The Middlesex-Elgin Groundwater Study

Middlesex County, the City of London, the Municipality of Central Elgin, Malahide Township and the Town of Aylmer  initiated a Municipal Groundwater Study, retaining Dillon Consulting Ltd., in association with Golder Associates, to complete this comprehensive regional groundwater study. The Upper Thames River Conservation Authority managed the study. The study team included experts in the fields of hydrogeology, hydrology, engineering, groundwater modelling, mapping, municipal planning and agriculture.

Groundwater is one of the primary sources of drinking water within the study area. Protecting this valuable resource is essential to our future quality of life. Existing and future land uses may, however, threaten the sustainability of our groundwater resource. The study assessed our groundwater resources in the context of regional groundwater flow systems, and developed strategies and action plans to protect groundwater resources as a safe supply of potable water.

The Municipal Groundwater Study has three main components.

• Regional aquifer characterization involves developing an understanding of the aquifers throughout the study area and the processes that control how groundwater moves through them.
• Municipal water wellhead protection entails mapping all the areas that contribute water to the municipal wells in Dorchester, Thorndale, Birr, Melrose, Komoka/Kilworth, Delaware, the City of London stand-by wells, Belmont and Aylmer.
• Development of a groundwater protection and management strategy that will address both regional groundwater protection as well as local wellhead protection measures.

Public information sessions provided an opportunity for interested community members to learn more about the project and to provide their comments to the study team. Funding for the study was shared between the Ministry of the Environment and the various municipal partners. There were 31 similar studies conducted across Ontario.

What is Groundwater?

Groundwater is water found in the tiny spaces between soil particles and in cracks in bedrock. Aquifers are the underground areas of soil or rock where substantial quantities of water are found, and are the water source for wells and springs. Groundwater discharges when it leaves the ground wherever the water table meets the ground’s surface. This discharge is essential for maintaining surface waters.

Final Report

• Executive Summary
• Final Report
• Appendices
  • Appendix B – Map B.1: Dorchester Wellfield Area
  • Appendix B – Map B.2: Thorndale Wellfield Area
  • Appendix B – Map B.3: Birr Wellfield Area
  • Appendix B – Map B.4: Melrose Wellfield Area
  • Appendix B – Map B.5a: Komoka Wellfield Area
  • Appendix B – Map B.5b: Komoka Wellfield Area
  • Appendix C – Public and Agency Consultation Materials

Figures

• Figure 2.1: Glacial History of Southwestern Ontario
• Figure 4.1: Groundwater Principles
• Figure 4.2: Water Quality
• Figure 4.3: Types of Wells
• Figure 4.4: Well Depth Histograms
• Figure 5.1: Groundwater Use in Study Area by Category
• Figure 5.2: Agricultural Water Use

Maps

• List of Maps
• Map 1.1: Study Area
• Map 2.1: Topography
• Map 2.2: Surface Water
• Map 2.3: Physiography and Moraines
• Map 3.1: Bedrock Geology
• Map 3.2: Quaternary Geology
• Map 3.3: Bedrock Surface
• Map 3.4: Overburden Thickness
• Map 3.5: Regional Cross Sections
• Map 3.6: Regional Cross Sections
• Map 3.7: Regional Cross Sections
• Map 4.1: Overburden Wells
• Map 4.2: Bedrock Wells
• Map 4.3: Water Table
• Map 4.4: Potentiometric Surface Intermediate Depth Overburden Aquifer
• Map 4.5: Potentiometric Surface Deep Overburden Aquifer
• Map 4.6: Potentiometric Surface Bedrock Aquifer
• Map 4.7: Recharge-Discharge Intermediate Depth Overburden Aquifer
• Map 4.8: Recharge-Discharge Deep Overburden Aquifer
• Map 4.9: Recharge-Discharge Bedrock Aquifer
• Map 4.10: Bedrock Surface/Bedrock Water Level Relationship
• Map 4.11: Lucan-Biddulph Cross Sections
• Map 4.12: Potential Discharge Areas
• Map 4.13: Specific Capacity Map Overburden Wells
• Map 4.14: Specific Capacity Map Bedrock Wells
• Map 4.15: Aquifer Intrinsic Susceptibility
• Map 4.16: Intrinsic Susceptibility Wells Deeper than 15 M
• Map 5.1: Water Use
• Map 6.1: Regional Potential Contaminant Source Inventory
• Map 6.2: Regional Potential Contaminant Source Inventory (London Area)
• Map 6.3: Regional Potential Contaminant Source Inventory (St. Thomas Area)
• Map 7.1: Dorchester WHPA Land Use
• Map 7.2: Thorndale  WHPA Land Use
• Map 7.3: Birr  WHPA Land Use
• Map 7.4: Melrose WHPA Land Use
• Map 7.5: Komoka WHPA Land Use
• Map 7.6: Fanshawe WHPA Land Use