Vulnerable Aquifers

Highly vulnerable aquifers

When a municipality draws drinking water from a well, it gets that water from underground. This groundwater is found in aquifers which collect water much like a sponge does. When water can pass through soil, such as sand or gravel, we call that surface permeable. An aquifer is more vulnerable to contamination if the soil layer is thin.

Aquifers are areas of soil or rock under the ground where cracks and spaces allow water to pool. They are considered highly vulnerable based on factors such as how deep it is underground, what sort of soil or rock is covering it, and the characteristics of the soil or rock surrounding it.

Download map of Maitland Valley Source Protection Area Highly Vulnerable Aquifers at this link: Maitland Valley HVAs

Download map of Ausable Bayfield Source Protection Area Highly Vulnerable Aquifers at this link: Ausable Bayfield HVAs

Download fact sheet now.

A highly vulnerable aquifer (HVA) is an aquifer that can be easily changed or affected by contamination from both human activities and natural process 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.

Do planning policies apply in this type of vulnerable area?

An image of a map showing highly vulnerable aquifers.
An image of a map showing highly vulnerable aquifers.

Source protection planning policies are only recommendations in highly vulnerable aquifers (HVAs) and significant groundwater recharge areas (SGRAs) of this region (Ausable Bayfield Maitland Valley Drinking Water Source Protection Region).

Policies do not have legal effect that requires property owners to comply in HVAs and SGRAs (except in a wellhead protection area Zone A, B, or C) as there are no assessed significant threats to drinking water in HVAs and SGRAs. However, municipalities, implementing bodies, and local people should have regard for these policies, developed locally and approved by the Province of Ontario.

Thank you for all you do to protect drinking water sources in all vulnerable areas. Take a look on this website at some of the ways you can protect drinking water sources with your positive actions at home and work.

For complete definitions, legislation, and regulations visit

For maps, local source protection plans, assessment reports, and explanatory document, visit

Site map for the Keeping Water Clean website: