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• Response to Peer Evaluation of TRCA’s Preliminary Watershed Characterization Report – June 2006
• Interim Watershed Characterization Report: TRCA Watersheds – February 2007
• Conceptual Understanding Water Budget Report – March 2007
• Wellhead Protection Area Study for Municipal Residential Groundwater Systems Located within the TRCA Watersheds – May 2007
• Durham Region: Wellhead Protection Groundwater Studies FINAL REPORT – September 2007
• Vulnerability Assessment and Scoring of Wellhead Protection Areas: Regional Municipality of York – November 2007
• Watershed Characterization Peer Evaluation: Summary Report – December 2007
• Surface to Well Advection Time Analysis Wellhead Protection Areas for Municipal Residential Groundwater Systems Located within the TRCA Watersheds – February 2008
• Addendum Report: Wellhead Protection Area Study and Surface to Well Advection Time Analysis for Palgrave Well 4 Located within the TRCA Watersheds – August 2008
• Groundwater Modeling and WHPA delineation: Uxville Water Supply System – September 2009
• Updated Vulnerability Assessment and Scoring of Wellhead Protection Areas: Regional Municipality of York – November 2009
• Drinking Water Quality Threats Assessment: Uxville Water Supply System – November 2009
• Assessment of Drinking Water Quality Threats: Municipal Groundwater Supplies – June 2010
• Issues Evaluation and Threats Assessment: Region of Peel – July 2010
• SPC Accepted: Tier 1 Water Budget, TRSPA Watersheds | Tier 2 Water Budget, Whitchurch-Stouffville Area – July 2010
• Tier 3 Water Budget and Local Area Risk Assessment for the Region of York Municipal Systems – November 2013

• Region of Peel WHPA Study for Municipal Residential Groundwater Systems Located within Credit River Watershed – April 2007
• Regional Municipality of Peel – Wellhead Protection Area Delineations and Vulnerability Assessments for Alton 1-2 Standby Wells, Cheltenham PW1/ PW2 Amended PTTW and Caledon Village Proposed Well 5 (TW2-05) – April 2008
• Regional Municipality of Peel – Surface to Aquifer and Surface to Well Advection Time, Wellhead Protection Areas in Credit Valley Watershed:  Caledon Village Wells 3 and 4, Inglewood Wells 1/2 and 3, Cheltenham PW1/ PW2 and Alton Wells 3 and 4 – April 2008
• SPC Accepted: Integrated Water Budget Report – Tier 2 Credit Valley Source Protection Area – April 2009
  • Part 1
  • Part 2A
  • Part 2B
  • Part 3
• Delineation and Vulnerability Analysis of WHPA-Es and WHPA-Fs for the Georgetown and Acton Wellfields, Regional Municipality of Halton, Ontario – November 2009
• Towns of Orangeville and Mono: Wellhead Protection Area Delineation Report – March 2010
• Township of Amaranth – Pullen Well: Wellhead Protection Area Delineation Report – March 2010
• Groundwater Vulnerability Assessment: Pullen Well, Township of Amaranth – March 2010
• Groundwater Vulnerability Assessment: Town of Orangeville – March 2010
• Groundwater Vulnerability Assessment: Town of Mono – April 2010
• SPC Accepted: Groundwater Quality Vulnerability Analysis, Highly Vulnerable Aquifer Delineation – May 2010
• Issues Evaluation and Threats Assessment: Town of Erin Municipal Wells – June 2010
• Issues Evaluation and Threats Assessment: Pullen Well, Township of Amaranth – July 2010
• Issues Evaluation and Threats Assessment: Town of Orangeville – July 2010
• Issues Evaluation and Threats Assessment: Region of Peel – July 2010
• Peer Review – Issues Contributing Areas: Credit Valley Conservation Source Protection Area, CTC Source Protection Region – February 2011
• Inglewood Well 1 & 2: Issue Contributing Area – April 2011
• Drinking Water Threats in Issues Contributing Areas: Credit Valley Conservation Source Protection Area – May 2011
• Town of Orangeville: Issue Contributing Areas – May 2011
• Orangeville, Mono and Amaranth: Tier Three Water Budget and Local Area Risk Assessment – May 2011
• Orangeville, Mono and Amaranth: Tier Three Water Budget and Local Area Risk Assessment – Appendix A: Conceptual and Numerical Model Development – January 2011
• Region of Peel: Verification of Significant Drinking Water Quality Threats (Groundwater) – August 2012
• Updated Vulnerability Analysis, Acton and Georgetown Wellfields: Wellhead Protection Area Delineation Report – November 2012
• Issue Determination: Halton Region Wells – April 2013
• Issue Determination: Town of Orangeville Wells – September 2013
• Region of Peel: Verification of Significant Drinking Water Quality Threats (Groundwater) for Orangeville Municipal Wells in Caledon – Updated February 2014
• Halton Hills Tier Three Water Budget and Local Area Risk Assessment: Final Risk Assessment Report – October 2014
  • Appendix A: Conceptual Model Report
  • Appendix B: Municipal Well and Water Demand Summary Report
  • Appendix C: Monitoring Data Summary Report
  • Appendix D: Model Development and Calibration Report
• Drinking Water Quality: Verification of Significant Threats, Town of Halton Hills – January 2015
• Drinking Water Quality: Preliminary Verification of Significant Threats, Township of Amaranth – January 2015
• Drinking Water Quality: Preliminary Verification of Significant Threats, Townships of East Garafraxa – January 2015
• Drinking Water Quality: Preliminary Verification of Significant Threats, Town of Erin – January 2015
• Drinking Water Quality: Preliminary Verification of Significant Threats, Town of Mono – January 2015
• Drinking Water Quality: Preliminary Verification of Significant Threats, Town of Orangeville – January 2015

• Central Lake Ontario Conservation Authority: Regional Groundwater Mapping Study – May 2004
• Draft Conceptual Water Budget Report: Central Lake Ontario Conservation Authority Watersheds – March 2007
• Interim Watershed Characterization Report: Central Lake Ontario Conservation Authority Watersheds – March 2007
• SPC Accepted Tier 1 Water Budget: Central Lake Ontario Source Protection Area – February 2009
• Tier 3 Water Budget and Local Area Risk Assessment for the Region of York Municipal Systems – November 2013

• Collaborative Study to Protect Lake Ontario Drinking Water: Final Phase 1 Report for the Regional Municipality of Durham – January 2008
• Lake Ontario Collaborative Intake Protection Zone Studies – Volume 3: Toronto Water Supply System – January 2008
• Watershed Pollutant Load Assessments for the Canadian Side of the Western Basin of Lake Ontario – June 2011
• Spill Scenario Modelling for Lake Ontario Intakes – December 2011

Abandoned Well
A well that is deserted because it is dry, contains unpotable water, discontinued before completion, not being properly maintained, constructed poorly, or determined that natural gas may pose a hazard.

Activity
One or a series of related processes, natural or anthropogenic that occurs within a geographical area and may be related to a particular land use.

Aquifer
An underground saturated permeable geological formation that is capable of transmitting water in sufficient quantities under ordinary hydraulic gradients to serve as a source of groundwater supply.

Aquifer Vulnerability Index (AVI)
A numerical indicator of an aquifer’s intrinsic or inherent vulnerability susceptibility, to contamination expressed as a function of the thickness and permeability of overlying layers.

Chemical
A substance used in conjunction with, or associated with, a land use activity or a particular entity, and with the potential to adversely affect water quality.

Condition
A drinking water condition refers to contamination that exists already and is associated with past activities.

Confined Aquifers
An aquifer that is bounded above and perhaps below by layers of geological material that do not transmit water readily.

Consumptive Water Demand
The net amount of water that is taken from a source and not returned locally to the same source in a reasonable time.

Contaminant of Concern
A chemical or pathogen that is or may be discharged from a drinking water threat activity that could contaminate a drinking water source.

Designated System
A drinking water system that is included in a Terms of Reference for developing source protection plans, pursuant to resolution passed by a municipal council under subsection 8(3) of the Clean Water Act, 2006 or added by the Minister.

Drinking Water Issue
A substantiated (through scientific means) condition relating to the quality of water that interferes or is anticipated to soon interfere with the use of a drinking water source by a municipal residential system or designated system.

Drinking Water Threat
An existing activity, possible future activity or existing condition that results from a past activity, (a) that adversely affects or has the potential to adversely affect the quality or quantity of any water that is or may be used as a source of drinking water.

Ecological Integrity
The condition of ecosystems in which, a) the structure, composition and function of the ecosystem are unimpaired by stresses from human activity, b) natural ecological processes are intact and self-sustaining, and c) the ecosystems evolve naturally.

Event
Occurrence of an incident (isolated or frequent) with the potential to promote the introduction of a threat into the environment. An event can be intentional as in the case of licensed discharge or accidental as in the case of a spill.

Existing Drinking Water Source
The aquifer or surface water body from which municipal residential systems or other designated systems currently obtain their drinking water. This includes the aquifer or surface water body from which back-up wells or intakes for municipal residential systems or other designated systems obtain their drinking water when their current source is unavailable or in the event of an emergency.

Groundwater
Subsurface water that occurs beneath the water table in soils and geological formations that are fully saturated.

Groundwater Recharge Area
The area where an aquifer is replenished from (a) natural processes, such as the infiltration of rainfall and snowmelt and the seepage of surface water from lakes, streams and wetlands, (b) from human interventions, such as the use of storm water management systems, and (c) whose recharge rate exceeds a threshold specified in the regulations. The Director’s rules will specify the acceptable methodologies to determine groundwater recharge rates i.e. what qualifies as significant.

Hazard
In the context of this guidance, a hazard is equivalent to a contaminant and pathogen threat.

Hazard Rating
The numeric value which represents the relative potential for a contaminant of concern to impact drinking water sources at concentrations significant enough to cause human illness. This numeric value is determined for each contaminant of concern in the Threats Inventory and Issues Evaluation of the Assessment Report.

Highly Vulnerable Aquifer (HVA)
An aquifer that can be easily changed or affected by contamination from both human activities and natural processes as a result of (a) its intrinsic susceptibility, as a function of the thickness and permeability of overlaying layers, or (b) by preferential pathways to the aquifer. The Director’s rules will permit the use of various methods, such as the Intrinsic Susceptibility Index (ISI), to determine those aquifers that are highly vulnerable. Ontario’s ISI defines a highly vulnerable aquifer as having a value of less than 30. An ISI is a numerical indicator that helps to indicate where contamination of groundwater is more or less likely to occur as a result of surface contamination due to natural hydrogeological features. The ISI is the most commonly used method of index mapping and was the prescribed method set out in the provincial 2001/2002 Groundwater Studies.

Hydrogeology
Hydrogeology is the study of the movement and interactions of groundwater in geological materials.

Hydrologic Integrity
The condition of ecosystems in which hydrological features and hydrological functions are unimpaired by stresses from human activity.

Hydrological Features
a) Permanent and intermittent streams
b) Wetlands
c) Lakes and their surface catchment areas
d) Seepage areas and springs
e) Aquifers and recharge areas

Hydrologic functions
The functions of the hydrological cycle that include the occurrence, circulation, distribution, and chemical and physical properties of water on the surface of the land, in the soil and underlying rocks, and in the atmosphere, and water’s interaction with the environment including its relation to living things

Imminent Threat to Health
A contaminant of concern that can affect human health in a short period of time.

Intake Protection Zone (IPZ)
The contiguous area of land and water immediately surrounding a surface water intake, which includes:

• The distance from the intake
• A minimum travel time of the water associated with the intake of a municipal residential system or other designated system, based on the minimum response time for the water treatment plant operator to respond to adverse conditions or an emergency
• The remaining watershed area upstream of the minimum travel time area (also referred to as the Total Water Contributing Area) – applicable to inland water courses and inland lakes only

Intrinsic Vulnerability
The potential for the movement of a contaminant(s) through the subsurface based on the properties of natural geological materials.

Issues Contributing Area (ICA)
The area of land where drinking water threats may contribute to a known drinking water issue. For example, if Trichloroethylene (TCE) is determined to be an Issue, the area from which the source of TCE is determined is called the Issues Contributing Area.

Land Use
A particular use of space at or near the earth’s surface with associated activities, substances and events related to a particular land use designation.

Local Area
Specific area around a wellhead or surface water intake as determined through analysis. This area must encompass a drinking water system and surrounding potential quantity threats.

Model
An assembly of concepts in the form of mathematical equations or statistical terms that portrays a behaviour of an object, process or natural phenomenon

Municipal Residential System
All municipal drinking-water systems that serve or are planned to serve a major residential development (i.e. six or more private residencies).

Parcel Level
A parcel is a conveyable property, in accordance with the provisions of the Land Titles Act. The parcel is the smallest geographic scale at which risk assessment and risk management are conducted.

Pathogen
A disease causing organism.

Raw Water
Water that is in a drinking-water system or in plumbing that has not been treated in accordance with, (a) the prescribed standards and requirements that apply to the system, or (b) such additional treatment requirements that are imposed by the license or approval for the system.

Recharge
Recharge is the process by which water moves from the ground surface, through the unsaturated zone, to arrive at the water table.

Regulated Areas
Those areas for which Conservation Authorities delineate and restrict land uses by making regulations under subsection 28(1) of the Conservation Authority Act. This subsection applies to water courses, streams, lakes, valleys, flood plains, and wetlands in Ontario.

Reserve Amounts
Minimum flows in streams that are required for the maintenance of the ecology of the ecosystem.

Response Factor
Typical factors affecting the response include dilution, rate of discharge, absorption, and degradation of the contaminant or pathogen in question. Because of the nature of the water resource, certain contaminants and pathogens may not have an impact great enough to warrant concern or responsive action. The level of impact may not effectively degrade the water resource and therefore would not require a mitigative action.

Risk
The likelihood of a drinking water threat (a) rendering an existing or planned drinking water source impaired, unusable or unsustainable, or (b) compromising the effectiveness of a drinking water treatment process, resulting in the potential for adverse human health effects.

Sensitivity Area
That portion of a defined vulnerable area that has been assigned a vulnerability score.

Severity
The degree to which an impact is measured compared to an idealized value of some parameter of concern. In the case of water quality, the severity may relate to degree of measurable exceedance of some contaminant or pathogen. In the case of water quantity deviation from some measurable parameter (e.g. minimum annual flow, piezometric head or lake level) must also be established.

Site-level
The most refined scale at which technical assessment of hydrological and hydrogeological conditions can be conducted. These assessments may contribute to water budgets, vulnerability assessments, and issues evaluation.

Sub-Watershed
An area that is drained by an individual tributary into the main watercourse of a watershed.

Surface Water
Water that is present on the earth’s surface and may occur as rivers, lakes, wetlands, ponds, etc.

Tier 1, 2, and 3 Water Budgets
Numerical analysis at the watershed/subwatershed (Tier1 and 2) or local area (Tier 3) level considering existing and anticipated amounts or water use within the watershed, as well as quantitative flow between the groundwater and surface water systems.

Time of Travel (TOT)
An estimate of the time required for a particle of water to move in the saturated zone from a specific point in an aquifer into the well intake.

Tolerance of a Water Supply System
A measure of the ability to sustain required pumping levels even during exposure events.

Transport Pathway
Transport pathways are features or activities occurring at the surface that disturb the surface above the aquifer, or which artificially enhances flow to an aquifer. The presence of a transport pathway can increase the vulnerability rate of an area.

Unconfined Aquifer
An aquifer whose upper boundary is the water table.

Valuation of the Supply
An evaluation of the importance of a particular municipal well or intake to the whole municipal drinking water supply. For example, where there are multiple supplies, value may be smaller, versus a single supply where value may be greater.

Vulnerable Area
An area referring to a groundwater recharge area, a highly vulnerable aquifer, and a surface water intake protection zone or wellhead protection area.

Water Intake Reliability
The probability that a wellhead or surface water intake can meet demand.

Water Reserve
A proportion of surface water flow that must be sustained to support anthropogenic or ecological requirements.

Water Source
An aquifer or surface water body being used to supply drinking water.

Water Source Supply
The total amount of water flowing through a surface water or groundwater system.

Water Supply System
The group of surface water intakes and/or groundwater wells that pump water to supply a municipal water distribution system.

Watershed
A watershed is the area of land where all of the water that is under it or drains off of it goes into the same place. Its boundaries are defined by ridges of high land.

Wellhead Protection Area
The surface and subsurface area surrounding a water well or well field that supplies a municipal residential system or other designated system through which contaminants are reasonably likely to move so as to eventually reach the water well or well.