At our April meeting we had the treat of listening to Mark Lake’s enthusiastic update on the BWS aquifer mapping project. Since 2021 Mark has been working with faculty and students from the University of Victoria and local BWS volunteers to start mapping aquifers along the eastern Beaufort Watersheds. The technique uses vertical electric soundings (VES), which are resistivity surveys, to estimate the surficial geology (gravel, sand, clay, shale, glacial till etc.) and bedrock geology (shale, conglomerate, siltstone etc.) —down to a depth of around 100m below surface. To date, 29 sites have been surveyed.
The exciting find in the last couple years has been provincial online data from over 200 wells up to 100 years old, that were used for coal exploration. Drilling data from these wells provides very specific information on the type of geology, including freshwater aquifers, at various depths. These data provide excellent validity checks (“ground truthing”) for our vertical electric soundings at nearby locations.
With the help of students and faculty from the Vancouver Island University Geographic Information System (GIS) program, and Mark’s self-taught GIS course, the project benefits from a growing number of ArcGIS maps of our area. These maps show where the VES soundings have been done, and where the exploratory coal and community wells are located—all in relation to our watersheds. Mark is now starting to produce maps of bedrock elevation and glacial isopach. Glacial isopach is the thickness of glacial drift, the material deposited by glaciers, across a geographic area. Most of the freshwater aquifers in our area, are located within this zone. For those of us in Fanny Bay, Mark’s first maps show bedrock elevation, glacial isopach and the edge of glacial deposits around the Wilfred Creek watershed.
We are hoping to have another honours student from UVic in the 2025-26 academic year. That’s when BWS volunteers may once again, get to pound in and remove steel spikes for the soundings. It’s all fascinating!
A huge thank you to Mark for all the work he’s doing, and for teaching us introductory geology!