Orangeville, Mono, and Amaranth Water Quantity Risk Management ...

CTC Source Protection Region

Prepared by:Matrix Solutions Inc. forCTC Source Protection Region

Orangeville, Mono and Amaranth Water Quantity Risk Management and Climate Change Adaptation

Assessment Pilot Study

Credit Valley Source Protection Area

Toronto and Region Source Protection Area

Central Lake Ontario Source Protection Area

August 2014

PREFACE

Under the Clean Water Act, 2006, the Province of Ontario has funded the CTC Source Protection Region (CTC SPR) to carry out technical work to identify where activities may pose threats to the sources of municipal drinking water. On January 18, 2012 the Ministry of the Environment approved the Assessment Report for the Credit Valley Source Protection Area within the CTC SPR which identified a number of significant water quantity and quality threats to municipal wells serving the Town of Orangeville and a planned well in the Township of Amaranth. The Assessment Report also contains maps of vulnerable areas where the existing and future threats are located. The report is available on the CTC website – http://www.ctcswp.ca/the-science-ctc-assessment-reports/credit-valley-spa-assessment-report/.

As required, the Credit Valley Source Protection Authority submitted for approval a Proposed Source Protection Plan in October 2012 to the Minister of the Environment. This Plan contains a number of proposed policies which when implemented are intended to avoid or reduce the risk from existing or future significant threat activities. The Plan is available on the CTC website - http://www.ctcswp.ca/ctc-source-protection-plan/

Some of the policies in this Plan (as well as others across the province) rely on the implementation of risk reduction measures. To aid municipal staff when they implement such policies, the Ministries of the Environment and Natural Resources are identifying and assessing current best practices to develop a catalogue of Risk Management Measures as a support tool. As part of this work, a pilot project has been undertaken to assess the various risk management measures that could be used to reduce the water quantity threats identified through the Orangeville, Mono, Amaranth Tier Local Area Risk Assessment of water quantity threats.

This report has been prepared by Matrix Solutions Inc. under the direction of staff of the Ministry of the Environment and Climate Change and Ministry of Natural Resources. As part of this study a Technical Committee and an Advisory Committee were struck to participate in the project. The responsibility for communicating the results to the committee members was assigned to the CTC SPR. The funding for this technical assessment was provided by the Province of Ontario to the CTC SPR as part of the transfer payment agreement to carry out approved work in support of source water protection.

The Committee members were:

Technical Committee

Chair: Mike Garraway, Ministry of Natural Resources

Municipal Members: Craig Johnston (consultant to Amaranth), Doug Jones (Orangeville), Mark Early (Mono)

CTC SPR Members: Kerry Mulchansingh (Credit Valley Source Protection Area), Don Ford (Toronto and Region Source Protection Area), Beverley Thorpe (CTC)

http://www.ctcswp.ca/the-science-ctc-assessment-reports/credit-valley-spa-assessment-report/

http://www.ctcswp.ca/the-science-ctc-assessment-reports/credit-valley-spa-assessment-report/

Provincial Members: Clara Tucker (Ministry of the Environment), Lynne Milford (Ministry of Natural Resources)

Consultants: David Van Vliet (Matrix Solutions Inc.), Patty Meyer (Matrix Solutions Inc.)

Advisory Committee

Chair: Mike Garraway, Ministry of Natural Resources

Municipal Members: Susan Stone (Amaranth), Doug Jones (Orangeville), Mark Early (Mono), Mark Schiller (Peel) Source Protection Authority Members: Don Ford (Toronto and Region Source Protection Area), Beverley Thorpe (CTC), Dan Banks (Credit Valley Source Protection Area), Martin Keller (Lake Erie Source Protection Region), Ryan Post (Nottawasaga Valley Source Protection Area), Megan Price (CTC)

Provincial Members: Clara Tucker (Ministry of the Environment), Lynne Milford (Ministry of Natural Resources)

The findings and conclusions in the report are those of the consultant and do not necessarily reflect the opinions of the members of the committees or their organizations. The findings from the report provides information which may be considered in future decisions related to source water protection policies, risk management measures and development applications.

ORANGEVILLE, MONO AND AMARANTH WATER QUANTITY RISK MANAGEMENT AND CLIMATE CHANGE ADAPTATION ASSESSMENT PILOT STUDY

Report Prepared for: TORONTO AND REGION CONSERVATION AUTHORITY

Prepared by: MATRIX SOLUTIONS INC.

March 2014 Breslau, Ontario

31 Beacon Point Court Breslau, Ontario, Canada N0B 1M0 Phone: 519.772.3777 Fax: 519.648.3168 www.matrix-solutions.com

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TABLE OF CONTENTS 1 INTRODUCTION ................................................................................................................................ 1

1.1 Orangeville, Mono and Amaranth Tier Three Local Area Risk Assessment ........................ 2 1.2 Organization ........................................................................................................................ 3

2 SELECTING THE WATER BUDGET MODEL ........................................................................................ 3 2.1 Evaluation of the Tier Three Model .................................................................................... 3 2.2 Evaluation of Possible New Modeling Tools ....................................................................... 4 2.3 Update the Tier Three Assessment Model ......................................................................... 4

3 RANKING WATER QUANTITY THREATS ............................................................................................ 5 3.1 Identification of Significant Drinking Water Quantity Threats ........................................... 5

3.1.1 Consumptive Water Demands ............................................................................... 5 3.1.2 Reductions in Recharge ......................................................................................... 6

3.2 Threats Ranking Scenarios .................................................................................................. 6 3.3 Percentage Impacts and Threats Ranking .......................................................................... 8

4 EVALUATING WATER QUANTITY RISK MANAGEMENT MEASURES ............................................... 12 4.1 Evaluation of Historical Conservation Measures .............................................................. 13 4.2 Identification of Preliminary Additional Risk Management Measures ............................. 14

4.2.1 QT067: Optimization of Pumping Rates for Sustainable Yield ............................ 14 4.2.2 QT068: Distribution System Integration .............................................................. 15 4.2.3 QT031: Third Pipe Infiltration System .................................................................. 15

4.3 Evaluation of the Risk Management Measures ................................................................ 16 4.3.1 Design of the Risk Management Measures Scenarios ......................................... 16 4.3.2 Pumping Optimization Method ........................................................................... 17 4.3.3 Safe Additional In-Well Drawdown, Non-Linear In-Well Loss, and Convergent

Head Loss ............................................................................................................. 20 4.3.4 Risk Management Measures Scenarios Results................................................... 23

4.3.4.1 Scenario A .......................................................................................... 28 4.3.4.2 Scenario B .......................................................................................... 29 4.3.4.3 Scenario C .......................................................................................... 30 4.3.4.4 Scenario D .......................................................................................... 31 4.3.4.5 Scenario E to G ................................................................................... 31 4.3.4.6 Summary of Results ........................................................................... 32

4.4 Selection of Preferred Risk Management Measures ........................................................ 34 5 RE-EVALUATING WATER QUANTITY RISK MANAGEMENT MEASURES FOR CLIMATE CHANGE

ADAPTATION .................................................................................................................................. 34 5.1 Climate Change and the Clean Water Act Director’s Rules .............................................. 34 5.2 Climate Change Scenarios ................................................................................................. 36 5.3 Assessment of Climate Change Impacts on In-Well Drawdown and Groundwater

Discharge .......................................................................................................................... 36

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5.4 Summary of Climate Change Results ................................................................................ 39 6 DEVELOPING THE THREATS MANAGEMENT STRATEGY ................................................................ 40 7 SUMMARY ...................................................................................................................................... 41 8 LESSONS LEARNED FROM THIS PILOT STUDY ................................................................................ 42 9 REFERENCES ................................................................................................................................... 43

FIGURES FIGURE 1 Local Areas and Water Quantity Threats FIGURE 2 Monthly Recharge Time Series - MIKE SHE FIGURE 3 Development Areas – Level III Risk Ranking Scenarios FIGURE 4 Dimensions Used to Calculate Percentage Impact for Threat Ranking Scenarios FIGURE 5 Town of Orangeville Average Annual and Average Monthly Water Demands

LIST OF TABLES TABLE 1 Local Areas, Consumptive Water Uses and Water Quantity Threats ................................. 6 TABLE 2 Threats Ranking Scenarios .................................................................................................. 8 TABLE 3 Level I - Threat Ranking Scenarios - Local Area A ............................................................. 10 TABLE 4 Level III - Threat Ranking Scenarios - Local Area A ........................................................... 10 TABLE 5 Threat Ranking - Local Area A ........................................................................................... 11 TABLE 6 Town of Orangeville Water Conservation Measures ........................................................ 13 TABLE 7 Selected Water Quantity Risk Management Measures .................................................... 14 TABLE 8 Scenarios Incorporating Water Quantity Risk Management Measures ........................... 17 TABLE 9 Municipal Well Pumping Rate Details and Estimated Rates for RMM

Optimization/Integration Scenarios ................................................................................. 18 TABLE 10 Safe Additional In-Well Drawdown (2008 compared to 2013) ......................................... 20 TABLE 11 Non-linear In-Well Losses (2008 Compared to 2013) ....................................................... 22 TABLE 12 Convergent Head Losses (2008 Compared to 2013) ........................................................ 23 TABLE 13 Optimization/Integration Scenarios - Final Pumping Rates (m3/d) .................................. 25 TABLE 14 Maximum Drawdown and Remaining Safe Additional In-Well Drawdown (m) ............... 26 TABLE 15 Impacts to Groundwater Discharge .................................................................................. 27 TABLE 16 Summary of Results from the RMM Evaluation Process .................................................. 33 TABLE 17 Mean Annual Temperature, Precipitation and Recharge Change from Baseline ............. 36 TABLE 18 Maximum Drawdown and Remaining Safe Additional In-Well Drawdown (m) ............... 38 TABLE 19 Impacts to Groundwater Discharge .................................................................................. 38 TABLE 20 Summary of Results from the RMM Evaluation Process .................................................. 39

APPENDICES APPENDIX A Approach for the Water Quantity Risk Management Measures Evaluation Process APPENDIX B Information Sheets from the Water Quantity Risk Management Measures Catalogue APPENDIX C Developing the Climate Change Scenarios

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1 INTRODUCTION The Clean Water Act (MOE 2006a), which came into effect in July 2007, sets the legal framework that ensures communities are able to protect their municipal drinking water supplies by developing collaborative, locally driven, science-based protection plans. Communities will identify potential risks to local water sources and take action to reduce or eliminate these risks.

In October 2006, the Ministry of the Environment issued the document called Assessment Report: Draft Guidance Modules (MOE 2006b) to guide the tasks being undertaken for the source protection technical studies in advance of the technical rules and regulations under the Clean Water Act (MOE 2006a).

To assist the Source Protection Committees (SPC) and the municipalities in formulating water quantity policies, the province developed a Guide Water Quantity Risk Management Measures Evaluation Process (RMM Evaluation Process; TRCA 2013a) and a Water Quality and Quantity Risk Management Measures Catalogue (RMM Catalogue; TRCA 2013b).

The RMM Evaluation Process is undertaken in the planning and implementation phases to inform the policy development process. This process is used to select and evaluate measures, using the Water Budget models developed in the Tier Three Water Budget and Local Area Risk Assessment (Tier Three Assessment), to determine what measures can be used to manage the Water Quantity Risks to drinking water within the Local Area.

The objective of the process is to help prepare a Threats Management Strategy that would give guidance to the SPC to insure the sustainability of the water resource that supplies the municipal drinking water system.

In the long term, the RMM Evaluation Process, the RMM Catalogue and the Threats Management Strategy will assist risk management officials with the establishment of strategies where required by Source Protection Plans.

For this current study, the RMM Evaluation Process approach was applied to the municipal water supplies within the Towns of Orangeville and Mono and the Township of Amaranth that lie within or just outside the Headwaters Subwatershed within the Credit Valley Conservation Authority. This study has been formulated as a pilot study and represents the next step in the Credit Valley, Toronto and Region and Central Lake Ontario (CTC) Conservation Authorities SPC’s mandate to manage the water quality and quantity in the area, following the completion of their Tier Three Assessments. This report outlines the Risk Management Measures Evaluation approach used, the ranking of the Significant Water Quantity Threats identified in the Tier Three Assessment (AquaResource 2011), the application of the Water Quantity Risk Management Measures Catalogue and web-tool, and the evaluation of Risk Management Measures using the Tier Three Assessment Water Budget groundwater flow model.


Additionally, a climate change adaptation exercise was performed to assess the utility of the available climate change datasets for use in conjunction with the Water Budget models.

1.1 Orangeville, Mono and Amaranth Tier Three Local Area Risk Assessment A Tier Three Assessment was completed for the Towns of Orangeville and Mono and the Township of Amaranth (AquaResource 2011) to estimate the likelihood that the municipal drinking water wells will be able to supply their Allocated pumping rates while considering increased non-municipal water demand, future land development, drought conditions and other water uses.

As part of that study, four Local Areas (designated Local Areas A through D), were delineated following the Province’s Technical Rules (MOE 2009) based on a combination of the cone of influence of each municipal well as well as land areas where reductions in recharge have the potential to have a measurable impact on water levels at the municipal wells. These Local Areas (Figure 1) are areas on the landscape where increases in municipal pumping and reductions in recharge due to land use development (relative to the existing condition, 2008) have the potential to cause water levels at the municipal well to fall below safe water level elevations, or to reduce groundwater discharge to cold water streams that exceed the Province’s thresholds.

A series of scenarios were run using a calibrated MODFLOW groundwater flow model to identify the potential impacts associated with reductions in recharge due to land use development, increased municipal demand (Allocated Rates), and variable climatic conditions, including drought. Results of the Risk Assessment scenarios led to the designation of a Significant Risk Level for Local Area A, which includes all of Orangeville’s water supply wells as well as Mono’s Cardinal Woods Wells and the Township of Amaranth’s Pullen Well (AquaResource 2011). Specifically, Local Area A was classified as having a Significant Water Quantity Risk Level due to the impacts of pumping the Allocated Quantity of water and groundwater recharge reductions under both average climate and drought conditions. As Local Area A is designated as having a Significant Risk Level, all consumptive water takers (existing and proposed) and all reductions in recharge (future/proposed) within Local Area A are considered Significant Water Quantity Threats (Figure 1).

The RMM Evaluation Process was applied in this pilot study to demonstrate the implementation of methods to rank the Significant Threats, and evaluate potential Risk Management Measures using the Tier Three Assessment MODFLOW Water Budget models. Results from this pilot study may be used to inform the development of a Threats Management Strategy to address the Significant Water Quantity Threats and minimize the water quantity risk to the municipal water supplies.

The Risk Management Strategy suggested in this pilot study represents only a few of the possible measures that could be considered by the local municipalities. The final Risk Management Strategy for this area should be developed in consultation with all stakeholders and should consider all of the potential Water Quantity Risk Management Measures.


1.2 Organization This report has been organized into the following sections corresponding to the RMM Evaluation Process approach detailed in Appendix A:

Section 2: Selecting the Water Budget Model

• Evaluation of the Tier Three Assessment model

• Evaluation of possible new modeling tools

• Update the Tier Three Assessment model

Section 3: Ranking Water Quantity Threats

• Identification of Significant Drinking Water Quantity Threats

• Threats Ranking Scenarios

• Percentage Impacts and Threats Ranking

Section 4: Evaluating Water Quantity Risk Management Measures

• Evaluation of Historical Conservation Measures

• Identification of Preliminary Risk Management Measures

• Evaluation of the Risk Management Measures

• Selection of Preferred Risk Management Measures

Section 5: Re-Evaluating Water Quantity Risk Management Measures for Climate Change Adaptation

Section 6: Developing the Threats Management Strategy

Details of this approach are included in Appendix A.

2 SELECTING THE WATER BUDGET MODEL The Water Budget models created in the Tier Three Assessment were developed using HSP-F for the surface water system and MODFLOW for the groundwater system. These models were calibrated and verified against field observations of hydraulic head and streamflow. The calibrated MODFLOW model was used for the Water Budget and Local Area Risk Assessment (AquaResource 2011).

2.1 Evaluation of the Tier Three Model The Tier Three Assessment MODFLOW model was examined and found to be suitable for the RMM Evaluation Process. The hydrogeologic and hydrologic characterization and conceptualization as reported in the Tier Three Assessment is based on the most recent understanding, and no new geologic


information or monitoring results have changed the conceptualization applied in the numerical model. Additionally, there are no new permitted pumping wells, or intakes that are not already represented in the model. A well in Amaranth Township was recently proposed for a land development area, but it was not included in this study or the previous Tier Three Assessment as the well does not yet have a permit to take water and is pending approval.

2.2 Evaluation of Possible New Modeling Tools An integrated surface water and groundwater model was developed for the study area subsequent to the Tier Three Assessment using the MIKE SHE software program (DHI 2012; draft results presented at a Technical Committee Meeting, June 27, 2013). The MIKE SHE model provided a more complete representation of groundwater/surface water interactions than the combined HSP-F and MODFLOW models used in the Tier Three Assessment. In particular, MIKE SHE improved on the ability to evaluate the influence of climate change on groundwater recharge in comparison to the Tier Three Assessment HSP-F model.

Although the surface and groundwater interactions simulated in MIKE SHE are considered more refined than those simulated in the Tier Three Assessment Water Budget models, to meet the objectives of the RMM Evaluation Process, the MODFLOW model was used for the groundwater system simulations as it is computationally more efficient than MIKE SHE. Only the timing relative magnitude of groundwater recharge was used from the new MIKE SHE model as input to the existing MODFLOW model.

The scenarios conducted under the RMM Evaluation Process only required a testing of the response of the groundwater system, and thus the MODFLOW groundwater model was considered more suitable than the MIKE SHE model, and it provided results that could be compared to the Tier Three Assessment results. In addition, the MODFLOW model interfaced more easily with the parameter estimation software (PEST; Doherty 2004) that was used for the pumping optimization portions of this project.

2.3 Update the Tier Three Assessment Model The transient groundwater recharge derived from the MIKE SHE model was extracted for 1960 to 2012 and was used as input to the Tier Three Assessment MODFLOW model for use in this current study. The annual average recharge for the study area predicted by the MIKE SHE model was 228 mm/year as compared to 288 mm/year predicted by the HSP-F model, and used in the Tier Three Assessment. Given this result, in order to retain consistency in the volume of recharge, the spatial distribution of the average annual recharge from the Tier Three Assessment was retained for this study. However, a new monthly recharge multiplier series was derived from the MIKE SHE model for the 10-year transient drought scenarios, and was calculated as a percentage of the average monthly recharge on a monthly basis for 1960 to 1970. This transient recharge multiplier time series from MIKE SHE is shown on Figure 2. The drought period in the first half of the 1960s is evident in this series with more months of zero recharge occurring from 1960 to 1965. The Tier Three Risk Assessment scenarios were re-run using


the MODFLOW model with the updated recharge pattern from the MIKE SHE model. The final results were almost identical with equivalent drawdowns in the municipal wells and groundwater discharge to streams under current and future pumping, existing and future land use, and historical average and drought conditions.

The transient MODFLOW model with this updated recharge was used for the drought scenarios in the RMM Evaluation Process that follows. For the Threats Ranking exercise and the RMM Evaluation Process of baseflow impacts, the steady-state MODFLOW model was used with the same average annual recharge that was used in the Tier Three Assessment.

3 RANKING WATER QUANTITY THREATS Threats Ranking is undertaken where the Tier Three Assessment estimated the exposure at municipal intakes or groundwater wells is high, and the Threat within the Local Area was classed as Moderate or Significant. Where required, these Significant and Moderate Water Quantity Threats are evaluated and ranked according to the impact they create, relative to the safe additional drawdown, at a well or intake. A detailed methodology for the ranking of the Moderate and Significant Drinking Water Quantity Threats is presented in the Water Quantity Threats Ranking Scenarios Guidance Document (MOE and MNR 2009).

3.1 Identification of Significant Drinking Water Quantity Threats As outlined in the MOE Technical Rules (MOE 2009), a Drinking Water Quantity Threat is defined as any activity that reduces groundwater recharge to an aquifer or any consumptive water demand. Consumptive demands are activities that extract water from an aquifer or surface water body without returning that water to the same aquifer or surface water body.

3.1.1 Consumptive Water Demands

For each vulnerable area identified under clause 15 (2) (d) or (e) of the Clean Water Act (MOE 2006a), drinking water Threats that are or would be classified as Moderate or Significant need to be identified within each vulnerable area. In the Tier Three Assessment, Local Area A was assigned a Water Quantity Risk Level of Significant; as such, all consumptive demands within Local Area A are classified as Significant Water Quantity Threats.

Figure 1 illustrates the permitted and non-permitted consumptive water uses within the four Local Areas. The only permitted water takers within the Local Areas are the municipal water supply wells and these are summarized in Table 1. All non-permitted water uses, including rural domestic water uses that lay within Local Area A are also classified as Significant Water Quantity Threats.


TABLE 1 Local Areas, Consumptive Water Uses and Water Quantity Threats

Local Area Local Area Risk Level Permitted Consumptive Demand (Threat) Threat Classification

Local Area A Significant

Well 2A Significant Wells 5/ 5A Significant Well 6 Significant Well 7 Significant Well 8B Significant Well 8C Significant Wells 9A/ 9B Significant Well 11 Significant Well 12 Significant Pullen Well Significant Cardinal Woods Well 1 Significant Cardinal Woods Well 3 Significant Cardinal Woods Well 4 Significant

Local Area B Low Island Lake PW1 - Island Lake TW1 -

Local Area C Low Coles Wells 1 - Coles Wells 2 -

Local Area D Low Orangeville Well 10 -

The Risk Level applied to Local Areas B, C and D was classified as Low, and thus, there are no Moderate or Significant Water Quantity Threats in those areas.

3.1.2 Reductions in Recharge

The Technical Rules (MOE 2009) specifies that land use development activities that have the potential to lead to reductions in groundwater recharge are potential Water Quantity Threats within the Local Area. The Tier Three Assessment scenarios considered the impact of future land use development activities on water levels in the municipal aquifer at the wells. All reductions in groundwater recharge within Local Area A are also classified as Significant Water Quantity Threats and are shown on Figure 1.

These Significant Water Quantity Threats within Local Area A are ranked in the following sections.

3.2 Threats Ranking Scenarios A series of scenarios were run (Table 2) using the steady-state Tier Three Assessment MODFLOW model for Local Area A where more than one consumptive demand and land use development were identified as Significant Threats. The first model scenario run was the baseline scenario, and the results of this scenario set the benchmark against which all modeling results were compared. This baseline scenario is equivalent to the Risk Assessment Scenario C, which represents the “existing conditions” of the Tier Three Assessment year (2008).


The first set of scenarios conducted were Level 1 Scenarios that examined the cumulative impact of all current or future consumptive water uses, or future land use developments, on the municipal water supplies.

• Scenario I-A quantified the impact of the increased municipal pumping on the municipal supplies. The municipal wells were pumped at their Allocated Rates, as defined in the Tier Three Assessment. In this case, this scenario is equivalent to the Risk Assessment Scenario G(2).

• Scenario I-B quantified the impact of all non-permitted demands on the water supplies. In this study, the domestic wells were the only non-permitted takings within Local Area A. This scenario had all domestic wells pumped at an estimated rate, and the municipal wells pumped at their existing (2008) rates. The consumptive rate of the domestic wells was estimated by assuming 3.2 persons reside in each rural lot, and a domestic per capita water use of 335 L/day; these values are consistent with the Technical Rules (MOE 2009). In addition, a consumptive use coefficient equal to 0.20 (20%) was used to represent the fact that most rural domestic drinking water is returned to groundwater through septic systems. Thus, for each domestic well, water use was estimated to be 214 L/day. The domestic wells were assumed to be taking water from the aquifer at the interface of the overburden and bedrock, and returning water to the same aquifer through the septic systems.

• Scenario I-C was not conducted in this study as there are no non-municipal permitted takings in Local Area A.

• Scenario I-D quantified the impact of recharge reduction due to all future land developments specified in the Official Plans on municipal water supplies. The municipal wells are pumped at the existing (2008) rates and the recharge is reduced in the same manner as outlined in the Tier Three Assessment (AquaResource 2011). In this case, this scenario is equivalent to the Risk Assessment Scenario G(3).

The second set of scenarios conducted were Locally Relevant (Level III) Scenarios that were used to rank the impact of individual water takings or land use development changes on the municipal water supplies.

• Scenarios III-A-1 to A-14 quantified the impact of increased municipal pumping at a specific well on the municipal supplies. For each scenario, one municipal well pumped at the Allocated Rate while the remainder pumped at the existing rates.

• Scenarios III-B-1 to B-8 quantified the impact of specific areas of land use development on the water levels in the municipal wells. Each scenario examined a different land development area with an associated recharge reduction applied in the model. These areas are identified on Figure 3.


TABLE 2 Threats Ranking Scenarios

Scenario Description Municipal Takings

Permitted Takings

Non-Permitted Takings Land Use Rationale

Baseline Baseline Scenario Existing Rates

None None Existing This scenario forms the baseline to which the model scenarios below will be compared.

I-A Municipal Water Use (Allocated Rates)

Allocated Rates

None None Existing Quantify the impact of increasing municipal pumping to Allocated Rates (from existing rates) on the municipal supplies.

I-B All Non-permitted Takings

Existing None Existing Existing Quantify the impact of all non-permitted demands on the water supplies.

I-D Recharge Reduction - Official Plan (50% to 70% reductions for new developments)

Existing None None Official Plan

Quantify the cumulative impact of recharge reduction from all developments in the Official Plan on municipal water supplies.

III-A-x Local Water Demand Scenario - Consumptive Water Taking x

Existing Consumptive User x

None Existing Quantify the impact of individual consumptive takings on the municipal water supplies.

III-B-y Local Groundwater Recharge Reduction Scenario- Activity y

Existing None None Official Plan - Land Use Section y

Quantify the impact of individual developments on the municipal water supplies.

3.3 Percentage Impacts and Threats Ranking After the scenarios noted in Section 3.2 were completed, the percentage impact on the safe additional available drawdown at each well was calculated by comparing the drawdown of each scenario with the baseline scenario drawdown according to the following formula (see Figure 4 for dimensions):

% 𝐼𝑚𝑝𝑎𝑐𝑡 = 𝐷𝑟𝑎𝑤𝑑𝑜𝑤𝑛 𝑐𝑎𝑢𝑠𝑒𝑑 𝑏𝑦 “𝑇ℎ𝑟𝑒𝑎𝑡 𝐴”

𝐴𝑣𝑎𝑖𝑙𝑎𝑏𝑙𝑒 𝐷𝑟𝑎𝑤𝑑𝑜𝑤𝑛 × 100% =

𝑍𝑡ℎ𝑟𝑒𝑎𝑡 𝐴

𝑍𝑠𝑎𝑓𝑒 × 100%

The results for the Level I Risk Ranking Scenarios are given in Table 3.

Scenario I-A with all municipal wells pumping at the Allocated Rates caused a significant impact on the safe additional available drawdown within the municipal wells. The greatest percent impact (86%) occurs at Cardinal Woods 3 where 2.1 m of the 2.4 m of safe additional drawdown was predicted due to the increase in municipal pumping from the existing (2008) rates to the Allocated Rates. The next


greatest percent impact (79%) occurred at Well 6, again due to the cumulative impact of increased municipal pumping from the existing to the Allocated Rates.

Scenario I-B simulated all domestic wells pumping within Local Area A. This pumping had negligible impacts on the municipal wells (Table 3).

Scenario I-D simulated the impact of all future (Official Plan) recharge reductions due to land use changes. The reduced recharge had the greatest percent impact of 77% at Well 5/5A, with the second largest impact of 47% seen at Well 9A/9B (Table 3).

Overall, the greatest cumulative impacts due to the Level I scenarios are seen at Well 5/5A, Well 6 and Cardinal Woods 3 (total percentage impacts of 95%, 92%, and 97%, respectively; Table 3).

The Level III scenarios results are given in Table 4. As expected, pumping at each of the municipal wells had the greatest percent impact on the wells themselves and a lesser impact on the nearby surrounding wells. For example, increased pumping at Well 6 (Scenario III-A-3) had a 52% impact on Well 6, and a 5% impact at neighboring Well 11. Pumping at Well 7 (Scenario III-A-4) had a 35% impact on itself, and a 14% impact at nearby Well 2A (Table 4).

The individual land use development areas specified in the Official Plan impact the wells closest to the areas where recharge reduction is expected. The greatest impacts were predicted from two development areas, Amaranth (Scenario III-B-1) and East Garafraxa (Scenario III-B-2). The Amaranth development area was predicted to have the greatest percent impact on Well 5/5A (41% impact) and at Well 9/9A (27% impact). The East Garafraxa development area was predicted to cause a 13% impact at Well 9A/9B, and a 6% impact at Well 5/5A.


TABLE 3 Level I - Threat Ranking Scenarios - Local Area A

TABLE 4 Level III - Threat Ranking Scenarios - Local Area A

4.7 3.2 2.9 8.7 7.5 7.4 4.8 6.6 10 29.9 4.8 2.4

(m) (% Impact) (m) (% Impact) (m) (% Impact) (m) (% Impact) (m) (% Impact) (m) (% Impact) (m) (% Impact) (m) (% Impact) (m) (% Impact) (m) (% Impact) (m) (% Impact) (m) (% Impact)I-A All Municipal Wells 2.2 47% 0.6 18% 2.3 79% 4.0 46% 1.4 19% 1.4 19% 0.4 8% 2.8 43% 4.0 40% 2.7 9% 0.4 8% 2.1 86% 86%I-B Domestic Wells 0.0 0% 0.0 0% 0.0 1% 0.0 0% 0.0 0% 0.0 0% 0.0 1% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 1%I-D Recharge (OP) 0.8 17% 2.5 77% 0.4 12% 0.7 9% 0.5 6% 0.5 6% 2.3 49% 0.4 5% 0.7 7% 0.8 3% 0.2 5% 0.3 11% 77%

Total 3.0 64% 3.0 95% 2.7 92% 4.8 55% 1.9 25% 1.9 25% 2.8 58% 3.2 48% 4.7 47% 3.5 12% 0.6 13% 2.3 97%

Well 6 Well 7 Well 8B Well 8CSafe Additional Drawdown (m)

Incremental DrawdownModel Scenario

Municipal Supply Well Well 9A/9B Well 11 Well 12 Pullen Cardinal Woods 1Well 2A Well 5/5AGreatest Percent Impact

Cardinal Woods 3

4.7 3.2 2.9 8.7 7.5 7.4 4.8 6.6 10 29.9 4.8 2.4

(m) (% Impact) (m) (% Impact) (m) (% Impact) (m) (% Impact) (m) (% Impact) (m) (% Impact) (m) (% Impact) (m) (% Impact) (m) (% Impact) (m) (% Impact) (m) (% Impact) (m) (% Impact)

III-A-1 Well 2A 0.8 17% 0.0 1% 0.1 2% 0.2 2% 0.1 1% 0.1 1% 0.0 1% 0.1 1% 0.1 1% 0.1 0% 0.0 0% 0.0 0% 17%III-A-2 Well 5/5A 0.0 1% 0.3 10% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.1 1% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 10%III-A-3 Well 6 0.1 2% 0.0 0% 1.5 52% 0.1 1% 0.0 0% 0.0 0% 0.0 1% 0.3 5% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 52%III-A-4 Well 7 0.7 14% 0.1 2% 0.2 6% 3.1 35% 0.3 4% 0.3 4% 0.1 2% 0.2 3% 0.4 4% 0.3 1% 0.0 1% 0.0 1% 35%III-A-5 Well 8B 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.2 3% 0.1 1% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 3%III-A-6 Well 8C 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.1 1% 0.2 3% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 3%III-A-7 Well 9A/9B 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0%III-A-8 Well 10 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0%III-A-9 Well 11 0.2 3% 0.0 1% 0.4 14% 0.1 2% 0.1 1% 0.1 1% 0.0 1% 2.0 30% 0.1 1% 0.1 0% 0.0 0% 0.0 0% 30%

III-A-10 Well 12 0.3 6% 0.1 2% 0.1 3% 0.4 4% 0.5 7% 0.5 6% 0.1 1% 0.1 1% 3.0 30% 0.5 2% 0.1 1% 0.0 2% 30%III-A-11 Pullen Well 0.1 3% 0.0 1% 0.0 1% 0.1 2% 0.1 2% 0.1 2% 0.0 1% 0.0 1% 0.3 3% 1.6 5% 0.0 1% 0.0 1% 5%III-A-12 Cardinal Woods 3 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.2 4% 1.9 81% 81%III-A-13 Island Lake Wells 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0%III-A-14 Coles 1-2 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0%

III-B-1 Amaranth Area 0.4 8% 1.3 41% 0.2 6% 0.3 3% 0.2 2% 0.2 2% 1.3 27% 0.2 2% 0.3 3% 0.4 1% 0.0 1% 0.0 1% 41%III-B-2 East Garafraxa Area 0.1 3% 0.2 6% 0.1 3% 0.1 1% 0.1 1% 0.1 1% 0.6 13% 0.1 1% 0.1 1% 0.1 0% 0.0 0% 0.0 0% 13%III-B-3 Orangeville South Area 0.0 0% 0.0 0% 0.1 2% 0.0 0% 0.0 0% 0.0 0% 0.0 1% 0.0 1% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 2%III-B-4 Orangeville Area 0.2 3% 0.4 12% 0.1 2% 0.2 2% 0.2 2% 0.2 2% 0.1 1% 0.1 1% 0.2 2% 0.2 1% 0.0 0% 0.0 0% 12%III-B-5 Orangeville East Area 0.0 0% 0.0 0% 0.0 1% 0.0 0% 0.0 0% 0.0 0% -0.1 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 1%III-B-6 Mono South Area 0.0 0% 0.0 0% 0.0 1% 0.0 0% 0.0 0% 0.0 0% -0.1 0% 0.0 0% 0.0 0% 0.0 0% 0.1 2% 0.1 5% 5%III-B-7 Mono North Area 0.0 0% 0.0 0% 0.0 1% 0.0 0% 0.0 0% 0.0 0% -0.1 0% 0.0 0% 0.0 0% 0.0 0% 0.0 1% 0.0 2% 2%III-B-8 Mono West Area 0.0 0% 0.0 0% 0.0 1% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 0.0 0% 1%

Total 2.8 61% 2.3 77% 2.8 95% 4.6 54% 1.8 24% 1.7 24% 2.2 49% 3.1 47% 4.4 45% 3.1 11% 0.5 11% 2.2 94%

Greatest Percent Impact

III-A: Municipal Planned

III-B: Recharge (OP)

Cardinal Woods 1 Cardinal Woods 3Safe Additional Drawdown (m)

Model ScenarioIncremental Drawdown

Well 8B Well 8C Well 9A/9B Well 11 Well 12 PullenMunicipal Supply Well Well 2A Well 5/5A Well 6 Well 7


The municipal wells and proposed development areas are tabulated in ranked order in Table 5. The Threats are ranked according to the greatest percent impact at a municipal well for each Threat; the Threat with the greatest percentage impact receives a higher rank than a Threat with a lower percent impact. This serves to identify the Threats that have the greatest potential to benefit from measures to reduce the overall impact.

An increase in takings from Cardinal Woods 3 has the greatest percent impact (81% impact) ranking it first, with the second and third ranked Threats being the increase takings from Well 6 (52% impact) and the recharge reductions from the Amaranth development area (41% impact; Table 5).

TABLE 5 Threat Ranking - Local Area A

Water Quantity Threat Greatest Percent Impact Threats Ranking Cardinal Woods 3 81% 1

Well 6 52% 2

Amaranth Development Area 41% 3

Well 7 35% 4

Well 11 30% 5

Well 12 30% 5

Well 2A 17% 7

East Garafraxa Development Area 13% 8

Orangeville Development Area 12% 9

Well 5/5A 10% 10

Pullen Well 5% 11

Mono South Development Area 5% 11

Well 8C 3% 13

Well 8B 3% 13

Mono North Development Area 2% 15

Orangeville South Development Area 2% 15

Mono West Development Area 1% 17

Orangeville East Development Area 1% 17

Well 9A/9B 0% N/A

As the Threats Ranking is completed on a Local Area basis where there is a Significant Risk Level, Well 10, the Mono Island Lake wells and Mono Coles wells were not included in the Threat Ranking table as they lie outside of Local Area A. The results of the Threats Ranking were used to inform the next task, which involved selecting and evaluating the Risk Management Measures.


4 EVALUATING WATER QUANTITY RISK MANAGEMENT MEASURES The purpose of this task is to evaluate the potential for Risk Management Measures to mitigate the Water Quantity Threats and reduce the Water Quantity Risk Level identified through the Tier Three Assessment. This task makes use of the RMM Catalogue (TRCA 2013b), a web-based tool that is used to select Risk Management Measures. It presently contains about 80 Water Quantity Risk Management Measures, that are grouped into one or more of the following water conservation and “terrain” (e.g., land-use and land-practice) Management Targets to address Water Quantity Threats:

• indoor water use reduction

• outdoor water use reduction

• industrial, commercial, and institutional (ICI) water efficiencies

• municipal water loss management

• water resource awareness

• increase in recharge

• increase in water supply

• municipal water efficiencies

• agricultural water efficiencies - crop management

• agricultural water efficiencies - livestock management

The RMM Catalogue contains a dataset that is divided into these groups to allow the user to search for measures that are most applicable for managing the Water Quantity Threats activities in the Local Areas and that will be evaluated under the RMM Evaluation Process. The Tier Three Assessment Water Budget model may be used to evaluate certain measures, while other previously implemented measures may be evaluated with historical data.

In evaluating the potential for Risk Management Measures to mitigate the identified Water Quantity Risks, the water conservation measures implemented in the Local Area should be documented and the success of those conservation measures characterized. This will determine if other conservation-related Risk Management Measures may have the potential to succeed in reducing the water demand, and in turn, reducing the Risk Level assigned to the Local Area.

Water conservation measures implemented in the Local Area are summarized in the following section. Additional Water Quantity Risk Management Measures selected from the RMM Catalogue and evaluated using the Water Budget model as part of the RMM Evaluation Process are also described below.


4.1 Evaluation of Historical Conservation Measures The Town of Orangeville has experienced increasing demands placed on the groundwater system that are commensurate with its population growth (Figure 5). The Town experienced peak daily and monthly demands on the groundwater system between 2000 and 2002, which led the Town to proactively initiate a series of water conservation measures to reduce the peak daily (and overall) groundwater demands. The resulting reduction in water demand from the instituted water conservation measures was significant; between 2003 and 2005, the average maximum daily demand decreased by approximately 18% (AquaResource 2011). Table 6 outlines the water conservation measures implemented by the Town since the year 2000 to reduce the maximum daily and average annual water demands.

TABLE 6 Town of Orangeville Water Conservation Measures

Initiative Description Implementation Date

Water Use Audit Home audits offered as part of the WaterCare program. 2000 and 2001 Universal Metering Universal metering program began for residents within the Town. 2002; metering

started in Jan 2003 Water Efficient Fixtures

Water efficient fixtures were offered and distributed through the WaterCare and Universal Metering programs.

Toilet replacement program

Town reimburses residential, commercial, industrial, and institutional water users $50 for each >13 L per flush toilet that is replaced by a Town-approved 6 L per flush low-flow toilet.

2005 to present

Leak Detection Water main leak detection program. 2000 to present Public Information, Education, and Outreach

Posted water conservation tips on the website and made copies of Canada Mortgage and Housing Corporation’s “Household Guide to Water Efficiency” booklet available to residents.

2000 to present

Landscaping and Other Techniques

New Town projects are reviewed by the Mayor’s Environmental Advisory Committee, whereby consideration is given to water conservation features.

Present

Industrial Water Efficiency Processes

Agreement with a local industry to install cooling and water reuse equipment to reduce the use of once-through cooling water. Reduced the water use in one industry by one-third in 1 year.

2002

Economic Incentives and Cost Sharing

The Town offers rain barrels at subsidized rates. 2005 to present

The Town has successfully applied conservation measures and there has been good uptake by residential water users. The maximum benefit has likely been realized and any further reduction to water use through water conservation is interpreted to be minimal. The Town has also worked with large industrial water users to conserve water and like the residential sector, limited reduction in water use is likely to be realized going forward (Jones 2013, Pers. Comm.).


4.2 Identification of Preliminary Additional Risk Management Measures The RMM Catalogue web-tool was used to identify additional measures to be re-revaluated with the Tier Three Assessment Water Budget model beyond the previously implemented measures. The Catalogue was consulted under two specific categories of Threat: “Consumptive water use– wells,” and “An activity that reduces recharge to an aquifer–wells.” From these two categories of Threat, three Risk Management Measures were selected from the catalogue and are used to re-evaluate the Risk to the Local Area using the Tier Three Assessment Water Budget model. These three Measures fall within the “Municipal Water Efficiencies” Management Target, and are all applicable to the “Municipal Sector.” The selection of these measures was based on the results of the ranking process, which showed a high percent of impact for Cardinal Woods 3, Well 6 and the Amaranth Development Area (Table 5), and the previously implemented conservation-related Risk Management Measures (Table 6). Table 7 summarizes the measures chosen from the catalogue. Detailed information sheets from the RMM Catalogue for these three Risk Management Measures are provided in Appendix B.

TABLE 7 Selected Water Quantity Risk Management Measures

Reference ID Measure Name Associated Threat

QT067 Optimization of Pumping Rates for Sustainable Yield 19.2 Consumptive water use - wells

QT068 Distribution System Integration 19.2 Consumptive water use - wells

QT031 Third Pipe Infiltration System 20.1 - An activity that reduces recharge to an aquifer—wells

The first two measures, “Optimization of Pumping Rates for Sustainable Yield” and “Distribution System Integration,” were evaluated using the Tier Three Assessment Water Budget model. The third measure, “Third Pipe Infiltration System,” was evaluated indirectly. The intent of the modelled scenarios was to assess the effects of maintenance of pre-development recharge, and QT031 is an example measure that represents a broad category of Low Impact Development (LID) measures designed to maintain pre-development recharge to the water supply aquifers. Moreover, it is recognized that retrofits of LIDs for existing developments can also achieve the same outcome as LIDs for new developments.

4.2.1 QT067: Optimization of Pumping Rates for Sustainable Yield

The catalogue describes measure QT067 as:

Optimization is a process of re-allocating pumping rates considering a target of maximum amount of groundwater that could be withdrawn from aquifers/streams without violating hydraulic-head or stream-discharge constraints, thus determining the “sustainable yield” for the source of water. Water budgets - optimization modeling can be used for the purpose of evaluating potential pumping scenarios and optimizing maximum groundwater withdrawal rates


to determine sustainable yield for the aquifer while maintaining desirable hydraulic heads in the aquifer and streamflow in the outcrop. Additionally, the optimization models can determine the maximum available withdrawals from major streams for supplementing groundwater to meet the total water demand.

4.2.2 QT068: Distribution System Integration

The catalogue defines measure QT068 as:

Interconnection of separate municipal drinking water systems with pipelines to bulk deliver drinking water to several municipalities, optimizing the distribution to meet all local water demands and to maintain local self-sufficiency. Integration of systems increases the resiliency and reliability of the previously disconnected systems. The integration considers the total capacity of an integrated water supply system, where excess capacity in one of the previously disconnected system may be used to supply a deficit in capacity in another system. The system as a whole may be better able to meet peek demands and there may be an opportunity to reduce the stress on particular water sources.

4.2.3 QT031: Third Pipe Infiltration System

The catalogue defines measure QT031 as:

Installation of a pervious infiltration pipe in new subdivisions. The pipes are usually installed below the storm water sewer in the same trench. Because the pipes cross the entire subdivision, the system mimics pre-development recharge.

This measure was selected as a surrogate of management activities within the Local Area that would promote an increase of recharge in the area. The assumption is that recharge can be achieved post-development using various LID measures. For this pilot study, the intent of including this measure was to evaluate the effectiveness of increasing recharge and to test whether this approach might reduce the water quantity risk to the municipal wells, rather than evaluating the benefits of any particular measure(s) themselves.

Appendix B provides a list of Risk Management Measures for recharge threats, including LIDs. These measures from the RMM Catalogue could also be considered for implementation within the Local Area to manage the threat: “An activity that reduces recharge to an aquifer – wells.” These LID measures can either be implemented for new developments in the Local Area or as retrofits of existing developments. Both new development LIDs and retrofit LIDs can be effective in increasing recharge to the groundwater system.

For this pilot modelling exercise, the future development areas within the Local Area were selected for implementing recharge measures. This decision was based on the successful demonstration by Credit


Valley Conservation (CVC) that LID retrofits in existing urban areas would maintain recharge as reported in Headwaters Subwatershed Study Phase 2: Impact Assessment and Evaluation of Alternative Management Strategies (CVC 2010). To avoid duplication with CVC’s previous work, this pilot study focussed on modelling of LIDs for future development areas. Actual locations and most appropriate types of LID measures within the existing urban areas can be selected according to the following figures found in CVC’s Headwater Subwatershed Study Phase 3: Management, Monitoring and Implementation Plan (CVC 2014):

• Figure 7 Low Impact Development Retrofit Opportunities for Residential Properties

• Figure 8 Low Impact Development Retrofit Opportunities on Industrial and Commercial Properties

• Figure 9 Low Impact Development Retrofit Opportunities on Public Land Properties

• Figure 10 Low Impact Development Retrofit Opportunities in Subwatershed 19

These locations can be refined by municipalities during the implementation phase.

4.3 Evaluation of the Risk Management Measures The preliminary additional Risk Management Measures selected from the RMM Catalogue were evaluated for their success in reducing the Local Area Risk Level using the Tier Three Assessment Water Budget model. The application of the model in the evaluation process can help inform the development and implementation of policies that are intended to manage the Significant Water Quantity Threats activities so that they can become Moderate or Low Water Quantity Threats.

4.3.1 Design of the Risk Management Measures Scenarios

Seven scenarios incorporating the Risk Management Measures selected above were designed to evaluate the ability of the municipal wells to supply the Allocated Quantity of Water and cause lesser impacts on the wells and surface water features within the Local Area than identified as part of the Tier Three Assessment, and thereby reduce the Local Area Risk Level.

Scenarios A to D are designed to evaluate the optimization of pumping rates and the integration of the municipal systems, while Scenarios E to G are designed to evaluate the impacts of maintaining pre-development recharge. These six scenarios are summarized in Table 8.


TABLE 8 Scenarios Incorporating Water Quantity Risk Management Measures

Scenario Risk Management Measures Description

A Optimize Pumping Rates

This scenario considers each of the Mono, Amaranth and Orangeville systems as separate disconnected systems. Individual well pumping rates within each system are modified to reduce risk and maximize pumping.

B Optimize Pumping Rates Integrated Orangeville/Mono System

The scenario considers Mono and Orangeville wells as an integrated system, and Amaranth as a separate system. Pumping rates for the Mono and Orangeville wells are re-distributed to reduce risk and maximize pumping.

C

Optimize Pumping Rates Integrated Orangeville/Amaranth System

The scenario considers Amaranth and Orangeville wells as an integrated system, and Mono wells as a separate system. Pumping rates for the Amaranth and Orangeville wells are re-distributed to reduce risk and maximize pumping.

D

Optimize Pumping Rates Integrated Orangeville/Amaranth/Mono System

This scenario combines Scenario B and C having all municipalities connected. As an integrated system, this scenario evaluates the maximum amount of water than can be provided by all wells, minimizing water supply risk identified in the Tier Three Assessment.

E Maintain 70% Pre-Development Recharge

This scenario assumes that 70% of pre-development recharge can be achieved using various LID measures.

F Maintain 80% Pre-Development Recharge


G Maintain 90% Pre-Development Recharge


For Scenarios A to D, initial estimates of pumping rates for each of the wells were made in consultation with the three municipalities and based on the permitted rates, safe capacity, Allocated Rates from the Tier Three Assessment, operational experience, and other insights gain from the Tier Three Assessment. Table 9 summarizes the municipal well pumping rate details and initial estimated rates for the RMM Scenarios A to D (Optimization/Integration Scenarios). Additional details about the scenario objectives and their configuration are given with the scenario results in the following sections.

4.3.2 Pumping Optimization Method

Scenarios A to D involved optimizing and redistributing the pumping rates across various combinations of wells and municipalities to reduce the Water Quantity Risk Level under average climate and drought conditions, while maximizing total pumping in order to meet demand requirements. As in the Tier Three Assessment, an elevated Water Quantity Risk Level is triggered when the increase in municipal pumping or the reduction of recharge cause either: 1) drawdown at a water supply well to exceed the safe additional drawdown value under any climate condition (Significant); or 2) groundwater discharge to sensitive surface water features is reduced by more than 10% (Moderate) from the base case (2008) condition under average climate conditions (MOE 2013).


TABLE 9 Municipal Well Pumping Rate Details and Estimated Rates for RMM Optimization/Integration Scenarios

Town Municipal Well Aquifer

Permits and Capacity (m3/d) Demand / Pumping (m3/d) RMM Optimization/Integration Scenarios (m3/d)

Permitted Rates1

Combined Permit

Rated Capacity2

Maximum Safe Capacity3

Tier Three “Existing” Demand (2008) Actual 2012 Rate4 Tier Three Allocated

Rates A B C D

Ora

ngev

ille

Well 2A5 Bedrock 878 n/a 1,309 700 286 269 400 400 400 400 400

Well 5/ 5A Overburden 6,000 6,000 6,000 6,000 3,359 3,775 3,500 3,500 3,500 3,500 3,500

Well 6 Bedrock 3,600 n/a 3,600 2,500 1,358 350 1,600 1,600 1,600 1,600 1,600

Well 7 Bedrock 1,310 n/a 1,310 1,310 755 936 1,235 1,235 1,235 1,235 1,235

Well 8B, 8C Bedrock 656 656 654 654 478 442 550 550 550 245 245

Well 9A/ 9B Bedrock 878 878 878 878 559 558 560 560 560 560 560

Well 106 Overburden 1,453 n/a 1,453 1,452 121 585 1,235 1,235 1,235 1,235 1,235

Well 11 Bedrock 1,309 n/a 1,309 1,309 939 681 1,235 1,235 1,235 1,235 1,235

Well 12 Bedrock 1,309 n/a 1,309 1,309 781 1,029 1,240 1,240 1,240 491 491

Total Orangeville 17,393 17,822 16,112 8,636 8,625 11,555 11,555 11,555 10,501 10,501

Card

inal

W

oods

Cardinal Woods 37 Bedrock 1,571

1,5718 1,571 1,571

240 325 392 392 300 392 300

Cardinal Woods 17 Bedrock 817 8 13 8 8 150

8 150

Cardinal Woods 47 Bedrock 753 0 2 0 0 0

Cole

s and

Isla

nd L

ake

Wel

ls

Coles Well 1 Overburden 570 655 655 655 82 90 116 116 655 116 655

Coles Well 2 Overburden 570

Island Lake PW1 Overburden 1,958

2,61410 2,614 2,614

5 51 347

347 1,742 347 1,742 Island Lake TW1 Overburden 1,363 118 128

Island Lake 3 (PW06-2)9 603 not connected not connected not connected

Total Mono 8,205 4,840 4,840 4,840 453 609 863 863 2,847 863 2,847

Amaranth Amaranth Pullen Well Bedrock 1,473 220 220 220 1,473 1,473

Total 25,598 22,662 20,952 9,089 9,234 12,638 12,638 14,622 12,837 14,821 1The permitted withdrawal rate in m3/d. Note the permitted Rate in Orangeville Well 2A is lower than its rated capacity; as such the permitted rate governs in this circumstance 2The rated capacity of the treatment system(s) at that location in m3/d, as per the applicable Municipal Drinking Water License 3Maximum safe pumping capacity determined as of January 1, 2013. Capacities are subject to change upon further review. 42012 average day demand in m3/d; calculated by dividing total annual pumping by 366 days 5Well 2A - 878.4 m3/d for 6 months of the year (April - Sept) 6Well 10 - 1,453 m3/d for 10 months of the year except Oct and Nov where it is reduced to 903 m3/d 7Cardinal Woods 1 and 4 cannot be operated at the same time as Well 3 8Cardinal Woods Wells - 1,571 m3/d for the first 24 hours, then 818 m3/d thereafter 9Island Lake Well 3 (PW06-2) is not yet connected to the drinking water system 10Island Lake Wells - 72-hour combined average pumping rate not to exceed 2,614 m3/day


To determine the best combination of pumping rates that limits the risk for each of the scenarios, the Tier Three Assessment MODFLOW model was run using the parameter estimation software, PEST (Doherty 2004). PEST conducts a series of model runs where each pumping well is adjusted individually to determine the sensitivity of the drawdown at the municipal wells and the discharge at surface water features to incremental changes in the pumping rates. PEST then tests various combinations of pumping rates to arrive at one that meets the criteria of reduced impacts while maximizing the pumping rates.

These optimization model runs are conducted with both the steady-state and transient Water Budget model. The steady-state model runs represent average climate, while the transient model simulates the 10-year period from 1960 to 1970 that includes the drought of the mid-60s. For the steady-state model runs, the Tier Three Assessment G(2) scenario was used and the changes in discharge to surface water bodies were calculated in response to only an increased pumping demand. For the transient model with variable climate, the Tier Three Assessment H(1) scenario was used as it represents the worst case scenario of increased pumping demands, reduced recharge from future land use changes, and drought climate conditions.

Depending on the scenario, municipal pumping rates being optimized were permitted to vary up to the maximum safe capacity listed in Table 9. Other criteria constrain the scenarios such as total permitted well field pumping, or required demand from a well field or system. For example, Scenario A used the Allocated Rates from the Tier Three Assessment as the initial scenario pumping rates. At these rates, drawdown exceeded the safe additional drawdown at Wells 5/5A, 6, and Cardinal Woods 3 under the H(1) scenario (AquaResource 2011). The three municipal systems were treated as separate each with a target rate for the system (11,555 m3/d for Orangeville, 863 m3/d for Mono, and 220 m3/d for Amaranth Pullen Well). PEST was configured to allow the Orangeville wells to exchange pumping volumes within the Orangeville system, or reduce the pumping total to eliminate the risk. As the Cardinal Woods wells need to meet a total demand of 400 m3/d, pumping was allowed to be redistributed between Wells 1 and 4 (which pump alternately) and Well 3. The Island Lake and Coles wells made up the remainder of the required 863 m3/d for Mono, and the Amaranth Pullen Well was held constant at 220 m3/d for this scenario.

The PEST model results were analyzed to determine to what degree the groundwater discharge to surface water features was impacted under the steady-state Scenario G(2) model in comparison to the baseline (2008) conditions. PEST also determined whether the additional drawdown at each municipal well over the baseline (2008) case exceeded the safe additional in-well drawdown at any time during the transient Scenario H(1) drought model run. The optimization runs automatically accounted for the additional drawdown at the wells due to non-linear in-well losses and convergent head losses. These parameters were updated for this study, along with the safe additional in-well drawdown as described below.


4.3.3 Safe Additional In-Well Drawdown, Non-Linear In-Well Loss, and Convergent Head Loss

The safe additional in-well drawdown, non-linear in-well losses, and convergent head losses were updated for the scenarios by reviewing the current safe water levels, well construction details, and hydraulic test results as provided by the municipalities. The existing pumped water level for 2008, as determined in the Tier Three Assessment (AquaResource 2011), was maintained for this current study for consistency with the Tier Three Assessment. Table 10 summarizes the safe additional in-well drawdown for this current study calculated as the difference between the Existing Pumped Water Level (2008) and the Safe Water Level (2013). The safe additional in-well drawdown (2008) used in the Tier Three Assessment is provided for comparison with significant updates highlighted in blue in Table 10.

TABLE 10 Safe Additional In-Well Drawdown (2008 compared to 2013)

Well Name

Pump Intake (2008)

Safe Water Level

(2008)

Pump Intake (2013)

Safe Water Level

(2013)

Existing Pumped Water Level

(2008)

Safe Additional

In-Well Drawdown

(2008)

Safe Additional

In-Well Drawdown

(2013)

Elevation (m asl) (m) (m)

Orangeville 2A n/a 442.0 442.0 443.4 447.5 5.5 4.1 Orangeville 5/ 5A 454.5 458.1 456.5 458.1 461.3 3.2 3.1 Orangeville 6 n/a 432.0 429.1 432.1 435.7 3.7 3.6 Orangeville 7 n/a 435.4 434.0 435.4 445.5 10.1 10.1 Orangeville 8B 432.1 433.8 432.1 433.8 441.5 7.7 7.7 Orangeville 8C 432.1 434.8 432.1 433.7 442.3 7.5 8.6 Orangeville 9A/ 9B 455.0 456.0 455.0 456.0 460.8 4.8 4.8 Orangeville 10 355.3 365.3 397.7 399.3 402.0 36.7 2.71

Orangeville 11 n/a 427.1 425.5 427.1 434.5 7.4 7.4 Orangeville 12 435.6 436.6 435.6 437.2 450.3 13.7 13.1 Mono Cardinal Woods 1 417.8 418.8 417.8 418.8 423.6 4.8 4.8 Mono Cardinal Woods 3 411.4 412.4 411.4 412.4 415.4 3.0 3.0 Mono Coles 1 and 2 385.0 386.0 385.0 386.0 420.7 34.7 34.7 Mono Island Lake Wells 368.5 369.5 368.5 369.5 391.6 22.1 22.1 Amaranth Pullen Well 445.9 446.9 445.9 446.9 476.5 29.6 29.6 1Safe Additional In-Well Drawdown from 2008 (36.7 m) was used for the RMM Evaluation Process.

The safe additional in-well drawdown for Well 2A dropped from 5.5 to 4.1 m due to the determination of the pump intake level, and the subsequent setting of the safe water level 1.4 m above the pump intake. Well 8C gained 1.1 m of additional in-well drawdown due to the refining of the safe water level as closer to the pump intake. Well 10 exhibited the greatest loss in safe additional in-well drawdown


from 36.7 m to 2.7 m due to the recent movement of the pump intake to a shallower level. This change was made by the Town to “maximize its pumping and energy consumption at the current withdrawal rates and drawdowns,” but “this change does not preclude the pump from being lowered again to an as yet unspecified depth to increase available drawdown” (Thompson 2013, Pers. Comm.). For the purposes of the RMM Evaluation Process that tested higher withdrawal rates and the expected increased drawdown, the safe additional in-well drawdown of 36.7 m calculated in the Tier Three Assessment was used for Well 10.

For this study, recent step test results were analyzed to calculate the non-linear in-well loss coefficients (C coefficient) for the Orangeville wells. All the Orangeville wells except Well 6 were tested in 2011 as part of the “Orangeville Wellfield Capacity Assessment - Consolidated Permit to Take Water Application” conducted by SLR Consulting (Canada) Ltd. (2012). Well 6 was tested after undergoing rehabilitation in 2012 to remove a “Muni Pak Screen” as reported in Gerrits Drilling & Engineering Ltd. (2012). The analyses followed the same method as the Tier Three Assessment (AquaResource 2011).

Table 11 summarizes the previous and current well loss coefficients and the additional drawdown that occurs when increasing the pumping from the 2008 current conditions rates to the Allocated Rates used in the Tier Three Assessment. As the additional drawdown due to in-well losses is proportional to the square of the pumping rate increase, the well losses must be re-calculated for each pumping scenario. To facilitate the comparison of the revised well loss coefficients, the additional drawdown for the 2013 data is shown in the last column of Table 11. For the RMM Evaluation Process scenarios, the pumping rates vary with each optimization and the additional drawdown due to in-well losses are calculated within the model runs.


TABLE 11 Non-linear In-Well Losses (2008 Compared to 2013)

Well

Well Loss Coefficients

(2008) ([m/L]/s2)

Pumping Rate

Increase1

(m3/d)

Additional Drawdown

(2008 In-Well

Losses; m)

Well Loss Coefficients

(2013) ([m/L]/s2)

Pumping Rate

Increase1

(m3/d)

Additional Drawdown

(2013 In-Well Losses; m)

Orangeville Well 2A 5.5x10-2 114 0.58 8.6x10-2 114 0.90 Orangeville Well 5 1.2x10-4

141 0.02 1.0x10-4

141 0.01

Orangeville Well 5A 7.6x10-5 0 4.1x10-5 0 Orangeville Well 6 *1.9x10-3 242 0.18 7.4x10-3 242 0.71 Orangeville Well 7 *1.9x10-3 480 0.24 1.1x10-2 480 1.39 Orangeville Well 8B 1.3x10-2 36 0.13 3.2x10-3 36 0.01 Orangeville Well 8C 0 36 0 2.2x10-2 36 0.05 Orangeville 9A/9B 0 1 0 2.9x10-4 1 0.00 Orangeville Well 10 0 1,114 0 1.9x10-3 1,114 0.38 Orangeville Well 11 *1.9x10-3 296 0.16 2.4x10-2 296 2.09 Orangeville Well 12 1.2x10-2 459 1.49 1.6x10-2 459 2.01 Mono Cardinal Woods 1 0 0 0 *1.9x10-3 0 0 Mono Cardinal Woods 3 *1.9x10-3 152 0.02 *1.9x10-3 152 0.02 Mono Coles 1 and 2 *1.9x10-3 34 0 *1.9x10-3 34 0.00 Mono Island Lake Wells *1.9x10-3 224 0.03 *1.9x10-3 224 0.03 Amaranth Pullen Well *1.9x10-3 220 0.01 *1.9x10-3 220 0.01 1 Increased pumping rate from the existing (2008) to the Allocated Rates. *Well loss coefficient estimated from Walton, 1962.

The calculated additional drawdown due to in-well losses increased significantly (> 0.1 m) for 2013 at Wells 2A, 6, 7, 10, 11 and 12, while it decreased slightly for Well 8B. Mono and Amaranth wells are unchanged in this assessment using the same estimated well loss coefficient of 1.9 × 10-3 m/(L/s)2 that was used in the Tier Three Assessment.

Convergent head losses are required to be calculated when using MODFLOW groundwater flow models. Since a well is relatively small compared to a typical grid block, MODFLOW underestimates the drawdown at a pumping well, as it calculates the average head in the grid block that contains the well. The model results needed to be adjusted to compare simulated drawdown at a well against safe additional drawdown. The additional head losses that occur between the average water level in a grid block and the pumping well are referred to as the convergent head losses. Table 12 compares the convergent head losses used in the Tier Three Assessment with those calculated for this current study. In all cases, there is an increase of convergent head losses due to a refined understanding of the well construction details. Similar to the non-linear, in-well losses, the additional drawdown due to convergent head losses must be calculated using the increase in pumping rate and thus must be re-calculated for each pumping scenario. The additional drawdown for 2013 shown in the last column of


Table 12 is given to illustrate the impact of increasing the pumping from the 2008 current condition rates to the Allocated Rates. For the RMM Evaluation Process scenarios, the pumping rates vary with each optimization and the additional drawdown due to convergent head losses were calculated within the model runs.

TABLE 12 Convergent Head Losses (2008 Compared to 2013)

Well Name

Pumping Rate

Increase1 (m3/d)

Transmissivity2 (m2/d)

Well Radius (mm)

Additional Drawdown Convergent Head Losses

(2008, m)

Additional Drawdown Convergent Head Losses

(2013, m) Orangeville Well 2A 114 151 150 0.25 0.34 Orangeville Well 5/5A 141 3,100 125 0.02 0.02 Orangeville Well 6 242 152 125 0.58 0.76 Orangeville Well 7 480 166 100 1.16 1.48 Orangeville Well 8B 36 170 100 0.09 0.11 Orangeville Well 8C 36 166 100 0.09 0.11 Orangeville 9A/9B 1 726 100 0 0 Orangeville Well 10 1,114 138 150 2.96 3.61 Orangeville Well 11 296 166 125 0.65 0.85 Orangeville Well 12 459 83 125 2.22 2.64 Mono Cardinal Woods 1 0 108 100 0 0 Mono Cardinal Woods 3 152 108 100 0.57 0.72 Mono Coles 1 and 2 34 555 125 0.02 0.03 Mono Island Lake Wells 224 864 250 0.07 0.09 Amaranth Pullen Well 220 151 75 0.65 0.81 1 Increased pumping rate from the existing (2008) to the Allocated Rates. 2 Transmissivity simulated in the groundwater flow model at the pumping well.

4.3.4 Risk Management Measures Scenarios Results

The results of the Optimization/Integration Scenarios A to D are summarized in Table 13. For each scenario, the final optimized pumping rates determined using PEST with the Tier Three Assessment model are listed along with the difference from the Allocated Rate used in the Tier Three Assessment. The baseline current conditions (2008) pumping rates, the Allocated Rates, and the maximum average annual pumping rate are also provided on Table 13 for reference.

The total maximum drawdown and remaining safe additional in-well drawdown for each well for the seven scenarios are given in Table 14. The total maximum drawdown includes both the non-linear in-well losses and the convergent head losses for each well according to the pumping rate change from the baseline current conditions rate. This drawdown represents the lowest water level in a well under the drought conditions of the early 1960s (using the Tier Three Assessment transient H(1) scenario model). The Safe Additional In-Well Drawdown (2013) given in the table is the maximum safe allowable


drawdown from the 2008 water level. Any drawdown that results in 0.5 m or less of the safe additional in-well drawdown remaining is highlighted in blue in the table.

The impacts to groundwater discharge for the Optimization/Integration Scenarios A to D are given in Table 15. These impacts were predicted using the Tier Three Assessment steady-state G(2) scenario model that incorporated increased pumping, and did not include recharge reductions. When classifying the Risk Level in the Tier Three Assessment, impacts to other water users are only reviewed associated with increased demand when evaluating the Risk Level placed on the Local Areas. Table 15 gives the baseline existing conditions groundwater discharge (from the Tier Three Assessment C scenario), results from the Tier Three Assessment G(2) scenario with pumping at the Allocated Rates, and the results for each of the RMM scenarios. The predicted discharge (in L/s) is given as well as the percent change in discharge from the baseline conditions. Reductions of more than 10% and 20% are highlighted in blue and orange, respectively.

Scenario results are discussed separately in the following sections and refer to these three tables.


TABLE 13 Optimization/Integration Scenarios - Final Pumping Rates (m3/d)

Well Name Current 2008 Baseline

Allocated Rate

Max Annual

Average

Scenario A Separate Systems

Scenario B Mono/Orangeville Integrated

Scenario C Amaranth/Orangeville Integrated

Scenario D All Integrated

Optimized Pumping Rate

Difference from Allocated Rate







Orangeville Well 2A 286 400 4391 289 -111 289 -111 289 -111 289 -111 Orangeville Well 5/5A 3,359 3,500 6,000 2,899 -601 2,899 -601 2,899 -601 2,899 -601 Orangeville Well 6 1,358 1,600 2,500 1,400 -200 1,400 -200 1,400 -200 1,400 -200 Orangeville Well 7 755 1,235 1,310 1,204 -31 1,204 -31 1,204 -31 1,204 -31 Orangeville Well 8B 239 275 327 327 52 327 52 327 52 327 52 Orangeville Well 8C 239 275 327 327 52 327 52 327 52 327 52 Orangeville 9A/9B 559 560 878 582 22 582 22 582 22 582 22 Orangeville Well 10 121 1,235 1,3612 1,361 126 1,361 126 1,361 126 1,361 126 Orangeville Well 11 939 1,235 1,309 1,161 -74 1,161 -74 1,161 -74 1,161 -74 Orangeville Well 12 781 1,240 1,309 1,256 16 1,256 16 1,198 -42 1,198 -42

Total Orangeville 8,636 11,555 15,761 10,804 -751 10,804 -751 10,746 -809 10,746 -809 Mono Cardinal Woods 1 8 8 250 125 117 125 117 125 117 125 117 Mono Cardinal Woods 3 240 392 1,071 275 -117 275 -117 275 -117 275 -117 Mono Coles 1 and 2 82 116 655 116 - 655 539 116 - 295 179 Mono Island Lake Wells 123 347 2,614 347 - 1,878 1,531 347 - 540 193

Total Mono 453 863 4,840 863 - 2,933 2,070 863 - 1,235 551 Amaranth Pullen Well - 220 1,473 220 - 220 - 1,029 809 1,029 809

Total 9,089 12,638 22,074 11,887 -751 13,957 1,319 12,638 - 13,010 372 1Well 2A - 878.4 m3/d for 6 months of the year (April - Sept) 2Well 10 - 1,453 m3/d for 10 months of the year except Oct and Nov where it is reduced to 903 m3/d


TABLE 14 Maximum Drawdown and Remaining Safe Additional In-Well Drawdown (m)

Well Name

Safe Additional

In-Well Drawdown

(2013)

Scenario A Scenario B Scenario C Scenario D Scenario E Scenario F Scenario G

Separate Systems Mono/Orangeville Integrated

Amaranth/Orangeville Integrated All Integrated 30% Recharge Reduction 20% Recharge Reduction 10% Recharge Reduction

Total Max. Drawdown

Remaining SADD

Total Max. Drawdown

Remaining SADD

Total Max. Drawdown

Remaining SADD

Total Max. Drawdown

Remaining SADD

Total Max. Drawdown

Remaining SADD

Total Max. Drawdown

Remaining SADD

Total Max. Drawdown

Remaining SADD

Orangeville Well 2A 4.1 3.4 0.7 3.4 0.7 3.9 0.2 3.9 0.2 3.5 0.6 3.4 0.7 3.3 0.8

Orangeville Well 5/5A 3.1 2.6 0.5 2.6 0.5 2.9 0.2 2.9 0.2 1.5 1.6 1.2 1.9 1.0 2.1

Orangeville Well 6 3.6 3.7 -0.1 3.7 -0.1 3.8 -0.2 3.8 -0.2 3.6 0.0 3.6 0.0 3.5 0.1

Orangeville Well 7 10.1 8.8 1.3 8.8 1.3 9.3 0.8 9.3 0.8 8.9 1.2 8.8 1.3 8.7 1.4

Orangeville Well 8B 7.7 4.1 3.6 4.1 3.6 4.6 3.1 4.6 3.1 4.3 3.4 4.3 3.4 4.2 3.5

Orangeville Well 8C 8.6 3.8 4.8 3.8 4.8 4.3 4.3 4.3 4.3 4.0 4.6 3.9 4.7 3.8 4.8

Orangeville 9A/9B 4.8 3.9 0.9 3.9 0.9 4.1 0.7 4.1 0.7 2.8 2.0 2.5 2.3 2.2 2.6




Mono Cardinal Woods 1 4.8 3.0 1.8 3.0 1.8 3.1 1.7 3.1 1.7 3.0 1.8 3.0 1.8 2.9 1.9

Mono Cardinal Woods 3 3.0 2.1 0.9 2.1 0.9 2.2 0.8 2.2 0.8 2.0 1.0 2.0 1.0 2.0 1.0

Mono Island Lake Wells 22.1 1.3 20.8 9.7 12.4 1.3 20.8 2.3 19.8 2.3 19.8 2.3 19.8 2.3 19.8

Mono Coles 1 and 2 34.7 1.9 32.8 7.7 27.0 1.9 32.8 3.8 30.9 3.6 31.1 3.5 31.2 3.4 31.3

Amaranth Pullen Well 30.6 6.1 24.5 6.1 24.5 15.2 15.4 15.2 15.4 14.8 15.8 14.7 15.9 14.6 16.0

Note: 0.5 m or less remaining safe additional in-well drawdown is highlighted in blue. Negative values in red indicate where the safe level has been exceeded.


TABLE 15 Impacts to Groundwater Discharge

Stream / Reach

Scenario C - Existing

Conditions GW Discharge (L/s)

Tier Three Scenario G(2) Scenario A Scenario B Scenario C Scenario D

Risk Assessment Scenario Separate Systems Mono/Orangeville Integrated Amaranth/Orangeville Integrated All Integrated

GW Discharge (L/s)

Percent Change (%)*

GW Discharge (L/s)

Percent Change (%)*

GW Discharge (L/s)

Percent Change (%)*

GW Discharge (L/s)

Percent Change (%)*

GW Discharge (L/s)

Percent Change (%)*

North Arm of Lower Monora 20.0 17.1 -15% 17.5 -13% 17.4 -13% 16.2 -19% 16.2 -19%

South Arm of Lower Monora 5.3 4.4 -16% 4.5 -15% 4.5 -15% 4.3 -19% 4.3 -19%

Total Lower Monora 31.0 27.0 -13% 27.4 -12% 27.4 -12% 25.9 -17% 25.9 -17%

Upper Monora 38.0 34.1 -10% 34.0 -10% 34.0 -11% 32.4 -15% 32.4 -15%

Upper Mill 11.2 8.4 -25% 13.6 21% 13.6 21% 12.8 15% 12.8 15%

Lower Mill 14.8 11.5 -22% 16.9 14% 16.8 14% 16.0 9% 16.0 8%

Island Lake Tributaries 19.7 19.4 -1% 19.4 -2% 16.7 -15% 19.4 -2% 18.6 -6%

Caledon Tributaries 16.6 16.1 -3% 16.1 -3% 14.4 -13% 16.1 -3% 15.6 -6%

Caledon Lake Wetlands 11.6 10.3 -12% 10.9 -7% 10.9 -7% 10.7 -8% 10.7 -8%

Credit River 305.0 286.3 -6% 290.9 -5% 288.1 -6% 289.6 -5% 288.8 -5%

*Reductions in GW discharge from the Existing Conditions (2008) of more than 10% and 20% are highlighted in blue and orange, respectively *Positive values in black indicate where GW discharge increased from the Existing Conditions (2008)


4.3.4.1 Scenario A

Scenario A considered each of the Mono, Amaranth and Orangeville systems as separate disconnected systems. This scenario used the Allocated Rates from the Tier Three Assessment as the initial scenario pumping rates (a total of 12,638 m3/d; Table 9). As these pumping rates were already known to cause impacts that led to a Significant Risk Level under the average and drought climate scenarios, the goal of this scenario was to optimize the pumping within the separate systems, reducing pumping if necessary, to reduce the impacts and to minimize the Local Area Risk Level from Significant to Moderate or Low.

The Scenario A optimization process reduced total pumping at the Orangeville wells by 751 m3/d to minimize the impacts that led to a Significant Risk Level being assigned to the Local Area. This was accomplished by reducing pumping at Well 5/5A by 601 m3/d and Well 6 by 200 m3/d, and re-distributing pumping amongst the other Orangeville wells as shown in Table 13. Pumping was also re-distributed between the Mono Cardinal Woods wells to reduce the risk at Cardinal Woods 3. The total pumping for the three municipalities is 11,887 m3/d and does not meet the future water demand (Allocated Rates).

Total drawdown under the drought scenario was reduced at the municipal wells such that a majority are predicted to have more than 0.5 m of remaining safe additional in-well drawdown at the lowest point (Table 14). Well 6 is predicted to have low water levels that are 0.1 m below the safe water level while Well 5/5A only has 0.5 m of drawdown remaining. Minor adjustments to the pumping rates could have decreased the impacts at these two wells, but for the purposes of the RMM Evaluation Process, this level of predicted impact was considered tolerable. Although there is more remaining available drawdown at Wells 8B and 8C, and at Well 10, the maximum permitted pumping rates (on an annual average basis) was achieved at those wells.

This scenario was successful in reducing the impacts to groundwater discharge to the streams of interest (Table 15). With the reduced pumping at Well 2A and 5/5A, Upper and Lower Mill Creek have increased discharge over the existing conditions by 21% and 14%, respectively. Lower Monora Creek has reduced impacts relative to the base case with only a -12% reduction, down from -13% under the Risk Assessment G(2) scenario. Impact reduction is also seen at Caledon Lake Wetlands with impacts of -12% under the G(2) scenario, down to -7% under Scenario A. The Credit River experiences a slightly reduced impact from -6% under the G(2) scenario to -5% under Scenario A. Upper Monora Creek was not significantly impacted by re-distributing pumping between the Cardinal Woods wells.

Scenario A has reduced the impacts from what was predicted in the Risk Assessment such that a Moderate Risk Level could be assigned to the Local Area, but the total pumping from the three municipalities does not meet the future water demand (Allocated Rates) and thus the Risk Level remains as Significant.


4.3.4.2 Scenario B

Scenario B considered Mono and Orangeville wells as an integrated system, and Amaranth as a separate system. This scenario was designed to use the Allocated Rates from the Tier Thee Assessment as the initial pumping rates for Orangeville (11,555 m3/d) and Amaranth (220 m3/d). For Mono wells, the initial pumping rates were set higher than the Allocated Rates (2,847 m3/d versus 863 m3/d) in recognition that there may be additional capacity available at the Mono wells. The goal of this scenario was to re-distribute pumping between the Mono and Orangeville wells to reduce impacts and maximize pumping rates up to, or potentially in excess of, the Allocated Rates. The Amaranth Pullen Well was held constant at 220 m3/d.

As Scenario A was successful in optimizing the Orangeville and Mono Cardinal Woods wells while minimizing impacts, Scenario B used the final rates from Scenario A for those areas. The optimization in Scenario B concentrated on determining whether the 751 m3/d reduction in pumping from the Orangeville wells could be replaced by increased pumping from the remaining Mono wells at Island Lake or Coles. The final pumping results are shown in Table 13. The pumping at Mono Coles 1 and 2 was increased from 116 to 655 m3/d and the Island Lake Wells were increased from 347 to 1,878 m3/d; a net increase of 2,070 m3/d. Combined with the decrease in pumping from the Orangeville wells, these increases gives a total pumping for the three municipalities of 13,957 m3/d; a net increase of 1,319 m3/d over the Allocated Rates.

Maximum total drawdown under the drought scenario for Orangeville and Cardinal Woods wells was the same as Scenario A (Table 14). There was an increase in the total drawdown predicted for the Island Lake and Coles wells, but the abundance of safe additional in-well drawdown at those wells allows this level of pumping to avoid any Risk Level implications from a quantity perspective. As the pumping from the Pullen Well was unchanged from the base case scenario and Scenario A, the maximum drawdown was the same.

The impacts to groundwater discharge (Table 15) were similar to those of Scenario A for Upper and Lower Monora Creek, Mill Creek, and Caledon Lake Wetlands. Island Lake Tributaries and the Caledon Tributaries experienced greater impacts of -15% and -13% in discharge reductions, respectively, due to the increased pumping in those areas. There was also a slight increase in impacts at the Credit River over Scenario A from a reduction of -5% to -6%.

The predicted impacts from Scenario B are such that a Moderate Risk Level could be assigned to the Local Area, but there are increased groundwater discharge impacts relative to the Risk Assessment impacts at Island Lake Tributaries and the Caledon Tributaries. The total pumping rates for Scenario C exceeded the Allocated Rates by 1,319 m3/d.


4.3.4.3 Scenario C

Scenario C considered Amaranth and Orangeville wells as an integrated system, and Mono wells as a separate system. Pumping rates for the Mono wells were set at the Allocated Rates (863 m3/d) and held constant at the optimized pumping distribution from Scenario A. Initial pumping rates were reduced in Orangeville at Wells 8B and 8C and Well 12 in recognition of the Orangeville system being unable to supply the Allocated Rates without causing drawdown at the municipal wells to exceed the safe additional drawdown values, or reducing groundwater discharge to Lower Monora Creek and Mill Creek to unacceptable levels. The pumping rate for the Amaranth Pullen Well was initially set higher (1,473 m3/d versus 220 m3/d) due to the additional capacity available at that well. The pumping rates between the Pullen Well and the Orangeville wells were re-distributed to reduce the impact on surface water features and water levels in municipal wells, and to try to maximize pumping.

The final optimized pumping for Scenario C is shown in Table 13. Pumping at Wells 8B and 8C increased from the starting values to their maximum level of 327 m3/d each, while Well 12 increased pumping to 1,198 m3/d. The Pullen Well, which is known to compete for water with Orangeville Wells 8B, 8C and 12, decreased from the starting value of 1,473 m3/d down to 1,029 m3/d. The combined total pumping of Amaranth and Orangeville is 11,775 m3/d, which meets the water demand for those two municipalities.

There was a slight increase in total maximum drawdown for a majority of the Orangeville wells under Scenario C compared to Scenarios A and B as shown in Table 14. Wells 2A, 5/5A, 6, and 11 were predicted to have 0.5 m or less remaining safe additional in-well drawdown at the lowest point during the drought scenario. Well 6 is the only well that exceeds the safe additional drawdown, and similar to the preceding scenarios, minor adjustments to the pumping rates could have decreased the impact. The maximum drawdown for the Pullen Well increased from 6.1 m to 15.2 m under Scenario C with the pumping increased from 220 to 1,029 m3/d; however, this drawdown is below the safe additional available drawdown value of 30.6 m.

Scenario C predicted increased groundwater discharge impacts in Upper and Lower Monora Creek over those predicted by the Risk Assessment when pumping at the Allocate Rates (Table 15). This is due to the increased pumping from the Pullen Well. Lower Monora Creek is predicted to have a 17% reduction in discharge while Upper Monora Creek has a 15% reduction. The Risk Assessment G(2) scenario predicted 13% and 10%, respectively. The remaining areas have acceptable (< 10% reduction) impacts to groundwater discharge.

Scenario C reduced the predicted impacts at the municipal wells, but the groundwater discharge impacts at Lower and Upper Monora Creek increased over those predicted in the Tier Three Assessment. As the impacts to surface water features were less than a 20% reduction over the base case, this led to an assignment of Moderate Risk Level to the Local Area.


4.3.4.4 Scenario D

Scenario D combined Scenario B and C whereby the supply for all municipalities are connected. As an integrated system, this scenario evaluates the maximum amount of water than can be provided by all wells while minimizing water supply risk identified in the Tier Three Assessment. The initial pumping rates for Scenario D accounted for the increased capacity in the Mono and Amaranth wells and the reduced pumping from the Orangeville wells.

The final optimized pumping rates for the fully integrated systems are shown in Table 13. The rates for the Orangeville wells, Amaranth Pullen Well and the Mono Cardinal Woods wells are the same as Scenario C, while the rates for the Mono Island Lake and Coles wells increased bringing the total Mono pumping up from 863 to 1,029 m3/d. This resulted in a combined total of 13,010 m3/d for the three municipalities that is 372 m3/d more than the Allocated Rates.

The maximum drought drawdowns (Table 14) predicted for Scenario D is similar to that predicted for Scenario C. With the increased pumping from the Island Lake and Coles wells, there is an associated slight increase in drawdown at those wells (1 to 2 m), but 20 to 30 m of available drawdown remains at the wells.

The predicted impacts to groundwater discharge for Scenario D were the same as Scenario C except in the area of influence of the increased pumping from the Island Lake and Coles wells. There are small predicted discharge reductions of -6% at Island Lake Tributaries and Caledon Tributaries. As the results of Scenario D are similar to Scenario C, a Moderate Risk Level was assigned to the Local Area.

4.3.4.5 Scenario E to G

Scenarios E to G used the optimized pumping rates from Scenario D to test the Risk Assessment scenarios under drought and average climate conditions while maintaining 70%, 80% and 90% of pre-development recharge on undeveloped lands outlined in the various Official Plans. The assumption is that these levels of pre-development recharge can be achieved post-development using various LID measures. The measure QT031 was selected as a surrogate to represent the outcomes of implementing any LID(s) in the development area that would enhance post-development recharge.

The Tier Three Risk Assessment Scenarios that incorporated future land use had areas of recharge reductions of 50% to 80% from the existing conditions depending on the type of land use change. For the three RMM Scenarios E, F and G, the recharge in these areas was reduced by only 30%, 20% or 10%, respectively, relative to the average annual recharge.

The maximum drawdown and remaining safe additional drawdown for these three scenarios are shown in Table 14. In comparison to Scenario D, all the scenarios predicted decreased drawdown at a majority of the wells. The only wells that did not have significant reductions in drawdown were Well 10, located far from future land use changes, and the Coles Wells, which had limited drawdown (2.3 m or 10% of


the safe additional drawdown) under these pumping rates and were not affected by the recharge reductions.

Significant reductions in drawdown occurred at Well 2A and Well 9A/9B where maximum drawdowns decreased from 2.9 and 4.1 m, respectively, to 1.5 and 2.8 m under Scenario E (30% recharge reductions). These drawdowns decreased even more under Scenarios F and G (20% and 10% recharge reductions). Well 6 also experienced reductions in maximum drawdown from 3.8 m under Scenario D to 3.5 m under Scenario G putting it within the safe additional in-well drawdown of 3.6 m.

Similar to Scenario D, these results led to a Moderate Risk Level assigned to the Local Area.

4.3.4.6 Summary of Results

The results of the seven RMM scenarios presented above are summarized below in Table 16 along with the results from the Tier Three Assessment. In all the RMM scenarios, Well 6 was predicted to have maximum drought drawdowns that were within 0.1 to 0.2 m of the safe additional in-well drawdown. Minor adjustments to the pumping rates such as re-distributing pumping away from Well 6 and the adjacent Well 11 could have decreased the impacts at Well 6. Thus, for the purposes of the RMM Evaluation Process, this level of predicted impact was considered acceptable to not trigger a Risk Level assignment.

As shown in Table 16, the Tier Three Assessment scenarios impacts on municipal wells and groundwater discharge to surface water features led to a Significant Risk Level being assigned to the Local Area.

Scenario A, through optimization of the separate municipal systems, reduced impacts such that a Moderate Risk Level could be assigned, but the total pumping for Orangeville did not meet the future water demand (Allocated Rates) and thus the Risk Level remains as Significant.

The remaining Scenarios B to G met the Allocated Rates and reduced the Risk Level assigned to the Local Area from Significant to Moderate. This was achieved through combinations of pumping optimization, system integration, and maintaining pre-development recharge. In the Tier Three Assessment, Mill Creek was predicted to have greater than -20% reduction in groundwater discharge, but these RMM scenarios predicted reduced impacts to Mill Creek decreasing them to below -20%., Each of these scenarios predicted greater than -10% impacts to groundwater discharge at two or more surface water features reinforcing the Moderate Risk Level designation.


TABLE 16 Summary of Results from the RMM Evaluation Process

Scenario Description

Pumping Meets

Allocated Rates?

Maximum Drought

Drawdown Acceptable?

Impacts to Ground Water

Discharge

Risk Level Assigned to Local Area

Risk Management Measures Evaluated

Risk Assessment

Scenarios

Separate Systems Yes No >-20% Significant N/A

A Separate Systems No Yes -10%

to -20% Significant Pumping Optimization

B Mono/

Orangeville Integrated

Yes Yes -10% to -20% Moderate Pumping Optimization,

System Integration

C Amaranth/ Orangeville Integrated

Yes Yes -10% to -20% Moderate Pumping Optimization,

System Integration

D All Integrated Yes Yes -10% to -20% Moderate Pumping Optimization,

System Integration

E All Integrated/ 30% Recharge

Reduction Yes Yes -10%

to -20% Moderate

Pumping Optimization, System Integration, Low Impact Development

F All Integrated/ 20% Recharge


to -20% Moderate


G All Integrated/ 10% Recharge


to -20% Moderate


Scenario B predicted decreased groundwater discharge impacts in Mill Creek, Caledon Lake Wetlands, and Lower Monora Creek compared to the Risk Assessment scenarios, but the Island Lake and Caledon Tributaries experienced impacts of greater than -10%. These two areas previously had minimal impacts under the Risk Assessment scenarios.

Scenario C through G predicted increased groundwater discharge impacts in Lower and Upper Monora Creek over those predicted in the Tier Three Assessment, but the impacts are still less than -20% in groundwater discharge reductions leading to an assignment of Moderate Risk.


4.4 Selection of Preferred Risk Management Measures The Tier Three Assessment Water Budget model was used in the RMM Evaluation Process to evaluate the ability of the selected Risk Management Measures to manage the Risk Level assigned to the Local Area. The above scenarios and select measures address two key recommendations from the Tier Three Assessment:

1. Develop a Regional Water Supply Strategy. This Tier Three Assessment illustrates that the groundwater resource relied upon by the Towns of Orangeville and Mono and the Township of Amaranth is a shared water supply and ecological resource that does not follow municipal boundaries. The Local Area A, classified as having a Significant Water Quantity Risk Level, extends across these municipal boundaries into all three jurisdictions. As a result, drinking water management activities including permitting and monitoring would be best completed collaboratively by the three municipalities. A regional approach to groundwater management activities may also include working with the Ministry of the Environment to put in place new well field permits that replace individual permits and provide more flexibility to modify pumping rates within the Local Areas. The regional water supply strategy should also seek to identify and test potential future drinking water supplies as needed to promote growth and also to protect against risks that may affect existing supplies and other uses; and

2. Protect Recharge Areas. The Tier Three Assessment clearly illustrates the potential for recharge reductions to affect some of the municipal wells. The Towns of Orangeville and Mono and the Township of Amaranth should ensure that any future land developments do not have a negative impact on groundwater recharge and, where possible, attempt to enhance groundwater recharge. Where proposed developments overlie municipal Well Head Protection Areas, the infiltration of poor quality water, such as road runoff should be minimized whenever possible (AquaResource 2011). Retrofits within existing developments should also be considered.

The implementation of all three selected measures proved to be an effective solution to achieve a reduction in Risk Level, and thus all three could be included in the Threat Management Strategy for the Local Area. These results provide insight and can help guide the Source Protection Committee during policy development and the municipalities during implementation.

5 RE-EVALUATING WATER QUANTITY RISK MANAGEMENT MEASURES FOR CLIMATE CHANGE ADAPTATION

5.1 Climate Change and the Clean Water Act Director’s Rules As part of the continuous improvement in the application of the Clean Water Act (MOE 2006a), the Province permits the inclusion of climate change considerations in the water quantity risk


assessment in order to understand what actions need to be taken to reduce or manage climate change driven impacts on drinking water quantity. The goal is to inform updated assessment reports and to integrate climate change adaptation into decision making through Source Protection Plans and risk management plans. Assessment reports and Source Protection Plans will inform local decision making.

To assist the evaluation of the impacts of climate change for Source Water Protection, Ontario Ministry of Natural Resources and Ministry of the Environment in partnership with CVC developed the Guide for Assessment of Hydrologic Effects of Climate Change in Ontario (EBNFLO 2010). This guide contains methods for developing future local climate scenarios, a summary of potential hydrologic impacts of climate change, a seven-stage framework for climate change impact assessment, and a case study.

As part of the RMM Evaluation Process, a procedure to re-evaluate water budgets and the Water Quantity Risk Assessment with the inclusion of the provincial climate change data has been developed by the Province in order to:

• determine the impact of climate change on quantity threats to drinking water

• help municipalities select Risk Management Measures that may also have beneficial adaptation effects to reduce the risk to municipal drinking water sources in light of climate change

• assist Source Protection Committees on writing Source Protection Plan policies with considerations for climate change

Climate change is expected to affect weather patterns and lead to changes in temperature and precipitation that will affect hydrologic conditions such as the timing and volume of evapotranspiration, groundwater recharge and runoff. Climate change impacts on drinking water supplies may be mitigated through the use of water quantity Risk Management Measures, and re-evaluating those measures using future climate scenarios may support Source Protection Committees and municipalities in the development of source protection policies.

This section evaluates the selected water quantity Risk Management Measures using ten future climate scenarios selected for the Orangeville MOE climate station (#6155790) from the Ontario Ministry of Natural Resources (MNR) Future Climate Data Application (http://climate.aquamapper.com/). The period 1961 to 1990 was used as the reference (or baseline) climate and 2011 to 2040 was used for the future time period. The selection of the future climates and a comparison with the baseline climate are detailed in Appendix C.

Temperature, precipitation and evapotranspiration data from each of the ten future climate scenarios were used as input into separate MIKE SHE simulations and the MIKE SHE output (i.e., predicted groundwater recharge rates) were applied in the Tier Three Assessment MODFLOW model.

http://climate.aquamapper.com/


5.2 Climate Change Scenarios RMM Scenario G (see Table 8 and Section 4.3.4.5) was used as the baseline scenario for the climate change assessment. This scenario included the optimized pumping rates from RMM Scenario D (Table 13 and Section 4.3.4.4; all municipal systems integrated and optimized) while maintaining 90% of pre-development recharge for planned developments through the use of LIDs. Each climate change adaptation scenario included a transient simulation and a steady-state simulation. The ten transient MODFLOW model simulations included recharge rates estimated for each future climate to evaluate the drought scenario drawdown in each municipal well. Each of the ten steady-state model simulations was used with the mean annual recharge for each climate to evaluate groundwater discharge impacts.

Table 17 lists the change in mean annual temperature, precipitation and groundwater recharge for each future climate scenario as compared to the baseline climate. The mean annual recharge for the future climate scenarios varies from a decrease of 20% from the baseline, to an increase of 19% relative to the baseline, and the average change was 5% higher than the baseline. More details about the groundwater recharge predicted from the baseline and future climate scenarios are given in Appendix C.

TABLE 17 Mean Annual Temperature, Precipitation and Recharge Change from Baseline

Scenario ID

Climate Scenarios (2011 - 2040)

Mean Annual Temperature Change (°C)

Mean Annual Precipitation Change (%)

Mean Annual Recharge Change

(%)

CC 1 CGCM3T47-Run2 - SRB1 2.1 0.9 0% CC 2 CGCM3T47-Run3 - SRA2 1.6 8.1 18% CC 3 CGCM3T47-Run3 - SRB1 1.5 8.5 19% CC 4 CGCM3T47-Run5 - SRA2 2.2 2.3 6% CC 5 CSIROMk3.5 - SRB1 1.4 -4.1 -20% CC 6 ECHAM5OM - SRB1 1.0 3.7 7% CC 7 FGOALS-g1.0 - SRA1B 1.3 5.9 16% CC 8 GFDLCM2.0 - SRB1 1.5 4.4 7% CC 9 GISS-AOM - SRA1B 1.3 0.7 -2%

CC 10 GISS-EH - SRA1B 0.9 2.6 3%

Average 1.5 3.3 5%

5.3 Assessment of Climate Change Impacts on In-Well Drawdown and Groundwater Discharge

The simulation results were analyzed by examining the total maximum drawdown and remaining safe additional in-well drawdown (SADD) for the drought scenarios, and the percentage change in groundwater discharge calculated for each future climate under average conditions (steady-state).

Table 18 summarizes the total maximum drawdown and the remaining SADD for each municipal well for the ten scenarios in comparison to RMM Scenario G of this study (from Table 14). The total maximum drawdown includes both the non-linear well loss and the convergent head loss for each well.


The calculation methods for these losses are described in Section 4.3.3. This drawdown represents the lowest water level in a well simulated during the transient simulation. The SADD given in the table is the maximum safe additional available drawdown from the simulated 2008 water level determined in the Tier Three Assessment. Instances where the remaining safe additional in-well drawdown is within 0.5 m of the SADD are highlighted in blue in the table.

In general, the climate change scenarios resulted in higher groundwater recharge rates than the baseline conditions, and therefore, resulted in less drawdown at the municipal wells than the baseline climate under RMM Scenario G. Eight of the ten future climate change scenarios predicted groundwater recharge greater than or equal to the baseline climate, and as a result, eight of the ten scenarios predicted less drawdown at the municipal wells.

Where RMM Scenario G predicted only 0.1 m of remaining SADD in Well 6, eight of the climate change scenarios have greater remaining SADD ranging from 0.4 to 1.9 m. Conversely, two scenarios have less remaining SADD than the baseline scenario at -1.9 and 0.0 m. The average remaining SADD in Well 6 for the climate change scenarios is 0.7 m.

Table 19 summarizes the model-predicted groundwater discharge for the ten climate change scenarios and the percent change relative to the discharge for the existing (2008) conditions scenario determined in the Tier Three Assessment. The predicted discharge (in L/s) is given as well as the percent change in discharge from the baseline (2008) conditions. Reductions of more than 10% and 20% are highlighted in blue and orange, respectively. Also given in the table are the discharges under RMM Scenario D that used the baseline climate with fully integrated and optimized municipal pumping. Groundwater discharge is predicted using the steady-state model which only incorporates increased pumping and does not include development-induced recharge reductions. This is aligned with the Tier Three Assessment, which only considers baseflow impacts associated with increased municipal groundwater demand.


TABLE 18 Maximum Drawdown and Remaining Safe Additional In-Well Drawdown (m)

TABLE 19 Impacts to Groundwater Discharge

Orangevil le Well 2A 4.1 3.3 0.8 3.1 1.0 1.6 2.5 1.6 2.5 2.5 1.6 5.2 -1.1 2.6 1.5 1.8 2.3 2.6 1.5 3.4 0.7 2.9 1.2 2.7 1.4Orangevil le Well 5/5A 3.1 1.0 2.1 0.8 2.3 -0.6 3.7 -0.6 3.7 0.2 2.9 3.8 -0.7 0.3 2.8 -0.4 3.5 0.3 2.8 1.1 2.0 0.6 2.5 0.5 2.6Orangevil le Well 6 3.6 3.5 0.1 3.3 0.3 1.7 1.9 1.7 1.9 2.7 0.9 5.5 -1.9 2.8 0.8 1.9 1.7 2.8 0.8 3.6 0.0 3.2 0.4 2.9 0.7Orangevil le Well 7 10.1 8.7 1.4 8.5 1.6 7.2 2.9 7.1 3.0 8.0 2.1 10.5 -0.4 8.1 2.0 7.3 2.8 8.1 2.0 8.8 1.3 8.4 1.7 8.2 1.9Orangevil le Well 8B 7.7 4.2 3.5 4.1 3.6 3.1 4.6 3.0 4.7 3.7 4.0 5.6 2.1 3.8 3.9 3.2 4.5 3.7 4.0 4.2 3.5 4.0 3.7 3.8 3.9Orangevil le Well 8C 8.6 3.8 4.8 3.7 4.9 2.8 5.8 2.7 5.9 3.3 5.3 5.2 3.4 3.4 5.2 2.9 5.7 3.4 5.2 3.9 4.7 3.6 5.0 3.5 5.1Orangevil le Well 9A/9B 4.8 2.2 2.6 2.0 2.8 -0.1 4.9 -0.2 5.0 1.1 3.7 5.6 -0.8 1.3 3.5 0.1 4.7 1.3 3.5 2.4 2.4 1.7 3.1 1.5 3.3Orangevil le Well 10 36.7 6.2 30.5 6.2 30.5 6.1 30.7 6.0 30.7 6.1 30.6 6.4 30.3 6.1 30.6 6.1 30.6 6.1 30.6 6.2 30.5 6.2 30.5 6.2 30.5Orangevil le Well 11 7.4 6.6 0.8 6.4 1.0 4.6 2.8 4.6 2.8 5.7 1.7 8.7 -1.3 5.9 1.5 4.9 2.5 5.8 1.6 6.7 0.7 6.2 1.2 6.0 1.4Orangevil le Well 12 13.1 9.7 3.4 9.5 3.6 8.3 4.8 8.2 4.9 9.0 4.1 11.4 1.7 9.2 3.9 8.4 4.7 9.1 4.0 9.8 3.3 9.4 3.7 9.2 3.9Mono Cardinal Woods 1 4.8 2.9 1.9 2.8 2.0 2.2 2.6 2.1 2.7 2.6 2.2 3.8 1.0 2.6 2.2 2.2 2.6 2.6 2.2 2.9 1.9 2.8 2.0 2.7 2.1Mono Cardinal Woods 3 3.0 2.0 1.0 1.8 1.2 1.2 1.8 1.2 1.8 1.6 1.4 2.8 0.2 1.7 1.3 1.3 1.7 1.7 1.3 2.0 1.0 1.8 1.2 1.7 1.3Mono Island Lake Wells 22.1 2.3 19.8 2.3 19.8 2.0 20.1 1.9 20.2 2.1 20.0 2.7 19.4 2.2 19.9 2.0 20.1 2.2 19.9 2.3 19.8 2.3 19.8 2.2 19.9Mono Coles 1 and 2 34.7 3.4 31.3 3.2 31.5 0.5 34.2 0.4 34.3 2.1 32.6 7.2 27.5 2.3 32.4 0.8 33.9 2.3 32.4 3.7 31.0 2.9 31.8 2.5 32.2Amaranth Pullen Well 30.6 14.6 16.0 14.4 16.2 13.0 17.6 12.9 17.7 13.8 16.8 16.5 14.1 14.0 16.6 13.1 17.5 13.9 16.7 14.7 15.9 14.3 16.3 14.1 16.5

Mean Annual Recharge ChangeNote: 0.5 m or less remaining safe additional in‑well drawdown is highlighted in blue. Negative values in red indicate where the safe level has been exceeded.

5%

Average CC Scenarios

Total Max Drawdown

Remaining SADD

CC 6 CC 7

Remaining SADD

Safe Additional in-Well

Drawdown (m) (2013)

CC 5

7% 16%

Well Name

CC 1 CC 2 CC 3 CC 4RMM Scenario G

Total Max Drawdown

Remaining SADD

7% -2% 3%0% 18% 19% 6% -20%

Remaining SADD

Total Max Drawdown

Remaining SADD

Total Max Drawdown

Remaining SADD

Total Max Drawdown

CC 8 CC 9 CC 10

Total Max Drawdown

Remaining SADD

Total Max Drawdown

Remaining SADD

Total Max Drawdown

Remaining SADD

Total Max Drawdown

Remaining SADD

Total Max Drawdown

Remaining SADD

Total Max Drawdown

Remaining SADD

Total Max Drawdown

GW Discharge

(L/s)

Percent Change

(%)

GW Discharge

(L/s)

Percent Change

(%)

GW Discharge

(L/s)

Percent Change

(%)

GW Discharge

(L/s)

Percent Change

(%)

GW Discharge

(L/s)

Percent Change

(%)

GW Discharge

(L/s)

Percent Change

(%)

GW Discharge

(L/s)

Percent Change

(%)

GW Discharge

(L/s)

Percent Change

(%)

GW Discharge

(L/s)

Percent Change

(%)

GW Discharge

(L/s)

Percent Change

(%)

GW Discharge

(L/s)

Percent Change

(%)

GW Discharge

(L/s)

Percent Change

(%)North Arm of Lower Monora 20.0 16.2 -19% 16.1 -20% 23.0 15% 23.3 16% 18.8 -6% 9.0 -55% 18.9 -6% 22.3 11% 18.8 -6% 15.4 -23% 17.3 -14% 18.3 -9%South Arm of Lower Monora 5.3 4.3 -19% 4.3 -19% 5.6 6% 5.7 8% 4.8 -10% 2.9 -46% 4.8 -9% 5.5 4% 4.8 -10% 4.1 -22% 4.5 -15% 4.7 -11%Total Lower Monora 31.0 25.9 -17% 25.7 -17% 34.5 11% 35.0 13% 29.1 -6% 16.6 -47% 29.3 -6% 33.6 8% 29.2 -6% 24.9 -20% 27.3 -12% 28.5 -8%Upper Monora 38.0 32.4 -15% 32.2 -15% 43.0 13% 43.6 15% 36.1 -5% 22.6 -41% 36.3 -4% 41.9 10% 36.2 -5% 31.3 -18% 33.9 -11% 35.7 -6%Upper Mill 11.2 12.8 15% 12.6 13% 23.8 112% 24.4 117% 16.8 50% 2.0 -83% 17.0 52% 22.6 102% 16.9 51% 11.6 4% 14.5 29% 16.2 45%Lower Mill 14.8 16.0 8% 15.8 7% 27.9 89% 28.6 94% 20.4 38% 4.1 -72% 20.5 39% 26.7 81% 20.4 38% 14.7 0% 17.8 21% 19.7 33%Island Lake Tributaries 19.7 18.6 -6% 18.3 -7% 31.6 61% 32.3 64% 23.4 19% 5.0 -74% 23.5 20% 30.3 54% 23.4 19% 17.2 -13% 20.6 5% 22.6 15%Caledon Tributaries 16.6 15.6 -6% 15.3 -8% 31.5 90% 32.5 96% 21.2 28% 0.8 -95% 21.4 29% 29.8 80% 21.2 28% 13.9 -16% 17.9 8% 20.6 24%Caledon Lake Wetlands 11.6 10.7 -8% 10.6 -9% 16.1 39% 16.5 42% 12.6 8% 5.3 -55% 12.7 9% 15.5 33% 12.6 8% 10.1 -13% 11.5 -1% 12.3 6%Credit River 305.0 288.8 -5% 287.7 -6% 343.2 13% 346.3 14% 308.7 1% 229.7 -25% 309.5 1% 337.6 11% 308.9 1% 282.7 -7% 297.1 -3% 305.1 0%

Mean Annual Recharge Change 5%

Average CC Scenarios

*Reductions in GW discharge from the Existing Conditions (2008) of more than 10% and 20% are highlighted in blue and orange, respectively*Positive values in black indicate where GW discharge increased from the Existing Conditions (2008)

3%

CC 1 CC 2 CC 3 CC 4 CC 5 CC 6 CC 7 CC 8 CC 9 CC 10RMM Scenario D

-20% -2%0% 18% 19% 6%

Stream / Reach

Scenario C – Existing

Conditions GW Discharge (L/s)

7% 16% 7%


Seven of the climate change scenarios have the same or increased groundwater discharge than RMM Scenario D. For the North Arm of Lower Monora, for example, the baseline RMM Scenario D had a model-predicted discharge of 16.2 L/s while seven climate change scenarios had increased discharge ranging from 17.3 to 23.3 L/s. The three scenarios with less discharge ranged from 9.0 to 16.1 L/s. These three correspond to the scenarios with mean annual recharge that ranges from 0% to -20% of the baseline climate.

5.4 Summary of Climate Change Results The objective of the climate change assessment within this pilot study was to examine the procedure recommended in the RMM Evaluation Process for climate change evaluation. This was done in order to verify the opportunities to integrate the Future Climate Dataset developed by MNR into the water budgets developed within the Source Water Protection Program. Additionally, the pilot study evaluated how climate change would impact the selection of Risk Management Measures to manage the Drinking Water Quantity Threats in a Local Area that had been identified with Significant Risk.

The Risk Level to the Local Area was re-evaluated under the ten climate change scenarios described above. The results are summarized in Table 20. Nine of the ten climate scenarios predicted maximum in-well drawdowns under drought conditions that would be less than the safe available in-well drawdown. Scenario CC 5, which has lowest mean annual recharge (-20%), would have maximum drought drawdowns that exceed the safe water level and thus would trigger a Risk Level of Significant. TABLE 20 Summary of Results from the RMM Evaluation Process

Scenario ID

Climate Scenario (2011-2040)

Mean Annual Recharge Change

(%)

Maximum Drought Drawdown

Acceptable?

Risk Level Assigned to Local

Area

RMM Scenario G Yes Moderate CC 1 CGCM3T47-Run2 - SRB1 0% Yes Moderate CC 2 CGCM3T47-Run3 - SRA2 18% Yes Moderate CC 3 CGCM3T47-Run3 - SRB1 19% Yes Moderate CC 4 CGCM3T47-Run5 - SRA2 6% Yes Moderate CC 5 CSIROMk3.5 - SRB1 -20% No Significant CC 6 ECHAM5OM - SRB1 7% Yes Moderate CC 7 FGOALS-g1.0 - SRA1B 16% Yes Moderate CC 8 GFDLCM2.0 - SRB1 7% Yes Moderate CC 9 GISS-AOM - SRA1B -2% Yes Moderate

CC 10 GISS-EH - SRA1B 3% Yes Moderate

Under the Technical Rules (MOE 2009), only impacts to groundwater discharge for average historical climate are used to evaluate the water quantity Risk Level (i.e., in the Tier Three Risk Assessment). For this climate change adaptation pilot study, the impacts to groundwater discharge were examined for potential future climatic conditions. Therefore, it is not appropriate to use the predicted impacts to


groundwater discharge made in this pilot study to re-evaluate the Water Quantity Risk Level applied to the Local Area.

6 DEVELOPING THE THREATS MANAGEMENT STRATEGY The RMM Evaluation Process is not intended to prescribe an entire policy development process for managing the Significant Drinking Water Quantity Threats. Once the preliminary Risk Management Measures have been selected and evaluated, the most effective solutions are then suggested as the preferred Risk Management Measures and a “Threats Management Strategy” can be developed to help municipalities understand how these measures could be implemented.

A Threats Management Strategy will address the Moderate and Significant Threats identified in the Assessment Reports and ranked in this study. The Threats Management Strategy could include the following key elements:

• identification of Moderate and/or Significant drinking Water Quantity Threats

• identification of preferred Risk Management Measures

• summary of expected Management Targets and/or policy outcomes that would comply with the water quantity source protection plan polices

• summary of timelines, including public consultation, for implementation of the Risk Management Measures

• a summary of consultations held with the affected stakeholder(s)

As the evaluation process is completed; and the Significant Water Quantity Threats are identified and ranked, and the preferred Risk Management Measures for those Threats are selected; planning and implementation activities should be undertaken. As all of the potential impacts or concerns identified in this RMM Evaluation Process are based on model results, which have varying degrees of accuracy, the implementation of a Threats Management Strategy should consider the incorporation of field monitoring to verify model predictions and test the accuracy of the predicted impacts.

A Threats Management Strategy that outlines an approach to address the specific Threats identified herein should be developed. Based on the information obtained through this RMM Evaluation Process, the Source Protection Committee can draft policies to address these Water Quantity Threats, which can then be consulted on with stakeholders. These policies may then be included in the Source Protection Plan.

Some of the management activities can be translated into policies when they are directed at Significant Drinking Water Threats. Other management activities that are not directly related to Significant Drinking Water Threats (i.e., optimization of pumping) are suited to improving the ability of the drinking water system to meet demand. Although these types of non-threat directed management activities can have a significant impact on the sustainability of the system, there are limits on the way policies can be written.


For example, a Source Protection Committee cannot write a Significant Threat policy to address “the optimization of pumping”; however, it can write a Significant Threat policy directed at the operator of the drinking water system to reduce the peak water takings through specific actions. The municipality could then implement this policy through optimizing the use of all of its municipal wells or increasing storage, or it may find another means to reduce peak water takings and minimize risk to their supplies. These matters need to be considered when evaluating how to use the results of the RMM Evaluation Process to draft policies.

7 SUMMARY The Orangeville, Mono and Amaranth Tier Three Local Area Risk Assessment (AquaResource 2011) delineated four Local Areas with Local Area A being assigned a Significant Water Quantity Risk Level. This Risk Level led to the designation of any consumptive water use or any activity that reduces groundwater recharge within the Local Area as a Significant Water Quantity Threat.

The Significant Threats were identified and ranked through a series of Threats Ranking scenarios using the Tier Three Assessment Water Budget groundwater (MODFLOW) model to identify the percentage impact a Threat has on a neighboring municipal well.

Three Risk Management Measures were selected from the Risk Management Measures Catalogue and reviewed for their potential to mitigate the Water Quantity Risk and manage the Significant Threats. The three Measures selected from the Catalogue address two key recommendations from the Tier Three Assessment:

1) Develop a Regional Water Supply Strategy - The three municipalities would be best served by developing a regional water supply strategy and collaborating on water management activities including permitting and monitoring, and identification of new and alternative supplies to meet the water supply needs of the three municipalities.

2) Protect Recharge Areas - The three municipalities should ensure that any future land developments do not have a negative impact on groundwater recharge and, where possible, attempt to enhance groundwater recharge in existing urban areas.

Seven scenarios incorporating the selected Risk Management Measures were evaluated using the Tier Three Assessment MODFLOW model under average and drought climate conditions. Six of these scenarios met the required Allocated Quantity of water while reducing impacts on the wells and surface water features within Local Area A. As such, the Significant Water Quantity Threats and Risk Level of Local Area A were effectively managed by the selected Risk Management Measures.

A climate change adaptation assessment was conducted using ten future climate scenarios selected for the Orangeville MOE climate station. This assessment was conducted on RMM Scenario G that


incorporated fully integrated and optimized municipal pumping and LIDs on future development areas. Eight of the ten future climate change scenarios predicted groundwater recharge greater than or equal to the baseline climate, and as a result, eight of the ten scenarios predicted less drawdown at the municipal wells. Nine of the climate scenarios had results that would maintain the Moderate Risk Level of the RMM Scenario G and one scenario would lead to an assignment of a Significant Risk Level.

The results of this RMM Evaluation Process are valuable to inform a Threats Management Strategy and any policies drafted by the Source Protection Committee or the municipalities to address the Water Quantity Threats.

8 LESSONS LEARNED FROM THIS PILOT STUDY • It is possible to rank Water Quantity Threats in terms of their impact to municipal wells.

• Measures from the Risk Management Measures Catalogue can be used to reduce the impacts from Significant Water Quantity Threats.

• Modelling of water conservation measures must consider the success of pre-existing conservation initiatives.

• The Tier Three Assessment and this pilot study assumed that land use changes would cause a reduction of recharge of 50% for residential and 70% for commercial / industrial properties. These estimates must be refined to match the urban framework and hydrogeology of future study areas.

• Although the pilot study showed the benefits of including LIDs for new development areas, an increase of recharge can also be achieved by using LID retrofits in existing areas.

• Maintaining recharge through LIDs is not always effective to reduce the risk to municipal wells. For example, the Cardinal Woods 3 Well was affected more by pumping than by recharge changes within the Local Area.

• The Risk Management Strategy suggested in this pilot study represents only a few of the possible measures that could be considered by the local municipalities. The final Risk Management Strategy for this area should be developed in consultation with all stakeholders and should consider all of the potential Water Quantity Risk Management Measures.

• These evaluations are based on modelling and provide our best estimate of how the complex aquifer and surface water systems may respond to land use and pumping changes. The accuracy of the model predictions can to be confirmed and refinements made as new data became available and understanding of the area improves.


• Climate change may result in increased recharge, but the potential effect of fewer, higher intensity precipitation events was not considered in this analysis. This pilot study has demonstrated that climate change datasets can be used in modelling exercises and that a range of climate change scenarios should be considered.

• Climate changes and related hydrologic impacts are still uncertain and, depending on the future climatic conditions, there is some possibility that climate change effects could lead to the assignment of greater Risk Level in the Local Area, or to the assignment of a Moderate Risk Level to some drinking water systems. More certainty in climate change research is required.

9 REFERENCES AquaResource Inc. (AquaResource). 2011. Orangeville, Mono and Amaranth Tier Three Water Budget

and Local Area Risk Assessment Final Report. Updated and re-submitted to the CTC Source Water Protection Region and the Ministry of Natural Resources. Breslau, Ontario. May 2011.

Credit Valley Conservation Authority (CVC). 2014. Headwaters Subwatershed Study Phase 3 Report: Management, Monitoring and Implementation Plan. January 2014.

Credit Valley Conservation Authority (CVC). 2010. Headwaters Subwatershed Study Phase 2: Impact Assessment and Evaluation of Alternative Management Strategies. January 2010.

DHI. 2012. MIKE SHE Volume 1: User Guide. 2012 Edition. 442p.

DHI WASY. 2012 FEFLOW. Software. http://www.feflow.info

Doherty, J. 2004. PEST. Model -Independent Parameter Estimation -User Manual: 5th Edition - Watermark Reference Manual. Numerical Computing. 336 p. July 2004. http://www.wipp.energy.gov/library/cra/2009_cra/references/Others/Doherty_2004_Manual_for_PEST.pdf

EBNFLO Environmental and AquaResource Inc. (EBNFLO). 2010. Guide for Assessment of Hydrologic Effects of Climate Change in Ontario. Prepared for the Ontario Ministry of Natural Resources and Ministry of the Environment in partnership with Credit Valley Conservation.

Gerrits Drilling & Engineering Ltd. (GDE). 2012. Orangeville Municipal Well #6 - 2012 Muni Pak Screen Removal, Well Rehabilitation and Testing. Letter submitted to the Town of Orangeville. Grand Valley, Ontario. June 19, 2012.

Jones, Doug (2013), Director Public Works, Town of Orangeville.

http://www.wipp.energy.gov/library/cra/2009_cra/references/Others/Doherty_2004_Manual_for_PEST.pdf

http://www.wipp.energy.gov/library/cra/2009_cra/references/Others/Doherty_2004_Manual_for_PEST.pdf


Ontario Ministry of the Environment (MOE). 2013. Assignment of Water Quantity Risk based on Evaluation of Impacts to Other Water Uses. Memo from H. Malcolmson, Source Protection Programs Branch, December 2, 2013.

Ontario Ministry of the Environment (MOE). 2009. Technical Rules: Assessment Report. Clean Water Act, 2006. November 16, 2009. http://www.ene.gov.on.ca/stdprodconsume/groups/lr/@ene/@resources/documents/resource/std01_079849.pdf

Ontario Ministry of the Environment (MOE). 2006a. Clean Water Act. S.O. 2006, CHAPTER 22, Ontario Regulation 287/07. Royal Assent: October 19, 2006.

Ontario Ministry of the Environment (MOE). 2006b. Assessment Report: Draft Guidance Modules. Unpublished document.

Ontario Ministry of the Environment (MOE) and Ministry of Natural Resources (MNR). 2009. Water Quantity Threats Ranking Scenarios Guide. Prepared for The Ontario Ministry of the Environment and The Ontario Ministry of Natural Resources. Breslau, Ontario. October 14, 2009. http://waterbudget.ca/threatsrankingguide

SLR Consulting (Canada) Ltd. (SLR). 2012. Orangeville Wellfield Capacity Assessment - Consolidated Permit To Take Water Application. Submitted to the Town of Orangeville. Markham, Ontario. May 2012.

Thompson, Tim (2013), Water Works Technologist, Town of Orangeville.

Toronto and Region Conservation (TRCA). 2013a. Guide Water Quantity Risk Management Measures Evaluation Process. Prepared for The use of Source Protection Committees in preparation of the Source Protection Plans under the Clean Water Act. Toronto, Ontario. January 2013.

Toronto and Region Conservation (TRCA). 2013b. Water Quality and Quantity Risk Management Measures Catalogue. Version: 6.0. April 5, 2013. Accessed November 1, 2013. http://trcagauging.ca/RmmCatalogue/QuantityIndex.aspx.

http://www.ene.gov.on.ca/stdprodconsume/groups/lr/@ene/@resources/documents/resource/std01_079849.pdf

http://www.ene.gov.on.ca/stdprodconsume/groups/lr/@ene/@resources/documents/resource/std01_079849.pdf

http://waterbudget.ca/threatsrankingguide

http://trcagauging.ca/RmmCatalogue/QuantityIndex.aspx

Orangeville, Mono and Amaranth Water

Quantity Risk Management Assessment

Local Areas and Water

Quantity Threats

November 19, 2013 15163-527

P. Chin P. Chin P. Chin

Disclaimer: Prepared solely for the use of the Toronto and

Region Conservation Authority (TRCA) as specified in the

accompanying report. No representation of any kind is made to

other parties with which the TRCA has not entered into contract. 1

(after AquaResource, 2011)



Monthly Recharge Time

Series – MIKE SHE

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Development Areas - Level

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APPENDIX A APPROACH FOR THE WATER QUANTITY RISK MANAGEMENT

MEASURES EVALUATION PROCESS

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APPENDIX A

APPROACH FOR THE WATER QUANTITY RISK MANAGEMENT MEASURES EVALUATION PROCESS

The Clean Water Act (MOE 2006a), which came into effect in July 2007 sets the legal framework that ensures communities are able to protect their municipal drinking water supplies by developing collaborative, locally driven, science-based protection plans. Communities will identify potential risks to local water sources and take action to reduce or eliminate these risks.

In October 2006, the Ministry of the Environment issued the document called Assessment Report: Draft Guidance Modules (MOE 2006b) to guide the tasks being undertaken for the source protection technical studies in advance of the technical rules and regulations under the Clean Water Act (MOE 2006a).

To assist the Source Protection Committees (SPC) and the municipalities to formulate water quantity policies, the province developed a Risk Management Measures Evaluation Process (RMM Evaluation Process; TRCA 2013a) and a Water Quality and Quantity Risk Management Measures Catalogue (RMM Catalogue; TRCA 2013b).

The RMM Evaluation Process will be undertaken in the planning and implementation phases to inform the policy development process. This process is used to select and evaluate measures, using the Tier Three Water Budget model, to determine what measures can be used to manage the Water Quantity Risks to drinking water within the Local Area.

The objective of the process is to help prepare a “Threats Management Strategy” that would give guidance for SPC to assuring the sustainability of the water source to the municipal drinking water system.

In the long term, the RMM Evaluation Process, RMM Catalogue and Threats Management Strategy will assist risk management officials with the establishment of strategies, where required by Source Protection Plans.

The following approach is a tested and consistent alternative approach that can be applied by any Source Protection Committee (SPC) in the province to rank Water Quantity Threats, consider impacts of climate change, and make use of the Water Quantity Risk Management Measures database and web-tool.

This Technical bulletin has been organized into the following Sections:

Task 1: Selecting Water Budget Model

• Task 1.1: Evaluate applicability of existing Tier Three Assessment model


• Task 1.2: Evaluate possible new modeling tools

• Task 1.3: Update the Tier Three model or select new model, as required

Task 2: Ranking of Water Quantity Threats

• Task 2.1: Identify Significant Drinking Water Quantity Threats

• Task 2.2: Run Threats Ranking Scenarios

• Task 2.3: Identify Percentage Impacts and Rank Threats

Task 3: Evaluating Water Quantity Risk Management Measures

• Task 3.1: Document historical municipal water usage and implementation and success of conservation measures.

• Task 3.2: Use the RMM Catalogue Database to Identify Preliminary Risk Management Measures

• Task 3.3: Evaluate the Risk Management Measures using the Water Budget Models and Part IX Technical Rules to mitigate Water Quantity Threats

• Task 3.4: Select Preferred Risk Management Measures

Task 4: Develop Threats Management Strategy

Detailed descriptions of these tasks are given below.

TASK 1: SELECTING THE WATER BUDGET MODEL • Task 1.1: Evaluate applicability of existing Tier Three Assessment model

Identify new municipal pumping wells or intakes. Update hydrogeologic and hydrologic characterization or conceptualization based on new

geologic understanding, pumping wells, and/or monitoring results. Input any new permits to take water (PTTW) that were not previously included in the model.

• Task 1.2: Evaluate possible new modeling tools

Why was (were) the previous model(s) developed? How does (do) the current model(s) perform?

• Task 1.3: Update the Tier Three model or select new model, as required


TASK 2: RANKING OF THE TIER THREE LOCAL AREA MODERATE AND SIGNIFICANT THREATS

Significant Drinking Water Quantity Threats identified in the Tier Three process are then evaluated and ranked according to the impacts created relative to the safe additional drawdown at a well or intake. In some instances, there may be no requirement for the Threats to be ranked (e.g., if the Local Area contains only municipal systems that belong to a single municipality); therefore, appropriate preliminary Risk Management Measures may be selected.

Detailed methodology to undertake the ranking of the Moderate and Significant drinking Water Quantity Threats in a Local Area is presented in the Water Quantity Threats Ranking Scenarios Guide (MOE and MNR 2009).

• Task 2.1: Identify Significant Drinking Water Quantity Threats

• Task 2.2: Run Threats Ranking Scenarios

A series of scenarios are run (Table A-1) using the Tier Three Water Budget model for areas where more than one demand(s) and/or land use development(s) were identified as Significant Threats in a Local Area.

In all instances, the first model scenario run is the baseline scenario; the results of this scenario set the benchmark against which all modelling results will be compared.

Numerical groundwater or surface water flow models developed in a Tier Three Water Budget will be used to examine the impact of land use changes, or increased water demands, on the municipal water supplies and other water uses, in a tiered approach similar to the Water Quantity Risk Assessment:

Level 1 Scenarios examine the cumulative impact of all current or future consumptive water uses, or land use developments, on municipal water supplies.

Sector-based (Level II) scenarios are designed to examine the impact of each sector of water use or land use development (e.g., industrial, agricultural, etc.) on the municipal water supplies and other uses.

Locally Relevant (Level III) Scenarios are used to rank the impact of individual water takings or land use development changes on municipal water supplies or other water users.

In summary, ranking scenarios may have to be evaluated for areas where there are several types of water demands and/or land use developments. Table A-1 summarizes the model scenarios that should be run using the Water Budget tools (calibrated surface water or groundwater models). In all instances, the first model scenario run is the baseline scenario; the results of this scenario set the benchmark against which all modelling results will be compared.


Numerical groundwater or surface water flow models developed in a Tier Three Assessment will be used to examine the impact of land use changes, or water demands, on the municipal water supplies and other water uses. Scenarios that examine the cumulative impact of all current or future consumptive water uses, or land use developments, on municipal water supplies are termed Level I Scenarios. If a Level I scenario predicts an adverse impact on drinking water supplies or other water users, sector-based (Level II) scenarios or locally relevant (Level III) scenarios will be required to estimate the relative impact from specific consumptive water users.

Sector-based (Level II) scenarios are designed to examine the impact of each sector of water use or land use development (e.g., industrial, agricultural, etc.) on the municipal water supplies and other uses. Locally Relevant (Level III) Scenarios are used to rank the impact of individual water takings or land use development changes on municipal water supplies or other water users.

The scenarios include permitted, non-permitted, current, and future water uses as identified in the Tier Three Water Budget and Local Area Risk Assessment (Tier Three Assessment). For this Guide, the term “non-permitted” refers to wells or intakes that extract water at a rate less than 50,000 L per day; wells that were active prior to the start of the Ontario Permit To Take Water process (grandfathered), livestock watering, fire control, and those wells or intakes awaiting a new or renewed permit should be considered as permitted wells in this assessment.


TABLE A-1 Threats Ranking Scenarios

Scenario Description Municipal Takings Permitted Takings Non-Permitted

Takings Land Use Rationale

Baseline Baseline Scenario Existing or None

None None Existing This scenario forms the baseline to which the model scenarios below will be compared.

I-A Municipal Water Use (Allocated Rates)

Allocated Rates

None None Existing Quantify the impact of increasing municipal pumping to Allocated Rates (from existing rates) on the municipal supplies.

I-B All Non-Permitted Takings Existing or None

None Existing, Max Practical, or Future Consumptive

Existing Quantify the impact of all non-permitted demands on the water supplies.

I-C All Permitted Takings Existing or None

Existing, Max Practical, or Future Consumptive

None Existing Quantify the impact of all permitted water demands on municipal water supplies.

I-D Recharge Reduction - Official Plan

Existing or None

None None Official Plan Quantify the cumulative impact of recharge reduction from all developments in the Official Plan on municipal water supplies.

II-A-x Non-Permitted Takings - Sector Based -Sector X

Existing or None

Consumptive Sector X2

None Existing Quantify the impact of each non-permitted sector (e.g. agricultural, domestic, etc.) on municipal water supplies

II-B-x Permitted Takings - Sector Based -Sector X

Existing or None

Consumptive Sector X

None Existing Quantify the impact of each permitted sector (e.g., industrial, commercial) on municipal water supplies

II-C-x Recharge Reduction - Sector Based (Official Plan)

Existing or None

None None Official Plan Land Use Section X

Quantify the impact due to recharge reduction from each development sector (e.g. industrial, commercial) on municipal water supplies.

III-A-X Local Water Demand Scenario - Consumptive Water Taking X

Existing or one

Consumptive User X None Existing Quantify the impact of individual consumptive takings on the municipal water supplies.

III-B-Y Local Groundwater Recharge Reduction Scenario- Activity Y

Existing or None

None None Official Plan Land Use Section Y

Quantify the impact of individual developments on the municipal water supplies.


• Task 2.3: Identify Percentage Impacts and Rank Threats

After the scenario runs have been completed, the percentage impact changes to the safe additional drawdown at the wells or intakes are calculated by comparing the drawdown of each scenario with the baseline scenario drawdown.

Water users and proposed development(s) are tabulated in ranked order. This will identify the Threats that have the greatest potential to reduce the overall percent of impact on water quantity.

TASK 3: EVALUATING WATER QUANTITY RISK MANAGEMENT MEASURES The purpose of this task is to evaluate the potential for Risk Management Measures to mitigate the Water Quantity Risks identified through the Tier Three Local Area Risk Assessment. Presently the RMM Catalogue contains about 80 Water Quantity Risk Management Measures which can be grouped into one or more of the following water conservation and “terrain” Management Targets to deal with the prescribed Water Quantity Threats:

• Indoor water use reduction

• Outdoor water use reduction

• Industrial, commercial, and institutional (ICI) water efficiencies

• Municipal water loss management

• Water resource awareness

• Increase in recharge

• Increase in water supply

• Municipal water efficiencies

• Agricultural water efficiencies - crop management

• Agricultural water efficiencies - livestock management

The dataset was divided into these groups to allow the user to search for measures that are most applicable to manage the activities in the source protection areas. The Management Targets related to water conservation align with actions listed in other provincial initiatives.

• Task 3.1: Document historical municipal water usage and implementation and success of conservation measures.

Compile municipal water demands since completion of Tier Three.

Prepare list of water conservation measures implemented by municipality. Provide description or analysis of the success of these implementation measures.


• Task 3.2: Use the RMM Catalogue Database to Identify Preliminary Additional Risk Management Measures

After considering the ranked Threats and previously implemented Risk Management Measures, select additional Risk Management Measures from the catalogue to re-evaluate the risk to the Local Area using the Tier Three Water Budget Models.

Filter or group the Risk Management Measures by Sector or by Management Target. The purpose of this grouping is to direct and help focus the selection and analysis of measures based on the analysis of the results of the ranking process.

• Task 3.3: Evaluate the Risk Management Measures using the Water Budget Models and Part IX Technical Rules to mitigate Water Quantity Threats

Update the Tier Three Water Budget Models to reflect the selected preliminary Risk Management Measures and re-evaluate the Water Quantity Risk scenarios and the level of risk assigned to the Local Area.

Once the Water Budget models are modified to reflect the inclusion of the RMM, the models are re-run for the Tier Three risk scenarios to determine if the measure(s) will lower the risk assigned to the Local Area. If so, the user proceeds to the next step.

If the assigned Risk Level to the Local Area does not change, the user returns to the catalogue to select new or additional Risk Management Measures. This process is repeated iteratively until the Moderate and Significant Water Quantity Threats and Risk Level of the Local Area are effectively managed.

The minimum requirement of this task is to re-run the Tier Three Scenarios to evaluate risk under average and drought conditions. Depending on the number of Risk Management Measures and the number and types of Moderate or Significant Threats, the number of scenarios may be expanded to isolate the risk evaluation.

The selection of conservation measures applied to residential, ICI and municipal sectors are expected to lead to a cumulative reduction in water demand. The cumulative amount of water saved through conservation efforts will depend on local factors such as the estimated number of existing and planned residents, planned development and relevant conservation measures such as the installation of low flush toilets, recycling of water and water returned to the source in a reasonable time period.

• Task 3.4: Select Preferred Risk Management Measures


Once the preliminary Risk Management Measures have been selected and evaluated, the most effective solutions are then identified as the “Preferred Risk Management Measures.”

TASK 4: RE-EVALUATING WATER QUANTITY RISK MANAGEMENT MEASURES FOR CLIMATE CHANGE ADAPTATION

If required or recommended, a Climate Change Adaptation assessment may be conducted using multiple climate scenarios on the preferred Risk Management Measures.

TASK 5: DEVELOP THREATS MANAGEMENT STRATEGY The “Threats Management Strategy” will be developed to deal with Moderate or Significant Threats identified in the Assessment Reports. The Threats Management Strategy could include the following key elements:

• identification of Moderate and/or Significant drinking Water Quantity Threats

• identification of preferred Risk Management Measures

• summary of expected Management Targets and/or policy outcomes that would comply with the water quantity source protection plan polices

• summary of timelines, including public consultation, for implementation of the Risk Management Measures

• a summary of consultations held with the affected stakeholder(s)

Once the evaluation process is complete and the Significant Water Quantity Threats have been identified, ranked and the preferred Risk Management Measures for those Threats have been selected, planning and implementation activities should be undertaken.

A Threats Management Strategy that outlines an approach that is best for the specific Threats that have been identified should be developed. For example, this strategy could include a plan of how a municipality could optimize the use of all of their municipal wells or intakes and minimize risk to their supply.

Based on the information obtained through the evaluation process, the Source Protection Committee can draft policies to address these Water Quantity Threats which can then be consulted on with stakeholders. These policies may then be included in the Source Protection Plan.

APPENDIX B INFORMATION SHEETS FROM THE WATER QUANTITY RISK

MANAGEMENT MEASURES CATALOGUE

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APPENDIX C DEVELOPING THE CLIMATE CHANGE SCENARIOS

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APPENDIX C

DEVELOPING THE CLIMATE CHANGE SCENARIOS

1 INTRODUCTION To evaluate hydrologic effects that may be reasonably expected to occur under a future climate, climate change scenarios were developed for use within the Orangeville, Mono and Amaranth Water Quantity Risk Management and Climate Change Adaptation Assessment. The methodology followed was based on methods described in Guide for Assessment of Hydrologic Effects of Climate Change in Ontario (EBNFLO 2010) developed by EBNFLO Environmental and AquaResource Inc. for the Ontario Ministry of Natural Resources and Ministry of the Environment in partnership with Credit Valley Conservation. The purpose of this guide was to provide a method for conducting assessments of the effects of climate change on water resources in Ontario. Additional guidance for this assessment was provided by the Water Budget Reference Manual (AquaResource 2013) that included a chapter on evaluating hydrologic impacts due to climate change.

This appendix provides summaries of sections from the Guide and Reference Manual that introduce some of the possible hydrologic changes that may occur due to climate change, how predictions of future climate are made, and how one can quantitatively evaluate the hydrologic impacts due to climate change. This appendix also provides specific details on how the recommended methodology was applied to Orangeville, Mono and Amaranth Water Quantity Risk Management and Climate Change Adaptation Assessment.

1.1 Overview of Climate Change Assessments

1.1.1 Potential Hydrologic Impacts due to Climate Change

Climatic conditions are the driving forces of the hydrologic cycle. As such, perturbations produced by climate change that deviate from historic climate variations will impact all components of the hydrologic cycle both in terms of timing and quantity. Climate change has the potential to significantly modify water budget components such as overland runoff, groundwater recharge and evapotranspiration.

Climate projections for Ontario indicate a warmer and wetter future climate. Winter months are predicted to experience the majority of warming, which depending on location, may significantly impact snow accumulation and melt processes. Increases in temperature are also expected to elevate potential evapotranspiration rates. Changes in cloud cover and solar radiation may also lead to changes in the rate of evapotranspiration rates.


1.1.2 Climate Modelling

A number of international climate modelling centres exist around the world. These centres use Global Climate Models (GCMs) and predictions of greenhouse gas (GHG) emission concentrations to simulate the future climate. Eighteen modelling groups, using 25 Global Climate Models, performed a series of coordinated climate simulations in the Coupled Model Intercomparison Project Phase 4. This project contributed to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change released in 2007 (IPCC 2007).

The combination of multiple GCMs and multiple GHG emission scenarios results in a large number of possible climate scenarios or future climates. Currently, climate science is unable to identify any one GCM or GHG emission scenario most able to accurately predict future climate. As such, the climate science community regards each possible future climate generated by a specific GCM and GHG emission scenario as equally plausible. Recognizing that there are multiple possible futures, as well as the sensitivity of impact assessments to the future climate selected, it is recommended that a full range of future climates be investigated.

1.1.3 Future Local Climates

GCMs, with grid sizes on the order of hundreds of kilometres, lack the local-scale parameterization and feedback from locally significant features (e.g., topography and surface water) to reflect local-scale climate directly in model output. Various methods of downscaling GCM simulations continue to be developed and include statistical downscaling, weather generators and regional climate models (RCMs). The most established methodology for estimating future local climates uses the GCM simulations to estimate annual, seasonal or monthly changes for each climate variable for a future time period relative to a baseline climate period. These relative changes, termed change fields, are used to adjust observed historic climate station data to reflect future conditions. This approach results in an altered climate time series that reflects the average relative change in each parameter and, through the use of local observations, the local climate. The change field method is a simple approach to develop future local climates that reflect large-scale average features and allows the use of all GCM and GHG emission scenarios.

1.1.4 Selecting Future Climate Simulations

There are numerous GCMs and GHG emission scenarios to choose from when conducting a climate change impact assessment. A scenario selection method (termed the Percentile Method) is proposed that provides a rationale for selecting GCM - GHG scenarios that are representative of the full set of scenarios available to the user. The percentile method selects up to 10 scenarios on a statistical basis with five being selected because they represent the 5th, 25th, 50th, 75th and 95th percentiles of annual temperature change. A second set of five scenarios is chosen based on annual precipitation change. It is possible that one scenario satisfies more than one criterion and thus less than 10 scenarios in total are selected. This subset of climate scenarios represents the full range of predicted future climates and therefore can be used to investigate the


central tendency among the group of future climates as well as the effect of the more extreme climates (i.e., 5th and 95th percentiles).

1.1.5 Hydrologic Modelling

In order to assess climate change impacts using hydrologic models, data from a selection of climate scenarios are used as inputs to the hydrologic model and the predictive outputs from the model are examined. These outputs could include water budget components such as streamflow, overland runoff, groundwater recharge, and evapotranspiration.

Hydrologic models simulate the natural environment using numerical algorithms. The accurate representation of key hydrologic processes within a numerical model is critical to assessing possible impacts of climate change on water resources. The most important hydrologic processes are described below:

• Evapotranspiration. In Ontario, evapotranspiration is the dominant process in the hydrologic cycle, responsible for up to 60% of the water budget, and yet it cannot be accurately monitored. The selected hydrologic model should have an evapotranspiration algorithm that is physically-based.

• Soil Water Storage. The availability of storage in the soil column affects evaporation and transpiration rates. Hydrologic models used in climate change impact assessments should have the ability to track soil water content and to limit evapotranspiration rates based on soil water content.

• Snow Accumulation and Melting. In Ontario, the spring snowmelt period typically produces the majority of overland runoff and recharges the groundwater system. Any model assessing the impact of climate change within Ontario should have the ability to simulate snow accumulation and melting processes.

• Infiltration. Infiltration algorithms used in hydrologic modelling should be sensitive to the onset and thawing of frozen ground, especially as these conditions are altered by climate change.

• Groundwater recharge. Groundwater recharge is defined as water that infiltrates into the upper soil zone and percolates downward past the vegetative rooting zone (where evapotranspiration losses occur). Once past the vegetative rooting zone, water continues moving downwards until it reaches the saturated zone or groundwater flow system as groundwater recharge. The amount and timing of groundwater recharge is dependent on a number of factors including: precipitation, surficial geology, soil moisture conditions, interflow (subsurface stormflow), and vegetation/land use (which influence evapotranspiration rates). Accurately estimating groundwater recharge requires the characterization and consideration of all major hydrologic processes.


2 CLIMATE SCENARIOS SELECTION For the Orangeville, Mono and Amaranth Water Quantity Risk Management and Climate Change Adaptation Assessment, climate data was selected using the Ontario Ministry of Natural Resources (MNR) Future Climate Data Application (http://climate.aquamapper.com/). The MNR climate data application allows the user to download future climate data, which has been derived by combining historical climate data with GCM output. The GCM output included in the MNR application was obtained from the Canadian Climate Centre Scenarios Network (CCCSN). The CCCSN website consolidates published GCM output from various climate modelling centers around the world. At the time of this study, the CCCSN website was not updated with output from GCMs presented in the most recent Fifth Assessment Report (IPCC, 2013). As a result the climate scenarios considered as part of this study were derived from the Fourth Assessment Report (IPCC, 2007).

Future local climate data was retrieved for the Orangeville MOE climate station (#6155790). Baseline climate for 1961 to 1990 was chosen in order to capture droughts and high flow periods in the historical record, and the future climates representing 2011 to 2040 were selected. This period coincided with the drought scenarios conducted under the Risk Management Measures Evaluation Process.

The percentile method described above was used to select ten scenarios from the 76 climate change scenarios provided by the MNR. The ten selected climate scenarios had higher annual temperatures than the baseline climate and trended towards more annual precipitation (with the exception of one model CSIROMk3.5 - SRB1). Table C1 summarizes the ten climate scenarios and the predicted shifts in mean annual temperature and precipitation from the existing climate.

TABLE C1 Mean Annual Temperature and Precipitation Change of Selected Scenarios

Scenario ID Climate Change

Scenarios 2011 to 2040



CC 1 CGCM3T47-Run2 - SRB1 2.1 0.9 CC 2 CGCM3T47-Run3 - SRA2 1.6 8.1 CC 3 CGCM3T47-Run3 - SRB1 1.5 8.5 CC 4 CGCM3T47-Run5 - SRA2 2.2 2.3 CC 5 CSIROMk3.5 - SRB1 1.4 -4.1 CC 6 ECHAM5OM - SRB1 1.0 3.7 CC 7 FGOALS-g1.0 - SRA1B 1.3 5.9 CC 8 GFDLCM2.0 - SRB1 1.5 4.4 CC 9 GISS-AOM - SRA1B 1.3 0.7

CC 10 GISS-EH - SRA1B 0.9 2.6 Figure C1 shows the distribution of simulated future climates for the 76 scenarios for the Orangeville climate station. The climates are plotted according to the mean annual temperature change and mean annual precipitation change from the baseline climate. The climates selected for this study are highlighted and labeled.

http://climate.aquamapper.com/


This figure shows the significant disparity among GCM models and emission scenarios as mean annual temperature changes range from +0.6°C to +2.3°C, while annual precipitation changes range from -6.4% to +14.8%.

FIGURE C1 Annual temperature and precipitation change fields for the Orangeville MOE Climate Station. Scenarios used in the study are highlighted and labeled.

3 CLIMATE SCENARIOS ANALYSIS Analysis of the climate scenarios focused on comparing the amount of precipitation, the proportion of rain and snow, the temperature, and the potential evapotranspiration predicted by each scenario.

3.1 Precipitation Figure C2 illustrates the mean monthly precipitation for the ten climate scenarios. This plot shows both increases and decreases from the baseline climate in the summer and fall months, with the winter and spring months showing generally higher precipitation in the future climate scenarios.

(CC 10) GISS-EH-SRA1B

(CC 6) ECHAM5OM-SRB1

(CC 7) FGOALS-g1.0-SRA1B

(CC 9) GISS-AOM-SRA1B

(CC 5) CSIROMk3.5-SRB1

(CC 3) CGCM3T47-Run3-SRB1

(CC 8) GFDLCM2.0-SRB1

(CC 2) CGCM3T47-Run3-SRA2

(CC 1) CGCM3T47-Run2-SRB1

(CC 4) CGCM3T47-Run5-SRA2

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tatio

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FIGURE C2 Mean Monthly Precipitation of Current and Future Climates (2011 to 2040)

The annual precipitation over the time period for the climate scenarios is presented in Figure C3. This shows the future climate scenarios generally have increased precipitation over the baseline climate, with the exception of one climate scenario. 1963 (or 2013 for the future climates) is the driest year with the lowest precipitation for one future climate predicted to be 596 mm/year, while the greatest precipitation for a future climate (1110 mm/year) is predicted to occur in 1990 (or 2040 for the future climates).

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FIGURE C3 Annual Precipitation of Current and Future Climates (2011 to 2040)

3.2 Temperature Figure C4 shows the mean monthly temperature for the climate scenarios. The future climates mainly increase in temperature from the baseline climate, with few exceptions in January and February.

The annual mean temperatures for the climate scenarios are shown in Figure C5. The future climate scenarios all have greater annual mean temperatures than the baseline climate. 1972 (or 2022 for the future climates) is the coldest year of all the scenarios (5.7°C), while 1987 (or 2037) is the warmest (9.4°C).

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FIGURE C4 Monthly Temperature of Current and Future Climates (2011 to 2040)

FIGURE C5 Annual Mean Temperature of Current and Future Climates (2011 to 2040)

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3.3 Potential Evapotranspiration Potential evapotranspiration was estimated using the current and future climate data. Data for each of the scenarios was input into the UN Food and Agriculture Organization’s Potential Evapotranspiration (ETo) Calculator (FAO 2009) and the Pennman Monteith method (Allen et al. 1998) was used to calculate the potential evapotranspiration using daily wind-speed, humidity and radiation data estimated for the location. Figure C6 illustrates the mean monthly potential evapotranspiration for the climate scenarios. This plot shows slightly increased potential evapotranspiration in all months from the baseline climate for all future scenarios.

FIGURE C6 Mean Monthly Potential Evapotranspiration of Current and Future Climates (2011 to 2040)

The annual potential evapotranspiration for the climate scenarios is shown in Figure C7. Similar to temperature, the future climate scenarios have greater potential evapotranspiration than the baseline climate. 1972 (or 2022) has the least amount of potential evapotranspiration (778 mm/year), while 1988 (or 2038) has the most amount of potential evapotranspiration (924 mm/year).

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FIGURE C7 Annual Potential Evapotranspiration of Current and Future Climates (2011 to 2040)

4 HYDROLOGIC MODELLING An integrated groundwater and surface water model using the MIKE SHE software package (DHI 2012) was developed for the Orangeville, Mono and Amaranth Water Quantity Risk Management and Climate Change Adaptation Assessment. This model provides a more complete representation of groundwater/surface water interactions and allows for the influence of climate change to be examined.

Temperature, precipitation and evapotranspiration data from each of the ten future climate scenarios was used as input into separate MIKE SHE simulations and the predicted groundwater recharge was extracted and used as input to the Tier Three Assessment MODFLOW model for use in this study. Table C2 gives the percentage change in mean annual recharge from the baseline climate for each climate scenario along with the mean annual change in temperature and precipitation. The mean annual recharge for the future climate scenarios varies from a decrease of 20% from the baseline to an increase of 19%.

700

750

800

850

900

95019

6119

6219

6319

6419

6519

6619

6719

6819

6919

7019

7119

7219

7319

7419

7519

7619

7719

7819

7919

8019

8119

8219

8319

8419

8519

8619

8719

8819

8919

90

Annu

al P

oten

tial E

vapo

tran

spira

tion

(mm

/yea

r)


TABLE C2 Mean Annual Temperature, Precipitation and Recharge Change from Baseline

Scenario ID

Climate Change Scenario

(2011-2040)

Mean Annual Recharge Change (%)



CC 1 CGCM3T47-Run2 - SRB1 0% 2.1 0.9 CC 2 CGCM3T47-Run3 - SRA2 18% 1.6 8.1 CC 3 CGCM3T47-Run3 - SRB1 19% 1.5 8.5 CC 4 CGCM3T47-Run5 - SRA2 6% 2.2 2.3 CC 5 CSIROMk3.5 - SRB1 -20% 1.4 -4.1 CC 6 ECHAM5OM - SRB1 7% 1.0 3.7 CC 7 FGOALS-g1.0 - SRA1B 16% 1.3 5.9 CC 8 GFDLCM2.0 - SRB1 7% 1.5 4.4 CC 9 GISS-AOM - SRA1B -2% 1.3 0.7

CC 10 GISS-EH - SRA1B 3% 0.9 2.6 Figure C8 illustrates the mean monthly recharge for the climate scenarios. There is generally an increase of recharge during the winter months for all the future climate scenarios over the baseline climate and decreased recharge during the late spring and summer months.

Figure C9 illustrates the annual recharge for the climate scenarios compared to the baseline annual recharge. There is generally an increase in recharge over the baseline climate for all future climate scenarios except for one climate (CC 5-CSIROMk3.5-SRB1) that has 20% less recharge on average than the baseline. 1963 (or 2013) has the least amount of recharge (35 mm for one climate), while 1986 (or 2036) has the most amount of recharge (402 mm for one climate).

5 REFERENCES Allen, R.G., L.S. Pereira, D. Raes, and M. Smith. 1998. Irrigation and Drainage Paper 56, Food and Agricultural

Organization (FAO) of the United Nations. Rome, Italy.

AquaResource, a Division of Matrix Solutions Inc. 2013. Water Budget Reference Manual. Prepared for the Ontario Ministry of Natural Resources.

EBNFLO Environmental and AquaResource Inc. (EBNFLO). 2010. Guide for Assessment of Hydrologic Effects of Climate Change in Ontario. Prepared for the Ontario Ministry of Natural Resources and Ministry of the Environment in partnership with Credit Valley Conservation.

Food and Agriculture Organization (FAO). 2009. Potential Evapotranspiration Calculator, Version 3.1. (available from http://www.fao.org/nr/water/eto.html)


IPCC. 2007. Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 996 pp.

IPCC. 2013. Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.


FIGURE C8 Mean Monthly Recharge of Current and Future Climates (2011 to 2040)

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10

20

30

40

50

60

70

80

90


Mea

n M

onth

ly R

echa

rge

(mm

/mon

th)

(CC 1) CGCM3T47-Run2-SRB1 (CC 2) CGCM3T47-Run3-SRA2 (CC 3) CGCM3T47-Run3-SRB1 (CC 4) CGCM3T47-Run5-SRA2

(CC 5) CSIROMk3.5-SRB1 (CC 6) ECHAM5OM-SRB1 (CC 7) FGOALS-g1.0-SRA1B (CC 8) GFDLCM2.0-SRB1

(CC 9) GISS-AOM-SRA1B (CC 10) GISS-EH-SRA1B Current Climate (Baseline)


FIGURE C9 Annual Recharge of Current and Future Climates (2011 to 2040)

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50.0

100.0

150.0

200.0

250.0

300.0

350.0

400.0

450.0

Annu

al R

echa

rge

(mm

/yea

r)

(CC 1) CGCM3T47-Run2-SRB1 (CC 2) CGCM3T47-Run3-SRA2 (CC 3) CGCM3T47-Run3-SRB1

(CC 4) CGCM3T47-Run5-SRA2 (CC 5) CSIROMk3.5-SRB1 (CC 6) ECHAM5OM-SRB1

(CC 7) FGOALS-g1.0-SRA1B (CC 8) GFDLCM2.0-SRB1 (CC 9) GISS-AOM-SRA1B

(CC 10) GISS-EH-SRA1B Current Climate (Baseline)

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