northwest. Groundwater pathway and flux analyses also indicated that significant groundwater volumes were moving across subwatershed boundaries. These findings were used in an iterative manner to adjust calibration targets (i.e., baseflow estimates) for the hydrologic model.

The models were calibrated to observed values, primarily observed groundwater potentials, surface water flows, and estimated baseflow data extracted from the YPDT-CAMC database. The hydrologic model was run on a daily basis and at a 25-m cell size to provide a detailed representation of the time-dependence and spatial variability of the physical processes that occur within the natural system. The output from the hydrologic model was averaged spatially and over a 19-yr simulation period to provide long-term estimates of annual groundwater recharge for input into the steady-state groundwater flow model, which used a 100-m cell size.

It is recognized that all calculations and models used in this study involve simplifications and assumptions. However, the results provided a much better understanding of watershed behaviour on a seasonal and annual basis and a greater understanding of the interaction of the surface water and groundwater systems. The linked groundwater and surface water models developed in the Tier 1 analyses will provide a basis for management of water resources in the CLOCA area and continued improvement in the understanding of the hydrology and hydrogeology of the CLOCA watersheds.

2.2 Water Budget Elements

The Tier 1 water budget process is designed to assess the level of stress within each subwatershed utilizing existing information collected during the Conceptual Understanding

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CLOCA Tier 1 Water Budget Report January, 2009 phase. The water budget analysis estimates the various elements of the hydrologic cycle including precipitation (P), evapotranspiration (ET), recharge (R), and runoff (RO) and lateral groundwater inflow and outflow (QIN and QOUT) and groundwater discharge to streams (GD). The components of a steady-state water budget (which assumes that the change in the amount of water stored in the various surface and subsurface reservoirs is small over the time scale considered) is shown schematically in Figure 4.

As noted in Guidance Module 7, complex hydrologic models should be used for analyzing subwatershed stress if they are available because they will yield the best estimates of the water budget components. The province supports this approach under the Director‟s Rules. The PRMS-based hydrologic model was used in this analysis to estimate the principal component of the water budget on a daily basis (i.e., P, ET, R, and RO). Other significant processes such as: interception by the canopy; throughfall (i.e., water making it past the canopy after interception is satisfied); snow accumulation; sublimation; snowmelt; and depression storage in impervious areas were also simulated. Runoff from pervious and impervious areas were estimated separately because understanding these two processes is critical to predicting how the water balance changes with increased deforestation and urban development.

The model integrated information on land use, surficial geology, topography, and climate (i.e., rainfall, temperature, and solar radiation) to determine the spatial distribution of P, ET, R, and RO and other processes within each watershed. Daily values were summed up over a 19-year period to determine monthly and annual averages needed for the Tier 1 stress assessment. The Tier 1 assessment considered current conditions as well as a 25-year future water demand scenario.

2.2.1 Selection of Models

Guidance Module 7 notes that “while relatively simple approaches are considered adequate to determine the subwatershed stress at the Tier 1 screening level, it should be pointed out that if suitably calibrated complex models are already available within a watershed, they will likely yield the best estimates of the water budget components and should therefore be used instead of other more simple approaches for the Tier 1 stress”. This philosophy (which continues to be supported under the Directors Rules), guided the selection of the models used in this study and took into account that CLOCA has invested considerable effort in developing a sophisticated hydrologic model and groundwater flow model for the CLOCA watersheds.

The Conceptual Water Budget report (CLOCA, 2007) discussed the shortcomings of empirical methods used in a typical Tier 1 analysis to conduct a simplified analysis of the water balance. The report then presented the rationale for selecting the coupled PRMS-based hydrologic model and MODFOW-based groundwater model for the Tier 1 analyses.

2.2.2 Approach to Model Verification

The stress calculations for each subwatershed are based on estimated fluxes, in this case, produced by a set of numerical models. Estimates of “water supply” developed for the stress analysis are subject to the inherent uncertainty in representing natural systems and even estimates generated by complex models are subject to the uncertainties in model parameter value and limitations in the available data. Several general approaches were taken in this study

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CLOCA Tier 1 Water Budget Report January, 2009 to limit the uncertainty and to ensure that the model results were physically reasonable prior to proceeding with the stress calculations.

1. All gauged CLOCA watersheds were simulated simultaneously. Often, hydrologic models are calibrated one watershed at a time. This leads to a unique set of parameters for each watershed. By modelling all watersheds at the same time, parameter values were selected that applied to the whole watershed (for example, a parameter might be the runoff coefficient for high-density residential areas on Halton Till soils). While it is recognized that soils and land-use patterns may vary across the area, visual inspection of air photos, land-use maps, soils maps, and surficial geology maps showed that they were reasonably consistent. Thus, it was possible to assign the same parameter values to high-density residential areas on Halton Till soils in the Oshawa Creek watershed as in the Bowmanville Creek watershed. If the parameter values needed to be adjusted when calibrating the hydrologic model to the Oshawa Creek gauge, similar adjustments were made to the Bowmanville model and the calibration to the Bowmanville gauge was re-checked. 2. In a similar vein, the concept of “parsimony” was adhered to. In general, adding parameters can produce a better fit to the observed data, but each parameter introduced into the model adds another level of uncertainty. Many hydrologic models, including PRMS, have seasonal adjustment factors and watershed-based adjustment factors to improve calibration. Over-parameterization of the model can be done to improve the calibration statistics at a specific gauge but often leads to a decrease in the ability of the model to make future predictions. This occurs when the additional parameters are added or adjusted to improve the fit to observation data that have an unknown amount randomly-distributed error or “noise”. 3. Using results of the groundwater model to adjust calibration targets. For example, the Conceptual Water Budget study (CLOCA, 2007) noted that Bowmanville had a higher estimated baseflow than the other catchments and hypothesized that the high recharge was coming from ORM deposits within the basin. Analyses with the groundwater flow model, however, indicted that much of the additional recharge was coming from outside the watershed. By adjusting the baseflow targets for the hydrologic model to reflect this outside source (i.e., by subtracting the net amount of lateral groundwater inflow from the observed baseflow amounts), a good calibration was achieved using the same rate of recharge for the ORM deposits within the Bowmanville watershed as for ORM deposits in the other CLOCA watersheds. While it is recognized that the characteristics of the ORM deposits can vary spatially along the length of the moraine, (for example, ORM deposits were found to be much siltier in the upper Humber watershed), they are not expected to vary widely within the study area. 4. Results of the hydrologic model were used as input to the groundwater model. Often, the rates of groundwater infiltration or rates of “losses to deep groundwater” produced by the hydrologic models are not tested independently. Estimates produced by the recharge model were used directly in the groundwater model as a check on their reasonableness. Simulated heads were checked against the observed data and simulated baseflows were checked against separated baseflows. Although the tests are not definitive (since they depend, in part, on the values assumed for aquifer and aquitard properties) the independent checking narrows the range of possible parameter values and thereby reduces the level of uncertainty in the estimated recharge values. 5. The hydrologic and groundwater models used for this study are process-based codes, which attempt to represent the physical system as closely as possible. The area was broken up into small cells (25-m cell size for the hydrologic model and 100-m cell size for the groundwater model) to best represent the known variation in physical properties on the surface and in the subsurface. The hydrologic model was run on a daily basis to Earthfx Inc. 19

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better represent the time-dependent processes such as snow accumulation and melting and soil moisture balance (as opposed to using monthly or annual estimated values). The groundwater was run under steady-state conditions. Transient analysis, in which time variation of recharge is considered, is planned for future upgrades of the model.

2.3 Description of the Conceptual Hydrostratigraphic Model

The Tier 1 SWP approach is based on a staged development of understanding and analysis. This report builds on a considerable foundation of previous studies and data compilation efforts (CLOCA 2006, CLOCA 2007 and Kassenaar and Wexler, 2006). The reader is referred to these documents for a complete and comprehensive technical discussion of the conceptual hydrostratigraphic model of the study area. A summary of the conceptual hydrostratigraphic model is presented in Appendix A for the benefit of interested readers.

2.4 Description of Surface Water System

The Tier 1 SWP approach is also based on an understanding of the natural drainage system within the CLOCA area which includes five major watersheds that originate on the ORM and many smaller ones originating in the southern portion of the study area (Figure 2). Numerous small streams that drain directly into Lake Ontario have been grouped into the “Lake Ontario Catchments”.

The surface of the ORM is highly permeable and the area is almost devoid of perennial streams. Headwater streams originate as springs on the south slope of the ORM where the moraine deposits are truncated or thin below the Halton Till. Groundwater discharges to springs and seeps where the till is missing or fractured. The small streams coalesce and flow southward along the gently sloping till plain. The till soils are subject to weathering and, over time, steep gullies and valleys have been created. Many small streams originate as a result of groundwater discharge from the Iroquois Beach deposits in the middle part of the major watersheds. There are also areas in the middle part of the watersheds where the deeper tills (Newmarket Till and Sunnybrook Drift) have been cut through and groundwater can discharge from the deeper aquifers (Thorncliffe and Scarborough aquifer complexes). The lower aquifer deposits have also been exposed very high up in the Bowmanville Creek watershed in the Enniskillen area. South of the Iroquois Beach deposits, very few small tributaries exist, and the main channels convey the flow to the lake. Streams in the urban part of the CLOCA area have been altered significantly.

Stream reaches can be classified using a Strahler stream order system, which assigns reaches a number depending on their location in the network‟s branching pattern. Figure 5 presents a map of streams classified by their Strahler order based on data provided by MNR. An explanation of the rules for the Strahler classification scheme is shown in the legend.

The term “headwaters” generally refer to zero-order (unmapped swales), first-order and second- order streams. Typically, at least half the total length of the channels in a stream can be classified as first-order. Groundwater discharge to these reaches can represent a significant portion of the total baseflow. This was indicated, as well, in the results of the YPDT-CAMC groundwater modelling study of the Oak Ridges Moraine (Kassenaar and Wexler, 2006) where first- and second-order streams received almost half of the groundwater discharge. Accurate Earthfx Inc. 20

CLOCA Tier 1 Water Budget Report January, 2009 mapping of low-order streams is, therefore, critical in assessing the spatial distribution of groundwater discharge for water budgets and resource modelling.

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3 Water Supply Estimation

“Water Supply” is the term used in Guidance Module 7 and Part I of the Director‟s Rules to describe the amount of water available at any given instant for use as a water supply. In a surface water system, this has been defined based on expected monthly flows (as determined through statistical analysis of observed flows or through surface water modelling). For groundwater, this has been defined as the sum of the recharge and subsurface inflows (lateral inflow or underflow in). The Guidelines were followed in these analyses.

Guidance Module 7 identified the following seven steps that can be taken to estimate water supply:

1. Conduct a climate evaluation to obtain Precipitation (QP); 2. Estimate Evapotranspiration (QE); Runoff (QRO); and Recharge (QR) 3. Analyze Streamflow (QSW), for streamflow statistical parameters (i.e., QP90, QP50, QAVG); 4. Undertake a baseflow separation at gauged surface water stations; 5. Consider the influence of regulating features (e.g., dams, wetlands); 6. Estimate the groundwater inflow (QIN) (if any) to the subwatershed under examination; 7. Evaluate spatial and temporal distribution of water budget components using soil moisture budget, area weighting (Quaternary geology, land cover).

The seven steps and more were taken, although not in the particular order given, and at a much higher level of detail. The approach to evaluating and infilling the precipitation data, to estimating ET, RO, R and other water budget elements, to establishing calibration targets (streamflow, baseflow, and observed heads), and to estimating lateral inflows (QIN) are described in the following sections. Note that this approach was later reviewed against the CWA Technical Director‟s Rules to ensure compliance.

3.1 PRMS Continuous Surface Water Model

The USGS Precipitation-Runoff-Modelling-System (PRMS) is an open-source code for calculating all components of the hydrologic cycle on a watershed or subwatershed scale. PRMS is a modular, deterministic, distributed-parameter modelling system developed to evaluate the impacts of various combinations of precipitation, climate, and land use on streamflow and groundwater recharge. The modular design provides a flexible framework for model enhancement. The code is extremely well documented in Leavesley et al. (1983) and has been used in many applications across the U.S. and in Europe (see Barth, 2005, Ely, 2006, and Yeung, 2005 for examples of recent applications).

To use PRMS, each watershed is divided into subunits, referred to as “homogeneous response units” (HRUs) based on such basin characteristics as slope, aspect, elevation, vegetation type, soil type, land use, and precipitation distribution. Water and energy balances are computed daily for each HRU. The sum of the responses of all HRUs, weighted on a unit-area basis, produces the daily system response and streamflow for a basin. A second level of partitioning is available for storm hydrographs. While the storm mode includes more complex moisture routing processes, it must be run on a maximum five-minute time-step basis. The daily mode was felt to be adequate for the Tier 1 analysis and was more compatible with the types of climate data readily available.

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The 1991 version of the PRMS source code (available at http://water.usgs.gov- /software/prms.html) was limited to a maximum of 50 HRUs. Because there is no real reason, except computer memory limitations, to restrict the number of HRUs, Earthfx Inc. modified the PRMS code to allow each HRU to represent a cell in a rectangular grid. The ability to compute the water balance on a cell-by-cell basis made PRMS much more compatible with the existing MODFLOW model. When considering different Tier 1 approaches, it was noted that the USGS is currently working on similar PRMS modifications as part of a GSFLOW (Groundwater/ Surface-water Flow) model development initiative.

For this study, square cells, 25 metres on a side, were found to adequately represent the distribution of land use, topography, and soil properties within the CLOCA area. The grid contained 1008 rows and 1500 columns (over 1.5 million cells). Cells that covered areas outside of the watershed boundaries were designated as inactive and were not included in the water balance computations.

3.1.1 PRMS Operation

A flow chart describing the operation of the PRMS code is shown in Figure 6. The reader is referred to Leavesley et al. (1983) for a more complete description of the programme and underlying theory. Key inputs into the model are daily precipitation, solar radiation, and minimum and maximum air temperature. For this study, daily precipitation and temperature data for 1981 to 1999 water years (October 1, 1980 to September 30, 1999) were obtained for four Environment Canada climate stations (Bowmanville-Mostert, Burketon McLaughlin, Oshawa WPCP, and Tyrone) that had both data sets and solar radiation data from Toronto Airport. Daily precipitation and minimum/maximum temperatures were interpolated from the four stations to each HRU using an inverse distance squared weighting technique.

The model tracks volumes of water for each HRU in a number of “storage reservoirs”. These include interception storage, depression storage, snowpack, shallow soil moisture zone, “subsurface water” (i.e., a perched water zone), and groundwater storage. A complex two-layer, energy-balance model for the snowpack, shown schematically in Figure 7, computes snowpack depth, density, albedo, temperature, sublimation, and snowmelt on a daily basis using maximum and minimum air temperature, solar radiation, and precipitation data.

Each HRU can contain pervious and impervious surfaces and the water balance for each area is computed separately. For impervious areas, the model first determines whether a snowpack exists. If the temperature is below 0°C, the precipitation is added to the snowpack as new snow. If the temperature is warmer, the rain is added to the snowpack and its thermal energy is used to raise the temperature of the snowpack. If the energy input is high enough, all or part of the snowpack can melt and runoff. The snowpack can also melt or refreeze based on air temperature change and is subject to sublimation. If there is no snowpack, the model computes capture of precipitation by depression storage. If the depression storage capacity is exceeded, the surplus is assumed to run off. Water is removed from depression storage by evaporation.

For pervious areas, the model first computes interception by vegetation. The amount intercepted depends on the vegetation type and winter/summer vegetation cover density. If the interception storage capacity is exceeded, the surplus is assumed to fall though onto the snowpack, if present, or onto the soil surface. The snowpack energy balance model, described above, is used to determine the amount of snowmelt in pervious areas on a daily basis. Snowmelt is assumed to infiltrate the soil up to a maximum daily amount and any excess is allowed to runoff. For this study, a maximum rate was assigned based on the hydraulic Earthfx Inc. 23

CLOCA Tier 1 Water Budget Report January, 2009 conductivity of the frozen soil (assumed to be 0.05 times the non-frozen hydraulic conductivity). Throughfall, in the absence of a snowpack, is partitioned between infiltration and runoff. The original code used a “contributing area” method to partition flows (see Dickinson and Whiteley, 1970). Earthfx added the option of using a U.S. Soil Conservation Service (SCS) curve number technique and also allowed a percent of runoff from impervious areas to be redirected back to pervious soils. The curve number technique calculates actual runoff from potential runoff based on the size of the rainfall event and the CN value. CN values were determined for each HRU based on the combination of soil type and land use present. CN values are adjusted based on antecedent moisture conditions, so the PRMS code was modified to track rainfall over each HRU for a five-day period. More information on the CN technique can be found in sources such as U.S. Department of Agriculture – Soil Conservation Service (1985) or Chow (1964).

Water entering the soil in pervious areas is subject to evapotranspiration. The PRMS code has three methods for calculating potential ET: daily pan evaporation, the Hamon (1961) method, and the Jensen and Haise (1963) method. A fourth option was added to compute PET using the simpler Hargreaves model (see Hargreaves and Allen, 2003 or Wu, 1997) which requires only two climatic parameters, temperature and incident radiation. PET, in mm/day, is given by:

PET = 0.0135 (T + 17.78) RS [238.8/(595.5-0.55T)] where T is the mean temperature in °C and RS is the incident solar radiation in megajoules per square meter per day (MJ/m2/day). The incident solar radiation is adjusted for each HRU based on slope and aspect, vegetation type, winter/summer cover density, and winter transmission factor (i.e., percentage of short-wave radiation through the winter vegetation canopy).

Actual ET depends on the soil type and amount of water in interception storage and in the recharge zone (upper part of the active soil zone). If the amount of water in interception storage is insufficient to meet the PET demand, the deficit is extracted from the recharge zone at a rate based on soil type and the ratio of the current volume of water stored in the recharge zone to the maximum storage capacity. If the PET demand is still not met, then moisture is extracted from the lower part of the active soil zone but at a rate based on soil type and the ratio of the current volume of water stored in the lower soil zone to the maximum in storage capacity. Soil zone depth was defined by the average rooting depth of the predominant vegetation and adjusted in areas of shallow water table. Initial storage in the upper soil zone was determined based on the thickness of the recharge and soil zones multiplied by the available water. The water available for ET is equal to the difference between field capacity Excess water, defined as the soil moisture above field capacity, is allowed to percolate to the subsurface reservoir. Percolation to groundwater is assumed to have a maximum daily limit and excess infiltration is diverted to the subsurface reservoir. A daily limit was assumed based on the hydraulic conductivity of the soil at field capacity (assuming a unit gradient). Water in the subsurface reservoir can discharge to streams (as interflow) or infiltrate back to the groundwater reservoir over time. For this study, it was assumed that interflow was a small component of the overall water budget and assigned properties that allowed most of the water in the subsurface reservoir to drain back to the groundwater reservoir. The groundwater reservoir discharges to baseflow at a rate dependent on a discharge coefficient and the volume of water stored in the groundwater reservoir. In these simulations, the exponential decay coefficient was approximated by visually comparing the simulated recession with that observed in the streamflow hydrographs.

As previously noted, the model is “fully distributed”, meaning that unique values for all parameters, from precipitation to hydraulic conductivity, were used for each 25-m cell in the model.

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3.2 Application of the PRMS Model

Descriptions of the tasks carried out to apply the PRMS-based hydrologic model are provided below. The focus of these sections is on describing the input data used, the selection of calibration targets, and the steps taken to link the two models.

3.2.1 PRMS Data Compilation and Assessment

The first task included a review of previous studies conducted in the CLOCA area, including pioneering work by Funk (1977) and Singer (1981) in Bowmanville, Soper, and Wilmot Creeks as well as the Watershed Characterization Report (CLOCA, 2006) and the Conceptual Water Budget Report (CLOCA, 2007). Other reports included those compiled and scanned by YPDT- CAMC to create a digital library as part of the YPDT-CAMC Oak Ridges Moraine study. Previous modelling results were reviewed including work done for the Lynde Creek watershed (Gartner Lee, 1994), draft CANWET model runs (Greenland International Consulting Ltd., 2006), and the Oshawa Creek hydrologic model (Totten Sims Hubicki Associates, 1995).

The availability of data for the study area was assessed including: climate (daily precipitation, temperature, and solar radiation); streamflow (continuous daily flows and spot flows); surficial geology, soil maps, and topography; water wells and high-quality boreholes; land use (present and future) and data on vegetative cover; groundwater level data (static water levels and continuous recording); and aquifer properties (from aquifer tests, specific capacity, and lithologic characterization).

3.2.2 PRMS Model Parameters

There are numerous parameters that need to be defined prior to conducting a PRMS analysis. An attempt was made to apply consistent assumptions and parameter values, where possible, across the CLOCA watersheds. In this way, differences in response, as measured by observed streamflow and estimated baseflow, could be attributed to the relative ratios of land use and soil types within each watershed and to the effects of cross-basin transfer. In general, parameters were grouped into:

(1) topography-related properties such as slope, aspect, and depth to groundwater; (2) vegetative cover and imperviousness that could be related to land-use classification; (3) soil properties that could be correlated to surficial geology; (4) combined land-use/soil properties such as the SCS curve number; (5) climate-based properties such as daily climate inputs (precipitation, min/max temperature, and solar radiation); and (6) other parameters.

Methods for selecting and assigning parameter values are discussed in the following sections.

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3.2.3 Data related to Topography

Topography for the CLOCA area, based on a 30-m digital elevation model (DEM) provided by the Ontario Ministry of Natural Resources (MNR) is shown in Figure 8. Higher elevations occur along an east-west ridge that runs across the top of the study area and forms the northern surface water divide. Highest elevations, over 400 metres above sea level (masl), occur in the northwest corner of the study area. Lower elevations occur at the Lake Ontario shoreline (about 75.2 masl) and in the deeply incised stream valleys that generally trend north-south. Areas of hummocky topography associated with the Oak Ridges Moraine (ORM) deposits and thin Halton Till overlying ORM deposits, are shown in Figure 9. The depressions in the hummocky areas act as zones of focused recharge and were given special consideration in the hydrologic model. Depth to water was determined directly from the DEM and the simulated potentiometric surface maps (see Figure 37).

Slope and slope aspect affect the amount of shortwave solar radiation arriving at land surface used in snowmelt and ET calculations. Observed data for radiation received on a horizontal surface are adjusted in the PRMS model for land-surface slope and aspect as well as time of year. For example, a north-facing valley wall will get less solar radiation than the south-facing wall slope and will therefore have lower potential ET rates and the snowpack will persist longer. Slope and aspect values were calculated from the DEM using a five-point finite-difference approximation (the five-point approximation reduces to a standard central difference approximation when the cell sizes are equal). Slope aspects were classified into 13 classes based on direction (North, East, South and West) and magnitude (0, 0 to 5%, 5 to 10%, and greater than 10%) as shown in Figure 10. The majority of the CLOCA area lies on the South Slope and Iroquois Plain physiographic regions (see Figure 11) and has gentle south-facing slopes on the tablelands between streams. Many of the larger streams are steeply incised but there are transition zones with gentler east- and west-facing slopes on either side of the valleys.

3.2.4 Data related to Land Cover

The type of land cover has a strong affect on the water balance. Interception and ET are directly influenced by vegetation type and cover density which, in turn, affects runoff and infiltration rates. Conversion of natural to non-natural land use generally increases the amount of impervious cover leading to evaporation from depression storage and increased runoff. At the same time, however, ET and evaporation from interception storage are decreased, so the net effect on groundwater recharge is more difficult to predict and is best done with water- balance models.

Natural land cover has been determined through the Ecological Land Classification (ELC) system for Southern Ontario. Current land use for the CLOCA area, based on interpretation of 2005 FBS (First Base Solutions) orthophotography, is shown in Figure 12. Some of the classes shown in the figure are aggregated to simplify the presentation. For example, “Forest” includes coniferous, deciduous, and mixed forest land classes. However, each subtype was given a different set of properties in the PRMS model. As can be seen, the coverage is limited outside the watershed boundary and needs to be extended to better model groundwater inputs from outside the watershed.

The predominant land use is agricultural (including crop fields, treed fields, pasture and agricultural facilities). Urban residential land use is centred in the urbanized areas of Whitby, Oshawa, Bowmanville and Brooklin. Commercial and industrial land use is found mainly along

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CLOCA Tier 1 Water Budget Report January, 2009 and south of the Highway 401 corridor. According to CLOCA (2007), nearly 27% of the land cover is naturally occurring, either as forest, meadow or wetland (which includes marshes, fens, swamps, and open aquatic). Of the 27% natural cover, 11% (nearly 7200 ha) is forest. Another 8% (5600 ha) is wetland and an additional 8% is meadow/successional habitat (as meadow, thicket and savannah). Much of the wetland cover across the Lake Iroquois Shoreline is considered to be Provincially Significant by the Ministry of Natural Resources. Further details on land use can be found in the conceptual water budget report (CLOCA, 2007).

As mentioned, consistent parameter values were assigned to each land-use type across the entire study area. Vegetation type was determined from the land-use data compiled by CLOCA. Cover density and transmission factors were estimated initially from the available literature (e.g., Hardy et al., 2004) and refined during model calibration to improve the match between observed and simulated flows. Final calibrated parameter values for each land-use class are shown in Table 1.

It should be recognized that there are limitations in this approach because it is reasonable to expect that there will be variations in the physical properties in each land parcel even though they are assigned the same land-use classification. For example, an air photo inspection of the large industrial block occupied by the Oshawa GM plant had almost 100% imperviousness while the large industrial block to the west had mostly open area. Similarly, urban residential in CLOCA tended to have much more open land than urban areas in the TRCA watersheds which include the City of Toronto. The relatively low values of imperviousness in Table 1 reflect that roads were handled separately (in many other studies, roads are included when assigning imperviousness values for urban/rural residential and commercial/industrial areas). Open water and wetlands were treated as largely impervious so that recharge to these areas would be limited or zero. Depression storage values were assigned to allow for evaporation losses from the open water.

3.2.5 Data related to Soil Cover/Surficial Geology

Soils properties have a significant influence on hydrological processes as they control the amount of water that can infiltrate and be transmitted to the water table and how much water is lost to evaporation and transpiration by plants (ET). Soil water movement is controlled by two main factors: 1) the ability of the soil to transmit water (hydraulic conductivity), and 2) the gravity and suction forces acting on the soil water. Simulating flow in the unsaturated zone is much more complex than modelling saturated flow below the water table because both unsaturated hydraulic conductivity, K(θ), and suction potential, ψ(θ), vary as a function of moisture content (θ). For example, K(θ) decreases as the soil dries out while the suction potential ψ(θ) increases. Soil compaction and swelling of clay minerals in the soil can also alter the hydraulic conductivity of the soil over time.

Soil classification systems provide generalized information about the nature and properties of a soil in a particular location. For simplification, soil properties were estimated from the surficial geology maps (see Figure 13) which represent more generalized mapping of the parent material of the soils. Consistent parameter values were assigned to each geologic material type. Hydraulic conductivities for the soils were estimated from the calibrated values for the units determined from the YPDT-CAMC ORM study (Kassenaar and Wexler, 2006). Other properties were estimated initially from the available literature (e.g., Todd, 1980; Linsley et al., 1975; Chow, 1964) and refined during model calibration to improve the match between observed and simulated flows. Final calibrated parameter values for each geologic material type are shown in Table 2. Values presented in the table are in metric units while the PRMS code expects inputs Earthfx Inc. 27

CLOCA Tier 1 Water Budget Report January, 2009 in a mix of imperial units. Conversions were applied to the tabled values in the data pre- processors.

3.2.6 Data related to Combinations of Land Use and Soil Cover

Parameter values in Table 1 and Table 2 were assigned to all cells using a parameter lookup table function in the VIEWLOG pre-processor. An example of a land-use based parameter, in this case percent imperviousness, is shown in Figure 14. A special pre-processor was written to handle array-based parameters where values were assigned to specific land-use and soil type combinations such as the SCS curve number.

Table 3 provides a brief description of the hydrologic soil groups assigned to the different soil types as shown in Table 2. Three intermediate classes, AB, BC, and CD, have soil property values somewhere between the four main groups. Additional land use types were created to represent the different land-use classes on hummocky topography. These were assigned lower CN values to yield less runoff. Initial estimates for CN values were adjusted during model calibration. Final CN values are shown in Table 4.

3.2.7 Data related to Climate

Climate varies appreciably across the study area both spatially and temporally with local variation created by such factors as topography, prevailing winds, and proximity to Lake Ontario. Long-term climate data, including daily maximum and minimum temperature, precipitation, and solar radiation, were obtained from Environment Canada for the 20-year period from January 1, 1980 to December 31, 1999. Eight stations have long-term record covering this period. A subset of four stations that had joint precipitation and temperature measurements was selected (Bowmanville-Mostert, Oshawa WPCP, Burketon-McLaughlin and Tyrone). The station in Orono was excluded because of the many breaks in the precipitation record. Because the PRMS model works in “water years”, which begin in October of the previous calendar year, the data sets were pared down to the 19-year period from October 1, 1980 to September 30, 1999.

Prior to processing the daily data, data on climate normals (30-year averages) for the period 1971-2000 were examined to search for obvious patterns. Data were obtained from Environment Canada (http://www.climate.weatheroffice.ec.gc.ca/climate_normals/index_e.html) for stations within or near the study area. A summary of the climate normals is provided in Table 5.

Mean annual precipitation ranged from 858 millimetres per year (mm/yr) at Bowmanville-Mostert to 1001 mm/yr at Leskard. Figure 15 shows the distribution of precipitation over the study area interpolated using inverse-distance squared (IDS) weighting. The data show that annual average precipitation is higher in the northeast part of the study area, although the spatial coverage of data, particularly to the northwest, is limited. The findings are consistent, however, with the observation that Soper and Bowmanville Creek had higher annual average streamflow rates than the other gauged watersheds. While it appears that the data may be correlated with elevation within the study area, analysis of precipitation normals on a larger scale (e.g., Kassenaar and Wexler, 2006) shows that, while the high values are not anomalies, they are localized to this area. The other consistent patterns noted by Kassenaar and Wexler (2006) were the low values in the urban areas of the GTA (possibly due to heat island effects) and the

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CLOCA Tier 1 Water Budget Report January, 2009 higher values south and west of Georgian Bay, Lake Simcoe, and Lake Scugog (possibly due to lake effects). Monthly average precipitation values are shown graphically in Figure 16 for the four stations used in the PRMS model. Lowest values for monthly average precipitation occur in February while high precipitation rates occur in August, September, and November.

Monthly averages of maximum daily temperatures for the period 1971 to 2000 ranged from 10.8 to 12.0 °C while the monthly averages of minimum daily temperatures ranged from 1.9 to 3.6 °C. Mean daily temperature is not shown in the table because it is simply computed as the average of the reported minimum and maximum daily temperatures. The mean daily temperature for January (typically the coldest month) ranged from -8.1 at Burketon McLaughlin to -5.3 °C at Oshawa WPCP, showing the warming effect of Lake Ontario. The mean daily temperature for July (typically the warmest month) ranged from 19.8 to 20.3 °C.

Mean annual potential ET (PET) is calculated for “ecodistricts” across Canada by Agriculture and Agri-food Canada using climate normals and is available at (http://sis2.agr.gc.ca/cansis/nsdb/ecostrat/district/climate.html). Ecodistrict 553 covers most of the study area as well as several Conservation Areas to the north and east. Table 6 presents monthly and annual estimates of PET calculated by the Thornthwaite and Penman methods for Ecodistrict 553. Comparison with average precipitation for Ecodistrict 553 shows that PET exceeds available precipitation from May to August (Penman) or June to August (Thornthwaite method). Actual evapotranspiration in those months will depend on the availability of soil moisture and other factors discussed previously. These estimates were calculated for a very large area and do not take into account local variation in soils, land use, and solar radiation. The numbers did provide a check on the estimates of PET obtained with the PRMS model.

Daily climate data selected for use as input to the PRMS hydrologic model were nearly complete although some infilling of missing data was required. The PRMS code provided methods to infill solar data but these were not needed because the solar data were complete. Data pre-processors developed by Earthfx to infill precipitation and temperature built on procedures developed by Schroeter et al. (2000).

To fill in missing daily precipitation records, a search was done to find up to 12 stations near the one with the missing record. Next, each measured precipitation value at the 12 nearby stations was adjusted by multiplying the measured value for that day by the ratio of the mean monthly precipitation at the nearby station to the mean monthly precipitation at the station with the missing record. Finally, an inverse-distance weighting method was used to determine a weighted average of the adjusted measured values. Where daily precipitation values were missing, but an accumulated amount was provided at the end of a number of days, the method described above was first applied to each of the missing values. The sum of the estimates was determined and then each daily value was scaled such that the sum equaled the reported accumulated value.

If the maximum temperature value was missing for a particular day, it was estimated by adding the difference between the average monthly maximum temperature and the average monthly mean temperature for the station to the reported mean temperature. Similarly, if the minimum temperature value was missing for a particular day, it was estimated by subtracting the difference between the average monthly minimum temperature and the average monthly mean temperature from the reported mean temperature. Where all temperature data for a particular day were missing, a search was done to find the 12 nearest stations to the one with the missing records. Next, the measured mean temperature value at each of the 12 stations was adjusted by subtracting the difference between the mean monthly temperature at the nearby station and the mean monthly temperature at the station with the missing record (as per Schroeter et al., Earthfx Inc. 29

CLOCA Tier 1 Water Budget Report January, 2009

2000). Finally, inverse-distance weighting was used to determine a weighted average of the adjusted measured mean temperature values. Values for the missing maximum and minimum temperatures were then estimated from the infilled mean temperature data using information about the differences between the monthly average temperature values.

3.2.8 Other Parameters

Numerous other parameters must be specified for the PRMS model. These include items such as threshold values (e.g., the temperatures at which precipitation is assumed to be either all snow, all rain, or a rain/snow mix), correction factors (e.g., lapse rates for elevation-based temperature correction) and critical dates (e.g., dates for forcing snowpack melt). Many of the parameter values were estimated directly from known or measurable basin characteristics.

For some parameters without direct measurement (such as monthly temperature adjustment values), these were kept at default values or reasonable values were assumed through the process of model calibration. A sample data set for the PRMS model is shown in Figure 17. Additional descriptions of input parameters can be found in Leavesley et al., (1983).

3.3 Calibration Targets

The primary target for model calibration was to match annual average simulated total flows with observed average annual total flows at long-term surface water flow gauges maintained by Environment Canada in the major CLOCA watersheds. Gauge locations are shown on Figure 18. Total flows, averaged over the period of record for the gauges are presented in Table 7. Simulated monthly average and daily flows were checked against observed values, but because the PRMS model was not used to route flows through the watershed, simulated stormwater flows (as measured by net runoff, interflow, and groundwater recharge) did not have a time lag and tended to arrive earlier and at higher magnitudes than the observed.

Figure 19 shows a graph of mean daily flow averaged over the period of record at each gauge. The mean daily flow is the mean of all average daily flows observed on that date each year. The averaging technique filters out the peaks caused by individual storm events and reveals seasonal patterns in flow rates over the year that the PRMS model had to replicate. The following observations can be made based on the hydrographs:

1. Peak flows occur in Mid-March primarily due to enhanced run-off and groundwater discharge from snowmelt; 2. A steep recession in flow rates occurs from April to May and then a more gradual recession from June to August. The steep recession occurs as runoff from snowmelt and saturated soils decreases. The continued recession is due to the effects of evapotranspiration in the spring and summer; 3. Flow rates begin to increase in September through November due to increased precipitation in August, September and November (see Figure 16) and decreased ET in the fall; 4. Flow rates decline gradually during mid-December to mid-January as precipitation decreases, snow accumulates, and frozen ground conditions restrict infiltration; and 5. Flows increase from February to mid March due to occasional snowmelt and runoff events.

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CLOCA Tier 1 Water Budget Report January, 2009

A secondary target for model calibration was to match annual average simulated baseflow to estimated baseflow at the Environment Canada gauges that had long periods of record. If a particular gauged watershed is truly a closed system (where no significant amounts of groundwater cross catchment boundaries or bypass the gauge) then the amount of groundwater discharge to the stream (baseflow) can be equated directly to the average rate of groundwater recharge over the catchment. Because lateral groundwater flow across some watershed boundaries within the CLOCA area can be significant, the baseflow values could not be used as targets directly, but had to be adjusted based on estimates of net lateral inflow into each gauged watershed.

Numerous techniques are available to estimate baseflow including statistical techniques (e.g., MOE Guidance Module 7 which was used to prepare this report suggests that the median streamflow (QP50) is a good estimate of annual average baseflow) and techniques that analyze each storm hydrograph and separate out the baseflow, runoff, and interflow components. Several automated techniques have been applied to separate daily baseflow from long-term flow records, some more conservative (i.e., assuming no change in groundwater discharge during a storm event) to more aggressive (i.e., assuming that groundwater discharge increases significantly towards the end of the storm event). Conservative estimates can be used to determine a minimum value of baseflow while the more aggressive techniques can be applied to estimate baseflow in streams with a good hydraulic connection to the aquifer and where the groundwater response is known to be rapid. This approach is supported by the Technical Director‟s Rules.

One filter method (Clarifica, 2002) has been applied to several of the TRCA watersheds and was found to produce reasonable results. In the method, a six-day running minimum flow value is obtained from the daily flow data. In a second pass, a five-day running average of the minimum flow values is obtained and compared against the actual flow. The minimum of the actual flow and the running average is assumed to be the baseflow value. The running minimum flow and running average minimum flow are both forward weighted by one day. An example of the results from this method for Lynde Creek streamflow data is provided in Figure 20. The method tends to be biased towards increasing the amount of groundwater contribution to the storm hydrograph compared to other methods that tend to connect the low flow points on the hydrograph (e.g., the smoothed minima method (FREND, 1989) also shown in Figure 20) and may be more appropriate for basins with significant groundwater contribution to streamflow.

The results of comparing the two methods to the CLOCA streams are shown in Table 7. It should be noted that the separation methods cannot, by themselves, distinguish between groundwater discharge and other relatively steady flows, such as discharge from sewage treatment plans, discharge from leaky stormwater sewers that intercept the water table, and discharge from impoundments or large wetlands. The assumption in all these analyses was that groundwater is the primary source of discharge in the CLOCA streams.

Some general observations can be made regarding the characteristics of the streams based on the results of the baseflow separation:

1. Baseflow represents between 40 to 67% of flow in the streams (using the average minimum flow method) and at least 30 to 60% of streamflow using a more conservative separation method. 2. Streams with headwaters on South slope area (i.e., Harmony and Farewell Creeks) had the lowest baseflow values. This is likely due to the lower infiltration potential of the till soils that cover the area. Harmony Creek also has the highest degree of urbanization and impervious cover within the gauge catchment. Earthfx Inc. 31

CLOCA Tier 1 Water Budget Report January, 2009

3. Streams with headwaters on the ORM had higher baseflow values with the exception of Lynde Creek. (Decreased baseflow in Lynde Creek could be related to a west-trending bedrock valley diverting some of the deeper groundwater flow from the northwest back to Duffins Creek and/or that the upper reaches of Duffins Creek are more deeply incised into ORM deposits (while the upper reaches of Lynde are on top of Halton Till) and that is also diverting some of the groundwater flow to Duffins Creek.

Baseflow flow measurements have been taken by CLOCA beginning in 2002. Flows are measured in spring, summer, and fall at stream crossings and stream gauge stations during periods with no antecedent rainfall. Although these measurements are not continuous, they do represent an additional source of information for groundwater and water budget model calibration.

3.4 Three-Dimensional Groundwater Flow Model

3.4.1 Need for a Groundwater model

Hydrologic models, such as PRMS, can provide a good representation of the physical processes in the shallow soil zones but only offer an oversimplified representation of the process of groundwater flow. This limitation can be important in areas where the watersheds gain or lose significant quantities of water across external boundaries or where there are significant cross-watershed flows. By not accounting for these volumes, the calibration of the hydrologic models to the gauged flows will be incorrect. As an example, the Bowmanville gauge records higher rates of flow than other gauges in the study area even when the flow data are normalized to account for the different contributing areas and locally higher annual rainfall. Much of this additional flow is derived from groundwater recharge to the area north and east of the watershed that crosses into the CLOCA area and flows under the Soper Creek watershed. If this additional recharge is not accounted for, then the model can only be calibrated by assuming that the Bowmanville area has lower ET and/or more permeable soils than the other watersheds, which is not supported by the soils and surficial geology data and not believed to be the case.

Coupling a groundwater model to the PRMS serves two purposes. First, it provides a semi- independent check on the simulated rates of recharge. For example, if the PRMS model computes recharge rates that are higher than the groundwater system can “absorb”, the resulting simulated groundwater levels will likely be much higher than observed. Conversely, if the recharge rates are too low, the simulated water levels and gradients will also be too low. Second, the groundwater model provides a semi-independent method of determining baseflow and the cross basin flow contributing to a gauge. The net cross basin flow can be subtracted from the separated baseflow to estimate actual recharge (QR) within the gauged watershed.

The term “semi-independent” is used here to highlight the fact that the simulated water levels depend on the hydraulic conductivities and transmissivities determined in the model calibration process which, in turn, depend on the rates of recharge assumed. Similarly, the volume of simulated cross-basin flow depends on the rates of recharge in the area outside the gauged catchments. This interdependence necessitates an iterative approach to simulating Tier 1 water budgets where the groundwater model parameters and the PRMS model parameters are adjusted until both models produce reasonable results. This type of coupling is termed a “loose” coupling where models are run sequentially and feedback between models is done manually. Tightly coupled models where the two systems are solved simultaneously and, for example, the

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CLOCA Tier 1 Water Budget Report January, 2009 simulated changes in water table elevation affect the local ET, recharge and runoff rates are more appropriate to Tier 2 and Tier 3 levels of analysis.

3.4.2 MODFLOW Model Code

The groundwater flow model for the CLOCA area uses the U.S. Geological Survey MODFLOW code. This code is recognized worldwide and has been extensively tested and verified. The MODFLOW code is extremely well-suited for modelling regional and local-scale flow in multi- layered aquifer systems and can easily account for irregular boundaries, complex stratigraphy, and spatial variations in hydrogeologic properties. The version of MODFLOW used is documented in McDonald and Harbaugh (1988) and Harbaugh and McDonald (1996). Best practices for groundwater modelling and professional judgement were followed when applying and calibrating the numerical models as outlined in the ASTM (2000) standards for groundwater flow modelling.

The U.S. Geological Survey MODPATH code, as documented in Pollock (1989), was used to simulate groundwater flow paths for illustrative purposes. The MODPATH code uses the aquifer potentials determined by MODFLOW along with estimates of aquifer porosity to determine groundwater velocities. Particle tracks are drawn by following the paths of virtual particles released from the discharge points (such as a well or stream reach) and tracked backwards through the aquifer back to the point of recharge. Particles can also be tracked forward from known points of recharge to determine their discharge points.

A post-processing program, Zone Budget (Harbaugh, 1990), was used to calculate groundwater budgets based on model results: The program determines simulated lateral groundwater inflows and outflows across watershed boundaries as well as simulated groundwater discharge to streams. These lateral inflow and outflow values were used to adjust the calibration of the PRMS model and determine the QIN component of “water supply” used in the watershed stress analyses. Simulated groundwater discharge from the MODFLOW model was compared against simulated PRMS values as well as separated baseflows.

3.4.3 Groundwater Flow Model Development

The study used a numerical model, referred to as the “East Model”, for simulating groundwater levels and calculating groundwater discharge to streams in the CLOCA area. The extent of the East Model is shown in Figure 21. The numerical model, in turn, was based on a conceptual flow model that integrated data on the physical, geologic, and hydrogeologic features that govern groundwater flow (see Appendix A for more information). The conceptual flow model was originally developed for an area encompassing York Region, the City of Toronto, and parts of Durham and Peel Regions as part of the YPDT-CAMC study of the Oak Ridges Moraine area described in Kassenaar and Wexler (2006). The conceptual flow model was expanded eastward as part of an ongoing YPDT-CAMC effort to increase the understanding of the hydrogeology of the Oak Ridges Moraine. A description of the numerical model developed for the central part of the Oak Ridges Moraine, referred to as the “Core Model”, is provided in Kassenaar and Wexler (2006). Expansion of the Core Model to cover Durham Region and the CLOCA watersheds is the subject of a separate YPDT-CAMC report (in preparation). A relatively brief summary of model developed is provided in this report as a benefit to the reader.

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CLOCA Tier 1 Water Budget Report January, 2009

The East Model area is bounded to the south by Lake Ontario and to the west by the western extent of the Humber and Holland River watersheds. The model is bounded to the north by Lake Simcoe and to the east and northeast by segments of the Lake Scugog and the Ganaraska and Kawartha watershed boundaries (Figure 21). A sub-set of the East Model, which excluded the western half of the model area (west of the Duffins Creek watershed) and focussed on the CLOCA watersheds, was used in these simulations (Figure 21).

Constant head; no-flow, and head-dependent discharge boundaries were used to represent natural hydrologic boundaries in the East Model. Lake Ontario, Lake Simcoe, and Lake Scugog were all represented as constant-head boundaries with the water level set to average lake stage. No-flow boundary conditions were applied at the eastern and western watershed boundaries (located beyond the CLOCA area) and along the base of the lowest model layer to represent the unweathered bedrock. Groundwater discharge to streams was simulated using head-dependent discharge boundaries. Groundwater extraction for municipal water supply and other large users was represented. Simulated pumping rates were assigned based on the maximum rates listed in their permits to take water (PTTW), registered with the Ontario Ministry of the Environment.

3.4.4 MODFLOW Model Parameters

Hydraulic properties of the overburden aquifers and confining units are extremely variable. Methods were developed to represent spatial variations in aquifer hydraulic conductivity, because these variations influence the lateral movement of groundwater. Estimates of the distribution of aquifer properties in the original part of the model (i.e., the Core Model area) were determined primarily through an analysis of aquifer test data and through interpolation of hydraulic conductivities estimated from the lithologic log descriptions. These estimates were refined in the process of Core Model calibration as described in Kassenaar and Wexler (2006). The spatial distribution of hydraulic properties in the extended model area was determined primarily using the lithologic data analysis method.

The rate of groundwater recharge varies over the study area. Recharge rates for areas outside the CLOCA area were obtained from previous modelling studies and ranged from 30 to 420 mm/year as shown in Table 8 (see Kassenaar and Wexler, 2006 for more discussions). Estimates for recharge in the CLOCA watersheds were initially obtained from the values in Table 8 and then updated in an iterative manner using the PRMS model results as described above.

3.4.5 Groundwater Flow Model Calibration

Calibration of the East Model was a trial-and-error process in which results of successive model runs were used to refine the initial estimates of hydraulic conductivity, vertical anisotropy, and recharge rates. Statistical tests were applied to determine whether the calibration met the required goodness-of-fit criterion. Further adjustments were made to the interpretation of local hydrostratigraphy and model parameters within the study area to improve the match between observed and simulated flow patterns.

The primary target for model calibration was matching observed static water levels obtained from the MOE Water Well Information System (WWIS) database (which have been incorporated as part of the groundwater level data in the YDPT-CAMC database). As discussed in

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Kassenaar and Wexler (2006), there is a systematic error in the static water level data and trying to match heads at each well to a greater accuracy than the mean error is not justified. The focus instead was on matching interpolated heads and flow directions. Potentiometric surface and water-table maps for each aquifer (see Appendix A or CLOCA (2007) for discussions of the various aquifers/aquitards in the study area) were prepared using static water levels in water wells from the MOE WWIS database supplemented with other well data from geotechnical investigations and exploratory drilling. The WWIS water level data for the Oak Ridges aquifer complex (ORAC) were found to have a standard error of ±4.5 m while the Thorncliffe aquifer complex (TAC) water levels had a standard error of about ±7 m. Data on stream baseflow were compiled and analyzed to determine rates of groundwater discharge to streams as described earlier. Matching these baseflow rates (both inside and outside the CLOCA area) was a second calibration target for the groundwater model.

Estimates of annual recharge averaged over the 19-year simulation period (Figure 33) were merged with the recharge estimates for the areas outside CLOCA and used as input to the MODFLOW model. Simulated groundwater levels and baseflow values were then compared to observed data. Estimates of net lateral inflow from each gauged catchment were used to adjust the calibration target for net infiltration and baseflow in the PRMS model. The process was repeated until general agreement between the PRMS and MODFLOW results was achieved.

3.5 PRMS/MODFLOW Integrated Results

Calibration started with a focus on the contributing area to the gauge on Lynde Creek at Whitby (HYDAT gauge 02HC018). Once a reasonable calibration was obtained to observed flow at the Lynde Creek gauge, the PRMS model results were verified by applying the same parameters to the contributing areas for the rest of the gauges in study area. Multiple runs were made with additional refinement of model parameters to get the best overall calibration to all gauges and to determine model sensitivity to parameter changes. For example, results showed the PRMS model results to be very sensitive to factors such as percent imperviousness and thickness of the recharge zone. Once the model was calibrated for the contributing areas, the model was run for the entire study area by using the same model parameters for cells in the ungauged portions of the watersheds.

3.5.1 PRMS Results

Water-budget items were calculated on a daily basis for each cell-based HRU. These values were only output only for select observation points on a daily basis, due to the large size of the output files that would be generated. Daily values were summed on a monthly and annual basis and then output to disk. Annual and monthly values were averaged to determine annual average (for the simulation period) and monthly average flows. A list of model outputs is provided in Table 9. The list includes the standard outputs from PRMS plus some additional outputs that were added by Earthfx to obtain additional information (e.g., separate runoff values for impervious and pervious surfaces).

The following water balance equation was used as a check on the mass balance for any given model cell (see Table 9 for term descriptions):

Mass Balance Error = POBS – (INT+AET + RONET+USS+UGS)

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It should be noted that AET (Actual ET) in the PRMS model includes losses from depression storage (EVDP) and sublimation but not interception losses (INT). Annual average values would not be expected to sum up perfectly but excellent mass balance was obtained at the selected observation points and general mass balance was achieved when summing annual average fluxes.

Daily discharges (total flow, runoff, interflow and baseflow) were also generated on a daily basis. Figure 22 shows a scatterplot of observed versus simulated total flows for the gauged catchments. Ideally, all points should fall on the 45° line. Errors in the observed data and uncertainty related to model parameters prevent a perfect match. Figure 23 shows a scatterplot of estimated baseflow (using the running average minimum flow baseflow separation method) versus simulated baseflow for the gauged catchments. Uncertainty related to the baseflow separation techniques and uncertainty related to model parameters prevented a perfect match. The points fall both above and below the 45° line but model results are shown to be a little biased towards under-predicting flows. The largest difference occurs at the Bowmanville gauge. The difference is reduced after correcting the PRMS flows by adding in the net lateral groundwater inflow as simulated with the East Model.

Figure 24 presents a map of average annual precipitation (POBS) for the 19-year simulation period. This figure and the following ones show results in mm/yr of equivalent rainfall per unit area. Different scales had to be used in each figure to highlight the spatial variation in the results. The variation in POBS across the study area is due to the interpolation of the observed daily precipitation values to each model cell using the IDS weighting technique. In this way, the model has replicated the spatial variation shown in Figure 15, although the observation periods are different.

Net precipitation after interception losses have been subtracted is shown in Figure 25 (interception losses are a function of vegetation type, percent pervious area, winter/summer cover density, winter/summer rain interception storage, winter snow interception storage and all the other factors that affect the rate of evaporation from interception storage). The PRMS model does not include depression storage losses in its definition of “net precipitation”. A map showing adjusted net precipitation after accounting for depression storage losses from impervious areas is shown in Figure 26. As can be seen, forested areas (including forested wetlands) tend to get less net precipitation than the agricultural areas and much less than the urban areas. Pine forests get less net precipitation than oak forests on an annual basis even though the oak leaves intercept more rainfall than pine leaves in the summer. Net precipitation is very high in urban areas (due to low cover density) as shown in Figure 25. Adjusted net precipitation values after subtracting losses to depression storage are lower as shown in Figure 26. Adjusted net precipitation is then apportioned between ET, runoff and infiltration.

Figure 27 shows a map of annual average potential ET (PET). The map shows the influence of slope and aspect (e.g., the lower PET on the south side of the valley near Enniskillen and the higher values on the north side) and the lack of vegetative cover in the urban areas. Figure 28 shows a map of annual average actual ET which includes losses from depression storage on impervious areas. This map reflects a combination of factors including the factors that affect PET distribution, land use factors that control vegetation type and cover density, and soil factors controlling the ability to store and transmit water, and climate factors that control the availability of water. Initial examination of the map may raise concerns as to why AET is higher in the urban areas on Halton Till, for example, compared to crop fields on Halton Till. It should be recognized that because of the hierarchical representation of ET, AET losses from the soil occur only after evaporation from interception or depression storage. Interception is lower in the urban areas and EVDP is already included in AET). To clarify matters, a summation of all Earthfx Inc. 36

CLOCA Tier 1 Water Budget Report January, 2009 evaporation and transpiration losses (AET (which includes EVDP) +INT) is provided in Figure 29 and shows that total evapotranspiration follows the expected pattern with high rates in the wetland areas, in forested areas on Iroquois Beach deposits, and on crop fields and urban greenspace. Lower rates occur on the Oak Ridges Moraine with its well-drained soils and on urban areas with little vegetative cover. Average rates over the area are comparable with the regional estimates shown in Table 6 even through the methods used to derive the estimates are very different.

Figure 30 presents annual average runoff for the area. As expected, RO is high in the urbanized areas, especially along roads and in the areas designated as commercial and industrial. Runoff rates are low over the ORM and over the exposed Lower Sediment sands in the Enniskillen area. Moderate to high rates of runoff occur on the South Slope and Iroquois Plain areas due to the predominantly till soils. Runoff for the Iroquois Beach deposits is higher than for the ORM because of the shallow water table and underlying tills.

Figure 31 presents the simulated annual average direct recharge to the water-table. As explained earlier, this is generally equal to the water in excess of field capacity after ET. However, the PRMS code assumes that for soils of low permeability, water in excess of the daily infiltration capacity will be held in unsaturated zone storage (USS) for a period of time. Figure 32 presents the simulated annual average recharge to the unsaturated zone. Areas of significant USS are restricted primarily to exposures of weathered/fractured Newmarket Till which may have moderate infiltration rates but cannot rapidly transmit the water to the underlying aquifer. Some discharge may occur as interflow to the numerous streams whose headwaters are located on the till plain but most of the water held in the unsaturated soil zone was assumed to eventually recharge the groundwater system. Figure 33 shows net recharge to groundwater (QR) as the sum of UGS and USS over the study area. As with AET, the distribution of QR is a composite of all the soil-based, land-used based and climate-based factors that are represented in the PRMS model. Values for UGS (Figure 31) varied over a wide range from near-zero in parts of the areas underlain by Newmarket Till to over 430 mm/yr where the hummocky ORM deposits are exposed. Net groundwater recharge (Figure 33) ranges from about 70 mm/yr to over 430 mm/yr, assuming that all USS eventually ends up as groundwater recharge. The rates are generally consistent with those estimated in the East Model calibration (see Table 8) The PRMS estimates of annual recharge merged with the recharge estimates for the areas outside CLOCA is shown in Figure 36. These values were used as input to the East Model.

The province suggests that for the Tier 1 stress analyses, average monthly recharge values should be determined by dividing the annual average QR into 12 equal monthly values. Results of the PRMS simulations are still of interest and showed that average monthly recharge rates varied over a considerable range. Figure 34 shows simulated average monthly groundwater recharge (UGS+USS) for November, a high recharge month, while Figure 35 shows simulated monthly groundwater recharge (UGS+USS) for July, a low recharge month. Much of the area experiences little or no recharge during June through August, on average. Results of the 19- year simulation period showed that departures from the average monthly values were common with many occurrences of wet summers and dry falls.

3.5.2 East Model Results

A map showing the simulated heads in model Layer 3, which represents the Oak Ridges Aquifer Complex (ORAC) where present, is presented in Figure 37. The map shows two separate areas of higher groundwater levels underlying the east-west axis of the ORM: one to the west of Lynde Creek and one east of Soper Creek. The large groundwater mounds develop beneath Earthfx Inc. 37

CLOCA Tier 1 Water Budget Report January, 2009 the sediment wedges forming the ORM due to the sandy nature of the soil and the hummocky topography. Radial flow from these mounds provides lateral groundwater inflow to the Lynde, Bowmanville and Soper Creek watersheds. Observed water levels for wells screened within the ORAC (mostly static water levels from the MOE WWIS database) are posted on Figure 37 (the colour shading within the circles representing the observed heads in the wells using the same colour scale as for the simulated water levels). Very close agreement can be seen within the CLOCA area especially given the inherent variability in the data. Differences occur mostly outside (north) of the CLOCA boundary, indicating that the uniform rates of recharge assigned in the east model are likely too high and that the spatial distribution of recharge determined by PRMS may be more accurate. A scatterplot of simulated heads versus the observed water levels in the CLOCA area and a summary of local calibration statistics are provided in Figure 38. The results show that the model has a tendency to overpredict heads in the CLOCA area by about 4.7 m on average.

Simulated heads in the Thorncliffe Aquifer Complex, shown in Figure 39, are a subdued replica of the water levels in the ORAC and gradients tend to be downward over the northern part of the study area. Upward gradients occur in the southern part of the study area and in the vicinity of the stream valleys. Simulated heads tend to match fairly well with the observed although the observed TAC water levels show much greater local variability than the ORAC water levels. Flow directions and gradients in the ORAC and TAC matched well with the observed data over the study area.

Groundwater levels are strongly influenced by the surface water system and bending of contours around the streams indicates groundwater discharge to streams. A map of simulated groundwater discharge to streams, shown in terms of litres per second (L/s) per 100-metre cell, is presented in Figure 40. Figure 23 shows a scatterplot of estimated baseflow (using the running average minimum flow baseflow separation method) versus simulated groundwater discharge to streams. Ideally, all points should fall on the 45° line. Errors in the observed data, uncertainty related to the baseflow separation technique, and uncertainty related to groundwater model parameters prevent a perfect match. As with the PRMS model results, the points fall both above and below the line but tend to show a model bias towards under-predicting baseflow. The simulated groundwater discharge values were used in determining “significant” recharge areas, as described further on in this section.

3.6 Surface Water Supply

There are currently three municipal water intakes servicing CLOCA residents in the Town of Whitby and Brooklin, the City of Oshawa, and the urban area of Bowmanville. The intakes are located in Lake Ontario. Other surface water users (for agricultural and golf course irrigation) extract water directly from streams. To provide information needed to better manage and protect the surface-water supply, a Tier 1 analysis for the CLOCA watersheds was conducted as outlined in the Directors Rules. The provincial instruments indicates that estimating the surface-water supply should take into consideration seasonal variability and should therefore be evaluated using an estimate of expected monthly values. A list of methods for estimating flow was provided in order of preference. Two methods were used here.

The first method was a statistical analysis of gauged data (i.e., streamflow measurements) from long-term HYDAT stations maintained by Environment Canada in the major watersheds. Figure 41 shows a ranked flow curve for the observed flows at the Lynde Creek gauge to illustrate the statistics (i.e., mean annual flow, median flow, and 10th decile flows) used in these analyses.

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CLOCA Tier 1 Water Budget Report January, 2009

Median monthly streamflow values (QP50) were calculated for each month and the monthly values were averaged over the period of record. Data for the gauges are presented in Table 10. Median flows for the period of record (POR) for each gauge are shown as equivalent rainfall in mm/yr over the gauged catchments in Figure 42.

In the second method, the calibrated surface water model was configured to output daily streamflow at the outlet of each subwatershed. In this way, the entire CLOCA area was represented rather than just the contributing areas to the gauges. Monthly water-supply values were calculated as the median monthly streamflow (QP50) for each month averaged over the 19- year simulation period. Simulated median monthly flows are presented in Table 11. These values were used in subsequent watershed stress analyses.

Provincial instruments indicate that the future demand scenarios should utilize the same climate conditions as the current conditions stress analysis. Accordingly, it is assumed that the water source supply number will remain the same for both the current and future scenarios.

3.7 Groundwater Supply

There are currently no municipal wells in the CLOCA watershed. However, some communities, such as Macedonian Village and Mitchell‟s Corners (see Figure 1) are currently serviced by shallow private wells. To provide information needed to better manage and protect the groundwater supply, a Tier 1 analysis for the CLOCA watersheds was conducted as outlined in Guidance Module 7. The guidance module indicates that the amount of water available to supply groundwater users within a subwatershed should be estimated as the sum of groundwater recharge (QR) and lateral groundwater flow into the subwatershed (QIN). For the Tier 1 analysis of groundwater supply, aquifer storage was not considered and the water supply terms for each subwatershed were assumed to be constant on an average annual basis. Field observations and PRMS model results indicated that groundwater recharge is highly variable on a daily, monthly, seasonal, and annual basis. To filter out these variations, the PRMS model results were averaged over the 19-year simulation period to produce average annual and average monthly estimates of groundwater recharge and groundwater inflow. The groundwater flow model results were based on the assumption of steady-state flow and therefore implicitly assume no change in storage on a long-term basis.

Table 3 of Guidance Module 7 listed several methods for estimating groundwater recharge (QR) including:

1. Baseflow separation/water balance 2. Calibrated continuous surface water model or a calibrated groundwater model 3. Calibrated soil moisture balance methods 4. Experience

As discussed in previous sections, our analyses incorporated all of these methods. For the Tier 1 analyses, the recharge rates calculated were applied to both current and future conditions. Monthly rates of QR, as determined by the PRMS model are presented in Table 12 and shown graphically by catchment in Figure 43. These rates were not used in the stress analysis because provincial direction requires that the monthly recharge should simply be estimated as 1/12th of the annual average recharge.

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CLOCA Tier 1 Water Budget Report January, 2009

According to the province, QIN is the sum of all positive inflows into the catchment. Table 13 presents the annual average lateral groundwater flow rates from the steady-state groundwater model. Lateral inflow, (QIN), is shown graphically in Figure 44, and the figure indicates that Bowmanville watershed receives the greatest lateral inflow of all the CLOCA watersheds. Figure 45 shows lateral outflow by catchment for information purposes. Discharge of groundwater directly to Lake Ontario is included as part of QOUT. Discharge to the lake was a small part of QOUT for the major catchments but is significant for the Lake Catchments.

Model results indicated that the Bowmanville watershed received the highest lateral inflow (over0.3 m3/s) and had the highest net lateral inflow (0.19 m3/s). Lynde, Soper, and Oshawa Creek watersheds all received similar lateral inflows (around 0.2 m3/s), but of these, only Oshawa had a significant net lateral inflow (0.05 m3/s). Surprisingly, many of the small watersheds had net lateral outflows rather than inflows.

Finally, the Tier 1 Water Supply term (QSUPPLY), is shown graphically in Figure 46. This represents the total of the average annual ground water recharge (QR) from Table 12 and lateral inflow QIN from Table 13. As expected, the watersheds that include portions of the Oak Ridges Moraine exhibit the largest QSUPPLY. The Bowmanville watershed is somewhat unique, exhibiting the largest QSUPPLY, because of a large lateral groundwater inflow component. The QSUPPLY term is a primary component of the stress assessment, discussed in the Section 6.

3.8 Significant Recharge Areas

As part of the Water Supply Estimation, significant recharge areas were to be delineated for each watershed. The first step in this task is to delineate those areas that provide the highest volume of recharge per unit area of the watershed (Table 14). These areas are identified as “Significant Groundwater Recharge Areas” (SGRA). Rule V of the Directors Rules provides the following options for the delineation of SGRA:

44. Subject to Rule 45, an area is a significant groundwater recharge area if: (1) The area annually recharges water to the underlying aquifer at a rate that is greater than the rate of recharge across the whole of the related groundwater recharge area by a factor of 1.15 or more; or

(2) The area annually recharges a volume of water to the underlying aquifer that is 55% or more of the volume determined by subtracting the annual evaporation for the whole of the related groundwater recharge area from the annual precipitation for the whole of the related groundwater recharge area.

45. Despite rule 44, an area shall not be delineated as a significant groundwater recharge area unless the area has a hydrological connection to a surface water body or aquifer that is the source of a drinking water for a drinking water system.

46. The areas described in rule 44 shall be delineated using the models developed for the purposes of Part III of these rules and with consideration of the topography, surficial geology, and how land cover affects groundwater and surface water.

The PRMS model results were used to determine the location of the significant groundwater recharge areas (SGRAs). The PRMS model provided estimates of precipitation, interception, evaporation, potential and actual evapotranspiration, snowmelt, runoff, infiltration, interflow, and

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CLOCA Tier 1 Water Budget Report January, 2009 groundwater recharge. All physical properties, including land-use classes, were represented on a 25-metre cell grid covering the study area. To better represent the linkage, a model, based on the U.S. Geological Survey‟s MODFLOW was used. This groundwater model was developed as part of the Oak Ridges Moraine groundwater model. The model estimated groundwater items such as the exchange of water between shallow and deeper aquifers, lateral inflows and outflows from the catchments, and groundwater discharge to streams. The groundwater model was also used (reverse particle tracking) to confirm significant groundwater recharge areas (SGRA). The groundwater model was calibrated based on measured groundwater potentials and estimated baseflows.

An important finding was that preliminary SGRAs (High Volume Recharge Areas) outside of the CLOCA watersheds contribute to streamflow within the study area. This lateral groundwater flow below surface watershed boundaries is an important component of the flow system. Particularly notable is that groundwater recharge northeast of CLOCA flows in deep aquifers under Soper Creek before discharging to surface in Bowmanville Creek.

CLOCA has conducted single point stream temperature measurements to identify cold water fisheries. Generally CLOCA watersheds are classified as cold to cool water systems with a few warm water streams (CLOCA, 2007). CLOCA (2007) further identified the occurrence of brook trout (Salvelinus fontinalis), a species primarily confined to coldwater fish habitat. Brook trout were found in coldwater streams originating from the Oak Ridges Moraine and in the Black Creek watershed in the vicinity of the Iroquois Beach deposits (Figure 47).

An aerial thermography survey was flown over the ORM in February 1994 by the MNR. Data were interpreted to identify areas of open water which would indicate high volumes of groundwater seepage (Dyke et al., 1997). A portion of the map, covering the northern part of the CLOCA area, is shown in Figure 47. These locations, which also correlate well with the brook trout occurrences, were selected as starting points for backward particle tracking with the USGS MODPATH code. Particle tracks indicate that the source of the water is likely from the SGRA on the ORM. The coverage of the aerial thermography data is limited and CLOCA (2007) noted that, aside from this information, the location of springs and seepage areas are not generally well mapped within the study area.

Another confirmatory analysis was undertaken by selecting locations of high groundwater discharge to streams as determined by the numerical groundwater model and identifying where this area where the recharge was occurring. This backward tracking was conducted from all cells that had a discharge greater than 1 litre per second per 100 metre grid cell (Figure 48 and Figure 49). The areas identified as high recharge corresponded well with the SGRAs identified in the northern parts of the source protection area.

CLOCA performed three options for delineation of the whole of the related groundwater recharge area. The Threshold Criteria for annual recharge (in millimetre per year) were calculated as follows:

Scenario 1 - Threshold Criteria calculated for individual major watersheds that drain to Lake Ontario ranged from 114 to 246 mm/yr. The SGRA areas (Figure 50) generally coincide with the Oak Ridges Moraine deposits, exposed sands, and Iroquois Beach deposits, although not always. For example, in the Bowmanville Creek watershed the Iroquois Beach deposits do not show as SGRAs although it is known that there is important recharge occurring in these deposits and a number of private drinking water wells that depend upon this recharge. A large proportion of the headwaters of

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Bowmanville Creek are in the Oak Ridges Moraine and therefore the Threshold Criteria for this watershed is dominated by the recharge rate there, which masks the importance of local recharge occurring in the Lake Iroquois deposits.

Scenario 2 – Threshold Criteria calculated for three physiographic regions running horizontally through CLOCA as shown in Figure 51. The Threshold Criteria range from 149 to 390 mm/yr. With this approach several key recharge areas in the Oak Ridges Moraine do not show up as SGRAs. These are important known recharge areas for the aquifers that supply private wells as well as providing baseflow for watersheds south of the moraine. In contrast using this approach, there are SGRAs identified in the middle zones that are not significant to drinking water supplies and baseflow to the watersheds.

Scenario 3 - Threshold Criteria of 182 mm/yr calculated for the whole of the CLOCA (Figure 52). The SGRAs delineated with this approach are consistent with the surficial geology, soils data, as well as other analyses and information (reverse particle tracking, flow path analysis, historical reporting and model results). The Oak Ridges Moraine consistently shows up as well as key outwash deposits in the north east. Additionally, several particle tracks from points of discharge in some of the small watersheds in the eastern part of the study area originate on the Iroquois Beach deposits where many private drinking water systems are located. This underlines the need to preserve recharge on the beach. Though all approaches highlight portions of the Oak Ridges Moraine, other approaches as described above produce inconsistent results for these beach deposits.

As mentioned, to confirm that the SGRAs are associated with significant groundwater discharge areas in CLOCA, the following additional analyses were performed:

- key groundwater-dependent hydrological functions (e.g., key groundwater springs or areas of upwelling (coincident with cold water fisheries) that must be preserved were identified; - particle tracking analyses of these features/processes were conducted by placing virtual particles beneath the springs/upwelling; - the virtual particles were tracked as they travelled backwards to their point of entry to at the water table;

The Threshold Criteria used to calculate the SGRA for the whole source protection area (Figure 53) was decided upon for the following reasons:

1. The jurisdictional threshold appears to capture all the areas historically documented as important for recharge; 2. It correlates well with the provincial surficial geology maps and reverse particle track analyses conducted for the study area; and 3. It identifies the beach deposits in the east part of the source protection area that are connected with local private drinking water supplies and which provides the important and large amount of recharge to the small eastern watersheds (Tooley, Darlington, Westside).

Further, to comply with Rule 45, areas where there are no groundwater supplies, e.g. municipally serviced by Lake Ontario-based supplies, were “clipped” to remove them. The preliminary significant groundwater recharge areas located in the municipally serviced areas covering Whitby, Oshawa and Bowmanville were resultantly removed in the CLOCA study area Earthfx Inc. 42

CLOCA Tier 1 Water Budget Report January, 2009

.SGRAs located in the Brooklin serviced area were not removed as there are private drinking water systems located down-gradient of the SGRAs in the area that may be dependent. The clipped map was then labelled SGRA as the finalized map under the CWA.

Figure 53: Significant Groundwater Recharge Area (as defined under the Clean Water act, 2006)

Explanatory Note:

This report has been prepared to meet provincial requirements under the Clean Water Act, 2006 and should not be used for other purposes without consultation with the responsible conservation authority. The water budget process follows a tiered process to screen the areas to identify where there is potential water quantity stress. These potentially stressed areas that are associated with mandated drinking water supplies are then studied in more detail. The process is designed so that each successive tier in the analysis (up to and including Tier 3), becomes more complex, requiring increased sophisticated analysis and data. As a result, with each successive tier the certainty in the findings of the analysis is increased.

The analysis used to produce this report was based on best information available at the time. Priority should be given to site specific information collected in accordance with accepted scientific protocols when being used for other decision-making purposes, such as determining the impact of a specific water taking.

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CLOCA Tier 1 Water Budget Report January, 2009

4 Water Demand Estimation

4.1 Overview

The water demand component of the water budget refers to water taken as a result of an anthropogenic activity (e.g., municipal drinking water takings, private water well takings, as well as other permitted takers). The water demand can be estimated from a number of information sources, including the permit database, population estimates and water well record classifications. The demand estimates were tabulated for each watershed and then adjusted for „consumptive‟ demand and seasonal (monthly) extraction rates.

The most important source of consumptive demand information was the MOE Permit To Take Water (PTTW) database. CLOCA is presently in the process of updating this database and attempting to estimate actual extraction rates, which are likely less than the maximum permitted rates. Verifying and estimating actual consumption is difficult, but recent legislation (387/04) now requires that actual extraction rates be recorded and over time the actual demand estimates will improve. In addition to the MOE listed permits, three other classes of water users were identified by CLOCA. These included 11 “expired or possible permits”, and 10 golf courses with no known permit. Finally, 10 permits are tracked by CLOCA because they are either just outside the CLOCA boundary or at an unknown location (These are assigned to watershed 0 and not included in the water budget calculations). A summary of the most recent PTTW information is presented in Table 33 (in Appendix B). A more detailed permit table is included as a digital addendum and includes the monthly allocation factors and consumptive use correction factors for each permit. Best available location data for the surface water permits are shown in Figure 54. Best available locations for the groundwater permits are shown in Figure 55. Estimates of water use from these additional classes of water users were included.

There are no groundwater-based municipal water systems presently operating in the CLOCA SWP study area. The absence of municipal groundwater supplies reduces the analysis scope and requirements of the SWP water budget analysis required under the current Source Water Protection program. A number of communal systems are, however, present in the study area. The distinction between a municipal and a communal system is not based on population served or volume of water pumped. Some municipal water supply systems in other jurisdictions are actually smaller, in terms of volume pumped, than the communal systems in the CLOCA study area. No special handling of the communal systems was performed in this estimate, as communal system consumption is included in the population-based analysis of demand.

Monthly corrections for the consumptive demand were estimated from the database. Many of the permits are already limited in time, as only 36 of the 63 permits in the study area allow pumping on all 365 days of the year. The time-limited permits were allocated to months based on individual analysis of the permit. For example, the 36 golf course permits were allocated to the spring and summer months, while the 16 snowmaking permits were logically allocated to the winter months. Overall permitted water demand in the CLOCA watersheds is about 1.3 times higher in the spring and summer than in the fall and winter months.

To determine consumptive demand, the study team reviewed the permitted uses within the Permit to Take Water (PTTW) database. The consumption factor is defined as follows:

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CLOCA Tier 1 Water Budget Report January, 2009

Pumped QQ Re turned Consumptio Factorn QPumped

The selected consumptive demand factors for each permit were based on the guidance documentation.

Demand from other non-permitted water use sectors was estimated. Three types of non- permitted use were estimated, including estimates of unserviced population consumption, agricultural irrigation and agricultural livestock consumption.

For future scenarios, the consumptive demand was adjusted by increasing unserviced- population demand, taking into account population growth estimates for Durham Region. As noted in the guidance document, Tier 1 analysis should assume that the other permitted demands will remain constant with time with no change in the QSUPPLY except where significant land-use changes are anticipated.

4.2 Sources of Demand Estimation Data

A number of sources of information were used to estimate the demand. The following sections describe the information sources and the methodologies use to improve and process the data.

4.2.1 PTTW Database

The primary source of information for estimating demand is the Permit to Take Water (PTTW) database. A total of 58 checked permits were provided by CLOCA for use in this study. Of those, 10 permits are tracked by CLOCA because they are either just outside the CLOCA boundary or at an unknown location (These were assigned to watershed 0 and not included in the water budget calculations). Estimates of actual water use were not available, so the maximum permitted rate was used for the analysis.

In addition to the 58 MOE listed permits, two other classes of water users were identified by CLOCA. These included 11 “expired or possible permits”, and 10 golf courses with no known permit. CLOCA provided estimates of the extraction rates for the 11 expired or possible permits, and these were used unmodified. A total of 10 golf courses without known permits were identified by CLOCA. These were georeferenced and an estimate of 250,000 l/d, extracted from a groundwater source, was estimated as the consumption. Other golf courses in the study area have permits as high as 1.5 million l/d, so this estimated rate is considered reasonable.

4.2.2 Unserviced Population Consumption Estimate

The number of persons consuming groundwater water in each watershed is referred to as the “unserviced” population. CLOCA provided estimates of the unserviced population based on property fabric data and municipal service boundaries provided by Durham Region.

Non-serviced domestic water use was calculated by combining population density estimates with typical per-capita water use rates. Demand was estimated using the recommended rate of

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CLOCA Tier 1 Water Budget Report January, 2009

335 L/d/person (Environment Canada, Water Use Website). This was corrected for actual consumption because a significant portion of this water would be returned to the groundwater system through the septic field.

The unserviced population was adjusted for the future scenario based on a growth rate of 55% over a 25-year period. (Multiple projections are available, for example, the projected growth in Durham Region for 2004 to 2031 (25 yrs) is 52.58% according to Statistics Canada. See: http://www.greatertoronto.org/investing_demo_03.htm.) Note: no other demand estimates were adjusted for population growth.

4.2.3 Non-Permitted Agricultural Demand

Crop irrigation is not considered to be a significant water use within the study area, as only 5 wells in the permit database have a specific purpose of “irrigation”. An additional 32 wells in the Well Record database list “irrigation” as the primary purpose of the well.

Livestock consumption (and related water use such as barn cleaning, livestock cooling, etc.) is potentially more significant in the CLOCA watersheds. In total, there were 380 wells with a primary MOE usage code of Livestock. Livestock water consumption varies by type of animal, animal age, status (milking, etc.), number of animals, and related water use such as animal and barn washing requirements. Some general guidelines for estimating livestock demand were found at the BC Ministry of Agriculture website (http://www.agf.gov.bc.ca- /resmgmt/publist/500Series/590301-1.pdf) and the OMAFRA website (http://www.- omafra.gov.on.ca/english/engineer/facts/07-023.htm).

Attempts were made to estimate the farm/well status (confirm actual active livestock operation) and number of animals that might be dependant on a particular well. A number of these wells were confirmed as active livestock operations by cross checking the well location with other available database attribute information and GIS products. Many active operations were confirmed, even in the southern, generally more urbanized, areas of the CLOCA watersheds.

Despite these efforts to estimate the various factors that influence livestock water demand, a fully quantitative estimate for each of the farm operations could not be made because there were simply too many unknowns associated with each operation. Water demand for livestock consumption and irrigation was therefore estimated by multiplying the number of wells (with that specific usage code) by an assumed rate of consumption of 50,000 l/day. This consumption rate was selected because it is the threshold rate above which the MOE has historically required permit monitoring.

Total agricultural water demand was reduced by 50% to account for water returned to the watershed (actual consumption). This is simply an estimated value, as specific farm operations and different livestock types likely have significantly different consumptive values. Our research suggests there is considerable controversy about actual water use, particularly as it relates to manure production at hog operations. These estimates were based on best available information.

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Based on these assumptions, livestock consumptive demand, as calculated above, is approximately 10 times greater than unserviced human consumption (as determined in Section 4.2.2) in the CLOCA study area.

4.3 Water Demand Corrections

A number of corrections and adjustment factors were applied to the permitted and non- permitted consumptive demand estimates, as appropriate for a Tier 1 analysis.

4.3.1 Permit Confirmation and Actual Use Estimate

As noted, CLOCA is currently working to confirm permit status and actual water use for the permits with the PTTW database. As this update work is incomplete, the maximum permitted rate was used for the analysis. Part III of the Director‟s Rules supports the use of maximum permitted rates at the Tier 1 level of analysis.

4.3.2 Consumption Factor Correction

Consumption factors were applied to the PTTW permits based on the default values provided in Table 16 of the Water Budget Guidance Module, Appendix D.

Consumption factor for the unserviced population was estimated at 20% (80% of the water is returned to the watershed through the septic system). This value is consistent with water supply consumption values listed in Table 16 of the Guidance Module.

The consumption factor for the un-permitted agricultural use (primarily livestock, including dairy operations) was estimated as 50%.

4.3.3 Seasonal Water Use Correction (Monthly Allocation)

Many water permit holders do not require the use of water at a constant rate throughout the year. For example, there are 37 golf course permits and 8 snowmaking permits in the CLOCA study area.

As noted, many of the permits in the study area are limited by time, with only 36 of the 73 permits allowing pumping on all 365 days of the year. The time-limited permits were allocated to months based on individual analysis of the permit. In some cases, only a portion of a month was allocated. For example, the Cranberry Marsh drainage permit is only valid for 5 days of the year, resulting in a monthly allocation less than 1. In general the monthly allocation was applied in a consistent manner to that in Table 15 of the Water Budget Guidance Module, Appendix D.

Overall permitted water demand in the CLOCA watersheds is 1.3 times higher in the summer than the winter months.

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CLOCA Tier 1 Water Budget Report January, 2009

4.4 Water Demand Estimation Results

The results of the water demand are presented as a series of summary tables. The overall total water demand (Table 15) includes the total of permitted usage, population and agricultural demand. All values are corrected for consumption factors (i.e., locally returned flow is not included). Lynde, Oshawa, Bowmanville, Soper and Darlington watersheds have the highest total groundwater demand, with Lynde alone accounting for 39 percent of the total demand.

The detailed permit calculations, including the consumption correction factors and monthly demand allocations for each permit, are included in digital format on the enclosed CD-ROM in the file PTTW Water Demand Details.xls.

The total groundwater demand from all sources is 18,248.6 m3/d (Table 155). The total surface water demand for municipal drinking water from Lake Ontario greatly exceeds all other surface water demand (Table 15). After Lake Ontario is removed, The Lynde watershed again accounts for over 56% of the total surface water consumptive demands.

The summary of permitted groundwater and surface water usage by usage class is shown in Table 16 and Table 17 respectively. This indicates that golf course irrigation and snowmaking are the two most significant permitted groundwater uses in the CLOCA watersheds. For comparison, however, the total estimated un-permitted agricultural demand, at 10,627m3/d (0.123 m3/s in Table 18), exceeds both total permitted golf course irrigation (3750 m3/d) and total permitted snowmaking (1791 m3/d). The municipal surface water use from Lake Ontario greatly exceeds the other consumption classes (Table 17). Industrial uses (including the St. Mary‟s cement plant), snowmaking and golf course irrigation are the most significant surface water uses in the CLOCA watersheds.

Table 19 includes the final total current groundwater demand values tabulated on a monthly basis. Monthly demand is relatively uniform over the year, with snowmaking in the winter months and golf course irrigation in the summer months.

Table 20 includes the population-adjusted calculation details for the future water demand scenario. Population values were increased by 55% to represent the increase in unserviced demand over a 25-year time frame. No other components of the water demand were increased. Table 21 shows the monthly total future groundwater demand. Unserviced human consumptive demand is a small proportion (5.3%) of the total current water demand, so the impact of population growth is small. Population growth increases the overall groundwater water demand by about 3% (summarized in Table 15).

Finally, total current surface water demand by month is shown in Table 22. Total demand rises from about 0.05 m3/s in January to approximately 0.09 m3/s in July (after the municipal pumping from Lake Ontario is removed).

4.5 Water Demand Conclusions

The water demand estimates for the CLOCA watersheds have been developed from a number of information sources as per the Water Budget guidance document. The estimates suggest that water demand does show a typical increase in the summer months (after the large municipal taking from Lake Ontario is removed). Both groundwater and surface water demand is significantly greater in Lynde Creek watershed. A further discussion of the water demand is Earthfx Inc. 48

CLOCA Tier 1 Water Budget Report January, 2009 included in the later sections of this report, where the demand is compared to the available water supply in the watersheds.

5 Water Reserve Estimation

Guidance Module 7 (MOE, 2007) and Part I of the Director‟s Rules define “water reserve” as that portion of water required to support other water uses within the watershed including both ecosystem requirements (in-stream flow needs) as well as other human uses (aside from permitted uses). Examples of other human uses could include dilution for sewage treatment plant (STP) discharge, hydroelectric power needs, recreation, and navigation needs. The reserve quantity is subtracted from the total water source supply prior to evaluating the percent water demand.

5.1 Surface Water Reserve

It is our understanding that there are no hydroelectric power generating facilities on the streams and the nuclear generating stations at Darlington and Pickering get their cooling water supply directly from Lake Ontario. Recreational uses are associated primarily with Lake Ontario and activities such as white-water rafting and navigation on the local streams were assumed to be negligible.

The Region of Durham operates four water pollution control plants (WPCP). They are all located in the lower reaches of the streams in close proximity to Lake Ontario. All, with the exception of the Pringle Creek plant (shown in Figure 56), discharge directly to Lake Ontario. The Pringle Creek plant is the smallest of the plants and is to be decommissioned in 2012. Monthly discharge for the plant was provided by CLOCA based on data submitted to the MOE and is shown in Table 23. Required dilution factors depend on flow in the stream and on the concentration of the specific contaminant in the effluent. For discharge to Lake Ontario, the MOE requires a minimum dilution factor of 20 to 1 (MOE, 1994). As a conservative assumption, a 40 to 1 dilution factor was assumed for discharge to the streams. Minimum flow requirements based on monthly discharge rates and dilution factors are also provided in the table and were used in the estimation of surface water reserve.

Two methods are provided in Guidance Module 7 for estimating the water reserve for ecosystem requirements. The first method uses the lower decile flow (QP90) for areas with a surface water gauge. QP90 values for the catchments with the Environment Canada gauges (based on the period of record for each gauge) are provided in Table 24. The second method uses the Tessman modification to the Tennant Method of specifying minimum flows for aquatic habitat. Several conflicting descriptions of the method were found in the literature and the original source is an unpublished report. At the suggestion of CLOCA and MNR, the simulated lower decile flow (QP90) was used for all catchments as the estimated surface water reserve. The QP90 approach complies with the Director‟s Rules.

As noted earlier, the calibrated PRMS model was configured to output daily streamflow at the outlet of each subwatershed. In this way, the entire CLOCA area was represented rather than just the contributing areas to the gauges. Monthly groundwater reserve values were calculated as the lower decile flow (QP90) value for each month averaged over the 19-year simulation period. Simulated monthly lower decile flows for each catchment flows are presented in Table 25. These values were used in subsequent watershed stress analyses.

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5.2 Groundwater Reserve

Provincial instruments recognize that groundwater discharge to streams must be maintained to sustain baseflow throughout a watershed. The Guidance Module recommends that a simplified estimation method be applied for the Tier 1 analysis whereby the reserve is estimated as 10% of the existing groundwater discharge. Though this study follows the guidance, it is recommended that additional research be undertaken to determine whether such a low reserve is adequate for streams that are highly dependent on groundwater discharge to maintain baseflow such as those in the CLOCA watersheds.

The province allows several alternative methods for estimating groundwater discharge. Discharge can be determined either through (1) a groundwater flow model, if available; (2) baseflow separation applied to long-term flow gauge data, or (3) from spot flow measurements if no other are data available. Separated baseflow values were provided in Table 7 using several methods. Reserve estimates are provided in Table 26 using the same methods assuming a 10% minimum reserve.

Because of the difficulty of extrapolating the reserve estimates from the gauged catchments to the remainder of the CLOCA area, groundwater reserves for all catchments were estimated from the simulated groundwater discharge to streams. Estimated reserves for the 16 watersheds are provided in Table 27. Because the model was run under steady-state conditions, these values represent long-term average flows. Annual average values by catchment are shown in Figure 57.

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6 Subwatershed Stress Assessment

6.1 Overview

The Tier 1 stress assessment is designed to screen subwatersheds and highlight those where the degree of stress warrants refined water budget efforts for risk characterization. The stress assessment evaluates the ratio of the consumptive demand for permitted and non-permitted users to water supplies, minus water reserves, within a subwatershed.

The major components of the water budget have been estimated and tabulated in the preceding sections, including water supply, water demand and water reserve. Both surface water and groundwater components have been compiled on a monthly and average annual basis. The Tier 1 stress assessment integrates and compares these estimates to evaluate the overall stress within each catchment.

Particular care was made to integrate the analysis of both groundwater and surface water components in the CLOCA study area, as required by the Director‟s Rules. The linkage of the groundwater and surface water models and integrated model calibration helped to ensure a balanced assessment of stress levels.

At Tier 1, for each subwatershed, Director‟s Rule (32) under Part III, requires the evaluation of two scenarios: (1) current conditions; and (2) 25-year future demand. The goal of the current conditions scenario is to identify subwatersheds that are under stress as a result of existing water takings. The goal of the 25-year future scenario is to identify additional watersheds that may become stressed as a result of additional drinking water requirements. The CLOCA watersheds are experiencing rapid population growth, with an expected increase in population of 55% over the next 25 years. The province prescribes a methodology by which only human consumption should be increased in the future scenario. As noted in Section 4.4, unserviced human consumption is a small component of the current and future demand. It is expected, however, that considerable increases in related water demand (new golf courses, ski facilities, etc.) may develop over the next 25 years in conjunction with the considerable projected increase in population. This growth-related stress should be evaluated in subsequent water-use studies.

The percent water demand is evaluated independently for groundwater and surface water supplies. The subwatershed stress level is determined based on the greater level of stress evaluated for either the groundwater or surface water supplies. The following four scenarios are to be considered in a Tier 1 assessment.

Tier 1 Stress Assessment Scenarios

Average Annual Highest Monthly Time Period % Water Demand % Water Demand Groundwater and Surface Water Current Conditions Groundwater Supplies Supplies Groundwater and Surface Water 25-Year Future Demand Groundwater Supplies Supplies

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Groundwater sources are evaluated for both average annual and monthly conditions, whereas surface water sources are evaluated monthly. For surface water, an evaluation of the average annual water supply would not be useful due to the seasonal changes in flow. Conversely, an evaluation of the average annual supply for groundwater is useful for evaluating potential long- term stress conditions.

Based on the percent water demand (which will be compared to prescribed thresholds as explained below), each subwatershed will be assigned a stress level for groundwater and for surface water supply. Those subwatersheds receiving a low level of stress will require no further water budgeting or water quantity risk assessment work. Those areas experiencing a moderate to significant level of stress will be subject to further water budget evaluation under Tier 2, provided that the subwatershed contains a municipal drinking water system. Subwatersheds that have a high or moderate stress level but don‟t have municipal systems will be highlighted for consideration under the PTTW program and/or the federal fisheries program under the Department of Fisheries and Oceans.

6.2 Water Demand Calculation Methodology

6.2.1 Groundwater Calculation

Part I of the Director‟s Rules provides the following equation for calculating the percent water demand for groundwater:

% Water Demand QDEMAND = x 100 (Groundwater) QSUPPLY- QRESERVE

The module defines the terms of the equation as follows:

Term Definition Calculation Groundwater demand is calculated as the Groundwater Q estimated average annual and monthly rate of DEMAND Consumptive Demand groundwater takings in a subwatershed. Groundwater supply is calculated as the estimated annual recharge rate plus the QSUPPLY Groundwater Supply estimated groundwater inflow into a subwatershed. For monthly volumes these annual numbers are divided by 12 months. Component of baseflow discharge: suggest 10% QRESERVE Groundwater Reserve of the total groundwater discharge should be maintained as a reserve.

For the CLOCA watershed analysis, QDEMAND was calculated in the manner prescribed above. Though detailed monthly groundwater recharge estimates were available from the PRMS model, the monthly QSUPPLY was calculated using the average annual rate divided by 12 as directed by Part I of the Director‟s Rules. QRESERVE was estimated as follows as discussed in Section 5.2.

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6.2.1.1 Average Annual Groundwater Supply Calculation Methodology

For consistency with other studies, QSUPPLY was calculated in accordance with the Director‟s Rules as follows:

QSUPPLY = QRECHARGE + QIN

6.2.1.2 Monthly Groundwater Supply Calculation Methodology

While the PRMS model can be used to estimate average monthly recharge rates, the Director‟s th Rules requires that monthly supply be estimated as 1/12 of the annual average QSUPPLY for simplicity.

6.2.2 Surface Water Calculation

The prescribed approach for determining the surface water quantity stress in the Director‟s Rules considers seasonal variability and is therefore evaluated using an estimated monthly streamflow. Percent water demand is calculated for each month and the largest monthly stress is compared against the threshold values. Percent water demand is calculated on a monthly basis as:

% Water Demand QDEMAND = x 100 (Surface Water) QSUPPLY- QRESERVE

The terms of the equation are determined as follows:

Term Definition Calculation Surface water demand is calculated as the estimated Surface Water Q rate of consumptive takings from streams, ponds, and DEMAND Consumptive Demand lakes in a subwatershed. Monthly surface water supply is calculated as the median monthly flow in a stream or into a lake or QSUPPLY Surface Water Supply reservoir. Where median flow conditions cannot be obtained, best available monthly baseflow measurements or estimates should be used. As a minimum, surface water reserve is estimated Q Surface Water Reserve th RESERVE using the 10 percentile monthly flow.

For the CLOCA watershed analysis, QDEMAND was calculated in the manner prescribed above. QSUPPLY was calculated using the median monthly flows as determined in the PRMS model as discussed in Section 3.6 while QRESERVE was estimated using the simulated lower decile monthly flow (see Section 5.1).

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6.3 Stress Assessment Criteria

6.3.1 Groundwater Stress Assessment

To complete the Tier 1 analysis for groundwater, the guidance module prescribes that the stress be determined by calculating the average annual and maximum monthly percent water demand for each subwatershed and then comparing them to the following thresholds:

Tier 1 Groundwater Stress Thresholds Groundwater Monthly Quantity Stress Average Annual Maximum Assignment Significant > 25% > 50% Moderate > 10% > 25% Low 0 – 10% 0 – 25%

The thresholds for monthly maximum conditions are higher than average annual thresholds because groundwater supplies can typically tolerate short-term water demands that may not be sustainable over the entire year. The resultant groundwater stress level assignment is the maximum of the current and future assessment values for both annual and monthly conditions.

The thresholds are intended to be conservative, to ensure that areas potentially under hydrologic stress will be identified for additional work. As an example, the combined thresholds and water reserve values ensure that where the annual consumptive demand is more than 9% of the annual recharge into a subwatershed, that subwatershed will be assigned a „moderate‟ level of hydrologic stress (assuming that lateral inflows are a minor component of QSUPPLY).

6.3.2 Surface Water Stress Assessment

As noted, the percent water demand is calculated for each month and the largest monthly stress is compared against the following thresholds:

Tier 1 Surface Water Stress Thresholds Surface Water Quantity Stress Maximum Monthly % Water Level Assignment Demand Significant > 50% Moderate 20% - 50% Low <20 %

These thresholds apply to both current and future scenarios. The resulting surface water stress level assignment is the maximum of the current and future assessment values.

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6.4 Tier 1 Stress Assessment Results

6.4.1 Groundwater Stress Assessment: Current Conditions

Results of the groundwater stress assessment using annual average demand are shown in Table 28 for current demand conditions and the average annual percent water demand is shown graphically in Figure 58. As noted earlier (See Section 3.7), QIN values have been used in the average annual supply calculations. Two catchments, Lynde and Darlington, were found to have moderate levels of average annual stress, although for quite different reasons. In Lynde, demand is higher than all other catchments and more than twice as high as the second highest (Oshawa Creek). The percent water demand is over 10% despite the large size of the catchment, the presence of ORM deposits, and lateral inflow from the northwest. In the Darlington catchment, QDEMAND is large relative to the low QSUPPLY due to the small size and low permeability surficial material. Overall, the results provide a reasonable assessment of the annual groundwater supply and demand conditions, and the methodology can identify catchments with elevated levels of stress.

A summary of the groundwater stress assessment using monthly demand values (current conditions) is shown in Table 29. A more detailed table is presented in Table 35 in Appendix C. The monthly percent water demand was calculated using the methodology as presented in Section 6.2.1.2. Lynde and Darlington were found to have elevated stress levels, but these were below the monthly stress thresholds. A final stress assessment, which combines the maximum stress levels determined from the annual and monthly stress analysis, confirms that only Lynde and Darlington Creek watershed have moderate stress levels. Results are shown graphically on Figure 59. Neither of these watersheds will go on to a Tier 2 level of analysis under the SWP initiative given that there are no municipal supplies. They will, however, be prioritized for further study other watershed management studies by CLOCA.

6.4.2 Groundwater Stress Assessment: Future Conditions

Results of the stress assessment for annual average demand under future conditions are shown in Table 30. The monthly stress assessment for future conditions is summarized in Table 31. More detail is provided in Table 36 in Appendix C. Since the only change between current and future conditions is a 2.9% increase in overall groundwater demand, the percent water demand values exhibit only a minor increase. The assessment results are the same as current conditions: Lynde and Darlington Creek watersheds are moderately stressed.

6.4.3 Surface Water: Current and Future Conditions

A surface water stress assessment was conducted to calculate percent water demand on a monthly basis using simulated median flows (QP50) for QSUPPLY and lower decile flows (QP90) for QRESREVE. Current and future conditions were assumed to be identical because there is no population-based consumptive demand increase from the surface water system. Municipal extraction from Lake Ontario resulted in invalid percent water demand results for the small Lake Ontario watersheds and these were not considered in the final stress analysis.

Details of the analysis are presented in Table 34 in Appendix C. Results are summarized in Table 32 and indicate that high percent water demands can occur in watersheds with permitted Earthfx Inc. 55

CLOCA Tier 1 Water Budget Report January, 2009 pumping in the summer months. Lynde, Goodman, Oshawa, Darlington, and Soper Creek watersheds were therefore classified as having significant Tier 1 stress levels. Catchments with no surface water demand had low stress levels. The one exception was Bowmanville Creek which has relatively high water supply, even in the summer months, and relatively low surface water demand compared to the other large watersheds. Final stress levels in each watershed are shown graphically on Figure 60.

6.5 Stress Assessment Validation

The guidance module suggests that the stress assessment be validated through a comparison to field data and other information on water historic water use. Hydrologic monitoring data (specifically, long-term streamflow monitoring data), were analyzed for clear corroborating evidence that the areas were under hydrologic stress. A cumulative flow analysis (see Chow, 1964) for the Lynde Creek at Whitby gauge, shown in Figure 61, indicated a change in annual flow volumes starting about 1998. It is not certain whether this change is due to lower rainfall in the late 1990s, possible changes in the gauge or measured cross-section, or due to urban development. A cumulative rainfall analysis for the Bowmanville-Mostert rain gauge for 1968 to 2001 (not shown) did not exhibit any break in slope, indicating that changes in precipitation patterns were not significant over the period. A cumulative flow for the Oshawa Creek at Oshawa gauge, shown in Figure 62, also indicates a change in annual flow volumes, in this case, starting about 1990. Further investigation, beyond the Tier 1 level of analysis, is recommended.

6.6 Municipal Wellhead and Intake Assessment

As prescribed in the guidance module, the Tier 1 analysis must include a brief technical review of all municipal drinking water wellheads and intakes in each subwatershed. The purpose of this assessment is to identify drinking water wellheads and intakes that have had previous problems meeting their consumptive demand needs.

There are currently no municipal wells in the CLOCA watershed, so no consumptive demand issues have been identified for groundwater.

There are at least three municipal water intakes servicing the CLOCA residents, as indicated by the surface water permits for the Town of Whitby, the City of Oshawa and the intake servicing the urban area of Bowmanville. These intakes are located in Lake Ontario and no reported water quantity issues have been identified.

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7 Uncertainty, Data and Knowledge Gaps

Uncertainty is inherent in the water budget estimation process. The accuracy of estimates is reliant on the:

- Quantity and quality of the input data (e.g., related to stream flow, climate, groundwater well records); - Conceptual understanding of the watersheds; and - Modelling calculation methodology.

Overall, the issues related to uncertainty, data and knowledge gaps are complex and highly qualitative. There is a degree of uncertainty associated with every aspect of the water budget analyses; however, it is impossible to provide a quantitative assessment of the level of uncertainty. Rather, one can only say, in very general terms, that the level is low, moderate, or high.

The MOE SWP Guidance documents suggests that it would be reasonable to expect a low level of uncertainty in areas where data density is high, where hydrogeologic studies have been conducted, and where numerical models have been developed. This study generally satisfies all three of these criteria. It is recognized, however, that all hydrogeologic analyses have an intrinsic level of uncertainty because one can never have enough data to fully know how conditions vary in the subsurface.

Development of the YPDT-CAMC Core Model entailed a comprehensive process of (1) collecting and filtering the large amount of water well, monitoring well, and other geologic data; (2) interpreting the geologic logs as best as possible and building a conceptual geologic model; (3) assigning initial estimates of aquifer properties and recharge rates and then refining the estimates through model calibration; and (4) performing statistical and sensitivity analyses to demonstrate the validity of the model calibration. The report by Kassenaar and Wexler (2006) documents the procedures and focuses a great deal of attention on answering the questions related to assessing model uncertainty.

As noted in Phase 1 of an independent peer review of the model (Papadopulos and Associates, July 2006):

“It is clear from the modelling report and results that a very significant effort has been devoted to interpreting the hydrogeology of a complex setting. In our opinion, this effort has been conducted at a very high technical standard. The analyses are ambitious in scale, and in our opinion the resolution of the analysis is unprecedented for models of this extent.”

While these independent review comments increase the comfort level with the results of the modelling process, there is still the recognition that geologic data are always incomplete and that the WWIS data used in a large part to develop the models has a high degree of error and uncertainty. Data obtained from municipal monitoring networks and other high-quality sources have less uncertainty and have provided useful information in the vicinity of the municipal wellfields. The number of wells and spatial coverage of high-quality data are limited compared to the WWIS data, however. It is recommended that CLOCA continue to improve its monitoring network over time and incorporate the available high quality data, especially within the higher

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CLOCA Tier 1 Water Budget Report January, 2009 stressed watersheds, and thereby reduce the level of uncertainty associated with the numerical models.

One task at the end of Tier 1 is to identify and list data gaps that will require further assessment as part of Tier 2. Without operating municipal wells, a Tier 2 assessment will not be necessary in the CLOCA watersheds. CLOCA, however, is committed to improving their understanding of the watersheds, and as such has developed a list of data and knowledge gaps for their watersheds (CLOCA, 2007). Most significant of these, from a water budget perspective, is a more comprehensive understanding of the QDEMAND components of the water budget, including assessing the permits and actual water use.

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8 Conclusions

This study has quantified the stress levels of the CLOCA watersheds in accordance with the SWP Guidance Module and the Director‟s Rules. A range of stress levels have been identified, and the results are presented in the required map and table formats.

On a more general level, this analysis has demonstrated the benefits of an integrated assessment of groundwater and surface water resources. Lateral groundwater movement between catchments is significant, and in particular, lateral inflows from outside the CLOCA watersheds form an important component of the flow system, both from a water volume and SGRA protection perspective. Particularly surprising is that particle tracking suggests that groundwater recharge north-east of CLOCA flows in deep aquifers under Soper Creek before discharging in Bowmanville Creek. The groundwater and surface water catchments are significantly different.

Also important is the quantitative insight into the variability in groundwater recharge, both on a yearly and monthly basis. Many of the CLOCA watersheds exhibit a net outflow of water during the summer months, indicating that storage is a significant factor in the overall groundwater supply situation. Understanding the relative role of storage, and distribution of wells in storage sensitive aquifers, should be considered in conjunction with long term monitoring of water levels.

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9 Limitations

Services performed by Earthfx Inc. were conducted in a manner consistent with that level of care and skill ordinarily exercised by members of our technical profession. This report does not exhaustively address all possible conditions that may exist in the study area. Computer models are a simplification of the real world, built from limited and potentially erroneous data, so their results should be considered with care and independently verified. It should be recognized that the passage of time affects the information provided in this report. Environmental conditions can change. Computer simulations are based upon information that existed at the time the data and model was formulated.

Report prepared by:

E.J. Wexler, M.Sc., M.Sc. (Eng) Vice President, Senior Hydrogeologist

Dirk Kassenaar, M.Sc., P.Eng. President, Senior Hydrogeologist

Qing Li Hydrogeologist

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10 REFERENCES

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Barth, C., 2005, Hydrologic modelling of a groundwater dominated watershed using a loosely coupled modelling approach: Friedrich-Schiller-Universitat Jena.

Chapman, L.J. and Putnam, D.F., 1984, The physiography of southern Ontario: Ontario Geologic Survey Special Volume 2, 270p.

Chisholm, P.S., Irwin, R.W., and Acton, C. J., 1981, Interpretation of soil drainage groups from soil taxonomy-Southern Ontario: Can. J. Soil Science. 64: pp. 383-393.

Chow, V.T. (ed.), 1964, Handbook of applied hydrology – A compendium of water-resources technology: McGraw-Hill Book Company, New York, 1418p.

Clarifica Inc., 2002, Water budget in urbanizing watersheds – Duffins Creek watershed: Report prepared for the Toronto and Region Conservation Authority.

CLOCA, 2006, Watershed characterization -- Central Lake Ontario Conservation Authority watersheds: Prepared by the Central Lake Ontario Conservation Authority, June 30, 2006

CLOCA, 2007, Conceptual water budget interim report -- Central Lake Ontario Conservation Authority watersheds: Prepared by the Central Lake Ontario Conservation Authority, March 2007.

Dyke, L.D., Sharpe, D.R., Ross, I., Hinton, M., and Stacey, P., 1997, Potential springs in the Oak Ridges Moraine, Southern Ontario -- Mapping from aerial thermography: Geological Survey of Canada and Ministry of Natural Resources - GSC Open File 3374.

Dickinson, W.T. and and Whiteley, H.Q., 1970, Watershed areas contributing to runoff: International Association of Hydrologic Sciences Publication 96, p. 1.12 - 1.28.

Ely, D.M., 2006, Analysis of sensitivity of simulated recharge to selected parameters for seven watersheds modeled using the precipitation-run-off modeling system: USGS Scientific Investigations Report 2006-5041, 21p.

FREND, 1989, Volume 1: Hydrological Studies. II: Hydrological data. Flow regimes from experimental and network data: Wallingford, UK

Funk, G.F., 1977, Geology and water resources of the Bowmanville, Soper and Wilmot Creek, IHD representative drainage basin: Ontario Ministry of Environment, Water Resources Report 9a, 113p.

Gartner Lee Limited, 1994, Lynde Creek watershed resource management strategy: prepared for the Town of Whitby, 67p.

Greenland International Consulting, 2006, Oshawa Creek surface water assessment pilot project draft report - Preliminary findings and recommendations: prepared for CLOCA, May 2006, Greenland International Consulting, Collingwood, Ontario.

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Hamon, W.R., 1961, Estimating potential evapotranspiration: Journal of the Hydraulics Division, Proceedings of American Society Civil Engineers 87, 107-120.

Harbaugh, A.W. and M.G. McDonald, 1996, User‟s documentation for MODFLOW-96, an update to the U.S. Geological Survey modular finite-difference ground-water flow model: U.S. Geological Survey Open-File Report 96-485, 56p.

Harbaugh, A.W., 1990, A computer program for calculating subregional water budgets using results from the U.S. Geological Survey modular three-dimensional ground-water flow model: U.S. Geological Survey Open-File Report 90-392, 46 p.

Hardy, J.P., Melloh, R., Koenig, G., Marks, D., Winstral, A., Pomeroy, J.W. and Link, T., 2004, Solar radiation transmission through conifer canopies: Agriculture and Forest Metrology, 126, 257-270.

Hargreaves, G.A. and Allen, R.G., 2003, History and evaluation of Hargreaves evapotran- spiration equation: J.ASCE, Irrigation and Drainage Eng., Volume 129, Issue 1, pp. 53-63.

Jensen, M.E., and Haise, H.R., 1963, Estimating evapotranspiration from solar radiation: Journal of Irrigation and Drainage Div., ASCE 89(IR):15-41.

Kassenaar, J.D.C. and Wexler, E.J., 2006, Groundwater modelling of the Oak Ridges Moraine area: YPDT-CAMC Technical Report #01-06. Available at http://www.ypdt-camc.ca.

Leavesley, G.H., Litchty, R.W., Troutman, B.M. and Saindon, L.G., 1983, Precipitation-runoff modeling system - User‟s manual: Water Resources Investigations Report 83-4283. USGS. Denver Colorado.

Linsley, R.K., Kohler, M.A., Paulhus, J.L., 1975, Hydrology for engineers: McGraw-Hill Book Company. New York, 482 p.

McDonald, M.G. and Harbaugh, A.W., 1988, Chapter A1: A modular three-dimensional finite difference ground-water flow model, Book 6 modelling techniques: Techniques of Water- Resources Investigations of the United States Geological Survey.

Ontario Ministry of the Environment, 2007, WP draft assessment report: Guidance Module 7, Water budgets and water quantity risk assessment: MOE, March, 2007.

Ontario Ministry of the Environment and Energy, 1994, Deriving receiving-water based point- source effluent requirements for Ontario waters: MOE, Toronto, Ontario, 25 pp.

Ontario Ministry of the Environment, 2008, Technical Rules: Assessment Report, Clean Water Act, 2006, November, 2009.

Pollock, D.W., 1989, Documentation of computer programs to compute and display pathlines using results from the U.S. Geological Survey modular three-dimensional finite-difference groundwater flow model: U.S. Geological Survey Open File Report 89-381, 188 p.

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Russell, H.A.J, Sharpe, D.R. and Logan, C., 2002, Structural model of the Oak Ridges Moraine and Greater Toronto areas, Southern Ontario -- Oak Ridges Moraine sediment: Geological Survey of Canada, Open File 4240, scale 1:250,000.

Schroeter, H.O., Boyd, D.K., and Whiteley, H.R., 2000, A practical technique of filling-in missing values in meteorological data sets for long-term watershed modelling: Proceedings, Ontario Water Conference CWRA/CSE, Richmond Hill, Ontario, April 2000.

Singer, S.N., 1981, Evaluation of the ground water responses applied to the Bowmanville, Soper and Wilmot Creeks IHD representative drainage basin: Ontario Ministry of the Environment, Water Resources Report 9b.

Sloto R.A. and Crouse M.Y., 1996, HYSEP - A computer program for streamflow hydrograph separation and analysis: U.S. Geological Survey, Water Resources Investigations Report 96- 4040.

Todd, D.K., 1980, Groundwater hydrology: John Wiley and Sons, New York, 535p.

Totten Sims Hubicki Associates, 1995, Oshawa Creek watershed study: Report prepared for the Central Lake Ontario Conservation Authority.

U.S. Department of Agriculture – Soil Conservation Service, 1985, National engineering handbook, Section 4 – Hydrology: USDA-SCS, Washington, D.C.

Yeung, C.W., 2005, Rainfall-runoff and water balance models for management of the Fena Valley Reservoir, Guam: USGS Scientific Investigations Report 2004-5287, 52p.

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11 TABLES

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Table 1: Land use related parameter values (see Leavesley et al., 1983; Chow, 1964; Linsley et al., 1975). Winter Summer Winter Imper- Depres- Vegeta- Cover Cover Radiation Snow Rain Rain Land Use Type vious sion tion Density Density Trans- Interception Interception Interception Fraction Storage Index Winter Summer mission Storage Storage Storage (0 - 1) (mm) (0 – 3) (0 – 1) (0 – 1) (0 – 1) (mm) (mm) (mm) Deciduous Forest (oak) 0 0. 3 0.4 0.8 0.6 1.27 3.81 1.27 Coniferous Forest (pine) 0 0. 3 0.8 0.8 0.3 1.27 7.62 7.62 Mixed Forest 0 0. 3 0.5 0.8 0.45 1.27 5.08 3.81 Meadow 0 0. 1 0.7 0.8 0.8 1.02 3.81 2.54 Urban Residential 0.22 8.89 1 0.1 0.3 0.2 0. 2.54 1.27 Rural Residential 0.07 6.35 1 0.3 0.7 0.6 0. 2.54 1.27 Industrial 0.46 8.89 0 (bare) 0.2 0.3 0.4 0. 1.27 0.51 Commercial 0.47 8.89 0 0.2 0.3 0.4 0. 1.27 0.51 Golf Facility 0.03 1.27 2 0.4 0.6 0.8 1.02 3.81 2.54 Crop Field 0 0. 2 0.3 0.7 0.8 1.27 2.54 1.27 Agriculture Facility 0.15 3.81 1 (grass) 0.3 0.4 1 1.02 1.27 1.02 Pasture 0 0. 1 0.7 0.8 0.8 1.02 3.81 2.54 Treed Field 0 0. 3 0.5 0.8 0.45 1.27 5.08 3.81 Open Water 1 101.6 0 0 0 1 0. 0. 0. Ski Hill 0.05 1.27 2 (mixed) 0.5 0.7 0.8 1.02 3.81 2.54 Athletic Field 0.05 1.27 1 0.5 0.7 0.8 0.51 3.81 2.54 Park 0.05 1.27 2 0.5 0.7 0.8 0.51 3.81 2.54 Landfill 0.3 5.08 2 0.3 0.4 1 1.02 1.27 1.02 Aggregate 0 0. 0 0 0 1 0. 0. 0. Institutional Building 0.25 8.89 1 0.3 0.4 1 1.02 1.27 1.02 Institutional Greenspace 0.07 2.54 1 0.3 0.7 0.8 1.02 3.81 1.02 Airport 0.27 6.35 2 0.3 0.7 0.8 1.02 3.81 1.02 Forested Wetland 0.35 50.8 3 (tree) 0.4 0.9 0.6 1.27 3.81 1.27 Wetlands 0.35 101.6 1 0.4 0.9 1 0. 0. 0. Beach Bluff 0 0. 1 0.5 0.8 0.8 0.51 3.81 2.54 Utility Transfer Station 0.1 5.08 0 0 0 1 0. 0. 0.00 Transportation Corridor 0.12 6.35 1 0.3 0.6 0.9 0. 2.54 1.27 Transportation Greenspace 0.07 1.27 2 0.5 0.6 1 1.02 1.27 1.02 Open Aquatic 1 101.6 0 0 0 1 0. 0. 0. Thicket 0 0. 2 0.7 0.9 0.8 1.02 1.27 1.02 Railway 0.07 1.27 2 0.5 0.6 0.8 1.02 1.27 1.02 Roads 0.45 6.35 1 0.3 0.7 0.9 0. 2.54 1.27 Undefined 0.05 1.27 2 0.5 0.6 0.8 1.02 1.27 1.02

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Table 2: Soil properties related to surficial geology (see Todd, 1980; Linsley et al., 1975; Chow, 1964). Hydraulic Re- Total Re- Total Conduc- Soil charge Soil charge Soil Hydraulic tivity of Surficial Geology Soil Code Field Zone Zone Zone Zone Conduc- Frozen Type for Poro- Capa- Wilting Depth Depth Storage Storage tivity Soil (1-3) CN sity city Point (cm) (cm) (cm) (cm) (m/s) (m/s) Bedrock (Weathered Shale) 3 C 0.05 0.03 0.01 91 183 1.83 3.66 8.0E-06 4.0E-07 Lower Sediments (Undifferentiated) 1 (sand) AB 0.35 0.13 0.08 61 122 2.74 5.49 3.0E-05 1.5E-06 Scarborough 1 A 0.35 0.13 0.08 61 122 2.74 5.49 3.0E-05 1.5E-06 Sunnybrook 3 C 0.40 0.3 0.23 91 183 6.40 12.80 5.0E-08 2.5E-09 Thorncliffe 1 A 0.35 0.13 0.08 61 122 2.74 5.49 5.0E-05 2.5E-06 Till (Undifferentiated) 2 (loam) C 0.35 0.17 0.08 91 183 8.23 16.46 5.0E-08 2.5E-09 Newmarket - Weathered 2 B 0.35 0.17 0.08 91 183 8.23 16.46 5.0E-08 2.5E-09 Wildfield-Kettleby - Weathered 2 B 0.40 0.3 0.23 91 183 6.40 12.80 1.0E-07 5.0E-09 Halton – Weathered 2 B 0.40 0.3 0.23 91 183 6.40 12.80 5.0E-07 2.5E-08 Halton – Hummocky 2 AB 0.40 0.3 0.23 61 122 4.27 8.53 1.0E-06 5.0E-08 Moraine Deposits (Undifferentiated) 1 A 0.35 0.08 0.03 30 61 1.37 2.74 2.0E-04 1.0E-05 Moraine Deposits – Sand 1 A 0.35 0.08 0.03 30 61 1.37 2.74 2.0E-04 1.0E-05 Glacial River (Undifferentiated) 1 A 0.35 0.08 0.03 30 61 1.37 2.74 5.0E-04 2.5E-05 Glacial River (Undifferentiated) 1 A 0.35 0.08 0.03 30 61 1.37 2.74 5.0E-04 2.5E-05 Glacial River - Gravel 1 A 0.35 0.07 0.02 30 61 1.52 3.05 5.0E-03 2.5E-04 Glacial Lake Silt/Clay (Undifferentiated) 3 (clay) C 0.40 0.35 0.25 91 183 9.14 18.29 5.0E-07 2.5E-08 Glacial Lake Silt/Clay 3 C 0.40 0.35 0.25 91 183 9.14 18.29 5.0E-07 2.5E-08 Glacial Lake Sand/Gravel 1 AB 0.35 0.13 0.08 61 122 2.74 5.49 5.0E-05 2.5E-06 Glacial Lake Sand/Gravel (mainly sand and silty sand) 1 B 0.35 0.13 0.08 61 122 2.74 5.49 5.0E-06 2.5E-07 Glacial Lake Sand and Gravel (mainly sandy gravel/gravel) 1 AB 0.35 0.08 0.03 61 122 2.74 5.49 5.0E-04 2.5E-05 Organic 2 B 0.45 0.43 0.30 91 183 11.89 23.77 5.0E-07 2.5E-08 River - (gravel, sand, silt, clay, muck) 1 B 0.35 0.28 0.20 91 183 7.32 14.63 2.0E-07 1.0E-08 River - modern 1-2 m thick 1 BC 0.35 0.28 0.20 91 183 7.32 14.63 2.0E-06 1.0E-07 River - terrace/delta 1-8 m thick 1 BC 0.35 0.28 0.20 91 183 7.32 14.63 2.0E-05 1.0E-06 Recent 1 AB 0.35 0.13 0.08 61 122 2.74 5.49 2.0E-04 1.0E-05

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Table 3: Hydrologic soil groups (from Chisholm, 1981). Hydro -logic General Properties Soil Group Soils have low runoff potential and high infiltration rates even when thoroughly wet and consist A chiefly of deep, well to excessively drained sands, loamy sand, sandy loam or gravels and have a high rate of water transmission (>2x10-6 m/s). Soils have moderate infiltration rates when thoroughly wet and consist chiefly of moderately B deep to deep, moderately well to well drained soils with moderately fine to moderately course textures. These soils have a moderate rate of water transmission (1 to 2x10-6 m/s) Soils have low infiltration rates when thoroughly wetted and consist chiefly of soils with a layer C that impedes downward movement of water and soils with moderately coarse textures such as sandy clay loam. These soils have a moderate rate of water transmission (4x10-7 to 1x10-6 m/s) Soils have high runoff potential. They have very low infiltration rates when thoroughly wetted and consist chiefly of clay soils with a high swelling potential, soils with a permanent high water D table, soils with a clay pan or clay layer at or near the surface, and shallow soils over nearly impervious material. These soils, such as clay loam, silty clay loam, sandy clay, silty clay and clay have a very low rate of water transmission (0.0 to 4x10-7 m/s).

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Table 4: CN values based on land use classes and soil properties (see Chow, 1964). Soil Type Land Use Soil Type (on hummocky topography) Class A AB B BC C D A AB B C D Deciduous Forest (oak) 25 40 55 63 70 77 15 30 45 53 60 Coniferous Forest (pine) 25 40 55 63 70 77 15 30 45 53 60 Mixed Forest 25 40 55 63 70 77 15 30 45 53 60 Meadow 30 44 58 64 71 78 20 34 48 54 61 Urban Residential 39 50 61 67 74 80 Rural Residential 39 50 61 67 74 80 Industrial 39 50 61 67 74 80 Commercial 39 50 61 67 74 80 Golf Facility 39 50 61 67 74 80 Crop Field 62 67 71 74 78 81 52 57 61 64 68 Agriculture Facility 59 67 74 78 82 86 Pasture 39 50 61 67 74 80 29 40 51 57 64 Treed Field 25 40 55 63 70 77 Water Feature 25 40 55 63 70 77 Ski Hill 68 75 79 83 86 89 Athletic Field 49 59 69 74 79 84 Park 39 50 61 67 74 80 Landfill 30 30 30 30 30 30 Aggregate 30 30 30 30 30 30 Institutional Building 39 50 61 67 74 80 Institutional Greenspace 39 50 61 67 74 80 Airport 39 50 61 67 74 80 Forested Wetland 25 40 55 63 70 77 25 40 55 63 70 Wetlands 25 40 55 63 70 77 25 40 55 63 70 Beach Bluff 39 50 61 67 74 80 Utility Transfer Station 39 50 61 67 74 80 Transportation Corridor 39 50 61 67 74 80 Transportation greenspace 39 50 61 67 74 80 Open Aquatic 25 40 55 63 70 77 Thicket 25 40 55 63 70 77 15 30 45 53 60 Railway 39 50 61 67 74 80 25 40 55 63 70 Roads 39 50 61 67 74 80 Undefined 39 50 61 67 74 80

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Table 5: Climate normals for 1971 to 2000 from Environment Canada climate stations in the CLOCA area (Data from Environment Canada). Climate Normal Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual Bowmanville Mostert (#6150830) POR: 1967-2002 Daily Maximum Temp (°C) ¬1.9 ¬0.9 4.0 10.9 17.8 22.8 25.5 24.5 20.2 13.4 6.9 1.2 12.0 Daily Minimum Temp (°C) ¬10.7 ¬9.7 ¬4.9 1.1 6.6 11.3 14 13.2 9.2 3.4 ¬0.7 ¬6.6 2.2 Rainfall (mm) 33.1 30.8 47.2 70 73.7 81.5 63.7 81 90.5 67.8 77.9 47.4 764.6 Snowfall (cm) 30.0 16.4 13.5 2.9 0 0 0 0 0 0.1 6.1 24.2 93.2 Precipitation (mm) 63.1 47.2 60.7 72.9 73.7 81.5 63.7 81 90.5 67.9 84.0 71.6 857.9 Burketon McLaughlin (#6151042) POR: 1980-2002 Daily Maximum Temp (°C) -4.0 -2.8 2.4 10.0 17.5 22.1 24.9 23.9 19.1 12.3 5.1 -1.0 10.8 Daily Minimum Temp (°C) -12.1 -10.9 -5.8 0.8 7.3 12.0 14.8 14.0 9.9 3.9 -1.5 -8.1 2.0 Rainfall (mm) 24.5 21.1 39.1 66.7 83.2 95.7 74.9 88.5 92.4 79.2 73.9 34.9 774.1 Snowfall (cm) 38.2 27.2 19.5 5.8 0.1 0 0 0 0 0.6 11.5 32.1 135 Precipitation (mm) 62.7 48.3 58.6 72.5 83.3 95.7 74.9 88.5 92.4 79.8 85.4 67.0 909 Claremont (#6151545) Rainfall (mm) 21.1 25.9 52.3 68.8 78.2 75.5 72.7 92.4 82.2 73.0 76.0 46.3 764.3 Snowfall (cm) 33.4 27.1 16.5 2.8 0 0 0 0 0 0.4 4.5 31.4 116.0 Precipitation (mm) 54.5 53.0 68.8 71.5 78.2 75.5 72.7 92.4 82.2 73.4 80.5 77.7 880.3 Greenwood MTRCA (#6153020) Rainfall (mm) 19.9 26.7 54.2 68.3 70.3 75.4 69.2 91.5 83.6 72.6 76.0 48.2 755.9 Snowfall (cm) 37.4 27.8 20.3 4.0 0 0 0 0 0 0.4 5.5 34.9 130.3 Precipitation (mm) 57.2 54.5 74.4 72.3 70.3 75.4 69.2 91.5 83.6 73.0 81.5 83.2 886.1 Leskard (#6154410) Rainfall (mm) 31.3 24.5 45.4 82.4 78.9 77.2 79.3 91.4 100 88.2 87.7 38.9 825.1 Snowfall (cm) 47.1 36.5 24.5 8.1 0 0 0 0 0 1.2 12.8 46.2 176.4 Precipitation (mm) 78.4 61.0 69.8 90.5 78.9 77.2 79.3 91.4 100 89.4 100.4 85.1 1001.4 Orono (#6155854) POR: 1921-2005 Daily Maximum Temp (°C) ¬2.7 ¬1.6 3.6 11.0 18.4 23.2 26.3 24.9 20.0 13.4 6.6 0.2 11.9 Daily Minimum Temp (°C) ¬11.4 ¬10.9 ¬5.6 0.8 6.6 11.3 14.4 13.5 9.3 3.5 ¬1.1 ¬7.7 1.9 Rainfall (mm) 31.2 25.1 47.0 69.7 75.6 75.1 63.7 85.7 89.6 78.1 78.1 40.2 759.1 Snowfall (cm) 32.9 25.1 15.8 3.2 0 0 0 0 0 0 7.4 29.7 114.1 Precipitation (mm) 64.1 50.2 62.8 72.9 75.6 75.1 63.7 85.7 89.6 78.1 85.5 69.9 873.2 Oshawa WPCP (#6155878) POR: 1969-2005 Daily Maximum Temp (°C) ¬1.4 ¬0.6 4.1 10.5 17.0 21.9 25.0 24.0 19.7 13.1 7.2 1.5 11.8 Daily Minimum Temp (°C) ¬9.2 ¬8.2 ¬3.8 2.0 7.6 12.4 15.5 15.2 11.2 5.2 0.7 ¬5.4 3.6 Rainfall (mm) 32.1 29.5 46.8 70.1 74.7 80.6 67.3 83.3 87.9 66.2 74.2 46.8 759.5 Snowfall (cm) 38.9 23.2 15.5 3.1 0 0 0 0 0 0.1 5.7 31.9 118.4 Precipitation (mm) 71.0 52.7 62.3 73.1 74.7 80.6 67.3 83.3 87.9 66.3 79.9 78.7 877.9 Tyrone (#6159048) POR: 1980 - 1999 Daily Maximum Temp (°C) ¬3.1 ¬2.1 3.1 10.7 18.1 23.0 25.7 24.6 20.0 13.0 5.9 ¬0.1 11.6 Daily Minimum Temp (°C) ¬12.3 ¬11.3 ¬6.3 0.5 6.5 11.2 14.0 13.2 9.0 3.0 ¬1.7 ¬8.1 1.5 Rainfall (mm) 33.7 29.9 48.8 74.4 75.7 80.0 76.1 88.6 93.7 77.1 82.4 44.5 804.9 Snowfall (cm) 46.6 29.6 23.3 4.8 0 0 0 0 0 0.4 9.4 34 147.9 Precipitation (mm) 80.3 59.5 72.1 79.2 75.7 80.0 76.1 88.6 93.7 77.5 91.8 78.4 952.8

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Table 6: Monthly and annual estimated potential evapotranspiration for the CLOCA area. Estimate Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual Potential ET (mm) Thornthwaite Method 0 0 0 30.8 72.5 108.3 127.6 112.7 77.4 38.0 10.1 0 577.3 Potential ET (mm) Penman Method 0 0 11.7 63.0 97.6 114.5 129.4 103.0 64.7 30.5 8.2 0 622.56 Precipitation (mm) 62.2 57.5 65.9 67.0 74.0 73.8 67.2 82.5 79.1 73.9 84.5 81.6 867.4

Table 7: Total flow and separated baseflow for gauged streams in the CLOCA area Sepa rated Sepa- Base- rated flow: Base- Average flow: Catch- Avg. Minimum % of Smoothed Median ment Annual Flow Annual Minima Flow Station Area Flow Method Avg. Method Method ID Stream (km2) (mm/yr) (mm/yr) Flow (mm/yr) (mm/yr) 02HC018 Lynde Creek (1959-2003) 106 270 143 53 114 122 02HD008 Oshawa Cr. (1959-2003) 95.8 359 235 65 212 230 02HD013 Harmony Cr. (1980-2003) 41.6 324 127 39 98 117 02HD014 Farewell Creek (1980-93) 58.5 388 197 51 161 163 02HD006 Bowmanville Cr. (1959-95) 83.9 486 323 67 289 327 02HD007 Soper Creek (1959-87) 77.7 353 233 66 209 202

Table 8: Annual average recharge rates used in the East Model outside the CLOCA area (from Kassenaar and Wexler, 2006). Surficial Material Recharge (mm/a) Glacial Lake Sands 180 Glacial Lake Silts and Clays 90 Other Recent Deposits 160 Halton Till – Hummocky Topography 360 Halton Till – North of Moraine 120 Halton Till – South of Moraine 90 ORM Deposits – Hummocky Topography 420 ORM Deposits – Non-Hummocky Topography 320 Newmarket Till 30 Lower Sediments/Weathered Bedrock 30 Urban area recharge adjustment factor 60%

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Table 9: PRMS outputs stored on a monthly, yearly, average monthly, and average annual basis. Model Result Brief Description Observed Precipitation (POBS) Annual average precipitation Net Precipitation (PNET) Precipitation after interception losses (but not including depression storage) ET Potential (PET) Potential ET based on Solar and Temperature inputs ET Actual (AET) ET based on PET and available moisture (does not include INT but includes EVDP and sublimation from the snowpack) Losses from Interception (INT) Cumulative amount lost to evaporation through capture of water on leaves Losses from Depression Storage (EVDP) Cumulative amount lost to evaporation through capture of water on impervious surfaces Net Runoff (RONET) Cumulative amount of runoff from pervious and impervious surfaces. Runoff from Impervious Soils (ROIMP) Separate accounting for impervious surfaces Runoff from Pervious Soils (ROPER) Separate accounting for pervious surfaces Return Flow from Pervious Soils (RFIMP) Runoff from impervious surfaces redirected to pervious areas. Not used in baseline simulations. Recharge to unsaturated zone (USS) Water infiltrating the soil but not percolating to the water table (Interflow). Occurs mainly in low K soils. Recharge to saturated zone (UGS) Water infiltrating the soil and percolating to the water table under gravity drainage Snowmelt (SMLT) Cumulative amount of water captured by the snowpack.

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Table 10: Median monthly flows (m3/s) at Environment Canada HYDAT stations in the CLOCA area (see CLOCA 2000b for details on each gauge). Gauge Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec POR Lynde Creek near Whitby 0.44 0.57 1.44 1.37 0.63 0.32 0.22 0.21 0.28 0.38 0.63 0.61 0.41 Oshawa Creek at Oshawa 0.71 0.77 1.39 1.49 0.92 0.67 0.57 0.53 0.56 0.64 0.80 0.79 0.70 Harmony Creek at Oshawa 0.16 0.23 0.46 0.42 0.23 0.12 0.06 0.05 0.10 0.13 0.24 0.25 0.15 Farewell Creek at Oshawa 0.35 0.52 1.06 0.95 0.39 0.21 0.13 0.11 0.22 0.30 0.54 0.48 0.30 Bowmanville Cr. at Bowmanville 0.86 1.01 1.68 1.77 1.04 0.75 0.65 0.65 0.70 0.81 1.01 1.07 0.87 Soper Creek at Bowmanville 0.48 0.70 1.19 1.32 0.68 0.44 0.32 0.33 0.38 0.45 0.65 0.66 0.50

Table 11: Simulated median monthly flows (m3/s) at the catchment outlets based on the PRMS model. Watershed Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Lynde Creek 1.06 0.97 1.42 1.31 0.631 0.20 0.07 0.05 0.19 0.45 1.37 1.51 Pringle Creek 0.20 0.17 0.23 0.21 0.11 0.03 0.01 .004 0.03 0.08 0.23 0.27 Corbett Creek 0.09 0.09 0.11 0.09 0.05 0.01 .004 .001 .007 0.02 0.09 0.12 Goodman Creek 0.08 0.06 0.09 0.08 0.04 0.01 .005 .003 0.02 0.04 0.10 0.11 Oshawa Creek 0.89 0.81 1.17 1.16 0.56 0.17 0.05 0.03 0.14 0.40 1.27 1.31 Harmony Creek 0.30 0.24 0.39 0.37 0.18 0.05 0.01 .005 0.04 0.11 0.37 0.44 Farewell Creek 0.25 0.21 0.33 0.31 0.16 0.05 0.01 .003 0.03 0.10 0.35 0.38 Robinson Creek 0.04 0.03 0.04 0.04 0.02 0.01 .001 .000 .001 .006 0.03 0.05 Tooley Creek 0.08 0.06 0.09 0.08 0.04 0.01 .003 .001 .007 0.02 0.08 0.10 Black Creek 0.19 0.16 0.24 0.22 0.11 0.03 0.01 .003 0.04 0.10 0.29 0.30 Darlington Creek 0.12 0.10 0.14 0.12 0.06 0.02 .006 .002 0.02 0.04 0.14 0.17 Bowmanville Creek 0.82 0.71 1.22 1.25 0.56 0.20 0.09 0.09 0.23 0.49 1.26 1.22 Westside Creek 0.04 0.03 0.04 0.03 0.02 0.01 .001 .000 .002 .009 0.03 0.04 Soper Creek 0.66 0.54 0.85 0.81 0.37 0.11 0.04 0.02 0.12 0.29 0.87 0.93 Bennet Creek 0.06 0.05 0.06 0.05 0.02 0.01 .002 .000 .002 .008 0.04 0.06 Lake Catchments 0.15 0.15 0.18 0.14 0.07 0.02 .007 .003 0.02 0.04 0.14 0.18

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Table 12: Simulated monthly groundwater recharge (QR) by watershed.

Recharge Rates in mm/month Watershed Annual Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec (mm/yr)l Lynde Creek 14.96 15.06 24.89 19.88 5.15 1.00 0.32 1.14 6.25 10.32 35.93 26.13 161.05 Pringle Creek 12.42 10.73 16.54 15.14 4.08 0.53 0.08 0.51 4.82 8.07 27.19 23.12 123.23 Corbett Creek 11.53 8.63 14.28 12.92 3.50 0.43 0.00 0.19 2.74 4.41 20.71 20.96 100.30 Goodman Creek 13.32 11.25 17.51 15.93 4.53 0.97 0.17 0.99 7.52 11.34 32.52 25.48 141.51 Oshawa Creek 15.39 15.51 25.56 21.00 5.54 0.73 0.22 0.91 6.42 11.48 39.70 25.62 168.07 Harmony Creek 10.79 8.89 16.26 16.74 4.33 0.36 0.03 0.32 3.70 6.84 27.93 22.22 118.40 Farewell Creek 12.01 10.75 19.49 18.71 4.80 0.31 0.00 0.20 4.39 8.86 33.84 23.24 136.59 Robinson Creek 12.49 9.27 16.95 15.36 3.78 0.24 0.00 0.05 1.67 3.14 20.56 23.19 106.69 Tooley Creek 13.80 11.23 19.55 15.77 3.90 0.28 0.02 0.11 3.46 6.35 27.12 25.37 126.97 Black Creek 14.10 12.85 21.75 19.19 4.89 0.61 0.06 0.38 7.32 13.85 40.29 26.05 161.33 Darlington Creek 14.38 11.57 20.18 15.97 3.98 0.45 0.11 0.27 4.61 7.97 29.91 25.69 135.10 Bowmanville Creek 17.92 18.76 35.43 26.95 6.62 2.43 1.02 2.70 10.31 17.27 47.02 27.34 213.76 Westside Creek 12.10 8.08 14.16 12.98 3.18 0.11 0.00 0.02 2.19 4.80 21.05 20.24 98.93 Soper Creek 16.48 14.99 27.01 21.19 4.74 0.90 0.28 0.72 7.06 12.47 39.83 27.42 173.11 Bennet Creek 18.33 14.58 21.11 13.21 2.69 0.08 0.00 0.07 1.39 2.95 18.43 22.62 115.44 Lake Catchments 13.06 10.99 16.58 12.71 3.38 0.61 0.09 0.42 3.71 5.40 22.07 21.89 110.90

Recharge Rates in m3/s Watershed Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual Lynde Creek 0.738 0.815 1.227 1.013 0.254 0.051 0.016 0.056 0.319 0.509 1.831 1.289 0.6765 Pringle Creek 0.132 0.125 0.176 0.166 0.043 0.006 0.001 0.005 0.053 0.086 0.299 0.246 0.1115 Corbett Creek 0.063 0.051 0.078 0.073 0.019 0.002 0.000 0.001 0.015 0.024 0.116 0.114 0.0463 Goodman Creek 0.051 0.047 0.067 0.063 0.017 0.004 0.001 0.004 0.030 0.043 0.129 0.098 0.0462 Oshawa Creek 0.633 0.700 1.051 0.893 0.228 0.031 0.009 0.037 0.273 0.472 1.688 1.054 0.5892 Harmony Creek 0.188 0.170 0.283 0.301 0.075 0.006 0.001 0.006 0.067 0.119 0.503 0.387 0.1756 Farewell Creek 0.163 0.160 0.264 0.262 0.065 0.004 0.000 0.003 0.062 0.120 0.474 0.315 0.1577 Robinson Creek 0.027 0.022 0.036 0.034 0.008 0.001 0.000 0.000 0.004 0.007 0.045 0.049 0.0193 Tooley Creek 0.054 0.048 0.077 0.064 0.015 0.001 0.000 0.000 0.014 0.025 0.110 0.099 0.0423 Black Creek 0.128 0.128 0.197 0.179 0.044 0.006 0.001 0.003 0.068 0.125 0.377 0.236 0.1243 Darlington Creek 0.088 0.078 0.123 0.101 0.024 0.003 0.001 0.002 0.029 0.049 0.189 0.157 0.0702 Bowmanville Creek 0.605 0.695 1.197 0.940 0.223 0.085 0.034 0.091 0.360 0.583 1.641 0.923 0.6149 Westside Creek 0.026 0.019 0.030 0.029 0.007 0.000 0.000 0.000 0.005 0.010 0.047 0.043 0.0180 Soper Creek 0.464 0.463 0.761 0.617 0.134 0.026 0.008 0.020 0.206 0.351 1.160 0.772 0.4152 Bennet Creek 0.051 0.044 0.058 0.038 0.007 0.000 0.000 0.000 0.004 0.008 0.053 0.063 0.0272 Lake Catchments 0.103 0.095 0.131 0.104 0.027 0.005 0.001 0.003 0.030 0.043 0.180 0.173 0.0747

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Table 13: Estimates of Lateral Groundwater Flow (QIN) by Catchment. Highlighted watersheds are experiencing a net groundwater inflow. Annual Annual Annual Average Catchment Average Average Net Watershed Area Lateral Lateral 2 Lateral (km ) Inflow Outflow 3 3 Inflow QNET (m /s) (m /s) 3 (m /s) Lynde Creek 132 0.202 0.209 -0.0065 Pringle Creek 28.5 0.042 0.047 -0.0050 Corbett Creek 14.6 0.017 0.023 -0.0054 Goodman Creek 10.3 0.015 0.037 -0.0226 Oshawa Creek 110 0.197 0.142 0.0552 Harmony Creek 46.7 0.081 0.081 -0.0003 Farewell Creek 36.3 0.110 0.101 0.0086 Robinson Creek 5.7 0.015 0.031 -0.0157 Tooley Creek 10.5 0.020 0.033 -0.0139 Black Creek 24.2 0.067 0.086 -0.0184 Darlington Creek 16.4 0.022 0.048 -0.0263 Bowmanville Creek 90.5 0.305 0.113 0.1925 Westside Creek 5.7 0.022 0.027 -0.0058 Soper Creek 75.4 0.200 0.196 0.0046 Bennet Creek 7.4 0.021 0.031 -0.0099 Lake Catchments 23.7 0.110 0.099 0.0113

Table 14: Thresholds for high recharge Annual Average Annual QR 1.15 QR Watershed Surplus (mm/yr) (mm/yr) (S) (mm/yr) Lynde Creek 330.28 161.0 185.2 Pringle Creek 364.40 123.2 141.7 Corbett Creek 358.21 100.3 115.3 Goodman Creek 372.44 141.5 162.7 Oshawa Creek 338.14 168.1 193.3 Harmony Creek 345.78 118.4 136.2 Farewell Creek 330.26 136.6 157.1 Robinson Creek 310.02 106.7 122.7 Tooley Creek 311.84 127.0 146.0 Black Creek 346.03 161.3 185.5 Darlington Creek 320.46 135.1 155.4 Bowmanville Creek 364.03 213.8 245.8 Westside Creek 354.57 98.9 113.8 Soper Creek 348.26 173.1 199.1 Bennet Creek 307.29 115.4 132.8 Lake Catchments 331.29 110.9 127.5

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Table 15: Total Water Demand Summary Current Future Current Groundwater Groundwater Surface Water Watershed Demand Demand Demand (m3/s) (m3/d) (m3/s) (m3/d) (m3/s) (m3/d) Lynde Creek 0.0819 7,074.2 0.0832 7,190.6 0.03345 2,890.3 Pringle Creek 0.0043 367.6 0.0043 368.3 0.00000 Corbett Creek 0.0001 9.5 0.0002 4.8 0.00000 Goodman Creek 0.0009 75.2 0.0009 75.4 0.00135 116.6 Oshawa Creek 0.0300 2,596.0 0.0309 2,672.6 0.00687 593.4 Harmony Creek 0.0095 816.8 0.0099 858.1 0.00000 Farewell Creek 0.0100 867.1 0.0105 908.6 0.00000 Robinson Creek 0.0023 202.3 0.0024 203.5 0.00000 Tooley Creek 0.0038 324.2 0.0039 337.4 0.00000 Black Creek 0.0062 537.4 0.0065 558.0 0.00000 Darlington Creek 0.0149 1,289.0 0.0154 1,328.7 0.00309 266.6 Bowmanville Creek 0.0239 2,064.7 0.0253 2,187.4 0.00154 133.3 Westside Creek 0.0015 125.7 0.0015 126.1 0.00000 Soper Creek 0.0170 1,472.9 0.0176 1,524.3 0.01333 1,151.9 Bennet Creek 0.0018 153.3 0.0018 155.2 0.00000 Lake Catchments 0.0032 272.7 0.0032 277.6 0.72583 62,711.8 Totals 0.2112 18,248.6 0.2174 18,786.6 0.78546 67,863.8

Table 16: Summary of permitted groundwater usage by permit class Groundwater Usage by Permit Class Consumption (m3/s) (m3/d) Concrete Plant / Drinking 0.000187 16.19 Dewatering 0.011476 991.53 Golf Course Irrigation 0.043408 3750.47 Maintenance 0.000024 2.07 Other- Commercial 0.000188 16.21 Snowmaking 0.020737 1791.72 Water Supply 0.000009 0.74

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Table 17: Summary of permitted surface water usage by permit class Surface Water Usage by Permit Class Consumption (m3/s) (m3/d) Field and Pasture Crops 0.003085 266.521 Fish Hatchery and Rearing 0.000766 66.204 Fruit Orchards 0.001542 133.260 Golf Course Irrigation 0.023304 2013.497 Industrial 0.051117 4416.541 Irrigation 0.007536 651.133 Market Gardens 0.001735 149.918 Municipal 0.672132 58072.162 Remediation 0.000964 83.288 Snowmaking 0.020372 1760.183 Tender Fruit Irrigation 0.003085 266.521 Water level control 0.001208 104.403 Wildlife Conservation 0.000602 51.972

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Un-Permitted Current Groundwater Demand Total Total Watershed Name Watershed No. Area Unserviced Unserviced Unserviced Unpermitted Unpermitted Unpermitted Unpermitted Population Water use Water Use Irregation Wells Livestock Wells Agricultural Water Use 0.067 Water Use square metres Persons m^3/day m^3/sec count count m^3/sec m^3/sec Lynde Creek Watershed 1 132185159 3158.82 211.64 0.00245 17 76 0.02691 0.02936 Pringle Creek Watershed 2 28469527 20.34 1.36 0.00002 3 11 0.00405 0.00407 Corbett Creek Watershed 3 14551031 142.38 9.54 0.00011 0 0 0.00000 0.00011 Goodman Creek Watershed 4 10268041 3.39 0.23 0.00000 1 2 0.00087 0.00087 Oshawa Creek Watershed 5 110208540 2079.02 139.29 0.00161 1 80 0.02344 0.02505 Harmony Creek Watershed 6 46686069 1121.77 75.16 0.00087 3 22 0.00723 0.00810 Farewell Creek Watershed 7 36325904 1126.75 75.49 0.00087 2 25 0.00781 0.00869 Robinson Creek Watershed 8 5703453 33.90 2.27 0.00003 0 8 0.00231 0.00234 Tooley Creek Watershed 9 10501202 360.61 24.16 0.00028 1 11 0.00347 0.00375 Black Creek Watershed 10 24244428 558.29 37.41 0.00043 1 19 0.00579 0.00622 Darlington Creek Watershed 11 16362549 1078.38 72.25 0.00084 0 9 0.00260 0.00344 Bowmanville Creek Watershed 12 90453847 3329.87 223.10 0.00258 2 67 0.01997 0.02255 Westside Creek Watershed 13 5728380 10.17 0.68 0.00001 0 5 0.00145 0.00145 Soper Creek Watershed 14 75444554 1394.64 93.44 0.00108 4 46 0.01447 0.01555 Bennett Creek Watershed 15 7426897 49.79 3.34 0.00004 0 6 0.00174 0.00177 Lake Ontario Watersheds 16 23721555 132.21 8.86 0.00010 3 3 0.00174 0.00184 Note: .335 m3/ person/day 0.00029 Note: 80% returned 50 m3/day at 0.5 consumption Totals: 0.01132 0.12384 0.13516 Table 18: Un-permitted Current Groundwater Demand

Total Current Groundwater Demand Total Current Groundwater Consumption by month (PTTW Permitted GW demand plus total unpermitted consumption) Watershed Name Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec Average Average

m3/sec m3/sec m3/sec m3/sec m3/sec m3/sec m3/sec m3/sec m3/sec m3/sec m3/sec m3/sec m3/sec m3/day Lynde Creek Watershed 0.07915 0.07915 0.07915 0.06425 0.08317 0.08317 0.08317 0.08317 0.07983 0.07457 0.11459 0.07915 0.0819 7074.18 Pringle Creek Watershed 0.00407 0.00429 0.00429 0.00429 0.00429 0.00429 0.00429 0.00429 0.00429 0.00429 0.00427 0.00407 0.0043 367.56 Corbett Creek Watershed 0.00011 0.00011 0.00011 0.00011 0.00011 0.00011 0.00011 0.00011 0.00011 0.00011 0.00011 0.00011 0.0001 9.54 Goodman Creek Watershed 0.00087 0.00087 0.00087 0.00087 0.00087 0.00087 0.00087 0.00087 0.00087 0.00087 0.00087 0.00087 0.0009 75.23 Oshawa Creek Watershed 0.02505 0.02505 0.02505 0.02986 0.03348 0.03348 0.03348 0.03348 0.03348 0.03347 0.02964 0.02505 0.0300 2595.98 Harmony Creek Watershed 0.00810 0.00810 0.00810 0.01013 0.01013 0.01013 0.01013 0.01013 0.01013 0.01013 0.01013 0.00810 0.0095 816.79 Farewell Creek Watershed 0.00869 0.00869 0.00869 0.01071 0.01071 0.01071 0.01071 0.01071 0.01071 0.01071 0.01071 0.00869 0.0100 867.12 Robinson Creek Watershed 0.00234 0.00234 0.00234 0.00234 0.00234 0.00234 0.00234 0.00234 0.00234 0.00234 0.00234 0.00234 0.0023 202.27 Tooley Creek Watershed 0.00375 0.00375 0.00375 0.00375 0.00375 0.00375 0.00375 0.00375 0.00375 0.00375 0.00375 0.00375 0.0038 324.16 Black Creek Watershed 0.00622 0.00622 0.00622 0.00622 0.00622 0.00622 0.00622 0.00622 0.00622 0.00622 0.00622 0.00622 0.0062 537.41 Darlington Creek Watershed 0.00344 0.00344 0.00344 0.02066 0.02066 0.02066 0.02066 0.02066 0.02066 0.02066 0.02066 0.00344 0.0149 1289.00 Bowmanville Creek Watershed 0.02255 0.02255 0.02255 0.02457 0.02457 0.02457 0.02457 0.02457 0.02457 0.02457 0.02457 0.02255 0.0239 2064.73 Westside Creek Watershed 0.00145 0.00145 0.00145 0.00145 0.00145 0.00145 0.00145 0.00145 0.00145 0.00145 0.00145 0.00145 0.0015 125.68 Soper Creek Watershed 0.01555 0.01555 0.01555 0.01790 0.01794 0.01794 0.01794 0.01794 0.01757 0.01757 0.01757 0.01555 0.0170 1472.93 Bennett Creek Watershed 0.00177 0.00177 0.00177 0.00177 0.00177 0.00177 0.00177 0.00177 0.00177 0.00177 0.00177 0.00177 0.0018 153.34 Lake Ontario Watersheds 0.00184 0.00184 0.00184 0.00381 0.00381 0.00381 0.00381 0.00381 0.00381 0.00381 0.00381 0.00184 0.0032 272.69

Totals: 0.18496 0.18519 0.18519 0.20272 0.22529 0.22529 0.22529 0.22529 0.22158 0.21631 0.25248 0.18496 0.2112 18248.59

Table 19: Total Current Groundwater Demand (QD) by Month

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Future Un-Permitted Groundwater Demand Total Total Watershed Name Watershed No. Area Unserviced Population Unserviced Unserviced Unpermitted Unpermitted Unpermitted Unpermitted Population 25 year Growth 55% Water Use Water Use Irregation Wells Livestock Wells Agricultural Water Use Current 0.55 0.067 Water Use square metres Persons Persons m^3/day m^3/sec count count m^3/sec m^3/sec Lynde Creek Watershed 1 132185159 3158.82 4896.17 328.04 0.00380 17 76 0.02691 0.03071 Pringle Creek Watershed 2 28469527 20.34 31.53 2.11 0.00002 3 11 0.00405 0.00408 Corbett Creek Watershed 3 14551031 142.38 220.69 14.79 0.00017 0 0 0.00000 0.00017 Goodman Creek Watershed 4 10268041 3.39 5.25 0.35 0.00000 1 2 0.00087 0.00087 Oshawa Creek Watershed 5 110208540 2079.02 3222.48 215.91 0.00250 1 80 0.02344 0.02594 Harmony Creek Watershed 6 46686069 1121.77 1738.74 116.50 0.00135 3 22 0.00723 0.00858 Farewell Creek Watershed 7 36325904 1126.75 1746.46 117.01 0.00135 2 25 0.00781 0.00917 Robinson Creek Watershed 8 5703453 33.90 52.55 3.52 0.00004 0 8 0.00231 0.00236 Tooley Creek Watershed 9 10501202 360.61 558.95 37.45 0.00043 1 11 0.00347 0.00391 Black Creek Watershed 10 24244428 558.29 865.35 57.98 0.00067 1 19 0.00579 0.00646 Darlington Creek Watershed 11 16362549 1078.38 1671.49 111.99 0.00130 0 9 0.00260 0.00390 Bowmanville Creek Watershed 12 90453847 3329.87 5161.30 345.81 0.00400 2 67 0.01997 0.02397 Westside Creek Watershed 13 5728380 10.17 15.76 1.06 0.00001 0 5 0.00145 0.00146 Soper Creek Watershed 14 75444554 1394.64 2161.70 144.83 0.00168 4 46 0.01447 0.01614 Bennett Creek Watershed 15 7426897 49.79 77.17 5.17 0.00006 0 6 0.00174 0.00180 Lake Ontario Watersheds 16 23721555 132.21 204.93 13.73 0.00016 3 3 0.00174 0.00190 Note: .335 m3/ person/day 0.00029 Note: 80% returned 50 m3/day at 0.5 consumption Totals: 0.01755 0.12384 0.14139 Table 20: Future Un-Permitted Groundwater Demand Total Future Groundwater Demand

Watershed Name Total Future Groundwater Consumption by month (PTTW Permitted GW demand plus total unpermitted consumption) Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec Average Average

m^3/sec m^3/sec m^3/sec m^3/sec m^3/sec m^3/sec m^3/sec m^3/sec m^3/sec m^3/sec m^3/sec m^3/sec m3/sec m3/day Lynde Creek Watershed 0.08050 0.08050 0.08050 0.06560 0.08452 0.08452 0.08452 0.08452 0.08118 0.07591 0.11593 0.08050 0.0832 7190.58 Pringle Creek Watershed 0.00408 0.00430 0.00430 0.00430 0.00430 0.00430 0.00430 0.00430 0.00430 0.00430 0.00428 0.00408 0.0043 368.31 Corbett Creek Watershed 0.00017 0.00017 0.00017 0.00017 0.00017 0.00017 0.00017 0.00017 0.00017 0.00017 0.00017 0.00017 0.0002 14.79 Goodman Creek Watershed 0.00087 0.00087 0.00087 0.00087 0.00087 0.00087 0.00087 0.00087 0.00087 0.00087 0.00087 0.00087 0.0009 75.35 Oshawa Creek Watershed 0.02594 0.02594 0.02594 0.03075 0.03436 0.03436 0.03436 0.03436 0.03436 0.03436 0.03052 0.02594 0.0309 2672.59 Harmony Creek Watershed 0.00858 0.00858 0.00858 0.01061 0.01061 0.01061 0.01061 0.01061 0.01061 0.01061 0.01061 0.00858 0.0099 858.12 Farewell Creek Watershed 0.00917 0.00917 0.00917 0.01119 0.01119 0.01119 0.01119 0.01119 0.01119 0.01119 0.01119 0.00917 0.0105 908.64 Robinson Creek Watershed 0.00236 0.00236 0.00236 0.00236 0.00236 0.00236 0.00236 0.00236 0.00236 0.00236 0.00236 0.00236 0.0024 203.52 Tooley Creek Watershed 0.00391 0.00391 0.00391 0.00391 0.00391 0.00391 0.00391 0.00391 0.00391 0.00391 0.00391 0.00391 0.0039 337.45 Black Creek Watershed 0.00646 0.00646 0.00646 0.00646 0.00646 0.00646 0.00646 0.00646 0.00646 0.00646 0.00646 0.00646 0.0065 557.98 Darlington Creek Watershed 0.00390 0.00390 0.00390 0.02112 0.02112 0.02112 0.02112 0.02112 0.02112 0.02112 0.02112 0.00390 0.0154 1328.74 Bowmanville Creek Watershed 0.02397 0.02397 0.02397 0.02599 0.02599 0.02599 0.02599 0.02599 0.02599 0.02599 0.02599 0.02397 0.0253 2187.44 Westside Creek Watershed 0.00146 0.00146 0.00146 0.00146 0.00146 0.00146 0.00146 0.00146 0.00146 0.00146 0.00146 0.00146 0.0015 126.06 Soper Creek Watershed 0.01614 0.01614 0.01614 0.01850 0.01853 0.01853 0.01853 0.01853 0.01817 0.01817 0.01817 0.01614 0.0176 1524.32 Bennett Creek Watershed 0.00180 0.00180 0.00180 0.00180 0.00180 0.00180 0.00180 0.00180 0.00180 0.00180 0.00180 0.00180 0.0018 155.17 Lake Ontario Watersheds 0.00190 0.00190 0.00190 0.00387 0.00387 0.00387 0.00387 0.00387 0.00387 0.00387 0.00387 0.00190 0.0032 277.56

Totals: 0.19119 0.19141 0.19141 0.20895 0.23151 0.23151 0.23151 0.23151 0.22781 0.22254 0.25870 0.19119 0.2174 18786.62

Table 21: Total Future Groundwater Demand (QD) by Month

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Total Current Surface Water Demand Total Surface Water Consumption by month (PTTW Permitted SW consumption)

Watershed Name No. Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec Average Average

m3/sec m3/sec m3/sec m3/sec m3/sec m3/sec m3/sec m3/sec m3/sec m3/sec m3/sec m3/sec m3/sec m3/day Lynde Creek Watershed 1 0.04981 0.04981 0.04981 0.00817 0.02166 0.02166 0.03617 0.02166 0.02146 0.02076 0.05065 0.04981 0.03345 2890.28 Pringle Creek Watershed 2 0.00000 0.00 Corbett Creek Watershed 3 0.00000 0.00 Goodman Creek Watershed 4 0.00000 0.00000 0.00202 0.00202 0.00202 0.00202 0.00202 0.00202 0.00202 0.00202 0.00000 0.00000 0.00135 116.63 Oshawa Creek Watershed 5 0.00077 0.00077 0.00077 0.01069 0.01069 0.01069 0.01069 0.01069 0.01069 0.00892 0.00626 0.00077 0.00687 593.38 Harmony Creek Watershed 6 0.00000 0.00 Farewell Creek Watershed 7 0.00000 0.00 Robinson Creek Watershed 8 0.00000 0.00 Tooley Creek Watershed 9 0.00000 0.00 Black Creek Watershed 10 0.00000 0.00 Darlington Creek Watershed 11 0.00000 0.00000 0.00000 0.00463 0.00463 0.00463 0.00463 0.00463 0.00463 0.00463 0.00463 0.00000 0.00309 266.58 Bowmanville Creek Watershed 12 0.00000 0.00000 0.00000 0.00231 0.00231 0.00231 0.00231 0.00231 0.00231 0.00231 0.00231 0.00000 0.00154 133.29 Westside Creek Watershed 13 0.00000 0.00 Soper Creek Watershed 14 0.00000 0.00000 0.00000 0.00961 0.02803 0.02803 0.03465 0.02803 0.02238 0.00463 0.00463 0.00000 0.01333 1151.88 Bennett Creek Watershed 15 0.00000 0.00 Lake Ontario Watersheds 16 0.72341 0.72341 0.72341 0.72756 0.72756 0.72756 0.72756 0.72756 0.72756 0.72756 0.72341 0.72341 0.72583 62711.81 Total 0.77398 0.77398 0.77601 0.76501 0.79691 0.79691 0.81804 0.79691 0.79107 0.77084 0.79189 0.77398 0.78546 67863.85

Table 22: Total Current Surface Water Demand (QD) by Month

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Table 23: Discharge from water pollution control facilities and estimated reserve Monthly and Average Annual Discharge (m3/d) WPCP Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Avg Pringle Creek* 8.01 14.28 9.27 8.88 7.45 6.61 5.98 6.24 6.02 7.23 9.54 9.27 8.25 Monthly and Average Annual Reserve (m3/s) Pringle Creek 0.001 0.004 0.001 0.002 0.001 0.001 0.001 0.002 0.001 0.001 0.002 0.002 0.002 *Combined effluents from WPCP 1 and 2

Table 24: QP90 flows from Environment Canada gauges. 3 QP90 flows in m /s Gauge Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Lynde Creek near Whitby 0.33 0.30 0.62 0.74 0.37 0.19 0.14 0.14 0.18 0.26 0.41 0.38 Oshawa Creek at Oshawa 0.56 0.55 0.80 0.97 0.71 0.55 0.48 0.47 0.48 0.54 0.64 0.61 Harmony Creek at Oshawa 0.09 0.10 0.19 0.22 0.11 0.06 0.04 0.03 0.05 0.07 0.13 0.13 Farewell Creek at Oshawa 0.23 0.22 0.39 0.53 0.25 0.12 0.09 0.09 0.13 0.16 0.32 0.27 Bowmanville Cr. at Bowmanville 0.67 0.67 0.93 1.17 0.79 0.63 0.56 0.56 0.59 0.69 0.83 0.84 Soper Creek at Bowmanville 0.39 0.40 0.67 0.80 0.50 0.35 0.27 0.28 0.31 0.38 0.49 0.49

Table 25: Simulated monthly lower decile flows (m3/s) at the catchment outlets based on the PRMS model. Watershed Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Lynde Creek 0.605 0.477 0.726 0.795 0.379 0.114 0.039 0.020 0.067 0.174 0.729 0.973 Pringle Creek 0.115 0.083 0.112 0.120 0.063 0.017 0.005 0.002 0.010 0.030 0.120 0.172 Corbett Creek 0.050 0.037 0.048 0.050 0.027 0.008 0.002 .0004 0.002 0.009 0.034 0.069 Goodman Creek 0.046 0.033 0.042 0.045 0.025 0.007 0.002 0.001 0.006 0.015 0.060 0.070 Oshawa Creek 0.515 0.412 0.610 0.699 0.334 0.098 0.029 0.015 0.049 0.152 0.694 0.849 Harmony Creek 0.168 0.115 0.167 0.205 0.106 0.028 0.007 0.002 0.011 0.040 0.165 0.274 Farewell Creek 0.143 0.103 0.150 0.178 0.091 0.024 0.006 0.001 0.008 0.035 0.167 0.243 Robinson Creek 0.020 0.015 0.020 0.022 0.012 0.003 0.001 .0001 .0003 0.003 0.009 0.027 Tooley Creek 0.042 0.031 0.043 0.044 0.022 0.006 0.002 .0004 0.002 0.008 0.035 0.063 Black Creek 0.110 0.083 0.115 0.129 0.064 0.017 0.005 0.002 0.009 0.035 0.169 0.187 Darlington Creek 0.067 0.051 0.071 0.070 0.035 0.010 0.003 0.001 0.004 0.016 0.067 0.104 Bowmanville Creek 0.471 0.369 0.632 0.807 0.347 0.114 0.048 0.034 0.092 0.192 0.778 0.795 Westside Creek 0.019 0.014 0.018 0.019 0.010 0.003 0.001 .0001 .0003 0.003 0.013 0.028 Soper Creek 0.369 0.294 0.442 0.503 0.215 0.062 0.021 0.008 0.031 0.109 0.499 0.610 Bennet Creek 0.032 0.031 0.038 0.030 0.013 0.003 0.001 .0002 .0003 0.004 0.012 0.038 Lake Catchments 0.080 0.063 0.086 0.077 0.040 0.012 0.004 0.001 0.005 0.017 0.062 0.109

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Table 26: Groundwater reserve estimation for the gauged catchments. Reserve Estimation Method Average Minimum Smoothed Median Flow Minima Flow Method Method Method Gauge (m3/s) (m3/s) (m3/s) Lynde Creek 0.048 0.038 0.041 Oshawa Creek 0.071 0.064 0.070 Harmony Creek 0.017 0.0129 0.015 Farewell Creek 0.036 0.030 0.030 Bowmanville Creek 0.086 0.077 0.087 Soper Creek 0.057 0.051 0.050

Table 27: Groundwater reserve estimation for the CLOCA watersheds. Ground- water Watershed Reserve (m3/s) Lynde Creek 0.068 Pringle Creek 0.011 Corbett Creek 0.004 Goodman Creek 0.002 Oshawa Creek 0.065 Harmony Creek 0.018 Farewell Creek 0.018 Robinson Creek 0.0004 Tooley Creek 0.003 Black Creek 0.011 Darlington Creek 0.004 Bowmanville Creek 0.082 Westside Creek 0.001 Soper Creek 0.041 Bennet Creek 0.002 Lake Catchments 0.009

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Q % Demand Water Current Demand Stress Watershed Q Q Q Q Condi- Current Level Recharge In Supply Reserve tions Condi- Current (m3/s) (m3/s) (m3/s) (m3/s) (m3/s) tions Conditions Lynde Creek 0.6765 0.2020 0.8785 0.0679 0.0819 10.10 Moderate Pringle Creek 0.1115 0.0420 0.1535 0.0106 0.0043 2.98 Low Corbett Creek 0.0463 0.0170 0.0633 0.0041 0.0001 0.19 Low Goodman Creek 0.0462 0.0150 0.0612 0.0024 0.0009 1.48 Low Oshawa Creek 0.5892 0.1970 0.7862 0.0650 0.0300 4.17 Low Harmony Creek 0.1756 0.0810 0.2566 0.0175 0.0095 3.95 Low Farewell Creek 0.1577 0.1100 0.2677 0.0168 0.0100 4.00 Low Robinson Creek 0.0193 0.0150 0.0343 0.0004 0.0023 6.89 Low Tooley Creek 0.0423 0.0200 0.0623 0.0028 0.0038 6.30 Low Black Creek 0.1243 0.0670 0.1913 0.0106 0.0062 3.44 Low Darlington Creek 0.0702 0.0220 0.0922 0.0043 0.0149 16.97 Moderate Bowmanville Creek 0.6149 0.3050 0.9199 0.0816 0.0239 2.85 Low Westside Creek 0.0180 0.0220 0.0400 0.0013 0.0015 3.76 Low Soper Creek 0.4152 0.2000 0.6152 0.0407 0.0170 2.97 Low Bennet Creek 0.0272 0.0210 0.0482 0.0018 0.0018 3.82 Low Lake Catchments 0.0747 0.1100 0.1847 0.0086 0.0032 1.79 Low Table 28: Groundwater stress assessment summary - current conditions

Percent Water Demand = QDEMAND*100/(QSUPPLY-QRESERVE) Stress Watershed Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Level Lynde Creek 10 10 10 8 10 10 10 10 10 9 14 10 Low Pringle Creek 3 3 3 3 3 3 3 3 3 3 3 3 Low Corbett Creek 0 0 0 0 0 0 0 0 0 0 0 0 Low Goodman Creek 1 1 1 1 1 1 1 1 1 1 1 1 Low Oshawa Creek 3 3 3 4 5 5 5 5 5 5 4 3 Low Harmony Creek 3 3 3 4 4 4 4 4 4 4 4 3 Low Farewell Creek 3 3 3 4 4 4 4 4 4 4 4 3 Low Robinson Creek 7 7 7 7 7 7 7 7 7 7 7 7 Low Tooley Creek 6 6 6 6 6 6 6 6 6 6 6 6 Low Black Creek 3 3 3 3 3 3 3 3 3 3 3 3 Low Darlington Creek 4 4 4 24 24 24 24 24 24 24 24 4 Low Bowmanville Creek 3 3 3 3 3 3 3 3 3 3 3 3 Low Westside Creek 4 4 4 4 4 4 4 4 4 4 4 4 Low Soper Creek 3 3 3 3 3 3 3 3 3 3 3 3 Low Bennet Creek 4 4 4 4 4 4 4 4 4 4 4 4 Low Lake Catchments 1 1 1 2 2 2 2 2 2 2 2 1 Low Table 29: Monthly groundwater stress threshold assessment - current conditions

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Q % Demand Water Future Demand Stress Watershed Q Q Q Q Condi- Future Level Recharge In Supply Reserve tions Condi- Future (m3/s) (m3/s) (m3/s) (m3/s) (m3/s) tions Conditions Lynde Creek 0.6765 0.2020 0.8785 0.0679 0.0832 10.27 Moderate Pringle Creek 0.1115 0.0420 0.1535 0.0106 0.0043 2.98 Low Corbett Creek 0.0463 0.0170 0.0633 0.0041 0.0002 0.29 Low Goodman Creek 0.0462 0.0150 0.0612 0.0024 0.0009 1.48 Low Oshawa Creek 0.5892 0.1970 0.7862 0.0650 0.0309 4.29 Low Harmony Creek 0.1756 0.0810 0.2566 0.0175 0.0099 4.15 Low Farewell Creek 0.1577 0.1100 0.2677 0.0168 0.0105 4.19 Low Robinson Creek 0.0193 0.0150 0.0343 0.0004 0.0024 6.93 Low Tooley Creek 0.0423 0.0200 0.0623 0.0028 0.0039 6.56 Low Black Creek 0.1243 0.0670 0.1913 0.0106 0.0065 3.57 Low Darlington Creek 0.0702 0.0220 0.0922 0.0043 0.0154 17.49 Moderate Bowmanville Creek 0.6149 0.3050 0.9199 0.0816 0.0253 3.02 Low Westside Creek 0.0180 0.0220 0.0400 0.0013 0.0015 3.77 Low Soper Creek 0.4152 0.2000 0.6152 0.0407 0.0176 3.07 Low Bennet Creek 0.0272 0.0210 0.0482 0.0018 0.0018 3.87 Low Lake Catchments 0.0747 0.1100 0.1847 0.0086 0.0032 1.82 Low Table 30: Groundwater stress assessment summary - future conditions

Percent Water Demand = QDEMAND*100/(QSUPPLY-QRESERVE) Stress Level Watershed Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Future Conditions Lynde Creek 10 10 10 8 10 10 10 10 10 9 14 10 Low Pringle Creek 3 3 3 3 3 3 3 3 3 3 3 3 Low Corbett Creek 0 0 0 0 0 0 0 0 0 0 0 0 Low Goodman Creek 1 1 1 1 1 1 1 1 1 1 1 1 Low Oshawa Creek 4 4 4 4 5 5 5 5 5 5 4 4 Low Harmony Creek 4 4 4 4 4 4 4 4 4 4 4 4 Low Farewell Creek 4 4 4 4 4 4 4 4 4 4 4 4 Low Robinson Creek 7 7 7 7 7 7 7 7 7 7 7 7 Low Tooley Creek 7 7 7 7 7 7 7 7 7 7 7 7 Low Black Creek 4 4 4 4 4 4 4 4 4 4 4 4 Low Darlington Creek 4 4 4 24 24 24 24 24 24 24 24 4 Low Bowmanville Creek 3 3 3 3 3 3 3 3 3 3 3 3 Low Westside Creek 4 4 4 4 4 4 4 4 4 4 4 4 Low Soper Creek 3 3 3 3 3 3 3 3 3 3 3 3 Low Bennet Creek 4 4 4 4 4 4 4 4 4 4 4 4 Low Lake Catchments 1 1 1 2 2 2 2 2 2 2 2 1 Low Table 31: Monthly groundwater stress threshold assessment - future conditions.

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Percent Water Demand = QDEMAND*100/(QSUPPLY-QRESREVE) Stress Watershed Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Level Lynde Creek 11 10 7 2 9 25 123 78 18 8 8 9 Significant Pringle Creek 0 0 0 0 0 0 0 0 0 0 0 0 Low Corbett Creek 0 0 0 0 0 0 0 0 0 0 0 0 Low Goodman Creek 0 0 4 6 12 35 92 135 15 7 0 0 Significant Oshawa Creek 0 0 0 2 5 15 49 58 12 4 1 0 Significant Harmony Creek 0 0 0 0 0 0 0 0 0 0 0 0 Low Farewell Creek 0 0 0 0 0 0 0 0 0 0 0 0 Low Robinson Creek 0 0 0 0 0 0 0 0 0 0 0 0 Low Tooley Creek 0 0 0 0 0 0 0 0 0 0 0 0 Low Black Creek 0 0 0 0 0 0 0 0 0 0 0 0 Low Darlington Creek 0 0 0 9 18 57 185 514 37 16 7 0 Significant Bowmanville Creek 0 0 0 1 1 3 6 5 2 1 0 0 Low Westside Creek 0 0 0 0 0 0 0 0 0 0 0 0 Low Soper Creek 0 0 0 3 18 58 207 286 25 3 1 0 Significant Bennet Creek 0 0 0 0 0 0 0 0 0 0 0 0 Low Lake Catchments Not Applicable – Demand is only from Lake Ontario Note: QSUPPLY is the median flow (QP50) for the month. QRESERVE is the lower decile flow (QP90) for the month.

Table 32: Surface water stress assessment - current and future conditions.

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12 FIGURES

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Figure 1: Location of the Study Area

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Figure 2: Watersheds in the CLOCA area.

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Figure 3: Water Budget/Water Quantity Risk Assessment framework (from MOE, 2007).

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Figure 4: Components of a steady-state water budget (after MOE, 2007).

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Figure 5: Streams in the CLOCA area classified by Strahler Code.

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Figure 6: Flow chart for the PRMS code.

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Figure 7: Flowchart for the PRMS snowpack sub-model.

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Figure 8: Land surface topography in the CLOCA area from 30-m DEM (data from MNR).

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Figure 9: Areas of hummocky topography (data provided by MNR).

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Figure 10: Slope classification scheme for the CLOCA area classified from 30-m DEM.

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Figure 11: Physiography of the CLOCA area (Chapman and Putnam, 1984).

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Figure 12: Land use and ecological land classification for the CLOCA area (data provided by CLOCA).

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Figure 13: Surficial geology in the CLOCA area (Sharpe et al., 1997)

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Figure 14: Example of land-use based input parameter (% imperviousness) for the PRMS model.

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Figure 15: Precipitation normals 1971-2000 interpolated using inverse distance squared weighting.

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Figure 16: Monthly average precipitation for stations within the CLOCA area.

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Figure 17: Sample input data set for the PRMS model.

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Figure 18: Location of HYDAT and CLOCA stream gauges.

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Figure 19: Average daily flow for the period of record for HYDAT stations in the CLOCA area.

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Figure 20: Total flow and separated baseflow (two methods) for Lynde Creek near Whitby (02HC018).

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Figure 21: Extent of the East Model.

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Figure 22: Simulated versus observed annual average total flows at Environment Canada gauges

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Figure 23: Simulated versus estimated annual average baseflows at Environment Canada gauges

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Figure 24: Simulated annual average precipitation (POBS) for WY1981 to WY1999.

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Figure 25: Simulated annual average net precipitation (PNET).

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Figure 26: Simulated annual average net precipitation after depression storage losses.

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Figure 27: Simulated annual average potential evapotranspiration (PET).

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Figure 28: Simulated annual average actual evapotranspiration (AET).

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Figure 29: Simulated annual average total evapotranspiration (AET + Interception).

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Figure 30: Simulated annual average runoff (RO).

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Figure 31: Simulated annual average direct recharge to the saturated zone (UGS).

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Figure 32: Simulated annual average recharge to the unsaturated zone.

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Figure 33: Simulated annual average groundwater recharge (QR).

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Figure 34: Simulated monthly average groundwater recharge (UGS+USS) for November.

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Figure 35: Simulated monthly average groundwater recharge (UGS+USS) for July.

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Figure 36: Applied recharge for the East Model using PRMS results for the CLOCA area.

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Figure 37: Simulated and observed heads in model Layer 3 representing the Oak Ridges Aquifer Complex (where present).

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Figure 38: Simulated versus observed ORAC heads in the CLOCA area and local model calibration statistics.

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Figure 39: Simulated and observed heads in model Layer 5 representing the Thorncliffe Aquifer Complex.

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Figure 40: Simulated groundwater discharge to streams in the CLOCA area.

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Figure 41: Ranked-flow curve for Lynde Creek at Whitby (02HC018) showing streamflow statistics (1959 -2003).

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Figure 42: Median flows for the period of record at each gauge expressed in mm/yr.

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3 Figure 43: Annual average groundwater recharge (QR) by watershed (m /s).

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Figure 44: Average annual lateral inflow (QIN) by watershed.

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Figure 45: Average annual lateral outflow (QOUT) by watershed

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Figure 46: Average annual groundwater supply QSUPPLY (QR + QIN) by watershed.

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Figure 47: Backward particle tracking from potential seeps and springs in the ORM

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Figure 48: Reverse particle tracking from high groundwater discharge areas

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Figure 49: High volume recharge area identified by backward tracking from cells with simulated groundwater discharge to streams greater than 1 L/s

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Figure 50: High Volume Recharge Areas by Watershed

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Figure 51: High Volume Recharge Areas by Physiographic Region

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Figure 52: High Volume Recharge Areas by Jurisdiction

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Figure 53: Significant Groundwater Recharge Areas (as defined under the Clean Water Act, 2006)

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Figure 54: Location of surface water Permits to Take Water

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Figure 55: Location of groundwater Permits to Take Water

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Figure 56: Pringle Creek Sewage Treatment Plant near Hwy 401

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Figure 57: Annual average groundwater reserve by catchment

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Figure 58: Percent Water Demand by catchment (current conditions)

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Figure 59: Final groundwater stress levels by catchment

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Figure 60: Surface water stress levels by catchment

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Figure 61: Cumulative flow analysis for Lynde Creek at Whitby (1959 to 2003)

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Figure 62: Cumulative flow analysis for Oshawa Creek (1959 to 2003)

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13 Appendix A: Summary of Conceptual Understanding

13.1 Overview

The overall layout of the main body of this report addresses the components and issues related to a detailed Tier 1 water budget. As such, the main body focuses on water supply, demand, reserve and finally watershed stress assessment. A description of the conceptual hydrostratigraphic model is placed here as a reference and aid to the readers of this report. Some of the information in this appendix, presented here as a summary of the conceptual understanding, is also discussed, in the context of numerical model development, in the main body of the report. For a more complete description of the conceptual model the reader is referred to CLOCA (2006), CLOCA (2007), and Kassenaar and Wexler (2006).

13.2 Topography and Physiography

Topography for the CLOCA area is shown in Figure 8. Higher elevations occur along an east- west ridge that runs across the top of the study area and forms the northern surface water divide. Highest elevations, over 400 metres above sea level (masl), occur in the northwest corner of the study area. Lower elevations occur at the Lake Ontario shoreline (about 75.2 masl) and in the deeply incised stream valleys that trend north-south. Areas of hummocky topography associated with the Oak Ridges Moraine (ORM) are shown in Figure 9 and often act as areas of focused recharge.

The study area falls within three major physiographic regions (Figure 11) that include: the Oak Ridges Moraine; the South slope; and the Iroquois plain (Chapman and Putnam, 1984). The northern part of CLOCA area is within the ORM physiographic region. The ORM contains four major wedge-shaped sediment deposits with narrower bands of sediments connecting them. The middle two wedges, the Uxbridge wedge to the west and the Pontypool wedge to the east, are located near the northwestern and northeastern corners of the study area, respectively. The ORM represents the most significant groundwater recharge area in the watersheds and serves as the headwaters for Lynde, Oshawa, Bowmanville, and Soper Creeks.

The South Slope physiographic region extends southward from the base of the ORM towards Lake Ontario. Chapman and Putman (1984) describe the South slope as a drumlinized plain, consisting of areas of thin aeolian sand deposits underlain by glacial deposits, mainly till. The South Slope is characterized by south trending drainage with sharply incised valleys. Harmony, Farewell, Black and Pringle Creeks and some of the tributaries to the larger streams have their headwaters on the South Slope.

The southernmost physiographic region is the Iroquois plain which includes a northerly east- west trending band of sandy beach and shallow water lacustrine deposits approximately 2 km in width and a southerly plain formed by fine-grained lacustrine deposits. Both are remnants of Glacial Lake Iroquois. Because of the difference in material and hydrologic function, this physiographic region is often separated into two areas: the Iroquois beach and the Iroquois plain regions. The Iroquois beach region is marked by low-lying bluffs and gravel bars. The beach deposits have high rates of infiltration, but because they are underlain by a regional till

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CLOCA Tier 1 Water Budget Report January, 2009 unit, the water table is often shallow and high ET losses can occur. These deposits serve as an easily accessible source of groundwater for domestic use and provide supplementary groundwater discharge to streams. The Iroquois plain region south of the beach deposits is flatter and composed of much finer-grained deposits. The smaller streams that discharge directly to Lake Ontario, such as Corbett and Tooley Creeks, have their headwaters on the Iroquois plain.

The majority of the population of the CLOCA area is concentrated on the Iroquois plain with most settlements serviced by pipelines from Lake Ontario. The exceptions are Macedonian Village, located south of Highway 7 west of Cochrane Road, and Mitchell‟s Corners north of Courtice at Taunton Road. These communities are currently serviced by shallow private wells. Development on the Iroquois Beach and north to the boundary of the Greenbelt is expected to increase over the next decades. It is likely that municipal supplies using Lake Ontario or groundwater will be provided to settlements north of the Iroquois plain as further development takes place.

13.3 Hydrostratigraphy

The geology of the study area generally consists of Quaternary sediments of variable thickness overlying Ordovician bedrock. The Quaternary sediments consist of a sequence of glacial and interglacial (lacustrine/fluvial) units recording deposition over approximately the last 135,000 years. There are three important geologic features present within the CLOCA watersheds including:

bedrock and associated valley systems which may contain sand and gravel deposits; the ORM which forms a high recharge area and headwaters for the larger streams; and areas where low-permeability Quaternary sediments have been eroded and replaced with sands and silt (“tunnel channels“).

The stratigraphy described here is derived mainly from discussions in the ORM Groundwater Study conducted for YPDT-CAMC (Kassenaar and Wexler, 2006). The discussion here focuses on the link between the geology and groundwater and surface water systems.

13.3.1 Stratigraphic Framework

The stratigraphic framework for the study area is well established from previous work (Karrow, 1967; Dreimanis and Karrow, 1972; Singer, 1974; Funk, 1977; Brookfield et al., 1982; Sharpe et al., 2002a, b). The GSC constructed three-dimensional geologic surfaces which group the pertinent geological deposits into five units including:

1. Halton Till (youngest); 2. Oak Ridges Moraine Deposits; 3. Newmarket Till; 4. Lower Sediments; and 5. Bedrock (oldest).

Regional unconformities occur at the top of the bedrock and the top of the Newmarket Till. The GSC has provided preliminary information on the locations of tunnel channels that trend roughly north-south to northeast-southwest through part of the study area (Russell et al., 2003). The YPDT-CAMC study subdivided the Lower Sediment deposits into three additional stratigraphic

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CLOCA Tier 1 Water Budget Report January, 2009 units to provide the detail needed to develop a groundwater flow model. Names for these eight units were selected based on the stratigraphy along the Lake Ontario shoreline:

Layer 1: Surficial Deposits and/or weathered Halton/Kettleby Aquitard Layer 2: Halton/Kettleby Aquitard Layer 3: Oak Ridges Aquifer Complex (ORAC) and/or weathered Newmarket Layer 4: Newmarket Aquitard and/or Tunnel Channel silts Layer 5: Thorncliffe Aquifer Complex (TAC) and/or Tunnel Channel sediments Layer 6: Sunnybrook Aquitard Layer 7: Scarborough Aquifer Complex (SAC) Layer 8: Weathered Bedrock

13.3.2 Bedrock Geology

Bedrock underlying the study area consists of limestone and shale of the Middle Ordovician Lindsay Formation and shale of the Upper Ordovician Blue Mountain Formation (Figure 63). Regionally, the bedding dips gently toward the southwest. Bedrock exposure is limited to a few quarries, along stream beds, and along the Lake Ontario shoreline.

Bedrock topography, as interpolated from the available borehole data, is presented in Error! Reference source not found.. The topographic lows are likely the result of erosion related to fluvial drainage systems that originated at higher bedrock elevation north of the study area. The very distinct bedrock valley in the northern part of Lynde Creek was inferred from borehole data analyzed as part of the refinement of the bedrock surface in York Region and the City of Toronto (described in Kassenaar and Wexler, 2006). The bedrock low in the Oshawa Creek area, however, may be due an erroneously coded borehole depth. The bedrock geology is currently being reviewed and refined as part of on-going YPDT-CAMC work in Durham Region and better representation of the valley systems will be forthcoming.

Delineating bedrock valleys is important for understanding groundwater/surface water interaction. For example, where streams parallel the bedrock valleys, increases in valley width and depth in the direction of flow can result in an increase in transmissivity of the sediment package underlying the stream. The resulting decrease in the groundwater gradient could lead to a decrease in baseflow along the stream reach. Such decreases were noted in the lower reaches of the Rouge River west of the study area.

13.3.3 Quaternary Sediments

The Quaternary sediments are late Pleistocene in age and unconformably overlie Paleozoic bedrock. These sediments are up to 220 m thick and consist of glacial and interglacial deposits formed within the last 135,000 years (Eyles, 2002; Karrow, 1989). The sediment sequence is well exposed in the southern part of the study area along the Lake Ontario bluffs. This complex sedimentary package generally consists of till, glaciolacustrine sand, silt, clay and diamicton and includes Illinoian-age till and warm-climate interglacial sediments at the base of the Quaternary sequence (Karrow, 1967). Figure 64 summarizes the Quaternary deposits found within the CLOCA watersheds. The Don Formation and underlying York Till were not mapped within the study area because of their limited extent and very limited data. Detailed descriptions of the Quaternary sediments can be found in the two earlier CLOCA reports (2006 and 2007) and in Kassenaar and Wexler (2006).

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13.3.3.1 Scarborough Formation

The Scarborough Formation marks the start of the Wisconsinan glaciation (approximately 100,000 years B.P.). These deposits consist of organic-rich (peat) sands overlying silts and clays deposited in a fluvial-deltaic system fed by large braided melt-water streams (Karrow, 1967; Eyles, 1997). The lower prodelta silts and clays are up to 60 m thick at the Scarborough Bluffs along Lake Ontario and are thought to be in transitional contact with the muds of the underlying Don Formation (Eyles, 1987) Figure 65. The upper sands are channelized in some locations, possibly as a result of fluvial erosion due to fluctuating lake levels. Scarborough Formation deposits are thought to extend from the Lake Ontario shore northward (Fligg and Rodrigues, 1983; Eyles et al., 1985; Pugin et al., 1996; Sharp et al., 1996). It is interpreted to be absent (less than 0.5 m thick) throughout much of the study area and appears thickest in bedrock lows.

13.3.3.2 Sunnybrook Drift

The Sunnybrook Drift unit was deposited about 45,000 years ago and consists mainly of silt to silty clay diamicton. It is generally less than 10 to 20 m thick but is thicker over bedrock lows and in the northern part of the Lynde Creek watershed Figure 66. It has been partially removed by erosional activity or simply not deposited over much of the southern half of the study area (CLOCA, 2007).

13.3.3.3 Thorncliffe Formation

The Thorncliffe Formation deposits consist of stratified sand and silty sand and rhythmically stratified silt and clay, as well as minor local pebbly silt and clay diamicton units. This unit is present throughout most of the study area and the interpreted thickness is shown in CLOCA (2007). The unit thickens considerably under the Oak Ridges moraine to the Northwest of Lynde Creek and to the northeast of Bowmanville and Soper Creeks.

The Thorncliffe Formation is often exposed on the edges of the deeper ravines near Lake Ontario and along the shoreline. However, Figure 67 also shows an unusually large exposure of Thorncliffe deposits in the Enniskillen area in the northern part of the Bowmanville watersheds. Similar-sized exposures can be seen in the Wilmot Creek watershed to the east and smaller exposures are present in the Oshawa and Soper Creek watersheds. These areas would receive direct recharge from precipitation. Water discharging from exposures of the overlying aquifers at the edges of the valleys may also re-infiltrate the Thorncliffe Formation. Much of the recharge would likely discharge locally to the stream reaches within the valleys.

13.3.3.4 Newmarket Till

The Newmarket Till is a dense, over-consolidated diamicton deposited by the Laurentide ice sheet when it was at its maximum extent approximately 18-20,000 years ago. It is a massive, stony (3-10 %) and dense silty sand diamicton up to 60 m thick. It contains thin, 2-5 cm thick, interbeds of sand and silt, boulder pavements and fractures and joints. The till can be traced as a stratigraphic marker across the entire study area. The upper surface of the Newmarket Till was affected by widespread erosion and forms a regional unconformity (Sharpe et al., 2002a).

The Newmarket Till separates upper aquifer systems associated with the Oak Ridges Moraine from lower aquifer systems that occur within deposits of the Thorncliffe Formation and the

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Scarborough Formation. The till has been breached where it was eroded by rigorous meltwater activity (“tunnel channels”) in the northern part of the study area.

Hydrogeologic investigations (e.g., Gerber, 1999; Gerber and Howard, 1996; 2000; and Gerber et al., 2001) suggest that bulk hydraulic conductivity (K) of the Newmarket Till is controlled by structures or pathways such as sand seams and fractures. Isotopic data and regional water balance/groundwater flow modelling (Gerber, 1999 and Kassenaar and Wexler, 2006) suggest -9 -10 vertical bulk K values on the order of 5x10 to 10 m/s. Tests on core samples, in contrast, -11 -10 yield much lower estimates ranging from 10 to 10 m/s. Vertical leakage through the Newmarket Till to the underlying Thorncliffe Formation is estimated at 30-40 mm/yr. The amount of vertical leakage is much higher where the till has been partly or entirely removed by tunnel channel erosion. Rates of leakage in these areas depend on the thickness of the remaining till and the hydraulic properties of the channel infill sediments.

The Newmarket till is up to 65 m thick (Figure 68) locally but is generally less than 40 m thick. The till is thin in the tunnel channel areas to the north of the study area (for example, south of Lake Scugog). The till is also thin in the southern part of the study area where it may have been eroded by wave action by Glacial Lake Iroquois and by fluvial processes during subsequent lower lake stages.

13.3.3.5 Regional Unconformity (“Tunnel Channels”)

A network of south-southwest-oriented channels has been cut into or through the Newmarket Till, particularly to the north of the ORM. These channels are relatively easy to map from topographic data in the north but are harder to trace when they extend southward beneath the ORM. The channels can be one to four km wide at surface and tens of metres deep. As noted, the channels are cut into the Newmarket Till but, in some cases, they may penetrate into the Lower Sediments. The infill sediments in the channels consist mainly of sandy and silty sediments; however, some channels contain thick (10-15 m), cross-bedded gravels (Shaw and Gorrell, 1991; Pugin et al., 1999; Russell et al., 2002). Upward-fining of these sediments is attributed to waning flow (e.g. Shaw and Gorrell, 1991). Locally, coarse channel fill sediments may be hydrogeologically significant as high yield aquifers (Sharpe et al., 1996). More importantly, the erosion of the intervening Newmarket Till allows for direct hydraulic connection between the upper and lower aquifers.

Possible tunnel channel locations within the study area occur north of the headwaters of Oshawa Creek and near the YPDT-CAMC Grasshopper Road borehole located in the northeast Bowmanville Creek headwater area.

13.3.3.6 Oak Ridges Moraine Deposits

The ORM is an extensive stratified sediment complex 160 km long and 5 to 20 km wide. Rhythmically interbedded fine sands and silts are the dominant sediments, but coarse, diffusely- bedded sands and heterogeneous gravels are prominent locally, at the apex of fans and at depth in channels. Clay laminae are also present locally. The deposits are interpreted as glaciofluvial, transitional to glaciolacustrine subaqueous fan, and delta sediments. They were deposited in a glacial lake ponded between two glacial ice lobes (Simcoe and Ontario Lobes) and the Niagara Escarpment to the west approximately 12-13,000 years ago during the Mackinaw Interstade (Figure 69).

Generally, the Oak Ridges Moraine deposits are thickest (up to 90 m) along a narrow east-west ridge at the top of the CLOCA Watersheds (see CLOCA 2007). Figure 70. The deposits thin to Earthfx Inc. 152

CLOCA Tier 1 Water Budget Report January, 2009 less than 30 m along the south flank of the moraine where they are covered by surface tills. Borehole data show the presence of significant sand bodies between the Newmarket Till and overlying younger (Halton) till in the central part of the study area. These are considered to be Mackinaw Interstadial sediments but are not present everywhere (e.g., where Halton Till is in direct contact with Newmarket Till). The degree of hydraulic connection to the Oak Ridges Moraine decreases with distance from the moraine. Further south, there are isolated bodies of Mackinaw Interstadial sediments in depressions on the Newmarket Till surface.

The sandy nature of the soil and the hummocky topography allow for high rates of recharge where the ORM sediments are exposed at surface. Large groundwater mounds have developed beneath the sediment wedges to the northwest of Lynde Creek and to the northeast of Bowmanville and Soper Creeks. Radial groundwater flow from these mounds supplies significant amounts of groundwater underflow into these watersheds.

13.3.3.7 Halton Till

The latest glacial ice advance over the southern part of the study area occurred from the Lake Ontario Basin about 13,000 years ago, depositing the Halton Till. The interpreted thickness of the Halton Till is shown on Figure 71. The Halton Till is the youngest known till unit in the area and possibly extends as far south as the Lake Iroquois shoreline.

The Halton till is texturally variable but is generally a sandy silt to clayey silt till interbedded with silt, clay, sand and gravel (Russell et al., 2002). In some areas it is very clay-rich where the Halton ice has overridden and incorporated glaciolacustrine deposits. The Halton Till is typically 3 to 6 m thick but locally it exceeds 15 to 30 m in thickness (such as in the headwater areas of Oshawa, Farewell and Bowmanville Creeks). The Halton Till has overridden the granular Oak Ridges Moraine deposits in much of the northern part of the study area. The till is generally considered a low recharge unit (although where it is thin and weathered and where it retains some of the hummocky features of the ORM, recharge through the till may be significant)

The presence of a lower-permeability Halton till cap on parts of the Oak Ridges Moraine can have a significant impact on groundwater recharge into the CLOCA watersheds. For example, In the Oshawa and Soper Creek watersheds, the height of land and the location of the surface water divide are is defined by the northern extent of the till. However, the regional groundwater mound is often displaced further north, usually following the centerline of the exposed, high permeability ORM deposits. Significant amounts of groundwater flows southward from the regional groundwater divide across the watershed boundary.

13.3.3.8 Surficial Glaciolacustrine Deposits

The uppermost surficial geologic unit consists of a sequence of glaciolacustrine deposits that range from near shore sands and gravel beach deposits of the Lake Iroquois shoreline located within the southern part of the study area, to fine sands, silts and clays of ice-marginal pondings north of the Lake Iroquois shoreline. These sediments generally form a thin veneer over the underlying deposits, although locally they can be several meters thick. These units represent local ponding of water, or higher water levels in Lake Ontario and Lake Simcoe, following retreat of the glaciers approximately 12,500 years ago. For example, Glacial Lake Iroquois (ancestral Lake Ontario) water levels were at least 40 to 60 m higher than present due to ice blockage and damming of water along the St. Lawrence River (Anderson and Lewis, 1985; Eyles, 1997). Note that shoreline elevations are slowly changing as a result of postglacial isostatic rebound (Eyles, 1997). The extent of these deposits is shown on the surficial geology map (Figure 13). High rates of infiltration can occur through the beach deposits, but because they are thin and Earthfx Inc. 153

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13.3.3.9 Geologic Cross-section

A southwest-northeast trending cross section through the CLOCA watersheds is provided in Figure 72. The cross-section trends across the south slope region in the west and along the ORM in the east and represents a slice through the Quaternary sediments from Lynde Creek to Soper Creek. The geologic layers are based on the current interpretation by the YPDT-CAMC study team and are built into the three-dimensional groundwater flow mode (Kassenaar and Wexler, 2006). Visible in the cross section is the pinching out of the ORM deposits over the south slope, and the thickening of the ORM deposits near the crest of the moraine. Also note that as one moves east, the Scarborough Formation pinches out and often either the Sunnybrook Drift or the Thorncliffe Formation occurs immediately above bedrock. As mentioned previously, the Halton Till occurs along the flanks of the ORM and is interpreted to be largely absent south of the Lake Iroquois shoreline. Outcrops of till south of the Lake Iroquois shoreline are interpreted to be Newmarket Till. Erosion of the Newmarket Till is evident where the section passes through the western part of the Bowmanville Creek watershed.

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13.4 REFERENCES

Anderson, T.W. and Lewis, C.F., 1985, Postglacial water-level history of the Lake Ontario basin: in Quaternary Evolution of the Great Lakes, edited by P.F. Karrow and P.E. Calkin, Geological Association of Canada Special Paper 30, 231-253.

Brookfield, M.E., Q.H.J. Gwyn and P.I. Martini, 1982, Quaternary sequences along the north shore of Lake Ontario: Oshawa-Port Hope. Can. Journal of Earth Sci., v, 19, p. 1836-1850.

Chapman, L.J. and Putnam, D.F., 1984, The physiography of southern Ontario: Ontario Geologic Survey, Special Volume 2, 270p.

CLOCA, 2006, Watershed Characterization -- Central Lake Ontario Conservation Authority Watersheds: Prepared by Central Lake Ontario Conservation Authority, June 30, 2006

CLOCA, 2007, Conceptual Water Budget Interim Report -- Central Lake Ontario Conservation Authority Watersheds: Prepared by Central Lake Ontario Conservation Authority, March 2007.

Dreimanis, A. and Karrow, P.F. 1972. Glacial history of the Great Lakes-St. Lawrence region; The classification of the Wisconsin(an) Stage, and its correlatives. 24th International Geologic Congress, section 12, p. 5-15.

Eyles, N.E., 1987, Late Pleistocene depositional systems of Metropolitan Toronto and their engineering and glacial geological significance: Can. Journal of Earth Sci., 24, p.1009-1021

Eyles, N.E., 1997, Chapter 2. Environmental Geology of a Supercity: The Greater Toronto Area; in: Eyles, N. (Ed), Environmental Geology of Urban Areas, Geological Association of Canada, Geotext no.3, 7-80.

Eyles, N., 2002, Ontario Rocks : Three billion years of environmental change: Fitzhenry & Whiteside Limited.

Eyles, N., B.M. Clark, B.G. Kaye, K.W.F. Howard and C.H. Eyles, 1985, The application of basin analysis techniques to glaciated terrains: an example from the Lake Ontario basin, Canada. Geoscience Canada, v. 12, p. 22-32.

Fligg, K., and B. Rodrigues. 1983, Geophysical well log correlations between Barrie and the Oak Ridges Moraine. Water Resources Branch, Ontario Ministry of the Environment, Map 2273.

Funk, G.F. 1977. Geology and water resources of the Bowmanville, Soper and Wilmot Creek, IHD representative drainage basin; Ontario Ministry of Environment, Water Resources Report 9a, 113p.

Gerber, R.E. 1999. Hydrogeologic behaviour of the Northern till aquitard near Toronto, Ontario. Unpublished Ph.D. thesis, University of Toronto.

Gerber, R.E., and K.W.F. Howard. 1996. Evidence for recent groundwater flow through Late Wisconsinan till near Toronto, Ontario. Canadian Geotechnical Journal, v. 33, p. 538-555.

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Gerber, RE and K.W.F. Howard. 2000. Recharge through a regional till aquitard : three- dimensional flow model water balance approach. Ground Water, 38(3), 410-422.

Gerber, RE, J.I. Boyce and K.W.F. Howard. 2001. Evaluation of heterogeneity and field-scale groundwater flow regime in a leaky till aquitard. Hydrogeology Journal, 9 : 60-78.

Karrow, P.F., 1967, Pleistocene geology of the Scarborough area: Ontario Department of Mines, Geological Report 46, 108p.

Karrow, P.F., 1989, Quaternary geology of the Great Lakes subregion: in Chapter 4, Quaternary Geology of Canada and Greenland. Edited by J.O. Wheeler, Geological Survey of Canada, Geology of Canada, v. 1, pp. 326-350.

Kassenaar, J.D.C. and Wexler, E.J., 2006. Groundwater Modelling of the Oak Ridges Moraine Area. YPDT-CAMC Technical Report #01-06. Available at http://www.ypdt-camc.ca.

Pugin, A., Pullen, S.E. and Sharpe, D.R., 1996, Observations of tunnel channels in glacial sediments with shallow land-based seismic reflection; Annals of Glaciology, v. 22, p.176-180.

Pugin, A., Pullen, S.E. and Sharpe, D.R., 1999, Seismic facies and regional architecture of the Oak Ridges Moraine area, southern Ontario; Can. Journal of Earth Sci., v.36 , p.409-432.

Russell, H.A.J, Sharpe, D.R. and Logan, C., 2002. Structural Model of the Oak Ridges Moraine and Greater Toronto Areas, Southern Ontario -- Oak Ridges Moraine Sediment: Geological Survey of Canada, Open File 4240, scale 1 :250,000.

Russell, H.A.J, Sharpe, D.R. and Logan, C., 2003 (Draft), Tunnel Channels of the Oak Ridges Moraine and Greater Toronto Area, Southern Ontario: Geological Survey of Canada, Open File ####, scale 1:250,000.

Sharpe, D.R., L.D. Dyke, M.J. Hinton, S.E. Pullan, H.A.J. Russell, T.A. Brennand, P.J. Barnett and A. Pugin. 1996, Groundwater prospects in the Oak Ridges Moraine area, southern Ontario: application of regional geological models. In Current Research 1996-E. Geological Survey of Canada, p. 181-190.

Sharpe, D.R., Russell, H.A.J. and Logan, C., 2002a, Structural Model of the Oak Ridges Moraine and Greater Toronto Areas, Southern Ontario -- Newmarket Till: Geological Survey of Canada, Open File 4241, scale 1 :250,000.

Sharpe, D.R., Russell, H.A.J. and Logan, C., 2002b. Structural Model of the Oak Ridges Moraine and Greater Toronto Areas, Southern Ontario -- Lower Sediment: Geological Survey of Canada, Open File 4242, scale 1 :250,000.

Shaw, J., and Gorrell, G.A., 1991, Subglacially formed dunes with bimodal and graded gravel in the Trenton drumlin field, Ontario, Canada: Géographie physique et Quaternaire, v. 45, p. 21- 34.

Singer, S.N. 1974. A hydrogeological study along the north shore of Lake Ontario in the Bowmanville-Newcastle area. Ontario Ministry of the Environment, Water Resources Report 5d, 72p.

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14 FIGURES

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Figure 63: Bedrock topography in the CLOCA area

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Figure 64: Quaternary deposits found within the CLOCA area

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Figure 65: Interpolated thickness of the Scarborough Formation

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Figure 66: Interpolated thickness of the Sunnybrook Drift

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Figure 67: Interpolated thickness of the Thorncliffe Formation

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Figure 68: Interpolated thickness of the Newmarket Till

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Figure 69: Deposition of the Oak Ridges Moraine between two ice lobes

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Figure 70: Interpolated thickness of the Oak Ridges Moraine deposits.

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Figure 71: Interpolated thickness of the Halton Till

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Figure 72: Northeast-Southwest cross section through the CLOCA watersheds

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15 Appendix B: Permit to Take Water (PTTW) Details

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Table 33: Permit to Take Water (PTTW) Data Details Max Water- UTM UTM SW/ Source Specific Max. Max Max Max Consump- Ministry PTTW Appli- Source ID Type shed Applicant Location Easting Northing Category Approved GW Expires Name Purpose L/min hr/day L/day Day/yr tion Number Number cation Type No. (m) (m) 3 Source (m /yr) Carruther's Creek 650 Lakeridge Rd., N. Irrigation Golf Course 1 PTTW 16 GC Ajax 662016 4856513 Pond Irrigation Commercial 341 12 103000 214 22042 Yes 0511-6ZWKJC 2637-75LQ5S Renewal Pond S Dec. 31, 2012 Carruther's Creek 650 Lakeridge Rd., S.Irrigation Golf Course 2 PTTW 16 GC Ajax 662285 4857352 Pond Irrigation Commercial 2272 12 410000 214 87740 Yes 0511-6ZWKJC 2637-75LQ5S Renewal Pond S Dec. 31, 2012 Carruther's Creek 650 Lakeridge Rd., Golf Course 3 PTTW 16 GC Ajax 662350 4857350 Well #1 Irrigation Commercial 92 24 132000 365 48180 Yes 0511-6ZWKJC 2637-75LQ5S Renewal Well G Dec. 31, 2012 Carruther's Creek 650 Lakeridge Rd., Golf Course 4 PTTW 16 GC Ajax 662440 4857320 Well #2 Irrigation Commercial 78 24 112000 365 40880 Yes 0511-6ZWKJC 2367-75LQ5S Renewal Well G Dec. 31, 2012 3033 Taunton Rd., Other- Drilled 5 PTTW 14 Stonehenge GC Clarington 686762 4872340 TW-2 Commercial Commercial 46 10 45000 150 6750 Yes 4814-6Z9HSU 6638-752M8L New Well G July 31, 2012 3033 Taunton Rd., Golf Course Dugout 6 PTTW 14 Stonehenge GC Clarington 686822 4871781 TW-4 Irrigation Commercial 950 20 684000 150 102600 Yes 4814-6Z9HSU 6638-752M8L New Pond S July 31, 2012 745 Wichester Rd., Production Golf Course Long 7 PTTW 1 Devil's Den GC Brooklin 661004 4867514 Well Irrigation Commercial 218 24 314210 153 48074 Term Unknown 02-P-3120 New Well G 1220 Lakeridge Rd., 8 PTTW 0 Dagmar Resort Ltd. Ashburn 655623 4874717 PW2 Snowmaking Commercial 250 24 360000 120 43200 Yes 3255-737HXV 3864-65ZS3U Renewal Well G N/A 1220 Lakeridge Rd., 9 PTTW 0 Dagmar Resort Ltd. Ashburn 655743 4875299 PW5 Snowmaking Commercial 2046 24 2946240 120 353549 Yes 3255-737HXV 3864-65ZS3U Renewal Well G N/A 1220 Lakeridge Rd., 10 PTTW 0 Dagmar Resort Ltd. Ashburn 655760 4875286 PW10 Snowmaking Commercial 2500 24 3600000 120 432000 Yes 3255-737HXV 3864-65ZS3U Renewal Well G N/A 1220 Lakeridge Rd., 11 PTTW 0 Dagmar Resort Ltd. Ashburn 655389 4874832 PW1 Snowmaking Commercial 91 24 131040 365 47830 Yes 3255-737HXV 3864-65ZS3U Renewal Well G N/A 1220 Lakeridge Rd., 12 PTTW 0 Dagmar Resort Ltd. Ashburn 655597 4874741 PW3 Snowmaking Commercial 91 24 131040 365 47830 Yes 3255-737HXV 3864-65ZS3U Renewal Well G N/A 1220 Lakeridge Rd., 13 PTTW 0 Dagmar Resort Ltd. Ashburn 655470 4874965 PW4 Snowmaking Commercial 91 24 131040 365 47830 Yes 3255-737HXV 3864-65ZS3U Renewal Well G N/A 1220 Lakeridge Rd., 14 PTTW 0 Dagmar Resort Ltd. Ashburn 655499 4874994 PW6 Snowmaking Commercial 91 24 131040 365 47830 Yes 3255-737HXV 3864-65ZS3U Renewal Well G N/A 1220 Lakeridge Rd., Storage 15 PTTW 0 Dagmar Resort Ltd. Ashburn 655816 4875248 Pond Snowmaking Commercial 4546 24 6546240 120 785549 Yes 3255-737HXV 3864-65ZS3U Renewal Pond S N/A Columbus Golf & 3622 Simocoe St. N., Golf Course Long 16 PTTW 5 Country Oshawa 667010 4873025 PW1 Irrigation Commercial 182 24 262080 184 48223 Term N/A 6814-66URA7 Unknown Well G Mar. 31, 2008 Columbus Golf & 3622 Simcoe St. N., Golf Course Long 17 PTTW 5 Country Oshawa 667045 4872610 PW2 Irrigation Commercial 46 24 66240 365 24178 Term N/A 6814-66URA7 Unknown Well G Mar. 31, 2008 Columbus Golf & 3622 Simcoe St. N., Golf Course Long 18 PTTW 5 Country Oshawa 666775 4872865 PW3 Irrigation Commercial 146 24 210240 184 38684 Term N/A 6814-66URA7 Unknown Well G Mar. 31, 2008 5240 Lakeridge Rd., Golf Course Long 19 PTTW 1 Heather Glen GC Ashburn 656610 4873922 TW-1 Irrigation Commercial 380 24 547200 210 114912 Term N/A 99-0-3014 Unknown Well G Dec. 31, 2010 5240 Lakeridge Rd., Golf Course Long 20 PTTW 1 Heather Glen GC Ashburn 656426 4873803 W-1 Irrigation Commercial 45 18 6480 210 1361 Term N/A 99-0-3014 Unknown Well G Dec. 31, 2010 5240 Lakeridge Rd., Golf Course Long 21 PTTW 1 Heather Glen GC Ashburn 656544 4873838 Pond Irrigation Commercial 150 4 36000 210 7560 Term N/A 99-0-3014 Unknown Pond S Dec. 31, 2010 790 Chalk Lake Rd., In Drilled 22 PTTW 1 Lakeridge Ski Resort Uxbridge 655614 4876693 6" Well Snowmaking Commercial 160 16 150000 365 54750 Progress 2866-742TCL 1266-65CK2K Renewal Well G N/A 790 Chalk Lake Rd., In Drilled 23 PTTW 1 Lakeridge Ski Resort Uxbridge 655822 4876568 8" Well Snowmaking Commercial 1620 24 2332800 150 349920 Progress 2866-742TCL 1266-65CK2K Renewal Well G N/A 790 Chalk Lake Rd., In Dug 24 PTTW 1 Lakeridge Ski Resort Uxbridge 655574 4876666 Pond Snowmaking Commercial 4543 24 6541920 150 981288 Progress 2866-742TCL 1266-65CK2K Renewal Pond S N/A 995 Myrtle Rd W., Irrigation Golf Course Long Artesian 25 PTTW 1 Royal Ashburn GC Ashburn 659343 4873447 Well Irrigation Commercial 172 24 247680 365 90403 Term Whitby GC 4064-5VGRK3 N/A Flow G Jan 31, 2009 995 Myrtle Rd W., Irrigation Golf Course Long With 26 PTTW 1 Royal Ashburn GC Ashburn 659343 4873447 Well Irrigation Commercial 1410 16 1353600 180 243648 Term Whitby GC 4064-5VGRK3 N/A Pump G Jan 31, 2009 995 Myrtle Rd W., Irrigation Golf Course Long Drilled 27 PTTW 1 Royal Ashburn GC Ashburn 659343 4873444 Welll #2 Irrigation Commercial 8 24 10800 365 3942 Term Whitby GC 4064-5VGRK3 N/A Well G Jan 31, 2009 Irrigation 995 Myrtle Rd W., Pond Golf Course Long 28 PTTW 1 Royal Ashburn GC Ashburn 659343 4873447 System Irrigation Commercial 3640 6.5 1419600 180 255528 Term Whitby GC 4064-5VGRK3 N/A Pond S Jan 31, 2009 995 Myrtle Rd W., Clubhouse Other- Long Drilled 29 PTTW 1 Royal Ashburn GC Ashburn 659569 4873561 Well #1 Commercial Commercial 7 20 8400 365 3066 Term Whitby GC 4064-5VGRK3 N/A Well G Jan 31, 2009

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Max Water- UTM UTM SW/ Specific Max. Max Max Max Consump- Ministry PTTW Appli- Source ID Type shed Applicant Location Easting Northing Source Name Category Approved GW Expires Purpose L/min hr/day L/day Day/yr tion Number Number cation Type No. (m) (m) 3 Source (m /yr) 995 Myrtle Rd W., Clubhouse Other- Long Drilled 30 PTTW 1 Royal Ashburn GC Ashburn 659568 4873564 Well #2 Commercial Commercial 7 20 8400 365 3066 Term Whitby GC 4064-5VGRK3 N/A Well G Jan 31, 2009 995 Myrtle Rd W., Maintenance Long 31 PTTW 1 Royal Ashburn GC Ashburn 659822 4873491 Well Maintenance Commercial 3 24 3600 180 648 term Whitby GC 4064-5VGRK3 N/A Well G Jan 31, 2009 772 Chalk Lake Rd W. PW1 Drilled 32 PTTW 1 Skyloft Ski Club Uxbridge 654797 4877009 (Standby) Snowmaking Commercial 46 24 65520 190 12449 Expired N/A 5313-666RG4 N/A Well G May 31, 2007 772 Chalk Lake Rd W. Drilled 33 PTTW 1 Skyloft Ski Club Uxbridge 654787 4877000 PW2 Snowmaking Commercial 455 24 654624 190 124379 Expired N/A 5313-666RG4 N/A Well G May 31, 2007 772 Chalk Lake Rd W. Drilled 34 PTTW 1 Skyloft Ski Club Uxbridge 654655 4877183 PW3 Snowmaking Commercial 909 24 1309248 190 248757 Expired N/A 5313-666RG4 N/A Well G May 31, 2007 772 Chalk Lake Rd. W Holding Dugout 35 PTTW 1 Skyloft Ski Club Uxbridge 654782 4877005 Pond Snowmaking Commercial 1364 24 1963872 190 373136 Expired N/A 5313-666RG4 N/A Pond S May 31, 2007 35 Lauren Rd., Port Golf Course Long 36 PTTW 1 Oakridge Golf Club Perry 657572 4877019 Five Wells Irrigation Commercial 1512 24 2172000 365 792780 Term N/A 98-P-3007 N/A Wells G March 31, 2008 Lake Long 37 PTTW 16 Region of Durham Town of Whitby 667054 4857331 Ontario Municipal Municipal 75500 24 109000000 365 39785000 Term N/A 00-P-3026 N/A Surface S May 31, 2010 Lake Long 38 PTTW 16 Region of Durham City of Oshawa 676679 4859593 Ontario Municipal Municipal 93056 24 134000000 365 48910000 Term N/A 00-P-3025 N/A Surface S Dec. 31, 2010 Lake Water level Long 39 PTTW 1 Unknown Town of Whitby 663668 4857133 Ontario control Remediation 2660 24 3830400 40 153216 Term N/A 00-P-3060 N/A Surface S Oct. 31, 2010 Cranberry Water level Long 40 PTTW 1 Unknown Town of Whitby 663667 4857133 Marsh control Remediation 31800 24 45792000 5 228960 Term N/A 00-P-3060 N/A Surface S Oct. 31, 2010 Lake Long 41 PTTW 16 St. Mary's Cement Clarington 685346 4860825 Ontario Inlet Industrial Cooling/Other 12275 24 17675850 365 6451685 Term N/A 02-P-3015 N/A Surface S Mar. 31, 2012 Quarry Quarry Long 42 PTTW 11 St. Mary's Cement Clarington 685538 4860951 Sump Dewatering Dewatering 4134 24 5952465 365 2172650 Term N/A 02-P-3016 N/A G Mar. 31, 2012 Unknown Expired or Paul Watson 2216 Solina Rd., (Possible Tender Fruit 43 Possible 11 Farms Ltd. Clarington 680275 4863680 Pond) Irrigation Agricultural 250000 365 91250 03-P-3013 S Oct. 31, 2005 Long 43 PTTW 14 Unknown Newcastle 686097 4870628 Soper Cr Irrigation Agriculture 1362 20 1634400 14 22882 Term N/A 79-P-64 N/A Surface S Sep. 30, 2009 Expired or 1583 Male Grove Rd., Darlington Cr Tender Fruit 44 Possible 11 Watson Farms Ltd. Clarington 683350 4863360 (Pond) Irrigation Agricultural 250000 365 91250 72-P-150 S Oct. 31, 2005 Long Dugout 44 PTTW 14 Unknown Newcastle 685846 4871546 Pond Irrigation Agriculture 3450 10 2070240 150 310536 Term N/A 79-P-64 N/A Pond S Sep. 30, 2009 Township of Unnamed Wildlife Long 45 PTTW 1 Patterson-Tripp Scugog 658000 4876900 Watercourse Conservation Conservation 361 24 520000 365 189800 Term N/A 97-P-3027 N/A Surface S Aug. 31, 2008 Golf Course Quarry Lakes Golf 3705 Reg. Rd. 57. Golf Course 46 No Permit 12 and Rec Centre Bowmanville 683192 4868301 Irrigation Commercial 250000 365 91250 G Pine Valley RR #1, City of 2 Ponds Fish Hatchery Long 46 PTTW 5 Hatchery Ltd. Oshawa 665834 4876310 (Oshawa Cr) and Rearing Aquaculture 460 24 662400 365 241776 Term N/A 99-P-3006 N/A Unknown S Mar. 31, 2009 Expired or Unknown Bowmanville 47 Possible 12 (Empire Orchards?) Unknown 682470 4872040 Creek Fruit Orchards Agricultural 250000 365 91250 5286-63RQS4 S Dec. 31, 2006 3430 7th Con., Golf Course Long 47 PTTW 1 Watson's Glen GC Pickering 657628 4869964 Well 1 (TW3) Irrigation Commercial 318 12 491000 150 73650 Term N/A 99-P-3084 N/A Ground G Dec. 31, 2010 3430 7th Con., Golf Course Long 48 PTTW 1 Watson's Glen GC Pickering 657951 4870071 Well 2 (TW4) Irrigation Commercial 364 12 491000 150 73650 Term N/A 99-P-3084 N/A Ground G Dec. 31, 2010 3430 7th Con., Golf Course Long Dugout 49 PTTW 1 Watson's Glen GC Pickering 657767 4869586 Holding Pond Irrigation Commercial 342 6 246515 150 36977 Term N/A 99-P-3084 N/A Pond S Dec. 31, 2010 4615 Thickson Rd N., Concrete Long 50 PTTW 2 Miller Concrete Whitby 666274 4866252 Well Plant/Drinking Industrial 68 24 98194 300 29458 Term N/A 97-P-3014 N/A Ground G No Date Given Expired or 1145 Thornton Rd. N., Golf Course 51 Possible 4 Airport GC Oshawa 668486 4864880 Goodman Cr Irrigation Commercial 250000 365 91250 71-P-382 S Mar 31, 1983 Golf Course Dugout 51 PTTW 14 Bowmanville G&CC 3845 Middle Rd. 684202 4869105 Dugout Pond Irrigation Commercial 375 6 135000 150 20250 Yes 0722-74DHFF 1088-75KCE Approved Pond S July 31, 2017

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Max Water- UTM UTM SW/ Specific Max. Max Max Max Consump- Ministry PTTW Appli- Source ID Type shed Applicant Location Easting Northing Source Name Category Approved GW Expires Purpose L/min hr/day L/day Day/yr tion Number Number cation Type No. (m) (m) 3 Source (m /yr) 4145 Country Lane Golf Course Online 52 PTTW 1 Country Lane GC Rd., Whitby 662400 4864842 Online Pond Irrigation Commercial 1137 5 326760 214 69927 Yes 3641-73VS2H 2856-74TKF2 Approved Pond S Dec. 31, 2009 Golf Course 5210 Bethesda Rd., Golf Course 53 No Permit 14 Ayren Links GC Bowmanville 685110 4872216 Irrigation Commercial 250000 365 91250 G 750 Winchester Rd Other-Water In Drilled 53 PTTW 5 Winchester GC E., Whitby 666025 4869691 Drilled Well Water Supply Supply 10 12 6700 200 1340 N/A 4062-727U4W N/A progress Well G N/A Expired or Possibly Link Bragg Rd., Field and Irrigation 54 Possible 14 Greenhouse Clarington 688034 4870390 Spoer Creek Pasture Crops Supply 250000 365 91250 96-P-3024 S Mar. 31, 2006 750 Winchester Rd Golf Course In Online 54 PTTW 5 Winchester GC E., Whitby 666025 4869691 Online Pond Irrigation Commercial 1520 6 547200 200 109440 N/A 4062-727U4W N/A progress Pond S N/A Expired or Possibly Link Bragg Rd., Field and Irrigation 55 Possible 14 Greenhouse Clarington 688545 4870440 Pond Pasture Crops Supply 250000 365 91250 96-P-3024 S Mar. 31, 2006 Lakeridge Ski 790 Chalk Lake Rd., In Drilled 55 PTTW 1 Resort Uxbridge 654209 4876732 10" Well Snowmaking Commercial 2839 24 4088246 150 613237 N/A 2866-742TCL N/A progress Well G N/A 3160 Hwy. #7, Golf Course In In Dugout 56 PTTW 0 Unknown Pickering 657783 4866824 Pond #1 Irrigation Commercial 1482 5 400140 365 146051 Progress 4804-76AJ58 N/A Progress Pond S N/A 3160 Hwy. #7, Golf Course In In Drilled 57 PTTW 0 Unknown Pickering 657731 4866824 PW 1 Irrigation Commercial 278 24 400320 365 * Progress 4804-76AJ58 N/A Progress Well G N/A Golf Course 5055 Baldwin St. S., Golf Course 58 No Permit 1 Lyndebrook GC Brooklin 663536 4866318 Irrigation Commercial 250000 365 91250 G Golf Course 615 Winchester Rd., Golf Course 58 No Permit 5 Eldorado GC Brooklin 665820 4869462 Irrigation Commercial 250000 365 91250 G Golf Course Lakeridge Links 1355 Brawley Rd., Golf Course 59 No Permit 1 Whispering Ridge GC Brooklin 658284 4871008 Irrigation Commercial 250000 365 91250 G Golf Course Durham Driving 499 Simcoe St., Golf Course 60 No Permit 5 Range Oshawa 670689 4863646 Irrigation Commercial 250000 365 91250 G Golf Course 5450 Lakeridge Rd., Golf Course 61 No Permit 1 Hy Hope Farm Ashburn 656315 4874651 Irrigation Commercial 250000 365 91250 G Golf Course 1000 2nd Line Golf Course 62 No Permit 1 Golfers Dream Scugog, Pt Perry 661776 4878074 Irrigation Commercial 250000 365 91250 G Expired or 4120 Coronation Market 63 Possible 1 Zdanowics Farm Rd., Whitby 661157 4864746 Dugout Pond Gardens Agricultural 250000 365 91250 67-P-245 S Mar. 31, 1987 Expired or 389 Kingston Rd., Golf Course 64 Possible 1 Ken Fulton GC Ajax 661134 4859118 Unknown Irrigation Commercial 250000 365 91250 97-P-3036 S Mar. 31, 2008 Expired or 160 Alexandra St., Golf Course 68 Possible 5 Oshawa GC Oshawa 670500 4863759 Oshawa Cr Irrigation Commercial 250000 365 91250 64-P-375 S Mar. 31, 2003 Expired or 2400 Ritson Rd. N., E. Oshawa Golf Course 69 Possible 5 Kedron Dells GC Oshawa 669695 4869956 Creek Irrigation Commercial 250000 365 91250 73-P-131 S Mar. 31, 1988 Expired or Morris Chemicals 1182 Farewell Ave., Lake Dilution of 70 Possible 5 Inc. Oshawa 674999 4859486 Ontario Remediation CaCl2 250000 365 91250 95-P-3003 S May 31, 2005 Golf Course Pebblestone GC 1550 Pebblestone Golf Course 71 No Permit 6 Ltd. Rd., Courtice 675712 4866609 Irrigation Commercial 250000 365 91250 G Golf Course Harmony Creek 1000 Bloor St. E., Golf Course 72 No Permit 7 GCC Oshawa 675048 4861776 Irrigation Commercial 250000 365 91250 G Lake 73 PTTW 16 Region of Durham Clarke Twp (Bowmanville) 687753 4862407 Ontario Municipal Municipal 33000 24 47520000 365 17344800 Yes 00-P-3027 Surface S Apr. 30,2010

Note: Permits tracked by CLOCA but either just outside the CLOCA boundary or at an unconfirmed location are assigned to Watershed Number 0 and not used in the water budget calculations.

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16 Appendix C: Detailed Monthly Groundwater and Surface Water Stress Assessments

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Water- Detailed Monthly Surface Water Assessment by Catchment shed Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec QSUPPLY 1.059 0.967 1.418 1.315 0.631 0.201 0.068 0.048 0.185 0.445 1.374 1.509 Lynde QRESERVE 0.605 0.477 0.726 0.795 0.379 0.114 0.039 0.020 0.067 0.174 0.729 0.973 Creek QDEMAND 0.088 0.088 0.088 0.011 0.025 0.025 0.039 0.025 0.025 0.024 0.054 0.088 PWD 19 18 13 2 10 29 134 89 21 9 8 16 QSUPPLY 0.202 0.167 0.234 0.207 0.108 0.032 0.010 0.004 0.033 0.085 0.230 0.273 Pringle QRESERVE 0.115 0.083 0.112 0.120 0.063 0.017 0.005 0.002 0.01 0.030 0.12 0.172 Creek QDEMAND 0 0 0 0 0 0 0 0 0 0 0 0 PWD 0 0 0 0 0 0 0 0 0 0 0 0 QSUPPLY 0.093 0.089 0.114 0.091 0.046 0.014 0.004 0.001 0.007 0.023 0.085 0.116 Corbett QRESERVE 0.050 0.037 0.048 0.050 0.027 0.008 0.002 0 0.002 0.009 0.034 0.069 Creek QDEMAND 0 0 0 0 0 0 0 0 0 0 0 0 PWD 0 0 0 0 0 0 0 0 0 0 0 0 QSUPPLY 0.080 0.063 0.091 0.078 0.041 0.013 0.005 0.003 0.020 0.043 0.102 0.112 Goodman QRESERVE 0.046 0.033 0.042 0.045 0.025 0.007 0.002 0.001 0.006 0.015 0.060 0.070 Creek QDEMAND 0 0 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0 0 PWD 0 0 4 6 12 35 92 135 15 7 0 0 QSUPPLY 0.891 0.806 1.167 1.155 0.558 0.171 0.051 0.034 0.139 0.399 1.272 1.311 Oshawa QRESERVE 0.515 0.412 0.610 0.699 0.334 0.098 0.029 0.015 0.049 0.152 0.694 0.849 Creek QDEMAND 0.001 0.001 0.001 0.011 0.011 0.011 0.011 0.011 0.011 0.009 0.006 0.001 PWD 0 0 0 2 5 15 49 58 12 4 1 0 QSUPPLY 0.300 0.238 0.391 0.368 0.183 0.054 0.014 0.005 0.038 0.110 0.373 0.440 Harmony QRESERVE 0.168 0.115 0.167 0.205 0.106 0.028 0.007 0.002 0.011 0.040 0.165 0.274 Creek QDEMAND 0 0 0 0 0 0 0 0 0 0 0 0 PWD 0 0 0 0 0 0 0 0 0 0 0 0 QSUPPLY 0.249 0.211 0.332 0.312 0.155 0.046 0.012 0.003 0.031 0.104 0.347 0.381 Farewell QRESERVE 0.143 0.103 0.150 0.178 0.091 0.024 0.006 0.001 0.008 0.035 0.167 0.243 Creek QDEMAND 0 0 0 0 0 0 0 0 0 0 0 0 PWD 0 0 0 0 0 0 0 0 0 0 0 0 QSUPPLY 0.038 0.032 0.044 0.040 0.020 0.006 0.001 0.000 0.001 0.006 0.030 0.046 Robinson QRESERVE 0.020 0.015 0.020 0.022 0.012 0.003 0.001 0.000 0 0.003 0.009 0.027 Creek QDEMAND 0 0 0 0 0 0 0 0 0 0 0 0 PWD 0 0 0 0 0 0 0 0 0 0 0 0 Table 34: Detailed monthly surface water stress assessment - current and future conditions.

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Water- Detailed Monthly Surface Water Assessment by Catchment shed Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec QSUPPLY 0.079 0.061 0.089 0.077 0.038 0.011 0.003 0.001 0.007 0.022 0.077 0.099 Tooley QRESERVE 0.042 0.031 0.043 0.044 0.022 0.006 0.002 0 0.002 0.008 0.035 0.063 Creek QDEMAND 0 0 0 0 0 0 0 0 0 0 0 0 PWD 0 0 0 0 0 0 0 0 0 0 0 0 QSUPPLY 0.189 0.155 0.236 0.218 0.108 0.032 0.010 0.003 0.038 0.102 0.289 0.297 Black QRESERVE 0.110 0.083 0.115 0.129 0.064 0.017 0.005 0.002 0.009 0.035 0.169 0.187 Creek QDEMAND 0 0 0 0 0 0 0 0 0 0 0 0 PWD 0 0 0 0 0 0 0 0 0 0 0 0 QSUPPLY 0.124 0.099 0.141 0.123 0.061 0.018 0.006 0.002 0.016 0.045 0.136 0.167 Darling- QRESERVE 0.067 0.051 0.071 0.070 0.035 0.010 0.003 0.001 0.004 0.016 0.067 0.104 ton QDEMAND 0.000 0.000 0 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.000 Creek PWD 0 0 0 9 18 57 185 514 37 16 7 0 QSUPPLY 0.815 0.713 1.221 1.246 0.564 0.202 0.085 0.085 0.228 0.487 1.262 1.219 Bowman- QRESERVE 0.471 0.369 0.632 0.807 0.347 0.114 0.048 0.034 0.092 0.192 0.778 0.795 ville QDEMAND 0.000 0.000 0.000 0.002 0.002 0.002 0.00 0.002 0.002 0.002 0.002 0.000 Creek PWD 0 0 0 1 1 3 6 5 2 1 0 0 QSUPPLY 0.036 0.028 0.042 0.035 0.018 0.005 0.001 0 0.002 0.009 0.034 0.045 Westside QRESERVE 0.019 0.014 0.018 0.019 0.010 0.003 0.001 0 0 0.003 0.013 0.028 Creek QDEMAND 0 0 0 0 0 0 0 0 0 0 0 0 PWD 0 0 0 0 0 0 0 0 0 0 0 0 QSUPPLY 0.656 0.537 0.849 0.808 0.370 0.111 0.038 0.018 0.122 0.292 0.870 0.933 Soper QRESERVE 0.369 0.294 0.442 0.503 0.215 0.062 0.021 0.008 0.031 0.109 0.499 0.610 Creek QDEMAND 0.000 0.000 0.000 0.010 0.028 0.028 0.035 0.028 0.022 0.005 0.005 0.000 PWD 0 0 0 3 18 58 207 286 25 3 1 0 QSUPPLY 0.060 0.052 0.064 0.052 0.024 0.006 0.002 0 0.002 0.008 0.035 0.058 Bennet QRESERVE 0.032 0.031 0.038 0.030 0.013 0.003 0.001 0 0 0.004 0.012 0.038 Creek QDEMAND 0 0 0 0 0 0 0 0 0 0 0 0 PWD 0 0 0 0 0 0 0 0 0 0 0 0 QSUPPLY 0.150 0.148 0.178 0.138 0.069 0.022 0.007 0.003 0.018 0.044 0.137 0.181 Lake QRESERVE 0.080 0.063 0.086 0.077 0.040 0.012 0.004 0.001 0.005 0.017 0.062 0.109 Catch- QDEMAND 0.613 0.613 0.613 0.618 0.618 0.618 0.618 0.618 0.618 0.618 0.613 0.613 ments PWD Not Applicable – Demand is only from Lake Ontario QSUPPLY is the median flow (QP50) for the month from Table 32. QRESERVE is the lower decile flow (QP90) for the month from Table 25. NOTES: QDEMAND is the surface water demand for the month from Table 22. PWD (Percent Water Demand) = QDEMAND*100/(QSUPPLY-QRESERVE) Table 34 (continued): Detailed monthly surface water stress assessment - current and future conditions.

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CLOCA Tier 1 Water Budget Report January, 2009

Water- Detailed Monthly Groundwater Assessment by Catchment - Current Demand shed Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec QRECHARG 0.67 0.67 0.67 0.67 0.67 0.67 0.67 0.67 0.67 0.67 0.67 0.67 E 7 7 7 7 7 7 7 7 7 7 7 7 QINFLOW 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 2 2 2 2 2 2 2 2 2 2 2 2 QSUPPLY 0.87 0.87 0.87 0.87 0.87 0.87 0.87 0.87 0.87 0.87 0.87 0.87 Lynde 9 9 9 9 9 9 9 9 9 9 9 9 Creek QRESERVE 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 8 8 8 8 8 8 8 8 8 8 8 8 QDEMAND 0.12 0.12 0.11 0.06 0.08 0.08 0.08 0.08 0.08 0.07 0.11 0.12 2 2 8 8 7 7 7 7 4 8 8 2 PWD 15 15 15 8 11 11 11 11 10 10 15 15 QRECHARG 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 E 1 1 1 1 1 1 1 1 1 1 1 1 QINFLOW 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 2 2 2 2 2 2 2 2 2 2 2 2 QSUPPLY 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 Pringle 3 3 3 3 3 3 3 3 3 3 3 3 Creek QRESERVE 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 1 1 1 1 1 1 1 1 1 1 1 1 QDEMAND 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4 4 4 4 4 4 4 4 4 4 4 4 PWD 3 3 3 3 3 3 3 3 3 3 3 3 QRECHARG 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 E 6 6 6 6 6 6 6 6 6 6 6 6 QINFLOW 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 7 7 7 7 7 7 7 7 7 7 7 7 Corbett QSUPPLY 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 Creek 4 4 4 4 4 4 4 4 4 4 4 4 QRESERVE 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4 4 4 4 4 4 4 4 4 4 4 4 QDEMAND 0 0 0 0 0 0 0 0 0 0 0 0 PWD 0 0 0 0 0 0 0 0 0 0 0 0 QRECHARG 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 E 6 6 6 6 6 6 6 6 6 6 6 6 QINFLOW 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 5 5 5 5 5 5 5 5 5 5 5 5 Goodma QSUPPLY 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 n 1 1 1 1 1 1 1 1 1 1 1 1 Creek QRESERVE 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2 2 2 2 2 2 2 2 2 2 2 2 QDEMAND 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1 1 1 1 1 1 1 1 1 1 1 1 PWD 1 1 1 1 1 1 1 1 1 1 1 1 QRECHARG 0.58 0.58 0.58 0.58 0.58 0.58 0.58 0.58 0.58 0.58 0.58 0.58 E 9 9 9 9 9 9 9 9 9 9 9 9 QINFLOW 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 7 7 7 7 7 7 7 7 7 7 7 7 QSUPPLY 0.78 0.78 0.78 0.78 0.78 0.78 0.78 0.78 0.78 0.78 0.78 0.78 Oshawa 6 6 6 6 6 6 6 6 6 6 6 6 Creek QRESERVE 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 5 5 5 5 5 5 5 5 5 5 5 5 QDEMAND 0.02 0.02 0.02 0.02 0.03 0.03 0.03 0.03 0.03 0.03 0.02 0.02 5 5 5 9 3 3 3 3 3 3 9 5 PWD 3 3 3 4 5 5 5 5 5 5 4 3 QRECHARG 0.17 0.17 0.17 0.17 0.17 0.17 0.17 0.17 0.17 0.17 0.17 0.17 E 6 6 6 6 6 6 6 6 6 6 6 6 Harmon QINFLOW 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 y 1 1 1 1 1 1 1 1 1 1 1 1 Creek QSUPPLY 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 7 7 7 7 7 7 7 7 7 7 7 7 Earthfx Inc. 175

CLOCA Tier 1 Water Budget Report January, 2009

QRESERVE 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 8 8 8 8 8 8 8 8 8 8 8 8 QDEMAND 0.00 0.00 0.00 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.00 8 8 8 0 0 0 0 0 0 0 0 8 PWD 3 3 3 4 4 4 4 4 4 4 4 3 QRECHARG 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 E 8 8 8 8 8 8 8 8 8 8 8 8 QINFLOW 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0 0 0 0 0 0 0 0 0 0 0 0 QSUPPLY 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 Farewell 7 7 7 7 7 7 7 7 7 7 7 7 Creek QRESERVE 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 7 7 7 7 7 7 7 7 7 7 7 7 QDEMAND 0.00 0.00 0.00 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.00 9 9 9 1 1 1 1 1 1 1 1 9 PWD 3 3 3 4 4 4 4 4 4 4 4 3 QRECHARG 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 E 9 9 9 9 9 9 9 9 9 9 9 9 QINFLOW 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 5 5 5 5 5 5 5 5 5 5 5 5 Robinso QSUPPLY 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 n 4 4 4 4 4 4 4 4 4 4 4 4 Creek QRESERVE 0 0 0 0 0 0 0 0 0 0 0 0 QDEMAND 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2 2 2 2 2 2 2 2 2 2 2 2 PWD 7 7 7 7 7 7 7 7 7 7 7 7 Table 35: Detailed monthly groundwater stress assessment - current conditions.

Earthfx Inc. 176

CLOCA Tier 1 Water Budget Report January, 2009

Water- Detailed Monthly Groundwater Assessment by Catchment - Current Demand shed Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec QRECHARGE 0.042 0.042 0.042 0.042 0.042 0.042 0.042 0.042 0.042 0.042 0.042 0.042 QINFLOW 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 Tooley QSUPPLY 0.062 0.062 0.062 0.062 0.062 0.062 0.062 0.062 0.062 0.062 0.062 0.062 Creek QRESERVE 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 QDEMAND 0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.004 PWD 6 6 6 6 6 6 6 6 6 6 6 6 QRECHARGE 0.124 0.124 0.124 0.124 0.124 0.124 0.124 0.124 0.124 0.124 0.124 0.124 QINFLOW 0.067 0.067 0.067 0.067 0.067 0.067 0.067 0.067 0.067 0.067 0.067 0.067 Black QSUPPLY 0.191 0.191 0.191 0.191 0.191 0.191 0.191 0.191 0.191 0.191 0.191 0.191 Creek QRESERVE 0.011 0.011 0.011 0.011 0.011 0.011 0.011 0.011 0.011 0.011 0.011 0.011 QDEMAND 0.006 0.006 0.006 0.006 0.006 0.006 0.006 0.006 0.006 0.006 0.006 0.006 PWD 3 3 3 3 3 3 3 3 3 3 3 3 QRECHARGE 0.070 0.070 0.070 0.070 0.070 0.070 0.070 0.070 0.070 0.070 0.070 0.070 QINFLOW 0.022 0.022 0.022 0.022 0.022 0.022 0.022 0.022 0.022 0.022 0.022 0.022 Darling- QSUPPLY 0.092 0.092 0.092 0.092 0.092 0.092 0.092 0.092 0.092 0.092 0.092 0.092 ton QRESERVE 0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.004 Creek QDEMAND 0.003 0.003 0.003 0.021 0.021 0.021 0.021 0.021 0.021 0.021 0.021 0.003 PWD 4 4 4 24 24 24 24 24 24 24 24 4 QRECHARGE 0.615 0.615 0.615 0.615 0.615 0.615 0.615 0.615 0.615 0.615 0.615 0.615 QINFLOW 0.305 0.305 0.305 0.305 0.305 0.305 0.305 0.305 0.305 0.305 0.305 0.305 Bowman- QSUPPLY 0.920 0.920 0.920 0.920 0.920 0.920 0.920 0.920 0.920 0.920 0.920 0.920 ville QRESERVE 0.082 0.082 0.082 0.082 0.082 0.082 0.082 0.082 0.082 0.082 0.082 0.082 Creek QDEMAND 0.023 0.023 0.023 0.025 0.025 0.025 0.025 0.025 0.025 0.025 0.025 0.023 PWD 3 3 3 3 3 3 3 3 3 3 3 3 QRECHARGE 0.018 0.018 0.018 0.018 0.018 0.018 0.018 0.018 0.018 0.018 0.018 0.018 QINFLOW 0.022 0.022 0.022 0.022 0.022 0.022 0.022 0.022 0.022 0.022 0.022 0.022 Westside QSUPPLY 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 Creek QRESERVE 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 QDEMAND 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 PWD 4 4 4 4 4 4 4 4 4 4 4 4 QRECHARGE 0.415 0.415 0.415 0.415 0.415 0.415 0.415 0.415 0.415 0.415 0.415 0.415 QINFLOW 0.200 0.200 0.200 0.200 0.200 0.200 0.200 0.200 0.200 0.200 0.200 0.200 Soper QSUPPLY 0.615 0.615 0.615 0.615 0.615 0.615 0.615 0.615 0.615 0.615 0.615 0.615 Creek QRESERVE 0.041 0.041 0.041 0.041 0.041 0.041 0.041 0.041 0.041 0.041 0.041 0.041 QDEMAND 0.016 0.016 0.016 0.018 0.018 0.018 0.018 0.018 0.018 0.018 0.018 0.016 PWD 3 3 3 3 3 3 3 3 3 3 3 3 QRECHARGE 0.027 0.027 0.027 0.027 0.027 0.027 0.027 0.027 0.027 0.027 0.027 0.027 QINFLOW 0.021 0.021 0.021 0.021 0.021 0.021 0.021 0.021 0.021 0.021 0.021 0.021 Bennet QSUPPLY 0.048 0.048 0.048 0.048 0.048 0.048 0.048 0.048 0.048 0.048 0.048 0.048 Creek QRESERVE 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 QDEMAND 0.009 0.009 0.009 0.011 0.011 0.011 0.011 0.011 0.011 0.011 0.011 0.009 PWD 4 4 4 4 4 4 4 4 4 4 4 4 QRECHARGE 0.075 0.075 0.075 0.075 0.075 0.075 0.075 0.075 0.075 0.075 0.075 0.075 QINFLOW 0.110 0.110 0.110 0.110 0.110 0.110 0.110 0.110 0.110 0.110 0.110 0.110 Lake QSUPPLY 0.185 0.185 0.185 0.185 0.185 0.185 0.185 0.185 0.185 0.185 0.185 0.185 Catch- QRESERVE 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 ments QDEMAND 0.002 0.002 0.002 0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.002 PWD 1 1 1 2 2 2 2 2 2 2 2 1 QRECHARE is 1/12th of the simulated annual average recharge from Table 12. QINFLOW is 1/12th of the simulated annual average lateral inflow from Table 13. QSUPPLY is QRECHARGE + QINFLOW. NOTES: QRESERVE is 1/10th of the simulated annual average groundwater discharge to streams (divided into 12 equal monthly amounts) from Table 27 QDEMAND is the current groundwater demand for the month from Table 19. PWD (Percent Water Demand) = QDEMAND*100/(QSUPPLY-QRESERVE) Table 35 (continued): Detailed monthly groundwater stress assessment - current conditions.

Earthfx Inc. 177

CLOCA Tier 1 Water Budget Report January, 2009

Water- Detailed Monthly Groundwater Assessment by Catchment - Future Demand shed Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec QRECHARG 0.67 0.67 0.67 0.67 0.67 0.67 0.67 0.67 0.67 0.67 0.67 0.67 E 7 7 7 7 7 7 7 7 7 7 7 7 QINFLOW 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 2 2 2 2 2 2 2 2 2 2 2 2 QSUPPLY 0.87 0.87 0.87 0.87 0.87 0.87 0.87 0.87 0.87 0.87 0.87 0.87 Lynde 9 9 9 9 9 9 9 9 9 9 9 9 Creek QRESERVE 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 8 8 8 8 8 8 8 8 8 8 8 8 QDEMAND 0.12 0.12 0.11 0.06 0.08 0.08 0.08 0.08 0.08 0.08 0.12 0.12 3 3 9 9 8 8 8 8 5 0 0 3 PWD 15 15 15 9 11 11 11 11 10 10 15 15 QRECHARG 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 E 1 1 1 1 1 1 1 1 1 1 1 1 QINFLOW 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 2 2 2 2 2 2 2 2 2 2 2 2 QSUPPLY 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 Pringle 3 3 3 3 3 3 3 3 3 3 3 3 Creek QRESERVE 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 1 1 1 1 1 1 1 1 1 1 1 1 QDEMAND 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4 4 4 4 4 4 4 4 4 4 4 4 PWD 3 3 3 3 3 3 3 3 3 3 3 3 QRECHARG 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 E 6 6 6 6 6 6 6 6 6 6 6 6 QINFLOW 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 7 7 7 7 7 7 7 7 7 7 7 7 Corbett QSUPPLY 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 Creek 4 4 4 4 4 4 4 4 4 4 4 4 QRESERVE 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4 4 4 4 4 4 4 4 4 4 4 4 QDEMAND 0 0 0 0 0 0 0 0 0 0 0 0 PWD 0 0 0 0 0 0 0 0 0 0 0 0 QRECHARG 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 E 6 6 6 6 6 6 6 6 6 6 6 6 QINFLOW 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 5 5 5 5 5 5 5 5 5 5 5 5 Goodma QSUPPLY 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 n 1 1 1 1 1 1 1 1 1 1 1 1 Creek QRESERVE 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2 2 2 2 2 2 2 2 2 2 2 2 QDEMAND 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1 1 1 1 1 1 1 1 1 1 1 1 PWD 1 1 1 1 1 1 1 1 1 1 1 1 QRECHARG 0.58 0.58 0.58 0.58 0.58 0.58 0.58 0.58 0.58 0.58 0.58 0.58 E 9 9 9 9 9 9 9 9 9 9 9 9 QINFLOW 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 7 7 7 7 7 7 7 7 7 7 7 7 QSUPPLY 0.78 0.78 0.78 0.78 0.78 0.78 0.78 0.78 0.78 0.78 0.78 0.78 Oshawa 6 6 6 6 6 6 6 6 6 6 6 6 Creek QRESERVE 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 5 5 5 5 5 5 5 5 5 5 5 5 QDEMAND 0.02 0.02 0.02 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.02 6 6 6 0 4 4 4 4 4 4 0 6 PWD 4 4 4 4 5 5 5 5 5 5 4 4 QRECHARG 0.17 0.17 0.17 0.17 0.17 0.17 0.17 0.17 0.17 0.17 0.17 0.17 E 6 6 6 6 6 6 6 6 6 6 6 6 Harmon QINFLOW 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 y 1 1 1 1 1 1 1 1 1 1 1 1 Creek QSUPPLY 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 7 7 7 7 7 7 7 7 7 7 7 7 Earthfx Inc. 178

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QRESERVE 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 8 8 8 8 8 8 8 8 8 8 8 8 QDEMAND 0.00 0.00 0.00 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.00 9 9 9 1 1 1 1 1 1 1 1 9 PWD 4 4 4 4 4 4 4 4 4 4 4 4 QRECHARG 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 E 8 8 8 8 8 8 8 8 8 8 8 8 QINFLOW 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0 0 0 0 0 0 0 0 0 0 0 0 QSUPPLY 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 Farewell 7 7 7 7 7 7 7 7 7 7 7 7 Creek QRESERVE 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 7 7 7 7 7 7 7 7 7 7 7 7 QDEMAND 0.00 0.00 0.00 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.00 9 9 9 1 1 1 1 1 1 1 1 9 PWD 4 4 4 4 4 4 4 4 4 4 4 4 QRECHARG 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 E 9 9 9 9 9 9 9 9 9 9 9 9 QINFLOW 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 5 5 5 5 5 5 5 5 5 5 5 5 Robinso QSUPPLY 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 n 4 4 4 4 4 4 4 4 4 4 4 4 Creek QRESERVE 0 0 0 0 0 0 0 0 0 0 0 0 QDEMAND 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2 2 2 2 2 2 2 2 2 2 2 2 PWD 7 7 7 7 7 7 7 7 7 7 7 7 Table 36: Detailed monthly groundwater stress assessment - future conditions.

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CLOCA Tier 1 Water Budget Report January, 2009

Water- Detailed Monthly Groundwater Assessment by Catchment - Future Demand shed Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec QRECHARG 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 E 2 2 2 2 2 2 2 2 2 2 2 2 QINFLOW 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0 0 0 0 0 0 0 0 0 0 0 0 QSUPPLY 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 Tooley 2 2 2 2 2 2 2 2 2 2 2 2 Creek QRESERVE 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3 3 3 3 3 3 3 3 3 3 3 3 QDEMAND 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4 4 4 4 4 4 4 4 4 4 4 4 PWD 7 7 7 7 7 7 7 7 7 7 7 7 QRECHARG 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 E 4 4 4 4 4 4 4 4 4 4 4 4 QINFLOW 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 7 7 7 7 7 7 7 7 7 7 7 7 QSUPPLY 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 Black 1 1 1 1 1 1 1 1 1 1 1 1 Creek QRESERVE 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 1 1 1 1 1 1 1 1 1 1 1 1 QDEMAND 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 6 6 6 6 6 6 6 6 6 6 6 6 PWD 4 4 4 4 4 4 4 4 4 4 4 4 QRECHARG 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 E 0 0 0 0 0 0 0 0 0 0 0 0 QINFLOW 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 2 2 2 2 2 2 2 2 2 2 2 2 Darling- QSUPPLY 0.09 0.09 0.09 0.09 0.09 0.09 0.09 0.09 0.09 0.09 0.09 0.09 ton 2 2 2 2 2 2 2 2 2 2 2 2 Creek QRESERVE 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4 4 4 4 4 4 4 4 4 4 4 4 QDEMAND 0.00 0.00 0.00 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.00 4 4 4 1 1 1 1 1 1 1 1 4 PWD 4 4 4 24 24 24 24 24 24 24 24 4 QRECHARG 0.61 0.61 0.61 0.61 0.61 0.61 0.61 0.61 0.61 0.61 0.61 0.61 E 5 5 5 5 5 5 5 5 5 5 5 5 QINFLOW 0.30 0.30 0.30 0.30 0.30 0.30 0.30 0.30 0.30 0.30 0.30 0.30 5 5 5 5 5 5 5 5 5 5 5 5 Bowman QSUPPLY 0.92 0.92 0.92 0.92 0.92 0.92 0.92 0.92 0.92 0.92 0.92 0.92 - 0 0 0 0 0 0 0 0 0 0 0 0 ville QRESERVE 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 Creek 2 2 2 2 2 2 2 2 2 2 2 2 QDEMAND 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 4 4 4 6 6 6 6 6 6 6 6 4 PWD 3 3 3 3 3 3 3 3 3 3 3 3 QRECHARG 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 E 8 8 8 8 8 8 8 8 8 8 8 8 QINFLOW 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 2 2 2 2 2 2 2 2 2 2 2 2 Westsid QSUPPLY 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 e 0 0 0 0 0 0 0 0 0 0 0 0 Creek QRESERVE 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1 1 1 1 1 1 1 1 1 1 1 1 QDEMAND 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1 1 1 1 1 1 1 1 1 1 1 1 PWD 4 4 4 4 4 4 4 4 4 4 4 4 QRECHARG 0.41 0.41 0.41 0.41 0.41 0.41 0.41 0.41 0.41 0.41 0.41 0.41 E 5 5 5 5 5 5 5 5 5 5 5 5 Soper QINFLOW 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 Creek 0 0 0 0 0 0 0 0 0 0 0 0 QSUPPLY 0.61 0.61 0.61 0.61 0.61 0.61 0.61 0.61 0.61 0.61 0.61 0.61 Earthfx Inc. 180

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5 5 5 5 5 5 5 5 5 5 5 5 QRESERVE 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 1 1 1 1 1 1 1 1 1 1 1 1 QDEMAND 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 6 6 6 8 9 9 9 9 8 8 8 6 PWD 3 3 3 3 3 3 3 3 3 3 3 3 QRECHARG 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 E 7 7 7 7 7 7 7 7 7 7 7 7 QINFLOW 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 1 1 1 1 1 1 1 1 1 1 1 1 QSUPPLY 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 Bennet 8 8 8 8 8 8 8 8 8 8 8 8 Creek QRESERVE 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2 2 2 2 2 2 2 2 2 2 2 2 QDEMAND 0.00 0.00 0.00 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.00 9 9 9 1 1 1 1 1 1 1 1 9 PWD 4 4 4 4 4 4 4 4 4 4 4 4 QRECHARG 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 E 5 5 5 5 5 5 5 5 5 5 5 5 QINFLOW 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0 0 0 0 0 0 0 0 0 0 0 0 Lake QSUPPLY 0.18 0.18 0.18 0.18 0.18 0.18 0.18 0.18 0.18 0.18 0.18 0.18 Catch- 5 5 5 5 5 5 5 5 5 5 5 5 ments QRESERVE 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 9 9 9 9 9 9 9 9 9 9 9 9 QDEMAND 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2 2 2 4 4 4 4 4 4 4 4 2 PWD 1 1 1 2 2 2 2 2 2 2 2 1 QRECHARE is 1/12th of the simulated annual average recharge from Table 12. QINFLOW is 1/12th of the simulated annual average lateral inflow from Table 13. QSUPPLY is QRECHARGE + QINFLOW. QRESERVE is 1/10th of the simulated annual average groundwater discharge to streams (divided into 12 NOTES: equal monthly amounts) from Table 27 QDEMAND is the future groundwater demand for the month from Table 21. PWD (Percent Water Demand) = QDEMAND*100/(QSUPPLY-QRESERVE) Table 36 (continued): Detailed monthly groundwater stress assessment - future conditions.

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