Etobicoke Creek Headwaters Subwatershed Study Synthesis Report

Prepared by:

and

FINAL REPORT September 2008

in partnership with:

Preface

In 2002 the Etobicoke and Mimico Creek Watersheds Task Force released Greening Our Watersheds: Revitalization Strategies for Etobicoke and Mimico Creeks , which established a vision and objectives for healthier and more sustainable watersheds by the year 2025 (TRCA, 2002a). Protection of the natural features and functions of the headwaters was recognized as being vitally important to the overall health of Etobicoke Creek. As the urbanized portion of the Greater Toronto Area continues to grow, the headwaters of Etobicoke Creek are expected to experience significant development pressure. This area was identified as a high priority for subwatershed planning to inform an environmental assessment study for a proposed extension of the Region of Peel’s Lake Ontario-based water supply infrastructure to the north and to inform the Town of Caledon’s community planning process for the Mayfield West area, located north of Mayfield Road, east and west of Highway 10 (Hurontario Street).

In October of 2003, the Toronto and Region Conservation Authority (TRCA) initiated a subwatershed planning study for the Etobicoke Creek Headwaters in partnership with the Region of Peel, Town of Caledon, City of Brampton and the Etobicoke and Mimico Creek Watersheds Coalition. The subwatershed study provided an opportunity to examine local watershed management issues and formulate recommendations for actions that would contribute to achieving the objectives of Greening Our Watersheds in this area. While the original workplan envisioned studies to predict the response of the subwatershed system to different scenarios of land use change, the pace at which planning initiatives in the study area were proceeding necessitated that the workplan be modified in 2005. It was decided that a single report would be produced from the study that included recommendations for further study to inform the preparation of terms of reference for environmental planning studies that would be required by municipalities from development proponents in support of proposed new developments. Recommendations regarding management actions necessary for watershed protection, based on available knowledge of current conditions, and high priority initiatives to implement the study recommendations were also to be included.

This Etobicoke Creek Headwaters Subwatershed Study Synthesis Report summarizes, integrates and documents the findings and recommendations from the subwatershed planning study 1.

Part I provides background information on the purpose of the study and process followed.

Part II describes current conditions in the subwatershed regarding land use 2, groundwater 2 surface water quantity 2 and quality, fluvial geomorphology 2, terrestrial and aquatic ecosystems 2 and cultural heritage.

Part III describes the framework of objectives, indicators and targets for watershed management established by Greening Our Watersheds . It includes recommendations for

1 Preparation of this report occurred between October 2004 and November 2005, at which time a draft was circulated to Steering Committee members for review and comment. While finalization of this report to address Steering Committee comments was completed in 2008, the information on subwatershed conditions represents what was available between October 2004 and November 2005. 2 Updated and more comprehensive information on current conditions for the entire Etobicoke and Mimico Creek watersheds will be integrated and reported through the TRCA’s 2008/09 Etobicoke and Mimico Creek watersheds update study.

management actions necessary to protect and enhance watershed health, recommendations regarding further study needs, and outlines immediate next steps to be taken to implement the recommendations and in further environmental planning work to be conducted in the subwatershed.

ii Table of Contents

PART 1 INTRODUCTION ...... 1

1. Background ...... 1

1.1 Subwatershed Planning for Etobicoke Creek Headwaters ...... 1

1.2 Study Process ...... 2

1.3 Planning Context ...... 3

2. Study Area ...... 9

2.1 Location ...... 9

2.2 Physiography, Surficial Geology and Soils...... 9

2.3 Climate ...... 12

2.4 Local Watershed Management Issues and Opportunities ...... 14

PART 2 CURRENT CONDITIONS ...... 17

3. Land and Resource Use...... 17

3.1 Rural and Urban Land Use...... 17

3.2 Major Servicing ...... 20

3.3 Anticipated changes to land and resource use ...... 21

3.4 Links to Other Subwatershed System Components ...... 24

3.5 Management Considerations...... 25

4. Groundwater Quantity and Quality...... 28

4.1 Measuring Groundwater Quantity and Quality ...... 28

4.2 Groundwater Flow ...... 28

4.3 Groundwater Recharge and Discharge ...... 29

4.4 Groundwater Use...... 33

4.5 Groundwater Quality ...... 33

4.6 Current State of the Groundwater System...... 34

iii 4.7 Management Considerations ...... 34

5. Surface Water Quantity...... 36

5.1 Water Balance ...... 36

5.2 Measuring Surface Water Quantity ...... 38

5.3 Stream Flow ...... 41

5.4 Flooding ...... 43

5.5 Surface Water Use...... 44

5.6 Current Surface Water Quantity Conditions...... 48

5.7 Management Considerations ...... 48

6. Surface Water Quality...... 51

6.1 Provincial Water Quality Data ...... 51

6.2 TRCA Water Quality Sampling Data...... 57

6.3 Current State of Water Quality...... 60

6.4 Management Considerations ...... 60

7. Fluvial Geomorphology ...... 62

7.1 Measuring Fluvial Geomorphology...... 62

7.2 Reach Delineations and Assessments...... 63

7.3 Channel stability ...... 66

7.4 Current State of Fluvial Geomorphology ...... 67

7.5 Management Considerations ...... 67

8. Terrestrial System ...... 68

8.1 Measuring the Terrestrial System...... 68

8.2 Quality ...... 69

8.3 Quantity ...... 72

8.4 Distribution ...... 75

8.5 Connectivity ...... 75

8.6 Biodiversity ...... 76

iv 8.7 Current State of the Terrestrial System ...... 79

8.8 Management Considerations ...... 79

9. Aquatic Systems ...... 82

9.1 Measuring the Aquatic System...... 82

9.2 Fish ...... 84

9.3 Benthic Invertebrates...... 88

9.4 Aquatic Habitat ...... 90

9.5 Thermal Regimes...... 94

9.6 Current State of Aquatic Systems ...... 96

9.7 Management Considerations ...... 96

10. Cultural Heritage...... 100

10.1 Historical Context...... 100

10.2 Measuring Cultural Heritage...... 101

10.3 Current State of Cultural Heritage ...... 103

10.4 Management Considerations ...... 103

11. Policy Review ...... 104

11.1 Source Water Protection Planning ...... 104

11.2 Generic Conservation Authority Regulations ...... 105

11.3 Nutrient Management Act...... 105

11.4 Greenbelt Plan for the Greater Golden Horseshoe...... 106

11.5 Growth Plan for the Greater Golden Horseshoe...... 106

PART 3 CONCLUSIONS ...... 108

12. Management Plan Framework ...... 108

13. Management Plan Recommendations...... 109

14. Recommendations for Further Study...... 113

15. Next Steps ...... 116

16. References ...... 117

v

Appendix A: Recommended study requirements to support proposals for new development in the Mayfield West community planning area...... 122 Appendix B: Framework of objectives, indicators and targets for management of the Etobicoke and Mimico Creek watersheds...... 126

LIST OF TABLES

Table 1-1: Summary of recent watershed management or planning related studies of relevance to the Etobicoke Creek Headwaters subwatershed ...... 5 Table 2-1: Soils in the Etobicoke Creek Headwaters subwatershed ...... 12 Table 2-2: Reports identifying opportunities to improve the health of the Etobicoke Creek Headwaters subwatershed...... 15 Table 2-3: Watershed management issues affecting the Etobicoke Creek Headwaters...... 16 Table 3-1: Land use in the Etobicoke Creek Headwaters Subwatershed...... 17 Table 5-1: Etobicoke Creek stream gauges ...... 38 Table 5-2: Summary of hydrologic models...... 39 Table 5-3: Summary of hydraulic models ...... 44 Table 6-1: Provincial Water Quality Monitoring Network (PWQMN)...... 53 Table 7-1: Existing conditions of reaches assessed within Etobicoke Creek Headwaters subwatershed ...... 65 Table 7-2: Erosion threshold values...... 66 Table 8-1: Quantity of natural cover ...... 73 Table 9-1: Historical fish sampling records in the Etobicoke Creek Headwaters...... 85 Table 9-2: Criteria used in benthic analysis ...... 89 Table 9-3: Site condition ratings using benthic invertebrate data...... 90 Table 9-4: Mussel species observed in the Etobicoke Creek Headwaters subwatershed...... 90 Table 9-6: Thermal regime category definitions ...... 94 Table 9-7: Aquatic management components and targets for the Upper Etobicoke Creek ...... 98

LIST OF FIGURES

Figure 2-1: Study Area...... 10 Figure 2-2: Surficial Geology...... 11 Figure 2-3: Soils...... 13 Figure 3-1: Land Use ...... 18 Figure 3-2: Existing Stormwater Management Controls and Known Retrofit Opportunites ...... 22 Figure 3-3: Watershed Response Model ...... 24 Figure 4-1: Orientation of Cross Sections...... 30 Figure 4-2: North-South Cross-Section of Geologic Model...... 31 Figure 4-3: West-East Cross-Section of Geologic Model ...... 32 Figure 5-1: Average Annual Groundwater Recharge Rates ...... 37 Figure 5-2: Flood Vulnerable Areas and Roads...... 40 Figure 5-3: Baseflow Measurements...... 42 Figure 5-4: Floodplain Mapping...... 45 Figure 5-5: Water Use in the Etobicoke Creek Headwatetrs Subwatershed ...... 46 Figure 5-6: Water Takings ...... 47 Figure 5-7: Stormwater Management Criteria...... 50

vi Figure 6-1: Surface Water Quality Sampling Stations ...... 52 Figure 7-1: Fluvial Geomorphology Monitoring Stations...... 64 Figure 8-1: Overall Quality of Habitat Scores...... 71 Figure 8-2: Natural Cover in the Etobicoke Creek Headwaters Subwatershed...... 74 Figure 8-3: Observations of Flora Species of Concern ...... 77 Figure 8-4: Observations of Fauna Species of Concern ...... 78 Figure 9-1: Aquatic System Monitoring Stations ...... 83 Figure 9-2: Potential and Known In-stream Barriers...... 86 Figure 9-3: Stream Order...... 92 Figure 9-4: Thermal Regimes ...... 95 Figure 10-1: Cultural Heritage Features...... 102

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PART 1 INTRODUCTION

1. Background

1.1 Subwatershed Planning for Etobicoke Creek Headwaters Located within the Greater Toronto Area, the most populous region in Canada, the Etobicoke Creek watershed has undergone rapid urbanization in recent years. An unfortunate consequence of this period of rapid urban growth has been the loss and degradation of natural habitats and ecosystem functions once supported by the watershed. In 1999, the Etobicoke and Mimico Creek Watersheds Task Force was formed and given the mandate to develop an ecosystem-based management strategy for the Etobicoke and Mimico Creeks. In 2002, with the release of Greening Our Watersheds: Revitalization Strategies for Etobicoke and Mimico Creeks, the Etobicoke and Mimico Creek Watersheds Task Force (now known as the Etobicoke and Mimico Creek Watersheds Coalition) established a vision for healthier and more sustainable watersheds by the year 2025, and management objectives and targets to help achieve this vision (TRCA, 2002a). At that time, it was noted that the majority of natural land cover and highest quality aquatic habitats that remain in the Etobicoke Creek watershed are concentrated in the headwaters area. Protecting the natural features and functions of the headwaters was recognized as being vitally important to maintaining and improving the overall health of Etobicoke Creek.

The Etobicoke Creek Headwaters subwatershed is located in the northernmost portion of the Etobicoke Creek watershed, where the creek first appears in the landscape as many small tributaries, groundwater springs and wetland pockets surrounded by predominantly agricultural land uses. This subwatershed includes portions of the Town of Caledon, including the communities of Victoria, Campbell’s Cross, and Valleywood, and the community of Snelgrove in the City of Brampton. As the urbanized portion of the Greater Toronto Area continues to grow, the headwaters of Etobicoke Creek are expected to experience significant development pressure in the near future. Several planning initiatives are underway that will have profound influence on future land and water use within the Etobicoke Creek Headwaters subwatershed and surrounding areas: • Extension of Highway 410 north from Bovaird Drive to Mayfield Road to link with Highway 10 (Hurontario Street), north of Mayfield Road; • A class environmental assessment, initiated by the Region of Peel, to extend a municipal water supply feedermain pipeline (Lake Ontario based water source) north of Mayfield Road; and, • The Mayfield West Community Development Plan process, initiated by the Town of Caledon, to set the planning framework for establishing the Mayfield West area as a Rural Service Centre that will accommodate a population of approximately 13,000 by the year 2021.

Recognizing the need for an up-to-date, comprehensive and integrated environmental study to inform these planning initiatives, and the need for detailed direction regarding specific policies, programs and actions necessary to achieve the objectives and targets of the watershed revitalization strategy in this area, the Toronto and Region Conservation Authority (TRCA) initiated a subwatershed planning study for the Etobicoke Creek Headwaters in partnership with the Region of Peel, City of Brampton, Town of Caledon and Etobicoke and Mimico Creek

1 Watersheds Coalition. Subwatershed planning is an integrated, ecosystem-based approach to land and water use planning using the boundary of a subwatershed to define the study area (MOE, 1993). A subwatershed can be defined as all lands draining to a creek, or other subsection of a watercourse or watershed. Subwatershed plans reflect the objectives of the watershed strategy or plan, but focus on addressing local watershed management issues and opportunities.

1.2 Study Process A Steering Committee was established in 2003 to direct the organization and management of the Etobicoke Creek Headwaters subwatershed planning study process. The Steering Committee was made up of representatives from the Public Works, Planning, and Parks and Recreation Departments of the Region of Peel, Town of Caledon, and City of Brampton, the Etobicoke and Mimico Creek Watersheds Coalition and the Toronto and Region Conservation Authority. Representatives of the Ontario Ministry of the Environment, Ministry of Natural Resources and Ministry of Agriculture and Food were invited to take part in the Steering Committee but chose not to participate.

The subwatershed planning process involved characterization of subwatershed conditions through a review of available information and field studies to fill critical information gaps. The subwatershed system was conceptualized as being composed of the following components: • Groundwater quantity and quality; • Surface water quantity; • Surface water quality; • Fluvial geomorphology; • Aquatic system; • Terrestrial system; • Cultural heritage; and, • Land and resource use.

New information collected through field studies included: • Field assessment of terrestrial natural heritage, including inventories and mapping of vegetation community types and flora and fauna species, following the TRCA Terrestrial Natural Heritage Program protocols, to establish a consistent baseline of information for all natural cover patches in the study area; • Assessment of riparian vegetation using 1999 land cover information interpreted from aerial photos to help identify opportunities for ecological restoration plantings on public and private lands; • Field measurements of summer stream flow during dry periods (i.e. baseflow) at indicator sites to develop an improved understanding of surface water/groundwater interactions, influences of upstream surface water takings on stream flow, and reaches that exhibit intermittent flow; • Dry and wet weather flow surface water quality sampling for rural non point source contaminants to develop an improved understanding of contaminants of concern in the rural portion of the study area, their potential sources, and to inform the work of Rural Clean Waters Program staff to promote rural and agricultural best management practices; • Permeameter measurements to field verify groundwater infiltration rates, and piezometer measurements to field verify groundwater discharge locations and rates, to

2 strengthen assumptions in the regional groundwater flow model that was being developed through the York-Peel-Durham-Toronto Groundwater Study partnership; and • Compilation and summary of available information on Euro-Canadian history and historical land ownership in the subwatershed to inform cultural heritage investigations to be undertaken prior to new developments. This information also provides a resource for municipalities or local heritage associations to use in assigning street names and place names or developing interpretive programming to help people connect with the cultural heritage of the area.

Input on the key watershed management issues and opportunities in the subwatershed was received through meetings with the Steering Committee and at a public open house event held at the beginning of the study. Available information on current conditions for each component of the subwatershed system was compiled and summarized in background technical briefs. Workshops were held at which key findings from the review of current conditions and input on local watershed management issues was presented by TRCA technical staff and discussed. Through this process a better understanding of interdependencies between the subwatershed system components was developed. Recommendations for further study to address remaining knowledge gaps, and actions to help ensure that watershed health is protected or improved in the future were identified.

1.3 Planning Context A number of watershed management and urban planning initiatives have been completed or are underway that provide context, direction and background information for the Etobicoke Creek Headwaters Subwatershed Planning Study. Table 1-1 provides a summary of these initiatives and associated reports.

One of the main triggers for initiating the Etobicoke Creek Headwaters Subwatershed Study was to provide watershed management direction to the Mayfield West community development plan process that has been initiated by the Town of Caledon. In 1997 the Town of Caledon adopted a "tri-nodal" growth management strategy for the period of 1997 to 2007 that directs the bulk of the Town's new urban growth and services to the three rural service centres of Bolton, Caledon East and Mayfield West. A planning process to prepare a Mayfield West Community Development Plan has been initiated by the Town of Caledon. In 2003 two community design workshops were held to develop creative ideas and the fundamental planning and design principles for the future Mayfield West community. A workshop summary report was prepared in July 2003 (Water H. Kehm and Associates Ltd. et al ., 2003). The Etobicoke Creek Headwaters Subwatershed Planning Study was designed to provide recommendations to the Town of Caledon regarding targets for environmental protection, management actions needed to improve and protect watershed health, criteria for implementing urban best management practices (e.g., stormwater management), and lands to be targeted for securement and ecological restoration.

The City of Brampton portion of this subwatershed is close to being fully developed and changes to land use would be through infill or redevelopment of existing urban areas. Considerable work has already been completed to identify opportunities to improve stormwater management in the portions of the Etobicoke Creek watershed in the City of Brampton where existing stormwater controls do not meet current standards. A stormwater retrofit study has been completed for the City of Brampton that identifies opportunities to build new stormwater management ponds and improve existing ponds (Aquafor Beech Ltd., 2003). The City of Brampton stormwater retrofit study has been extended to include quantifying the potential in-

3 stream benefits and cost savings which may result from the implementation of proposed stormwater retrofits in terms of quality and erosion.

Additionally, in support of the TRCA’s Living City Vision, the TRCA’s Toronto and Region Terrestrial Natural Heritage System Strategy (TNHSS) has been completed (TRCA, 2007). The TNHSS provides a strategy for achieving the TRCA’s Living City objective, “to protect and restore regional biodiversity” by seeking to increase the amount and quality of natural habitats in TRCA watersheds. The TNHSS defines a target terrestrial natural heritage system including the land base needed to rebuild a healthy and functioning terrestrial system. The target terrestrial natural heritage system has been designed to enhance biodiversity and the quality of life for the residents of TRCA watersheds. It uses a science-based analytical tool, based on ecological criteria, to identify a targeted land base for inclusion in the terrestrial natural heritage system. The target terrestrial natural heritage system defined in the TNHSS will be further examined and refined at a watershed scale to identify priority lands within the Etobicoke and Mimico Creek watersheds that should be protected from urban development, and restored to natural land cover.

4 Table 1-1: Summary of recent watershed management or planning related studies of relevance to the Etobicoke Creek Headwaters subwatershed

Agency lead Initiative Description Reports available

City of Brampton Citywide Lake Management A report summarizing the results of an evaluation Gartner Lee Limited (2006) Interim Report – and Monitoring Report and comparison of all the lakes in the City of Citywide Lake Management and Monitoring Brampton regarding overall ecosystem health to Report. Prepared for the City of Brampton and determine which lakes require immediate Toronto and Region Conservation Authority. management and those that may require longer term management to ensure current conditions are maintained.

Toronto and Region Etobicoke Creek Headwaters Background report summarizing the findings from - Narhi, B. and C. Freisenhausen (2006) Conservation Subwatershed Study historical land titles research Historical Overview of Lands Adjacent to the Authority (TRCA) Etobicoke Creek Headwaters. Prepared for the Toronto and Region Conservation Authority. TRCA Etobicoke Creek watershed Report summarizing results of recent watershed- - Parish Geomorphic Ltd. (2003) TRCA Fluvial wide fluvial geomorphological assessment work Geomorphology Study and Erosion Assessment – Etobicoke Creek.

TRCA Etobicoke Creek Headwaters Background report summarizing available - Toronto and Region Conservation Authority Subwatershed Study information describing current conditions and (2004) Terrestrial Biological Inventory and watershed management issues regarding the Assessment Report - Upper Etobicoke Creek terrestrial system of the Etobicoke Creek Headwaters Subwatershed Headwaters

TRCA TRCA Toronto and Region A strategy for protecting and restoring biodiversity - Toronto and Region Conservation Authority Terrestrial Natural Heritage to TRCA watersheds by increasing the amount and (2007) Toronto and Region Terrestrial Natural System Strategy (TNHSS) quality of forest and wetland habitats according to Heritage System Strategy a target terrestrial natural heritage system land base TRCA Generic Master A guidance document that outlines the minimum - Toronto and Region Conservation Authority Environmental Servicing Plan required components to be included in a Master (2003) Draft TRCA Generic Requirements for Requirements Environmental Servicing Plan prepared in support Master Environmental Servicing Plans. of a development proposal

5 Agency lead Initiative Description Reports available

Town of Caledon Mayfield West Community A planning process to develop a community - Walter H. Kehm and Associates Ltd. et al (July Development Plan development plan for the Mayfield West area which 2004) Mayfield West Community: A Summary is targeted as a new centre of urban growth in the Report of the Planning and Design Workshops, Town of Caledon, in accord with the Town’s “tri- June 18 and 25, 2003; nodal” growth management strategy - Town of Caledon Council reports 2003-69 and 2004-18, 2004-71, 2004-78, 2004-92, and 2005- 43.

Regions of York, York-Peel-Durham-Toronto An on-going initiative involving multi-regional scale - Gerber, Richard and Steve Holysh (draft 2005) Peel, Durham and Regional Groundwater data collection, 3-D computer modelling, mapping, Geology and Groundwater Resources Toronto City of Toronto Management Project and preparation of management policy and and Region Conservation Authority Watersheds. program recommendations. Prepared for Ontario Ministry of Northern Development and Mines and Ontario Geological Survey. TRCA Habitat Implementation Plan A plan identifying priority natural habitat restoration - Toronto and Region Conservation Authority (HIP) and enhancement projects on publicly owned (2003) Habitat Implementation Plan - Etobicoke valleyland within the Etobicoke and Mimico Creek and Mimico Creek Watersheds watersheds

Region of Peel Groundwater studies Provincially funded groundwater studies to provide - AMEC (2003) Region of Peel - Land Use and information and tools needed to develop and Chemical Occurrence Inventory Project; support groundwater management and water - Beatty and Associates (2003) Region of Peel - source protection initiatives Regional Water Use Assessment Study;

City of Toronto Wet Weather Flow A stormwater management plan to reduce and - Totten Sims Hubicki Associates (2003) City of Management Master Plan ultimately eliminate the adverse effects of wet Toronto Wet Weather Flow Management Master (WWFMMP) weather flow on the built and natural environment Plan Final Report For Etobicoke and Mimico in a timely and sustainable manner and to achieve Creek Watersheds; a measurable improvement in ecosystem health of the watersheds City of Brampton Stormwater Retrofit Study A study report identifying opportunities to retrofit - Aquafor Beech Limited. (2003) City of existing stormwater management ponds to bring Brampton Stormwater Retrofit Study - Final their treatment capacities up to current standards Report; Aquafor Beech Limited (2005) and opportunities for built new facilities. The study Stormwater Retrofit Study Extension. has been extended to quantify the potential instream benefits and cost saving of implementing proposed stormwater retrofits in terms of water quality and erosion.

6 Agency lead Initiative Description Reports available

The Etobicoke and Greening Our Watersheds: A watershed revitalization strategy that establishes - Toronto and Region Conservation Authority Mimico Creek Revitalization Strategies for a watershed vision, ten management strategies (2002a) Greening Our Watersheds: Revitalization Watersheds Task the Etobicoke and Mimico and objectives, 31 indicators of condition, and Strategies for Etobicoke and Mimico Creeks, The Force Creeks numerous management criteria, targets and Etobicoke and Mimico Creek Watersheds Task recommendations for action, aimed at achieving Force. healthier and more sustainable Etobicoke and Mimico Creek watersheds by the year 2025 Town of Caledon Stormwater Retrofit Study A study report identifying opportunities to retrofit - Toronto and Region Conservation Authority existing stormwater management ponds to bring (2001) Town of Caledon Stormwater Retrofit their treatment capacities up to current standards Study - Phase I and II Report and opportunities for built new facilities TRCA Valley and Stream Corridor A reach restoration plan report providing specific - Toronto and Region Conservation Authority Reach Plan recommendations for restoration works, resource (1999) Etobicoke Creek Watershed: Valley and management and maintenance practices and Stream Corridor Reach Plan for Snelgrove provides direction for future management decision- making processes

TRCA State of the Watershed A report summarizing current watershed - Toronto and Region Conservation Authority Report - Etobicoke and management issues and conditions and an (1998) State of the Watershed Report - Mimico Creek Watersheds assessment of watershed health according to Etobicoke and Mimico Creek Watersheds report card indicators. The report includes information and analysis pertaining to aquatic and terrestrial systems, water quality, water quantity (stream flow and flooding), recreation opportunities, cultural heritage, and stewardship.

Town of Caledon Mayfield West Natural A report summarizing the results of natural heritage - Toronto and Region Conservation Authority Features Study field inventory work undertaken by TRCA staff (1998) Mayfield West Natural Features Study between 1994 and 1995 in support of planning work to develop a Mayfield West Community Development Plan Town of Caledon Mayfield West Community A report on hydrogeological conditions, prepared - CG&S CH2M Gore and Storrie Ltd. (1996) Development Plan during initial planning work undertaken to develop Mayfield West Community Development Plan Hydrogeological Analysis a Mayfield West Community Development Plan Hydrogeological Analysis

7 Agency lead Initiative Description Reports available

Town of Caledon Mayfield West Community Two reports on agricultural land use, prepared - CG&S CH2M Gore and Storrie Ltd. (1997) Development Plan during initial planning work undertaken to develop Mayfield West Community Development Plan Agricultural Land Analysis a Mayfield West Community Development Plan Agricultural Land Analysis - CG&S CH2M Gore and Storrie Ltd. (1997) Mayfield West Community Development Plan Agricultural Land Analysis Phase II

8 2. Study Area

2.1 Location The Etobicoke Creek Headwaters subwatershed is located in the northernmost portion of the Etobicoke Creek watershed, where the creek first appears in the landscape as many small tributaries, groundwater springs and wetland pockets surrounded by predominantly agricultural land uses. The study area boundary for the Etobicoke Creek Headwaters Subwatershed Planning Study is based on surface drainage and represents all lands contributing drainage to the main channel of Etobicoke Creek at the point where it intersects Bovaird Drive in the City of Brampton. The Etobicoke Creek Headwaters subwatershed drains a roughly 6300 hectare (63 km 2) portion of land that lies within the Region of Peel and includes portions of the Town of Caledon and City of Brampton (Figure 2-1). A special study area has also been included within the scope of this subwatershed planning study which covers the headwater area draining to the portion of Spring Creek (a tributary of Etobicoke Creek) north of Countryside Drive. This area is being included in the subwatershed planning study at the request of City of Brampton and Town of Caledon staff, in anticipation of proposals for new development. Available information pertaining to the terrestrial and aquatic systems within this special study area have been compiled and analysed. The subwatershed study recommendations are applicable in this area also.

2.2 Physiography, Surficial Geology and Soils The subwatershed is located entirely within the South Slope physiographic region and features the characteristic gently sloping topography and fertile soils which make the land highly suitable for agriculture (Chapman and Putnam, 1984). The surficial geology of this area is dominated by the Peel Plain, a physiographic unit consisting of thin, clay soils (Figure 2-2). The Peel Plain is comprised of Halton Till (clay and silt) and fine-textured glacio-lacustrine deposits (Chapman and Putnam, 1984). The creeks have cut into and reworked these deposits, since deglaciation, creating corridors of alluvial sediments within the floodplain (Karrow, 1991). Overburden in this subwatershed is not deep. Owing to the fact that the Halton Till deposits are quite dense and do not have high capacity to conduct groundwater flow, and that there are few beds of sandy deposits to serve as shallow aquifers, stream flows are naturally very low during extended dry periods.

Most of the land within the subwatershed is prime agricultural land (Canada Land Inventory Soil Capability for Agriculture rating of Class 1, 2 or 3), meaning it has few constraints for agricultural production (Agriculture and Agri-Food Canada, 1998). Agricultural land use in this area has prevailed since the arrival of the first European settlers in the early 19 th century.

9

Figure 2-1: Study Area

Figure 2-2: Surficial Geology

Soil types within the subwatershed are predominantly clay-loam soils (OAC & DDA, 1953). The majority of clay loam soils are classified as Chinguacousy series clay-loam which generally exhibit imperfect natural drainage (Figure 2-3). The portion of the subwatershed to the east of the main channel of Etobicoke Creek and south of Old School Road is dominated by Oneida series clay-loam soils which generally exhibit good natural drainage. An area of Fox series sandy-loam soils has also been identified in this area. Fox series sandy-loam soils generally exhibit good natural drainage. Pockets of Jeddo series clay-loam soils are dispersed throughout the area which generally exhibit poor natural drainage. Areas of variable-type soils are associated with the floodplain of Etobicoke Creek. Isolated areas of organic mucky soils occur in the study area in association with wetlands.

Clay loam soils typically exhibit moderate to slow permeability. These soils have high moisture holding capacities and moderate to rapid surface run off characteristics. Their fine and medium textured surface materials make these soils susceptible to water erosion. Under good management, these soils are moderate to high in productivity for a wide range of common field crops (forages, small grains, and corn), special field crops (e.g., soybeans, white beans, and canola) and fruit crops (e.g., strawberries, apples and pears).

Table 2-1: Soils in the Etobicoke Creek Headwaters subwatershed

Symbol Soil Series Soil Type Soil Materials Parent Material Natural Drainage Chc Chinguacosy clay loam heavy textured clay imperfect till Fsl Fox sandy loam well sorted calcareous grey good outwash sand Jc Jeddo clay loam heavy textured clay poor till Oc Oneida clay loam heavy textured calcareous good till M Muck variable organic organic material very poor B.L. Bottom land variable alluvial variable variable

2.3 Climate Climate varies appreciably across southern Ontario both spatially and temporally with local variation created by such factors as topography, prevailing winds, and proximity to the Great Lakes.

July is typically the warmest month of the year in the study area, with an average maximum temperature of 26.7 degrees Celcius (°C) and average minimum temperature of 14.8 °C. January is typically the coldest month, with an average maximum temperature of -2.1°C and an average minimum temperature of -10.5°C.

12

Figure 2-3: Soils

Mean annual precipitation in the Etobicoke Creek watershed has been estimated at 792.7 millimetres per year (mm/yr). Mean annual snowfall is approximately115 mm/yr and mean annual rainfall is approximately 685 mm/yr. On average, 45 millimetres of precipitation (both snow and rain) falls during winter months while an average of 80 millimetres of precipitation falls during spring, summer and fall months (Meteorological Service of Canada, 2005, Canadian Climate Normals, Lester B. Pearson Airport) . August is the month when heaviest precipitation typically occurs. Variation in precipitation levels between seasons is likely a result of convective thunderstorms that occur in this area during the summer. Despite the occurrence of thunderstorms in the summer and the corresponding elevated stream flows that follow, historical stream flow data indicates that the periods of highest annual stream flow are associated with the spring snow melt which typically occurs in March or April (Environment Canada, 2000)

2.4 Local Watershed Management Issues and Opportunities An important first step in the subwatershed planning process was developing a better understanding of local watershed management issues that are affecting the study area and opportunities to improve watershed health that have already been identified through previous initiatives.

Consultation with municipal and agency staff, elected representatives, local residents, and other stakeholders was undertaken during the preparation of State of the Watershed Report: Etobicoke and Mimico Creek Watersheds (TRCA, 1998c ) and Greening Our Watersheds (TRCA, 2002a) to identify watershed management issues and opportunities. The State of the Watershed Report: Etobicoke and Mimico Creek Watersheds identified a range of watershed management issues that are affecting the Etobicoke and Mimico Creek watersheds (TRCA, 1998c). The Etobicoke and Mimico Creek watersheds revitalization strategy, Greening our Watersheds, identified priority areas on which management efforts need to be focused in order to address these watershed management issues and achieve the objectives of the revitalization strategy (TRCA, 2002a). Since the completion of Greening Our Watersheds , several other studies and watershed management initiatives have been completed that have identified opportunities to improve watershed health. Table 2-2 provides a summary of existing study reports that identify opportunities to improve the health of the subwatershed.

Further consultation with agency staff, municipal staff and stakeholders regarding local watershed management issues was undertaken at the onset of the Etobicoke Creek Headwaters Subwatershed Study. Table 2.3 provides a summary of local watershed management issues in the Etobicoke Creek Headwaters subwatershed that were identified.

14 Table 2-2: Reports identifying opportunities to improve the health of the Etobicoke Creek Headwaters subwatershed

Report title Relevance to the Etobicoke Creek Headwaters subwatershed TRCA (2007) Toronto and Region Terrestrial - identifies lands where protection of existing, Natural Heritage System Strategy and restoration of new natural land cover would provide the greatest benefit to the quality and function of the regional terrestrial natural heritage system TRCA (2006) Etobicoke Creek GTAA Living - defines management objectives, targets and City Project – Aquatic Ecosystem recommends actions to maintain and improve the aquatic ecosystem. Gartner Lee Ltd. (2005) Identification of Sites - identifies lands where, based on For Wetland Creation in Peel and York environmental conditions, the greatest Regions. potential for recreating wetlands exists TRCA (2003) Habitat Implementation Plan - - provides concept plans for restoring natural Etobicoke and Mimico Creek Watersheds land cover and improve wildlife habitat within the Etobicoke Creek watershed, where opportunities are known to exist. Aquafor Beech Ltd. (2003) Stormwater Retrofit - identifies opportunities within the Study - Final Report, City of Brampton; Aquafor subwatershed to improve stormwater control. Beech Ltd. (2005) Stormwater Retrofit Study Extension TRCA (2002a) Greening Our Watersheds: - establishes a vision, objectives and targets Revitalization Strategies for Etobicoke and for a healthier and more sustainable Etobicoke Mimico Creeks, The Etobicoke and Mimico Creek watershed and identifies priority areas Creek Watersheds Task Force. on which to focus management efforts. TRCA (1999) Etobicoke Creek Watershed: - identifies concept plans and an Valley and Stream Corridor Reach Plan for implementation plan for restoring natural land Snelgrove cover and improving wildlife habitat along the valley and stream corridor of the Snelgrove reach of Etobicoke Creek.

15 Table 2-3: Watershed management issues affecting the Etobicoke Creek Headwaters Watershed management issues* Relevance to the Etobicoke Creek Headwaters subwatershed changes to groundwater and - future urban growth will increase the portion of the subwatershed surface water flows with impervious cover which will change the existing pattern of groundwater and surface water flows. risk of groundwater and surface - potential sources of groundwater and surface water contamination water contamination are associated with both current (agricultural) and future (urban) land uses within the subwatershed. risk of flooding and erosion - flood vulnerable areas, and erosion control sites exist within and downstream of the subwatershed. - future urban growth will increase the portion of the subwatershed with impervious cover which will increase the potential for accelerated stream bank erosion. inadequate stormwater control in - portions of the subwatershed were developed without the level of developed areas stormwater control now required by current standards loss of natural land cover and - remaining natural land cover within the subwatershed is restricted natural features to isolated patches of insufficient size and quality to support many species of conservation concern. loss of small and ephemeral - as a headwaters subwatershed, a majority of the area is drained by streams first and second order (i.e., small) streams. - many of the tributary streams in the subwatershed exhibit intermittent flow during extended periods of dry weather. impaired condition of flora, fauna - terrestrial and aquatic habitats in both rural and urban portions of and aquatic species this subwatershed are in varying states of impairment. alteration of significant landforms - the Etobicoke Creek valley and stream corridor and Brampton and landscapes Esker are significant landforms within or near the subwatershed. planning for new urban - planning and studies for the extension of municipal Lake Ontario development based water supply infrastructure north of Mayfield Road, extension of Highway 410 north of Bovaird Drive to Highway 10 (Hurontario Street) north of Mayfield Road, and the growth of urban settlements in the Mayfield West area is underway, which affects portions of the subwatershed. disconnected greenspace and - planning of an extension to the existing public greenspace trail trails along the Etobicoke Creek valley corridor to service the new community of Mayfield West is underway. loss of built heritage and - several built heritage features are known to exist within the archaeological resources subwatershed that may warrant protection and integration into the new community of Mayfield West. - archaeological surveys will need to be undertaken within the subwatershed prior to implementation of plans for urban growth. lack of awareness regarding - the new Mayfield West community will provide opportunities to cultural heritage raise local awareness of the cultural heritage/history of this area through street names and/or programs at new public facilities limited angling and wildlife - wildlife viewing opportunities are limited in the subwatershed. viewing opportunities - no sport fish are known to reside in this subwatershed so limited angling opportunities is not a key issue. implementing agricultural best - the majority of the subwatershed is in active agricultural use. practices threats to the quantity of water - local farmers have recently reported declining water levels in available for domestic use private groundwater wells in this subwatershed. * these general watershed management issues were identified in the TRCA report, State of the Watershed: Etobicoke and Mimico Creeks (TRCA, 1998).

16 PART 2 CURRENT CONDITIONS

3. Land and Resource Use

Land use in the subwatershed is predominantly rural, despite the rapid expansion of urban settlements that have occurred in the rest of the watershed over the last 20 years.

3.1 Rural and Urban Land Use Currently, agriculture remains the predominant land use within the subwatershed with associated rural settlements dispersed along the concession roads. Rural settlements within the subwatershed boundary are the Villages of Victoria, and Campbell’s Cross in the Town of Caledon. Existing suburban-style residential settlements are limited to the community of Snelgrove (Brampton), and Valleywood (Caledon). Valleywood is located within the area referred to as the Mayfield West Rural Service Centre in the Town of Caledon Official Plan. This area is the subject of the Town of Caledon’s Mayfield West Community Development Plan process (Town of Caledon 2002, Town of Caledon 2003). Table 3-1 shows the approximate breakdown of land use types that exist within the Etobicoke Creek Headwaters subwatershed. Based on this breakdown it is estimated that approximately eight percent (8%) of the total surface area of the subwatershed is impervious cover (i.e., roofs, roads, parking areas, etc.) that prevents precipitation from infiltrating into the ground. Figure 3-1 shows the distribution of current land uses and anticipated future land uses.

Table 3-1: Land use in the Etobicoke Creek Headwaters subwatershed (Source: TRCA, 2002a)

Percentage of total Etobicoke Creek Approximate area Headwaters Land Use Type Description (in hectares) subwatershed

Industrial Manufacturing and industrial purposes 170.4 3% Office/Commercial Retail, commercial and office space 26.9 <1% Institutional Government, schools and religious institutions 16.2 <1% Residential Low to medium density residential uses including fully and semi-detached houses, condos, and apartments. 802.9 13% Future Development Lands approved for development 42.0 <1% Open Lands including parks, open space and Space/Parkland/ natural areas Greenspace 293.6 5% Rural/Agricultural Rural and agricultural uses 4966.6 79% Total 6318.6 100%

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Figure 3-1: Land Use

Agriculture Agriculture is the predominant land use in this subwatershed. Most of the agricultural land in the area is rated as prime agricultural land (Class 1, 2, or 3) according to the Canada Land Inventory Soil Capability classification system (Agriculture and Agri-Food Canada, 1998). This land has few constraints for agricultural production. Types of agricultural operations in the subwatershed include row crops (corn, soybeans), mixed grains, tree nurseries, feed crops (hay production), and livestock operations (CG&S, 1997). In 1997, an analysis of trends in the local agricultural industry was undertaken and found that from 1981 to 1995, the land area utilized for mixed grain production fell by 50 percent. The area of improved pasture fell by 55 percent and the area allocated for hay production fell by 12 percent. Grain corn production remained relatively stable during the same period and beef cattle numbers rose 17 percent. Milk production in the area remained stable. Another trend evident in the distribution of farms is that the numbers of farms has dropped by 25 percent while the total area of these farms fell by less than 15 percent (CG&S, 1997).

Industrial Existing industrial land in the subwatershed consists of industrial and business-industrial lands adjacent to Hurontario Road (Highway 10) and between Bovaird Drive and Conservation Drive. Highway 10 is an important transportation route that supports the industrial lands which, in turn, support light and heavy manufacturing.

Historically, aggregate extraction operations in the subwatershed have been an important industry. Two of the former extraction areas have been rehabilitated and are now known as Loafer’s Lake and Esker Lake North. No active aggregate pits currently exist in the subwatershed and no lands have been designated as mineral and aggregate resource areas (for future extraction).

Office/Commercial There are three primary pockets of office/commercial development in the headwaters subwatershed area. The largest of these areas is centered at the intersection of Sandalwood Parkway East and Kennedy Road North. The second area is just south of Sandalwood Parkway on the west side of Hurontario Street. The third area is adjacent to Hurontario Street at Valleywood Boulevard.

Institutional Institutional land uses in the subwatershed is composed of schools, which are mainly concentrated in the developed areas of the City of Brampton. Brampton Christian School is located adjacent to the community of Valleywood, on the west side of Hurontario Street in the Town of Caledon.

Residential Most residential development in the urban portion of the subwatershed is low-to-medium density single family dwellings. Outside of the communities of Snelgrove (Brampton) and Valleywood (Caledon), in the rural portion of the subwatershed, rural residences are dispersed along major concession roads and in the villages of Victoria and Campbell’s Cross. In 2003, the rural population in this subwatershed was estimated to be approximately 1400.

Open Space, Parkland, and Greenspace The open space trail along the main channel of Etobicoke Creek that links the communities of Snelgrove and Valleywood, and surrounding valleylands are the only publicly accessible greenspace in the subwatershed. Other areas of public greenspace in the vicinity include

19 Heart Lake Conservation Area, located along the Spring Creek tributary of Etobicoke Creek; Terra Cotta Conservation Area and Ken Whillans Conservation Area, located in adjacent Credit River Conservation Authority subwatersheds; and, the Caledon Trailways portion of the Trans- Canada Trail.

Major municipal parkland in the subwatershed includes Loafer’s Lake Park, Conservation Drive Park, Sandalwood Park, Todd Bayliss Park, Camden Park, Morris Kerbel Park, Wexford Park, and Dexfield Park, in the City of Brampton.

3.2 Major Servicing Transportation The major transportation corridors within the study area are Bovaird Drive, Mayfield Road and King Street (east-west routes), and Hurontario Street (Highway 10) and Mississauga Road (north-south routes). The construction of Highway 410 is currently underway which will extend the highway north from Bovaird Drive to Mayfield Road and link it with Highway 10 (Hurontario Street), north of Mayfield Road, just south of the community of Valleywood ( Figure 3-1). The Orangeville-Brampton Railway transects the study area. The Orangeville-Brampton Railway (OBRY) is a 55 kilometre long short line railway between Orangeville and Streetsville Junction in Mississauga, passing through the City of Brampton and the Town of Caledon. The railway's main purpose is freight transport, servicing industries in Orangeville and Brampton . Since 2004, a seasonal public excursion train, marketed as Credit Valley Explorer, operates between Orangeville and Snelgrove on this line. The Brampton Airfield is situated off of McLaughlin Road, south of King Street, serving the needs of small engine aircraft pilots and the Brampton Flying Club.

Public transit opportunities are limited to City of Brampton bus routes servicing the communities of Snelgrove and Valleywood.

Water Supply and Wastewater The area serviced by municipal water supply and sanitary sewers within the subwatershed includes all of the City of Brampton and the community of Valleywood in the Town of Caledon. These areas are serviced by the South Peel Water Supply System. This system draws water from Lake Ontario at the Clark Water Filtration Plant, in the City of Mississauga. Wastewater from these areas is collected in municipal sanitary sewers and is treated at the Lakeview Sewage Treatment Plant, in the City of Mississauga, before it is returned to Lake Ontario.

Rural residents and businesses in the remaining portions of the subwatershed depend on private groundwater wells to provide water supplies for domestic, irrigation and livestock purposes and private septic systems for treatment of wastewater (see section 5 for more information on water use).

Stormwater Management Figure 3-2 describes the locations of existing stormwater management facilities in the subwatershed, areas serviced by these facilities, and the level of stormwater control provided. The remaining developed portions of the subwatershed have no stormwater management controls in place. A stormwater retrofit study has been completed for the City of Brampton that identifies opportunities for retrofitting existing facilities to provide water quality control, opportunities to build new stormwater management facilities to provide quality and quantity control where none exist and channel restoration work (Aquafor Beech Ltd. 2003).

20 3.3 Anticipated changes to land and resource use Greenbelt Plan The recently introduced Greenbelt Plan for the Greater Golden Horseshoe (MMAH, 2005) is anticipated to have a significant influence on future land and resource use in this subwatershed. The Greenbelt Plan designates portions of the subwatershed as Protected Countryside, where growth of urban settlements will not be permitted to occur ( Figure 3-1).

Protected Countryside areas are intended to continue to accommodate a range of commercial, industrial and institutional uses serving the rural resource and agricultural sectors. They are also intended to support a range of recreation and tourism uses such as trails, parks, golf courses, bed and breakfasts and other tourism based accommodation, serviced playing fields and campgrounds, ski hills and resorts. Non-agricultural uses will not be permitted on Prime Agricultural Lands. Recreational and tourism-related uses must be designed to maintain and enhance existing conditions. Development of new infrastructure will be permitted to service existing settlements in the Greenbelt and to facilitate long-term growth of settlements outside of the Greenbelt. Renewable resource uses (e.g., forestry) are be permitted, whereas, non- renewable resources uses (e.g., aggregate extraction) are not permitted in some features and must demonstrate no adverse impacts on water resources and natural system linkages.

Mayfield West Community The portion of the subwatershed where the majority of changes to land and resource use are anticipated to occur is within the Town of Caledon, Mayfield West community development plan study area ( Figure 3-1). In 1997 the Town of Caledon adopted a "tri-nodal" growth management strategy for the period of 1997 to 2007 that directs the bulk of the Town's new urban growth and services to the three rural service centres of Bolton, Caledon East and Mayfield West. A planning process for the Mayfield West community has been initiated by the Town of Caledon (Town of Caledon 2003, Town of Caledon 2004) In 2003 two community design workshops were held to develop creative ideas and the fundamental planning and design principles for the future Mayfield West community. The workshop established the following set of community design principles (Walter Kehm and Associates Ltd. et. al., 2003):

• Regional Context – Recognize the regional context and its unique natural and cultural heritage qualities. • Public Transportation – Integrate with regional public transportation plans. Minimize automobile use and ensure that all residents have safe, economic, and convenient access to transit. Explore potential for future train transportation. • Pedestrian Based Design – Adopt a 5- to 10-minute walking radius as an important planning parameter. Design street-based pedestrian systems whereby public transit, schools, shops, public facilities and such are within a 5- to 10-minute walking distance. • Mixed Housing – Provide a mix of housing types and tenures (freehold, condominium, non-profit) in integrated street patterns. Avoid single use segregation. • Concentrate Public Buildings – Locate and concentrate public buildings at strategic locations to help create landmarks, thereby contributing to the image and identity of the community.

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Figure 3-2: Existing stormwater management controls and known retrofit opportunity sites

• Design Public Spaces – Design public spaces as accessible neighborhood focal points. Plan events and activities and frame them with public entrances and access points. Avoid public spaces and school grounds that back onto private rear yards. • Protect/Regenerate Natural Habitats – Protect and regenerate natural habitats to provide continuous vegetative and wildlife corridors. Establish new core forests wherever possible by reconnecting isolated woodlots. Integrate with hiking and bicycle riding paths and trails. • Develop Local Economy – Support local farmers, artisans, and craftspeople to develop a distinct economy. Create an environment where people can support and integrate with each other. • Design for Human Scale – Design road, parking standards, and structures that are respectful of human neighboring and social interaction, enhance the visual quality of the community, and assist in creating safe streets. • Utilize Sustainable Energy Systems – Plan for the integration of sustainable energy systems that utilize solar, wind and ground effect systems. Consider district heating opportunities and plan for the southerly orientation of dwelling units for active and passive solar utilization.

• Conserve/Protect Water – Conserve and re-use water by capturing site rain and snow run off, and by using water reduction devices in all buildings. Highway 410 Extension and Snell’s Hollow Other areas where land use changes are anticipated to occur include the lands affected by the extension of Highway 410 through the subwatershed, and the areas south of the Highway 410 road alignment and north of Mayfield Road, which are referred to as the Snell’s Hollow area. The Snell’s Hollow area has already been designated for urban development in the Town of Caledon Official Plan. Future land use within the Snell’s Hollow area is anticipated to be for residential uses ( Figure 3-1).

The City of Brampton portion of the subwatershed is nearing full urbanization and any changes to land use within this area would be through redevelopment or intensification of existing urban areas. The City of Brampton has no plans for intensification in the community of Snelgrove at this time.

As required by the official plan policies of the Region of Peel and Town of Caledon, a range of planning studies will need to be completed in support of major development proposals at appropriate stages in the planning process including a comprehensive environmental management plan and master servicing plan studies. Planning studies in support of the Snell’s Hollow draft plan of subdivision, the Mayfield West community development planning process, and detailed design of the Highway 410 extension will benefit from the information on current conditions and targets for management from the Etobicoke Creek Headwaters subwatershed study.

23 3.4 Links to Other Subwatershed System Components The major changes to land and resource use that can be anticipated to occur within the subwatershed will be associated with future growth of urban settlements in the Town of Caledon and the extension of Highway 410. The potential impacts of urban growth on the health of watersheds have been well-documented and include such changes as decreased groundwater infiltration, increased run off to streams, changes to stream flow regime, degraded water quality, accelerated stream channel erosion, and loss or deterioration of natural land cover and wildlife habitats. The conceptual watershed response model outlined in Figure 3-3 describes the ecological linkages that exist between different components of a watershed system and the sequential order of changes that can be anticipated to occur following a change in land use or land cover. In this conceptual model such changes could include: • direct “footprint” effects, such as the loss of natural land cover or destruction of a built heritage feature; • indirect “flow related” effects such as increased frequency of high stream flows and accelerated stream channel erosion and deterioration of downstream water quality; and, • cumulative effects such as changes in aquatic community composition that may arise from a combination of changes affecting upstream areas.

Figure 3-3: Watershed Response Model

Climate Geology

Changes in Land Use or Land Cover

Changes in Water Balance Changes in Air Quality

Changes in Groundwater Changes in Stream Hydrology Quality and Quantity

Changes in Stream Morphology Changes in Surface Water Quality

Changes in Aquatic Systems Changes in Terrestrial System

ENVIRONMENTAL INTEGRITY

Social Well Being Economic Vitality Cultural Heritage Recreation, Health, Agriculture, Urban Built Heritage, Infrastructure Security, Development, Tourism Archaeology, Living Water Supply Culture

This model has been adapted from an initial model developed by Snodgrass (Snodgrass et. al.,1996), which focussed on impacts on aquatic ecosystems contained within streams and rivers, and on a later adaptation of that work by Credit Valley Conservation in a subwatershed study (CVC, 2001), which also focussed on flow related impacts to the aquatic system. TRCA has expanded the model to include air quality, terrestrial system and cultural heritage

24 components. The expanded model also identifies linkages between environmental integrity (or watershed health) and the beneficial uses that human derive from watershed resources (TRCA, 2003e).

3.5 Management Considerations Existing Rural and Agricultural Areas Rural and agricultural land uses occur on the majority of this subwatershed. The predominant soil types and underlying surficial geology that produce moderate to high run off rates makes the many small streams in this headwater area vulnerable to contamination from land-based sources of pollutants. Therefore, implementation of best management practices on rural and agricultural lands that reduce the risk of contamination of surface waters from land-based activities will be an important part of an effective management plan for this subwatershed. Work to promote rural and agricultural best management practices (BMPs) in the rural portion of the subwatershed should continue through the Region of Peel and TRCA’s Rural Clean Water Program. Rural Clean Water Program staff should use available information obtained through terrestrial natural heritage field inventories to focus work on promoting implementation of BMPs that reduce livestock access to natural areas where observations of severe livestock grazing have been made. Further studies are needed to help focus work to promote agricultural BMPs where opportunities to improve existing practices are known to exist and where the greatest benefits to the overall health of the subwatershed system would be realized. In order to do this, updated mapping information on agricultural land uses is needed. An assessment of predominant source areas for surface water contaminants of concern (e.g., sediment , phosphorus and nitrate) could also be undertaken utilizing subwatershed knowledge and available modelling tools (e.g., AGNPS model). Rural residents rely on groundwater for domestic water supplies. A preliminary assessment of potential sources of groundwater contamination has been completed for the Region of Peel that identifies several properties in the subwatershed where a high level of risk for groundwater contamination may exist (AMEC, 2003). Further investigation of high potential risk areas should be undertaken, to assess actual risks and whether contaminant management plans are needed or already in place, on a site-by-site basis. Existing Urban Areas The majority of urban settlements in the City of Brampton portion of the subwatershed were developed prior to the requirement for stormwater management controls. As a result, surface water quality parameters are often found to exceed provincial water quality guidelines (see section 6), stream channels are unstable and adjusting to a changed stream flow regime (see section 7) and aquatic habitats communities are rated as being in poor health (see section 9). A number of opportunities have been identified to retrofit existing stormwater management controls or build new facilities in order to meet current standards for stormwater control and to carry out stream channel restoration work (Aquafor Beech Ltd. 2003). The City of Brampton and TRCA should continue to work together to implement these opportunities that will help to mitigate the negative impacts of urban stormwater on the health of Etobicoke Creek.

Concept plans for restoring natural land cover and improving wildlife habitats have already been developed and are in the process of being implemented along the valley and stream corridor of Etobicoke Creek in the community of Snelgrove (TRCA 1999).

25 Future Urban Growth Areas The Town of Caledon’s on-going urban planning processes for the Mayfield West community and Snell’s Hollow community, and the Ministry of Transportation’s plans to extend Highway 410 through this area represents the major changes to land and resource use that can be anticipated in the subwatershed in the near future.

As required by the official plan policies of the Region of Peel and Town of Caledon, environmental planning studies need to be completed in support of major development proposals at appropriate stages in the planning process. A summary of required studies that should be completed in support of major development proposals, such as community or secondary plans, has been developed by the TRCA to provide guidance to developers and municipalities with regard to what types of information are needed at various stages in the planning process to ensure an efficient development proposal review process (TRCA, 2003d). Based on the TRCA generic study requirements and available subwatershed knowledge, recommendations for study requirements in support of proposed new developments in the Mayfield West community have been prepared ( see Appendix A).

To be consistent with the Mayfield West community design principles, it is generally recommended that the planning and design of new urban settlements in this subwatershed should: • be based on low impact development principles that minimize changes to predevelopment water balance (i.e. rates of run off, infiltration and evapotranspiration) and maintain natural ecosystem functions; • should protect the land base needed to both protect existing natural habitats, and regenerate or improve their function and quality; and, • should require that buildings meet some level of green building design standards (e.g., Canadian Green Building Council, 2004) Growth of urban settlements can potentially affect the existing water balance in the watershed through changes to surface drainage patterns, and increases to impervious land cover. These changes affect the watershed’s capacity to infiltrate precipitation and store run off and thereby, to attenuate stream flows. Planning and design of new urban settlements and road infrastructure in this subwatershed should be based on low impact development principles that minimize changes to predevelopment water balance . Innovative urban designs that minimize impervious surfaces, maintain the function of significant headwater drainage features, incorporate stormwater controls that promote infiltration of clean run off, utilize green roof technologies, and harvest and re-use rainwater should be considered as part of an overall stormwater management strategy. Planning and design of the open space system within new urban settlements should take into consideration that lands within the subwatershed have been targeted for securement and restoration of natural land cover in the TRCA’s Toronto and Region Terrestrial Natural Heritage System Strategy (TRCA, 2007). Lands in the target terrestrial natural heritage system should be considered by the Town of Caledon for designation as Environmental Policy Areas (EPA) and development should be directed to lands outside the targeted system to the greatest extent possible. Where this is not possible, a “net-gain” principle should be adhered to that recognizes the need to improve on existing conditions, and that any losses of existing or targeted natural land cover should be compensated elsewhere (TRCA, 2007). Appropriately sized ecological buffers around important surface water and natural heritage features should be established for their protection. Planning and design of new public greenspace trails should

26 consider available information on the sensitivities of the natural features (e.g., vegetation communities and flora and fauna species) and avoid features that are highly sensitive to human disturbance or particularly vulnerable to typical negative impacts associated with trail uses ( see section 8 ). Based on a review of the Town of Caledon Environmental Policy Area (EPA) designations in the Mayfield West community plan study area, it has been noted that a number of tableland woodlots in the headwaters of the Spring Creek tributary, that have been identified and mapped through terrestrial natural heritage inventory work completed by the TRCA (TRCA, 1998b; TRCA, 2004i), are not currently protected through current EPA designations. The Town of Caledon should review their Official Plan Environmental Policy Area designations to ensure that their policies are sufficient to both protect the existing significant natural heritage features in this area, and provide the land base needed to improve the quality of habitat they are capable of supporting. To be consistent with the Mayfield West community design principle to “Protect/Regenerate Natural Habitats”, these woodlots should be retained in the landscape and the land base needed to restore them as a new core forest area should be secured through the urban planning process. Planning and design of stream crossings associated with road or footpath infrastructure should utilize available information on the form and sensitivity of the stream channel (see section 5). Further study is needed to delineate the meander belt width along the reaches of Etobicoke Creek where road crossings are proposed. This information should be used to inform the design of the bridge or footpath infrastructure that will be needed for these crossings. Past clearing of the land for agricultural purposes and rural and urban settlements has reduced the quantity of natural land cover in the landscape and negatively impacted the health of the terrestrial system. Efforts to restore natural land cover and wildlife habitat in this subwatershed should draw upon direction provided by the TRCA’s Toronto and Region Terrestrial Natural Heritage System Strategy (TRCA, 2007), the Habitat Implementation Plan for Etobicoke and Mimico Creeks Watersheds (TRCA, 2003c) and the Snelgrove Reach Plan (TRCA 1999) regarding lands where initiatives to restore natural land cover and improve wildlife habitats should be undertaken. Further analysis of available information is needed to identify priority areas for ecological restoration initiatives in the subwatershed, particulary regarding restoration of natural riparian vegetation. Further work should be undertaken to develop concept plans for privately-owned lands, in cooperation with private landowners, that have been targeted for restoration of natural land cover by the TRCA Terrestrial Natural Heritage System Strategy, and new open space lands that will be part of the new Mayfield West community.

27 4. Groundwater Quantity and Quality

Protecting the quality and quantity of groundwater flowing through the subwatershed system is integral to the rural communities that use this resource for domestic and agricultural water supply purposes, and critical to sustaining the health of local terrestrial and aquatic ecosystems.

4.1 Measuring Groundwater Quantity and Quality The quantity of water in any groundwater system is dependent on both recharge and discharge. Recharge rates measure the quantity of precipitation (i.e. rain and snowmelt) that infiltrates into the ground to recharge aquifers. Discharge rates measure the amount of groundwater that returns to the surface water system. Groundwater recharge is directly affected by land use and especially by impervious land cover associated with urban settlements. The greater the impervious land cover, the less potential there is for infiltration, which in turn decreases groundwater discharge, which is a major component of baseflow in watercourses. A common approach to developing a better understanding of groundwater systems is to develop conceptual and numerical models that simulate the subsurface geology and groundwater flow patterns within a certain study area. A regional-scale geologic model has been developed, and a numerical groundwater flow model is in the process of being calibrated, for the geographic area encompassing the Regions of Peel, York, Durham and the City of Toronto (Gerber and Holysh, 2005). This information is being compiled as part of a regional scale groundwater management project involving the Ontario Geological Survey, Regions of York, Peel, and Durham, and the City of Toronto (YPDT), as well as the Conservation Authorities Moraine Coalition. The groundwater flow model will utilize the regional geologic model to predict groundwater movement through the subsurface, and groundwater discharge to the surface water system. In 2005 information from the geologic model was available for the Etobicoke Creek Headwaters subwatershed, but calibrated data from the groundwater flow model was not. A surface water balance modelling exercise was completed for the Etobicoke Creek watershed in 2004. This surface water balance model gives an initial estimate of average annual groundwater recharge rates for the study area (EBNFLO, 2004). This information will be input to the groundwater flow model to provide preliminary estimates of average annual groundwater flows through the various geologic units and locations and rates of groundwater discharge. Groundwater quality is monitored by the Ontario Ministry of the Environment, the TRCA, the Geological Survey of Canada, and by regional municipalities. Regular monitoring of groundwater quality is undertaken at municipal water supply wells and at Provincial Groundwater Monitoring Network (PGMN) wells. There are no monitoring wells in the subwatershed, however a PGMN well is located at the nearby Heart Lake Conservation Area.

4.2 Groundwater Flow Groundwater flow, or flux, depends on hydraulic conductivity (permeability) and hydraulic gradient, which are determined by soil types and surficial geology. Aquifers are saturated geological deposits capable of yielding water supplies. The three main aquifer complexes within the Etobicoke Creek watershed area are the Oak Ridges (or equivalent outwash/ice contact sand and gravel deposits), Thorncliffe, and Scarborough aquifer complexes. Aquitards are geological deposits with low permeability that do not yield large amounts of water, but can store water or slowly transfer water from one aquifer to another. Four main aquitards within the

28 Etobicoke Creek watershed area are the Halton, Newmarket, and Sunnybrook aquitards (Gerber and Holysh, 2005). Surface drainage boundaries in the headwaters areas of TRCA watersheds appear to coincide with groundwater divides for the three aquifer systems (Gerber & Holysh, 2005). In general, the local topography and surficial geology direct groundwater flow toward Lake Ontario (Gerber & Holysh, 2005). In areas near streams, flow tends to be towards the streams (Gerber & Holysh, 2005). Within the Etobicoke Creek Headwaters subwatershed, the surficial deposits are predominantly Halton Till, which is an aquitard. Figure 2-2 shows the surficial geology for the area. The most important aquifer in this area is the Oak Ridges aquifer (or equivalent outwash/ice contact sand and gravel deposits) . Figure 4-1 shows the orientation of cross sections of the regional geologic model. Figure 4-2 and Figure 4-3 present the cross-sections of the regional geologic model which show the orientation of aquifer and aquitard complexes in the headwaters portion of the Etobicoke Creek watershed.

4.3 Groundwater Recharge and Discharge Recharge rates were estimated using the Etobicoke Creek watershed surface water balance model (EBNFLO, 2004). The Etobicoke Creek surface water balance model indicates that recharge rates are highest in the headwaters area. This preliminary assessment estimates that recharge rates in the rural portions of Etobicoke Creek Headwaters subwatershed range from 117 to 168 millimetres per year (mm/yr) (see section 5, Figure 5-1). Estimated recharge rates are relatively low due to the area being underlain by Halton Till deposits, which generally exhibit low hydraulic conductivity (EBNFLO, 2004). Baseflow is a measure of stream flow during dry weather conditions. Areas where groundwater discharge may be occurring can often be inferred by measuring baseflow. Baseflow in Etobicoke Creek was measured at several sites in the subwatershed, on multiple occasions between 2000 and 2004. Section 5 of this report provides further details with regard to these field measurements. Baseflow rates in the upper reaches of Etobicoke Creek were observed to be generally low (0 to 1 L/s/km). A small portion of the subwatershed exhibited higher discharge rates of 1 to 20 L/s/km. Correlation of baseflow measurements with information from the YPDT regional-scale geologic model suggests that the Oak Ridges aquifer (or equivalent outwash/ice contact sand and gravel deposits) outcrops along the main channel of Etobicoke Creek between Mayfield Road and Bovaird Drive ( see Figure 4-2). Groundwater discharge from the aquifer to Etobicoke Creek is estimated to account for 50 percent of the total stream flow leaving the subwatershed during dry weather conditions. Considering that discharge from the Oak Ridges aquifer (or equivalent outwash/ice contact sand and gravel deposits) may be a major contributor of baseflow to Etobicoke Creek, maintaining predevelopment infiltration rates in areas that contribute recharge to the Oak Ridges aquifer (or equivalent outwash/ice contact sand and gravel deposits) will be vitally important to protecting and enhancing the health of Etobicoke Creek. Once calibration is completed, the regional groundwater flow model should be used to identify locally significant groundwater recharge areas that are contributing flow to locally significant groundwater discharge areas such as along the main channel between Mayfield Road and Bovaird Drive, and along reaches of the westernmost headwater tributary classified as coldwater aquatic habitat ( see Figure 9-4).

29

Figure 4-1: Orientation of Cross-sections

Figure 4-2: North-South Cross-section of Geologic Model

Figure 4-3: West-East Cross-section of Geologic Model

4.4 Groundwater Use In the rural portion of this subwatershed, groundwater is used for domestic and agricultural water supply purposes. The aquifers within the subwatershed are not suited to production wells for municipal water supply purposes, and there are no municipal water supply wells in the subwatershed. The Ministry of Environment’s Permit To Take Water database does not contain any records of groundwater takings greater than 50,000 L/day within the subwatershed. The water use database for Peel Region confirms this absence of major groundwater users in the study area (Beatty & Assoc., 2003) . The Region of Peel’s water use assessment study identified a total of 39 minor groundwater water takings in the subwatershed. The water takings were found to be predominantly for domestic purposes, with the second largest users being for livestock purposes (Beatty & Assoc., 2003). Section 5 of this report provides locations and more detailed description of these users. It is notable that in the late 1990s, it was reported that approximately 22 farms in the Etobicoke Creek watershed had to import water to meet their farming operations needs (TRCA, 1998c).

4.5 Groundwater Quality

The major threats to groundwater quality in the subwatershed are nitrate and bacteria contamination from agricultural activities and private septic systems and de-icing salt from winter road maintenance practices (TRCA, 1998c) . Nutrients from fertilizer and manure applications on agricultural lands can leach into the soil and contribute nitrates and bacteria to the groundwater system. Septic systems servicing rural residences also contribute nitrates and bacteria to the groundwater system. Winter road maintenance practices that involve the spreading of de-icing salt also represents a threat to groundwater quality, as the spreading of these de-icing compounds often results in the salts being transported to nearby soils. The de-icing compounds rapidly dissolve in water and can be transported with the groundwater to contaminate shallow and deeper aquifers. Considering that private wells are often located near roads, the potential for winter road maintenance practices to affect the quality of water being derived from these private wells is high. In 2003, the Region of Peel completed a land use and chemical occurrence inventory study that provided an assessment of potential groundwater contamination risks (AMEC, 2003). An aquifer vulnerability index was applied to identify areas where the shallow aquifer is more vulnerable to contamination based on hydrogeologic characteristics. Two main factors in determining aquifer vulnerability are the depth to the water table and the hydraulic conductivity of surficial deposits. Assessing groundwater contamination risk involved consideration of potential contaminant sources and their proximity to vulnerable aquifers. The vulnerability of a given area was rated on an Intrinsic Susceptibility Index (ISI) that ranked areas as either high, medium or low vulnerability. Within the Etobicoke Creek Headwaters subwatershed, the vulnerability was mostly low-to-medium with some areas of high vulnerability. Land use information was correlated with the assessment of aquifer vulnerability to assess potential groundwater contamination risks. Lands were ranked as either having a high, medium or low level of risk as potential sources of groundwater contamination. The majority of the subwatershed received ratings of low or medium in terms of groundwater contamination risk, with a few areas receiving high ratings (AMEC, 2003). These findings represent a preliminary assessment of potential risk. Further study and field investigations are required to assess actual level of risk and to determine whether or not contaminant management planning work is needed, or if plans are already in place.

33 4.6 Current State of the Groundwater System Available information from baseflow monitoring, regional groundwater modelling and water balance modelling work completed for the Etobicoke Creek watershed provides a preliminary understanding of the local groundwater system.

Based on information from baseflow measurements and the regional geologic model, groundwater discharge zones in the subwatershed are believed to be limited to a few reaches of the creek. The most significant groundwater discharge zone identified thus far is believed to coincide with an outcropping of the Oak Ridges aquifer (or equivalent outwash/ice contact sand and gravel deposits) along the main channel of Etobicoke Creek, between Mayfield Road and Bovaird Drive.

Based on the relatively low permeability of the Halton Till deposits that underlie the headwaters subwatershed, the aquifer vulnerability in the area is generally considered to be low-to- medium, with a few more vulnerable areas (AMEC, 2003). The majority of current land use activities in the subwatershed pose either low or medium risks in terms of potential for groundwater contamination (AMEC, 2003).

4.7 Management Considerations Considering that discharge from the Oak Ridges aquifer (or equivalent outwash/ice contact sand and gravel deposits) may be a major contributor of stream flow to Etobicoke Creek during extended dry periods, protecting the infiltration capacity of lands that contribute recharge to the Oak Ridges aquifer (or equivalent outwash/ice contact sand and gravel deposits) is vitally important to protecting and enhancing the health of Etobicoke Creek. Although groundwater discharge areas are believed to be limited in this subwatershed, those that do exist are important sources of water that are critical to supporting local aquatic ecosystems. Once predictions regarding the distribution of groundwater discharge areas, and rates of discharge are made available for the Etobicoke Creek watershed from regional-scale groundwater flow modelling work, this information should be correlated with available baseflow measurements, aquatic system monitoring data and thermal regimes to gain a better understanding of how the local groundwater system influences other components of the subwatershed system.

Planning of new urban settlement areas should consider the vulnerability of local shallow aquifers to contamination. Land uses that represent potentially high risk sources of groundwater contamination should either be directed away from areas of high aquifer vulnerability, or should require contaminant management plans to be developed and implemented. Field investigations should be undertaken for areas identified as having high potential risk of groundwater contamination in the Region of Peel Land Use and Chemical Occurrence Inventory study to assess actual risk and whether or not contaminant management plans are needed. Planning and design of new urban settlements in this subwatershed should strive to minimize changes to existing groundwater recharge rates through implementation of low impact development principles that minimize impervious surfaces and incorporate stormwater management measures that infiltrate as much clean run off as possible.

34 Hydrogeology field investigations should be undertaken in support of proposals for new urban settlements to better identify the extent of the Brampton Esker in this area and to improve the current understanding of groundwater recharge rates and local groundwater levels. Monthly monitoring of surface and groundwater levels should be undertaken as soon as possible in hydrologically sensitive natural features that may be affected by anticipated changes to land use (e.g., wet forest areas in headwaters of Spring Creek tributary, downstream wetlands and Heart Lake wetland complex). Considering recent reports of low water levels in private wells in the rural portion of the subwatershed, local monitoring of groundwater levels should be implemented as part of the Provincial Groundwater Monitoring Network and steps should be taken to promote best management practices and technologies to rural residents and farmers that help to conserve water through the Region of Peel’s Water Smart Peel and Rural Clean Water programs. Implementation of nutrient management plans will also play an important role in protecting groundwater quality in this subwatershed. The Nutrient Management Act requires agricultural operations to manage nutrients applied to their lands, which will help to control the amount of contaminants that could potentially contaminate groundwater. The size of the operation will determine when this legislation will apply (MOE, 2002a). The scope of the Etobicoke and Mimico Creek watersheds revitalization strategy, Greening Our Watersheds (TRCA, 2002a) should be expanded to include objectives and targets regarding management of the groundwater system. To do this, regional scale groundwater modelling work that is underway through the regional (YPDT) groundwater study partnership, needs to be completed to gain a better understanding of the groundwater system in these watersheds. Drinking water source protection planning work to be completed to meet the requirements of the Province of Ontario’s Clean Waters Act, 2006 will help address this knowledge gap.

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5. Surface Water Quantity

Etobicoke Creek begins in the rural areas of the Town of Caledon and flows southwest into the urbanized portion of the watershed. Many of the tributary streams appear in the landscape as small wetlands and drainage features in rural and agricultural lands.

5.1 Water Balance The accounting of the total quantity of water and its distribution within a watershed is known as the water balance. The main components that are accounted for in a water balance equation include: the total amount of precipitation input to the system, including both rain and snow; the percentage of precipitation which returns to the atmosphere through both evaporation and transpiration; the percentage which enters the groundwater system through infiltration (recharge); the percentage which becomes run off and flows overland to collect in rivers and streams; and, the percentage which returns to the surface water system from the groundwater system (discharge). The processes by which these components move through the atmosphere, over land, and through the ground are collectively referred to as the hydrologic cycle. The physical properties of a watershed, such as drainage area, slope, soils, geology and land use affect the distribution of water within the water balance and the processes that function within a watershed hydrologic cycle. A preliminary water balance model has been developed for the Etobicoke Creek watershed that describes the average annual rates of evaporation/transpiration, groundwater recharge, surface run off, and their distribution across the watershed (EBNFLO, 2004). This preliminary assessment estimates that average annual groundwater recharge rates in the rural portions of Etobicoke Creek Headwaters subwatershed generally range from 117to 168 mm/year (Figure 5-1). However, preliminary water balance assessment work underway for the Humber River watershed estimates that average annual groundwater recharge rates in the West Humber subwatershed (also located on the Peel Plain and underlain by Halton Till deposits) generally range from 50 to 100 mm/year (HCCL, draft 2005). It is believed that the Etobicoke Creek watershed water balance model may be over estimating groundwater recharge rates in the Etobicoke Creek Headwaters subwatershed, but due to a lack of stream gauge data for this subwatershed, further work to improve the calibration of the water balance model is not possible at this time. The predominance of imperfectly drained clay-loam soils underlain by Halton Till deposits in the Etobicoke Creek Headwaters subwatershed tends to favor the generation of surface run off over infiltration during storm events . This has produced a higher density pattern of surface drainage than would be the case if the soils and geology favored higher rates of infiltration. The stream flow regime within the subwatershed is heavily influenced by precipitation patterns, with many of the first, second and third order streams exhibiting intermittent flow during extended dry periods of the year.

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Figure 5-1: Average Annual Groundwater Recharge Rates

5.2 Measuring Surface Water Quantity Stream flow can be measured in several ways. Permanent gauge installations provide the means to continuously monitor stream flow. Field measurements provide information on stream flow at a given location and time. Predictive modelling methods are used to estimate stream flow conditions under various rainfall events and various land use scenarios. All of these methods have been used to characterize the stream flow regime of the Etobicoke Creek. Permanent Stream Flow Gauges Within the Etobicoke Creek watershed, flow is measured continuously at four stream gauge locations. The Water Survey section of Meteorological Services of Canada (WSC), a division of Environment Canada, operates and maintains two gauges as part of the Federal and Provincial flow network (Environment Canada, 2000). The Toronto and Region Conservation Authority operates another two gauges. Table 5-1 describes the permanent stream gauge network on Etobicoke Creek. All of the gauges in operation at this time are located downstream of the headwaters subwatershed. The TRCA’s monitoring network plan anticipates the need for an additional stream gauge within the Etobicoke Creek watershed which may be located within the subwatershed.

Table 5-1: Etobicoke Creek stream gauges

TRCA Reference ID No. Location Operator WSC No. Recorded Dates

3 Main Etobicoke south of QEW WSC 02HC030 1966 to current 27 Upper Etobicoke at Dec. 1957 to 1991; Church St. E. N/Queen reopened 2003 to St. and E/Main St. WSC 02HC017 current 90 Spring Creek N/Derry and W/Bramalea TRCA n/a 2003 to current 91 Upper Etobicoke N/ Derry and East Dixie TRCA n/a 2003 to current

Field Measurements Field measurements have been taken at numerous locations throughout the subwatershed in order to gain a better understanding of low stream flow conditions, or baseflows. Numerous, well-distributed baseflow measurements can provide a better understanding of groundwater- surface water interactions and can help identify natural and human influences on low stream flow conditions in the subwatershed.

TRCA first carried out baseflow measurements in the Etobicoke watershed during the summer of 2000, at a total of 93 individual locations, 31 of which were within the headwaters subwatershed (TRCA, 2000). TRCA continued sampling the Etobicoke Creek watershed in 2002 at another 64 sites, focusing mainly on the headwater reaches north of Bovaird Drive (TRCA, 2002b). This 2002 data was supplementary for comparison with previous findings. A total of 87 individual baseflow measurements were taken in 2000 and 2002 within the subwatershed study area.

38 TRCA applied Water Survey of Canada flow measurement standards and the Geological Survey of Canada (GSC) sampling protocol to ensure that measurements were taken under baseflow conditions. Given the geology and climate in the TRCA jurisdiction, a minimum 72- hour waiting time was established following any precipitation event before measuring. This would ensure that all surface run off had cleared the system and that the measured flow only reflected baseflow volumes. Measurements were made using electromagnetic current velocity meters. At each baseflow measurement site, several other meteorological and physical parameters were recorded including channel dimensions, air and water temperatures, measurements to establish a stage/discharge relationship (ratio between water level and water volume) where possible, and weather conditions. Additional measurements were performed at specific indicator sites across the watershed on a monthly basis through the summers of 2003 and 2004 (TRCA, 2003b; 2004h). Indicator sites have also been selected within the study area to monitor local changes to baseflow that may result from future growth of urban settlements in this area. These stations are located along Old School Road, and north and south of Mayfield Road. Measurements at these indicator sites are proposed to be conducted on a monthly basis throughout the spring and summer months each year.

Hydrologic Simulation Models TRCA has been using hydrologic simulation models on the Etobicoke Creek watershed since 1979 to assist in floodplain management (McLaren, 1979). They use the models to predict the hydrologic response of the watershed to rainfall events and snowmelt events under various development scenarios. Table 5.2 indicates the models that have been developed.

Table 5-2: Summary of hydrologic models

Model Hydrologic Simulation Land use Data Program 1979 McLaren Study HYMO 1977 1995 Schaeffer's study OTTHYMO-89 1992 2007 Update Visual OTTHYMO(V02) 1999

In the mid-1990s, the TRCA commissioned a Flood Control Study for Etobicoke Creek to develop a management strategy for the watershed (Fred Schaeffers & Assc., 1996). This watershed wide study incorporated the findings of numerous smaller studies and hydrologic updates to portions of the watershed. Changes in land use and stormwater management (SWM) practices necessitated this update. The study recommended general levels of control and specific levels of stormwater management and flood controls for the various tributary catchments within the watershed. The controls were established to maintain current or acceptable flood risk levels. The study updated the original 1979 HYMO hydrologic model to OTTHYMO-89 and 1992 land use conditions. Figure 5-2 illustrates the location of flood vulnerable areas and roads within the headwaters subwatershed study area that were identified through this process.

An update to the OTTHYMO model was recently completed (TSH, 2007). The model now utilizes the Visual OTTHYMO (V02) hydrologic simulation model with land use updated to 1999 data. Based on 1999 land use data it is estimated that approximately 8% the total surface area of the Etobicoke Creek Headwaters subwatershed is covered by impervious surfaces (rooftops, roads, parking lots, etc.) at present time.

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Figure 5-2: Flood Vulnerable Areas and Roads

5.3 Stream Flow Because the soils and underlying surficial geology in this subwatershed area tends to favor the generation of surface run off over infiltration, the stream flow regime is heavily influenced by precipitation. During dry periods, many of the first, second and third order streams exhibit intermittent flow. During storm events, much of the precipitation becomes run off. This stream flow regime has significant influence on surface water quality conditions, as high rates of surface run off result in rapid transport of pollutants from the land surface to the creek. The majority of urban settlements in the City of Brampton portion of the subwatershed were developed prior to the requirement for stormwater management controls. During precipitation or snowmelt events, storm sewers in these areas convey run off from impervious surfaces directly to watercourses, causing water levels and stream flow rates to rise rapidly. The changed stream flow regime that results typically destabilizes the stream channel, impairs the health of aquatic ecosystems, and degrades water quality. Evidence of this is found in the urban portion of the subwatershed, where surface water quality parameters are often found to exceed provincial water quality guidelines (see section 6) , stream channels are unstable or in- adjustment (see section 7) and aquatic habitats communities are rated as being in poor health (see section 9) .

Baseflow Baseflow is defined as the amount of water flowing in a watercourse during periods of extended dry weather conditions. Baseflow conditions represent the lowest stream flow rates that typically occur in a given watercourse. Groundwater discharge is typically the main source of baseflow. In urban areas, contributions to baseflow from such sources as lawn-watering and groundwater seepage into municipal storm sewer infrastructure can also contribute to baseflow. Any land use changes that affect groundwater recharge and discharge rates, such as the growth of urban settlements, has the potential to change baseflow conditions in an affected watercourse, which could result in the degradation or loss of aquatic habitat, deterioration of downstream surface water quality and subsequent impairment of beneficial uses.

Baseflow studies within other watersheds in the TRCA jurisdiction have shown seasonal shifts in patterns of low flow conditions, where stream flows are higher in March and April and lower in July and August (TRCA, 2002b). In the Etobicoke Creek Headwaters subwatershed, baseflow data collected in July 2000 showed some upper reaches with very low stream flows while measurements made in the same locations in August 2002 were all observed as dry (no stream flow).

Due to the predominantly clay-loam soil types and underlying low hydraulic conductivity Halton Till deposits, it is likely that areas where groundwater discharge occurs are limited in this subwatershed. Baseflow measurements collected in the study area have helped to identify reaches within the subwatershed where groundwater discharge is occurring (Figure 5-3).

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Figure 5-3: Baseflow Measurements

A potential groundwater discharge zone may occur along the southernmost reach of the creek between Creditview Drive and Chinguacousy Road, south of Old School Road (TRCA, 2002b). Baseflow measurements at Mayfield Road were not possible due to pooling within the channel. Because of this pooling, a flow measurement of 0 L/s was assigned, and the contributing stream segment is classified as a reach were stream flow decreased over its length (TRCA, 2005a). However, significant increases in baseflow were measured at Conservation Drive, and Bovaird Drive. These increases were present in all data collected from 2000, 2002, and in spot measurements taken in 2004. Correlation of these baseflow measurements with information from the regional geologic model suggests that the Oak Ridges aquifer (or equivalent outwash/ice contact sand and gravel deposits) outcrops along the main channel of Etobicoke Creek between Mayfield Road and Bovaird Drive, where there is an absence of Halton Till deposits ( see Figure 4-2). Groundwater discharge from the aquifer to Etobicoke Creek is estimated to account for 50 percent of the total stream flow leaving the subwatershed during baseflow conditions, and 24 percent of total baseflow flowing into Lake Ontario at the creek mouth (TRCA, 2005a). Considering that discharge from the Oak Ridges aquifer (or equivalent outwash/ice contact sand and gravel deposits) may be a major contributor of baseflow to Etobicoke Creek, protecting the infiltration capacity of areas that contribute recharge to the aquifer will be vitally important to protecting and enhancing the health of Etobicoke Creek.

Historical Stream Flow Stream flow data from the permanent Water Survey of Canada stream gauge station on the main channel of Etobicoke Creek as it crosses Church Street in the City of Brampton (north of Queen Street/Highway 7) is the primary source of historical stream flow information for this study area. Through an analysis of historical stream flow data in the Etobicoke Creek in support of the State of the Watershed document, it was found that low stream flow conditions have shown an increasing trend between 1973 and 1990 (TRCA, 1998c), and this increasing trend has continued into the 1990s. It was found that mean summer baseflow discharges have increased by approximately 35 percent since 1973, with an annual increase of about 1.2 percent. The average annual summer baseflow output of Etobicoke Creek over the gauging period (1973 to 1990) was found to be approximately 21 percent of the total annual flow. This observation of an increasing trend in baseflow contrasts with the widely held belief that as the portion of a watershed with impervious cover increases, that baseflows would decrease as a result of reduced groundwater recharge and discharge rates. While further study is needed to better understand this trend, it is speculated that it is partly due to groundwater seeping into municipal storm sewers or flowing along trenches in which they are installed and being discharged to surface streams more rapidly than before the infrastructure was built.

5.4 Flooding Etobicoke Creek floods regularly (TRCA, 1998c). Accounts of this flooding indicate that it happens in the more downstream, developed sections of the watershed and not in the headwaters subwatershed area. Without adequate stormwater management within urbanizing areas, the headwaters subwatershed may also experience some degree of flooding and aggravate downstream flood risks. Modelling of the subwatershed has been conducted to identify areas and infrastructure that are vulnerable to periodic flooding (Figure 5-2). A summary of the history of hydraulic modelling work completed for the Etobicoke Creek watershed is presented in Table 5-3.

43 Table 5-3: Summary of hydraulic models

Model Hydraulic Program Hydrology Data 1979 McLaren Study HEC-2 1977 HYMO 1995 Schaeffer’s Study HEC-2 (original 1979 model) 1992 OTTHYMO 2008 Update HEC-RAS 1999 VO2

The backwater sub-model used in the original McLaren study was the HEC-2 program from the US Army Corps of Engineers. The model determines flood stage profiles corresponding to flood flows, which are used to delineate flood hazard areas, or the lateral extent of inundation. Given a starting discharge and stage, the computer program employs the principles of conservation of mass and energy to calculate river stages at successive pre-selected upstream locations. The hydraulic effect of bridges, culverts and roadways are also evaluated. Model inputs include floodplain cross-section, Manning’s roughness coefficients and geometry of all hydraulically significant structures. The Etobicoke Conservation Report of 1947 documented numerous accounts of flooding as a result of snowmelt plus rainfall in the winter and spring, or of intense rainfall during the remainder of the year. Occurrences of ice jams were also noted in Brampton. This led to the construction of the Brampton Diversion channel in 1952, which is capable of conveying the floodwaters during a 100 year storm event. Figure 5-4 illustrates the extent of the available floodplain mapping at this time. An update to the hydraulic model is underway with an expected completion date of 2008. The update will utilize the windows-based HEC-RAS program and the new V02 hydrology information based on 1999 land use. The floodplain mapping will also be updated as part of this project.

5.5 Surface Water Use Water use information within the Etobicoke Creek Headwaters subwatershed is currently available from the following sources: • TRCA Water Use Assessment Database; • Ministry of the Environment, Central Region, Permit To Take Water Database; • Environmental Bill of Rights – Online database; • Peel Region Water Use Assessment (Beatty & Assoc., 2003) . The Ministry of the Environment (MOE) is the agency responsible for the review and issue of permits to take water (PTTWs) for all water takings greater than 50,000 L/day, with a few exceptions. The MOE database was provided to the TRCA in October 2002 and was revised by TRCA staff, removing records for redundant and non active users. New water taking permit applications require posting on the Environmental Bill of Rights online registry so the EBR can also be a source of information on water takings. The MOE PTTW database and the EBR database do not contain any records of water takings greater than 50,000 L/day in the study area. The Beatty and Associates Water Use Assessment database for Peel Region, confirmed this observation.

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Figure 5-4: Floodplain Mapping

Information collected through the TRCA Water Use Assessment project in 2003 expanded this assessment of water use to include information on water takings less than 50,000 L/day, which are not regulated by the MOE (TRCA, 2005a). Through this initiative, a total of 39 potential water takings were identified and located within the subwatershed (Figure 5-6). Of these users, 34 were confirmed through a water user survey distributed by the TRCA. The majority of these water takings are groundwater based (private wells). One water user (a tree nursery operation) indicated that they use surface water as a source. As shown in Figure 5-5, the majority of water takings within the study area are for domestic purposes (Beatty & Assoc., 2003). Water takings for livestock watering accounts for the second largest portion of total water takings occurring in the study area. Livestock operations in the subwatershed primarily consist of beef and dairy cattle, horses, and one large broiler chicken farm. These water takings for livestock watering purposes all identify groundwater as the source, but vary with respect to volumes withdrawn, along with the duration and timing of the withdrawals. Water takings for irrigation purposes accounts for the third largest portion of total water takings occurring in the study area with the largest single water taking being by a driving range and mini-putt centre.

Figure 5-5: Water Use In The Etobicoke Creek Headwaters Subwatershed

Water Uses by Volume (m3/yr Withdrawn) Livestock Watering

Golf Course 43,626 Irrigation

Nursery Operation Unknown

86,700 4,497 Self Supply 4,363 Domestic

It is notable that during field surveys in 2003, some landowners voiced concern that water levels in their private wells were low. These complaints were localized along the east side of Chinguacousy Road, and were received predominantly from landowners with shallow wells (10 to 12 metres deep) (TRCA, 2005a).

Surface Water Vulnerability Given the intermittent flow regime that characterizes much of the headwaters reaches of Etobicoke Creek, local residents and businesses generally do not rely on surface water sources for water supply, and instead use groundwater based sources. As previously mentioned, surface water use within the study area is limited to one identified user that removes water from an offline pond for a nursery/landscaping operation. This particular use has little to no effect on the surface water system within the headwaters subwatershed of Etobicoke Creek.

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Figure 5-6: Water Takings

The groundwater taking associated with the driving range/mini-putt centre could potentially be affecting the shallow groundwater system that feeds the upper reaches of Etobicoke Creek. During baseflow measurements, the tributary of Etobicoke Creek nearest to the driving range/mini-putt centre was observed to be dry; however, this is consistent with many of the reaches sampled in this area. At this time it is believed that water takings for irrigation of this driving range/mini-putt centre is likely not significantly altering natural baseflow conditions in the watercourse (TRCA, 2005a). The remaining 33 known water takings utilize groundwater as the source and withdraw water in relatively small volumes (<1,000 L/day). These water takings are likely having no significant impacts on baseflows in local watercourse and water levels in local wetlands (TRCA, 2005a).

5.6 Current Surface Water Quantity Conditions The stream flow regime in this subwatershed is largely influenced by precipitation and exhibits intermittent flow conditions in many of the first, second and third order streams during periods of extended dry conditions. The predominantly clay-loam soils and underlying Halton Till deposits are primarily responsible for the moderately high density drainage system and high run off rates that characterize this subwatershed. The extent of impervious land cover and lack of stormwater controls in the majority of the urban portion of the subwatershed have contributed to a “flashy” stream flow response in these reaches during storm events that is characterized by rapid rise in stream flow rates during a precipitation or snowmelt event and a rapid fall following the event. This is likely contributing to accelerated rates of stream channel erosion, poor surface water quality and poor aquatic ecosystem health in urban areas. Baseflow measurements suggest that several reaches within the subwatershed receive inputs from groundwater discharge. The Oak Ridges aquifer (or equivalent outwash/ice contact sand and gravel deposits) is believed to outcrop along the main channel of Etobicoke Creek south of Mayfield Road. Groundwater discharge occurring along these reaches represents a major contributor to baseflow in the subwatershed and the rest of the watershed. Maintaining the current distribution of groundwater discharge areas and discharge rates, will be essential in order to maintain the health of aquatic ecosystems associated with creeks and wetlands. Historical stream flow data suggests that baseflow rates have been steadily increasing, which requires further investigation to determine the cause. Current water takings within the subwatershed are not believed to represent a significant threat to maintaining low stream flow conditions that are required to sustain the aquatic communities of Etobicoke Creek.

5.7 Management Considerations It is imperative to plan future changes to land use so that the available surface water storage within the watershed is not adversely impacted. Land use changes should be planned in such ways that strive to maintain or improve the existing capacity of the watershed to infiltrate, evaporate, transpire and store precipitation. Considering the high drainage density that exists in this subwatershed, maintaining the function of significant small drainage features should be an important consideration in the planning of future land use changes. Planning and design of new urban settlements and road infrastructure in this subwatershed should be based on low impact development principles that minimize changes to predevelopment water balance. Innovative urban designs that minimize impervious surfaces,

48 maintaining the function of significant small drainage features and incorporate porous paving materials and other stormwater controls that promote infiltration of clean run off, green roof technologies, and harvesting and re-use of rainwater should be considered as part of an overall stormwater management strategy. The design of stormwater management controls to service new urban settlements in this subwatershed should include capacity to provide quantity, quality and erosion control as per current standards (MOE, 2003) and TRCA criteria (Figure 5-7) such that the potential impacts of urban growth in Caledon on risk of flooding, water quality and stream channel erosion in downstream areas (i.e. Brampton and Mississauga) are mitigated. The City of Brampton and TRCA should continue to work together to implement known stormwater retrofit opportunities that will help to mitigate the negative impacts of untreated urban stormwater run off on the health of Etobicoke Creek. There are currently no permanent stream gauge installations located in this subwatershed. Consideration should be given to installing a new permanent stream gauge along the main channel of Etobicoke Creek, either at Conservation Drive or Bovaird Drive, to better enable monitoring and evaluation of the performance of innovative urban designs and stormwater controls that will be implemented in new urban settlements. Surface water takings within the subwatershed are not significantly affecting surface flows or baseflows, due to the limited number of users and volumes of withdrawals. The review of any new applications for surface water takings needs to consider the minimum stream flows required to support existing aquatic ecosystems. The increasing trend in baseflows that have been observed in Etobicoke Creek should be investigated further to determine the main contributing factors. Both hydrologic and hydraulic simulations should continue to be used as part of an integrated approach to floodplain management, in which alterations to lands within the floodplain are minimized, development in the floodplain is restricted, and corrective measures are introduced to reduce the potential for damage to existing property and infrastructure from flooding. Planning and design of new urban settlements should consider areas regulated by the TRCA and direct development outside of areas vulnerable to periodic flooding.

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Figure 5-7: Stormwater Management Criteria