Forward ii 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 ..........................