UW Extension

Pulling together the pieces of the Bayfield County Groundwater Atlas

Grace Graham

WGNHS geologist Grace Graham heading out to do fieldwork.

Grace Graham, a geologist at the UW-Extension’s Wisconsin Geological and Natural History Survey (WGNHS), is producing a map of the depth to bedrock in Bayfield County using a passive-seismic geophysical survey to supplement data from well construction reports.

The combination of new methods (passive seismic) and old (depths taken from driller reports) is a cost-effective way to get good data about the depth to bedrock. Grace says, “The seismic data helps fill in information between the ‘dots’ of the wells.”

This depth-to-bedrock map will join a suite of maps that Graham and Madeline Gotkowitz, the project manager and senior hydrogeologist, will use to determine the susceptibility of groundwater in Bayfield County. Together those maps will make up the Groundwater Atlas for Bayfield County.

The Bayfield County Groundwater Atlas will include and expand upon the county water-table map and water well database produced by Survey hydrogeologists Anna Fehling and Madeline Gotkowitz in 2017.

Grace Graham pointing at peak in passive-seismic data.

Grace Graham reviews data from the passive-seismic recorder. She’s pointing to a peak in a graph that shows the frequency at which vibrations in the sediment are resonating. The higher the frequency, the shallower the bedrock.