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Groundwater Quality

Surficial aquifers exhibit extensive variability in depth, extent and quality. They tend to have the best water quality, but are also the most vulnerable to contamination because they are near the surface and often covered by material that has high infiltration rates. Groundwater in shallow aquifers retains many of the characteristics of the infiltrating surface water, and can become a pathway for contaminants to reach groundwater after rain.

For example, viruses and bacteria (such as E. coli) associated with livestock manure production may pose a threat to the water source. Contaminants can travel with runoff or stream water and infiltrate a shallow aquifer some distance away. Further groundwater movement could carry the contaminants to a drinking water source. Tracking where contaminants originate is difficult, and those who rely on shallow wells for drinking water need to understand the highly variable and sometimes vulnerable nature of shallow groundwater. Only the areas where most of the watershed's population and human development are located have been mapped for aquifer vulnerability. This mapping should be expanded to the rest of the watershed.

In deeper aquifers, water quality tends to decline and become saline. Saline groundwater (TDS > 4,000 mg/L) is used for industrial purposes. Allocation of saline groundwater is under the jurisdiction of the Alberta Energy Regulator (AER), which will phase out the usage of freshwater for oil field injections for in situ and SAGD operations.

Little monitoring data are available on groundwater quality in the watershed. Most information exists in baseline data that describe aquifers in their natural state between the late 1960s and early 1980s. In the Wabasca sub-watershed, approved industrial facilities produce groundwater monitoring reports that are available from the Government of Alberta. However, these are locally specific and should not be used for assessing regional water quality. The impacts of climate change and various land uses on groundwater quality and aquifers are unknown. Municipal growth, along with agricultural, industrial and commercial activities, could all have an effect. The watershed could benefit enormously from a monitoring program.

Aquifer Vulnerability

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Source: Agricultural Land Resource Atlas of Alberta.34

Mapping of groundwater resources in the Mighty Peace watershed, including delineation of areas that recharge groundwater to derive relationships between climate and water resources (river flow, lake water levels and water quality, and aquifer levels). In addition to this, groundwater vulnerability mapping is required in less settled areas of the watershed.

Alberta Health and Wellness. 2000. Arsenic in groundwater from domestic wells in three areas of Northern Alberta. Edmonton, AB