PROTECTING THE WAGNER NATURAL AREA THROUGH AQUIFER DELINEATION

Wagner Natural Area (WNA), near Edmonton, Alberta, is a 260 hectare conservation area, which demonstrates great ecological diversity within a very small region. Marl ponds, mixed spruce forests, mineral-rich fens, and meadows play host to an exceptional array of flora and fauna, including 16 of Alberta's 26 orchid species. For example, the Bog Adder's Mouth orchid, one of the rarest native plant species within Alberta, is found amongst the spruce-tamarack forest of WNA. Ecological diversity and survival of WNA relies on groundwater discharge for a constant supply of mineral-rich water to its ponds and wetlands; however, the groundwater flow system may be placed under increasing pressure due to increasing urbanization. Despite the importance of groundwater to WNA and its well-studied flora and fauna, the local hydrologic regime associated with it remains poorly understood.

Electrical Resistivity Imaging (ERI) and borehole drilling were completed to delineate and refine the geologic and hydrogeologic models. Previous work suggests that a complex geologic setting of scour channels and pitted delta deposits focuses groundwater discharge within the WNA. Lithologic information obtained from groundwater well records surrounding the study area indicate that complicated glacial sand and gravel deposits overlying bedrock form the primary aquifers. Borehole results confirm that areas indicating high electrical resistivity represent zones of coarse-grained channel deposits. These buried channels focus groundwater discharge within discrete areas of WNA resulting in habitat creation and sustenance. Remote sensing was used to confirm channel margins by relating surface features to subsurface geophysical, geological and hydrogeological information. Long-term monitoring of water levels in wells and piezometers along the ERI transects has enhanced our understanding of the local groundwater regime by refining the recharge-discharge boundaries. This paper demonstrates how the integration of each of these techniques has been crucial for correlating the marl pond and vegetal distribution to the buried channel deposits sustaining this wetland.