Approved Updated Assessment Report: Water Budget and Stress Assessment Central Lake Ontario Source Protection Area 3.0 WATER BUDGET AND STRESS ASSESSMENT .............................................................. 3-1 3.1 Conceptual Water Budget ............................................................................................... 3-2 3.2 Physical Geography .......................................................................................................... 3-4 3.2.1 Topography .......................................................................................................... 3-4 3.2.2 Physiography ........................................................................................................ 3-4 3.3 Geology ............................................................................................................................ 3-9 3.3.1 Stratigraphic Framework ..................................................................................... 3-9 3.3.2 Bedrock Geology ................................................................................................ 3-10 3.3.3 Quaternary Sediments ....................................................................................... 3-10 3.3.4 Hydrogeologic Units ........................................................................................... 3-17 3.4 Surface Water Flow System ........................................................................................... 3-18 3.4.1 Surface Water and Drainage .............................................................................. 3-18 3.4.2 Fluvial Geomorphology ...................................................................................... 3-19 3.4.3 Stream Order ..................................................................................................... 3-19 3.4.4 Surface Water Control Structures ...................................................................... 3-20 3.4.5 Thermal Classifications ...................................................................................... 3-20 3.4.6 Surface Water Bodies, Flows, Levels, and Trends ............................................. 3-23 3.4.7 Wetlands ............................................................................................................ 3-31 3.5 Groundwater Flow System ............................................................................................ 3-35 3.5.1 Groundwater Recharge ...................................................................................... 3-45 3.5.2 Groundwater Discharge ..................................................................................... 3-46 3.6 Climate ........................................................................................................................... 3-55 3.6.1 Climate: Historical and Projections .................................................................... 3-55 3.6.2 Climate Trends ................................................................................................... 3-56 3.6.3 Climate Projections ............................................................................................ 3-56 3.7 Tier 1 Water Budget ....................................................................................................... 3-57 3.7.1 Stress Assessment Subwatersheds .................................................................... 3-64 3.7.2 Tier 1 Methodology ........................................................................................... 3-65 3.7.3 Uncertainty ........................................................................................................ 3-71 3.8 Tier 3 Water Budget Process ......................................................................................... 3-75 3.8.1 Overview ............................................................................................................ 3-75 3.8.2 Tier 3 Methodology ........................................................................................... 3-77 3.8.3 Study Area and Model Domain .......................................................................... 3-90 Approved July 24, 2015 Approved Updated Assessment Report: Water Budget and Stress Assessment Central Lake Ontario Source Protection Area 3.8.4 Municipal Water Usage and Requirements ....................................................... 3-90 3.8.5 Other Water Uses and Requirements................................................................ 3-98 3.8.6 Future Land Use ................................................................................................. 3-99 3.8.7 Model Development and Calibration ................................................................ 3-99 3.8.8 Water Budget Parameter Refinement ............................................................. 3-100 3.8.9 Delineation of Vulnerable Areas for Water Quantity ...................................... 3-100 3.8.10 Risk Assessment Scenario Results ................................................................. 3-104 3.8.11 Tier 3 Significant Groundwater Recharge Areas ............................................ 3-111 3.9 Water Budget Summary .............................................................................................. 3-111 3.9.1 Tier 1 Water Budget ......................................................................................... 3-111 3.9.2 Tier 3 Water Budget ......................................................................................... 3-112 FIGURES Figure 3.1: CLOSPA Conceptual Model of Flow System ............................................................................ 3-3 Figure 3.2: Ground Surface Topography (from 30-m Digital Elevation Model (DEM) Data from MNR) .. 3-6 Figure 3.3: Hummocky Topography .......................................................................................................... 3-7 Figure 3.4: Physiographic Regions (Chapman and Putnam, 1984) ........................................................... 3-8 Figure 3.5: GSC Stratigraphic Framework for the Oak Ridges Moraine and South Flank ......................... 3-9 Figure 3.6: Bedrock Geology ................................................................................................................... 3-11 Figure 3.7: Bedrock Topography ............................................................................................................. 3-12 Figure 3.8: Quaternary Deposits Found within CLOSPA’s Boundaries.................................................... 3-13 Figure 3.9: Surficial Geology (Sharpe et al., 1997) .................................................................................. 3-16 Figure 3.10: Dams and Weirs .................................................................................................................. 3-21 Figure 3.11: Thermal Regime of CLOSPA Watercourses (2005–2008) ................................................... 3-22 Figure 3.12: Average Monthly Streamflow, Lynde Creek ....................................................................... 3-24 Figure 3.13: Average Monthly Water Levels, Lake Ontario .................................................................... 3-25 Figure 3.14: Average Monthly Streamflow, Harmony Creek .................................................................. 3-27 Figure 3.15: Average Monthly Streamflow, Bowmanville Creek ............................................................ 3-29 Figure 3.16: Average Monthly Streamflow, Soper Creek........................................................................ 3-29 Figure 3.17: Average Monthly Streamflow, Oshawa Creek .................................................................... 3-30 Figure 3.18: Depth to Water Table ......................................................................................................... 3-37 Figure 3.19: Water Table Surface ............................................................................................................ 3-38 Figure 3.20: Water Levels in Oak Ridges Moraine and Mackinaw Interstadial Aquifers ........................ 3-39 Figure 3.21: Water Levels in Thorncliffe Aquifer .................................................................................... 3-40 Figure 3.22: Water Levels in Scarborough Aquifer ................................................................................. 3-41 Figure 3.23: Potentiometric Surface Elevation ....................................................................................... 3-42 Approved July 24, 2015 Approved Updated Assessment Report: Water Budget and Stress Assessment Central Lake Ontario Source Protection Area Figure 3.24: Flowing Water Well Locations ............................................................................................ 3-43 Figure 3.25: Downward Gradients .......................................................................................................... 3-44 Figure 3.26: Potential Discharge Areas ................................................................................................... 3-48 Figure 3.27: Simulated Groundwater Discharge to Streams .................................................................. 3-49 Figure 3.28: Daily Mean Streamflow Calculated at Six WSC Hydrometric Data (HYDAT) Sites .............. 3-50 Figure 3.29: Permit To Take Water (PTTW) Withdrawal Locations ........................................................ 3-54 Figure 3.30: Components of a Steady-State Water Budget (after MOE, 2007)