20210625 20085300 1.0 TRUE Aquifer Vulnerability Index The Aquifer Vulnerability Index (AVI) is a method for assessing the vulnerability of aquifers to surface contaminants. An aquifer is a geologic formation that is permeable enough to transmit sufficient quantities of water to possibly support the development of water wells. In the assessment of aquifer vulnerability to potential contamination, the depth to the aquifer and the types of geological materials above them are considered. For example, aquifers closer to the surface overlain with pervious surface materials are more vulnerable to contaminants, as compared to aquifers found deeper and covered with thick layers of impervious materials. The AVI ratings indicate the potential of surficial materials to transmit water with contaminants to the aquifer over a period of time. The AVI ratings are displayed on the map in classes ranging from low to high. An area with a low class rating implies that water percolating through the surficial materials in this area takes a long time (in the range of thousands of years) to reach the aquifer. On the other hand, in an area with a high rating, contaminated water is predicted to reach the aquifer within "tens" of years. Copyright Government of Alberta