Changes

# '''WHPA-E''' – the area on ground surface through which surface water flows in two hours to a point close to the well. This wellhead protection area is only delineated when studies have shown that surface water can relatively easily seep through the soil and impact the quality of the water at the well. This situation is known as groundwater under the direct influence of surface water, or a GUDI well<br>(Halton-Hamilton Source Protection Region, 2010;<ref name="example3">Halton-Hamilton Source Protection Region. 2010. Wellhead Protection Areas (WHPAs). Planning Process - Vulnerable Areas. Accessed 02 June 2022. http://protectingwater.ca/planning.cfm?smocid=1440&parentcatid=841#:~:text=A%20wellhead%20protection%20area%20(WHPA,both%20domestic%20and%20municipals%20wells.</ref>CTC SPR, 2019<ref name="example2" />)}}

# '''WHPA-E''' – the area on ground surface through which surface water flows in two hours to a point close to the well. This wellhead protection area is only delineated when studies have shown that surface water can relatively easily seep through the soil and impact the quality of the water at the well. This situation is known as groundwater under the direct influence of surface water, or a GUDI well<br>(Halton-Hamilton Source Protection Region, 2010;<ref name="example3">Halton-Hamilton Source Protection Region. 2010. Wellhead Protection Areas (WHPAs). Planning Process - Vulnerable Areas. Accessed 02 June 2022. http://protectingwater.ca/planning.cfm?smocid=1440&parentcatid=841#:~:text=A%20wellhead%20protection%20area%20(WHPA,both%20domestic%20and%20municipals%20wells.</ref>CTC SPR, 2019<ref name="example2" />)}}

'''Vulnerability'''  

'''Vulnerability''' <br>

As mentioned, WHPAs identify an area on the surface that reflects a zone within the underlying aquifer below where groundwater flows to a well. That said, this area is generally not equal to the total contributing water area that drains towards the well over a given duration of time. This contributing area is the location seen on the surface where water can infiltrate into the soil and still reach the well far away. Due to its distance there may be more urbanization within this expanded area and other contributing contaminants that can pollute the groundwater as it flows to the well. This area generally requires the most protection by the associated SPR/SPA, associated Conservation Authorities located within the area and subsequent municipalities as it is the area/zone most prone to surface contamination (Halton-Hamilton Source Protection Region, 2010<ref name="example3" />).

As mentioned, WHPAs identify an area on the surface that reflects a zone within the underlying aquifer below where groundwater flows to a well. That said, this area is generally not equal to the total contributing water area that drains towards the well over a given duration of time. This contributing area is the location seen on the surface where water can infiltrate into the soil and still reach the well far away. Due to its distance there may be more urbanization within this expanded area and other contributing contaminants that can pollute the groundwater as it flows to the well. This area generally requires the most protection by the associated SPR/SPA, Conservation Authorities located within the area and subsequent municipalities as it is the area/zone most prone to surface contamination (Halton-Hamilton Source Protection Region, 2010<ref name="example3" />).

Vulnerability for source water is simply calculated by:  

Vulnerability for source water is simply calculated by:  

# Adding that number to the modelled time it takes for groundwater to flow from the water table to the well based on the WHPA zone.  

# Adding that number to the modelled time it takes for groundwater to flow from the water table to the well based on the WHPA zone.  

As a result, these surface to well duration periods are categorized as "low" for over 25 years, "medium" for 5 - 25 years, and "high" for 0 - 5 years. These surface to well advection times are categorized as low for over 25 years, medium for 5 to 25 years, and high for 0 to 5 years of travel. The mapped groundwater vulnerability areas are overlain on the wellhead protection areas A through D in order to assign vulnerability scoring between 2 (lowest vulnerability) and 10 (highest vulnerability).

As a result, these surface to well duration periods are categorized as "low" for over 25 years, "medium" for 5 - 25 years, and "high" for 0 - 5 years. These surface to well advection times are categorized as low for over 25 years, medium for 5 to 25 years, and high for 0 to 5 years of travel. After this mapped groundwater vulnerability areas are then overlain on top of current WHPAs A - D to then assign vulnerability scoring between 2 - 10 (lowest - highest vulnerability scores). The location of a potential development site within the WHPA and its vulnerability score are then used to assign the significance of proposed or future potential actions/activities that have been labelled as potential threats to local drinking water sources. These 22 potential threats as laid out by the province can be seen in the table below in this section (Halton-Hamilton Source Protection Region, 2010<ref name="example3" />).

 

The location within the wellhead protection areas and its vulnerability score are used to assign significance to identified or potential activities that have been deemed threats to the drinking water sources. This topic is discussed in more detail on the Drinking Water Threats webpage.

====Intake Protection Zones (IPZs)====

====Intake Protection Zones (IPZs)====