The Grand River Watershed is the largest inland river system in southern Ontario with a total area of 6,800 square kilometers (Grand River Conservation Authority, 2016). The watershed has a population of approximately 900,000 residents across 38 municipalities including the major cities of Brantford, Cambridge, Guelph, Kitchener and Waterloo (Grand River Conservation Authority, 2016). The Grand River Watershed was chosen as the study site as it is located in an area dominated by agriculture and industry, increasing its potential for groundwater contamination. In addition, the watershed allows for greater infiltration of contaminants into the groundwater based on the varying soil texture (Meriano & Eyles, 2002). The watershed consists of sand, gravel and loams which all vary in texture and permeability.
Figure 1: Map of Study Site
Currently, there are various sources of contaminants that pose potential risk for groundwater contamination within the Grand River Watershed. These sources of contaminants, primarily agricultural and industrial, seep into the watershed through soil infiltration (Ritter et al., 2002). Agricultural sources such as animal waste and crop pesticides have significant impacts on the quality of the groundwater. These sources contribute to contamination through the process of surface runoff (Ritter et al., 2002). This introduces a significant risk for contamination in the Grand River Watershed as 70 percent of land use in the region is used for agricultural practices (Holeton, 2013). Similarly, industrial sources such as effluents and chemicals from manufacturing or processing plants also pose a risk as a result of the amount of outputs they emit in the Grand River Watershed (Ritter et al., 2002).
As a result of continuous development throughout the watershed, the landscape has altered significantly. One of the most significant transformations of the Grand River Watershed is the loss of forests and wetlands to urban, industrial and agricultural land uses. As a result of the impacts of urbanization on the quality of groundwater resources, it is important determine which areas are most vulnerable to contamination within the watershed (De Loë et al., 2002).
Land use in the Grand River Watershed is dominated by agriculture, whereas only 5-6 percent of land use is dedicated to urban development (Holeton, 2013). The combined amount of forests and wetlands on the landscape make up 20 percent of the land use in the watershed (Holeton, 2013). These landscapes are underlain by glacial deposits as the area was once glaciated by the Laurentide ice sheet between 20-12 thousand years ago (Meriano & Eyles, 2002). This environment is therefore composed of Pleistocene glacial sediments including sand, silt and gravel (Meriano & Eyles, 2002). Such materials in the watershed derive a rather permeable surface (Meriano & Eyles, 2002). As well, this glacial period developed the aquifers to lie above the bedrock, allowing for greater potential for contaminants to infiltrate into the groundwater (Meriano & Eyles, 2002). The geology of this site creates a permeable watershed thus making it more vulnerable to groundwater contamination.