Long-term threat of geogenic contaminants to water quality and quantity in the Midwestern Cambrian Ordovician Aquifer System

Regulatory and research efforts often focus on prevention and/or remediation of anthropogenic contaminants in groundwater; however, naturally occurring (geogenic) contaminants (e.g., U, Ra, As, Mn are already present within Wisconsin groundwater and is increasing in concentration and prevalence.1 Local-scale spatial variability (e.g., within a municipality) in well water quality, combined with annual and decadal temporal variation, complicate management of municipal well fields.2 In Wisconsin, low permeability formations (e.g., shales and other fine-grain deposits) within the Midwestern Cambrian Ordovician Aquifer System are rich in potential anthropogenic groundwater contaminants; however, the mechanism and timescale of processes controlling their speciation and partitioning within aquifer systems remains poorly understood. Thus, the goal of the proposed research is to quantify the contribution of release and transport of geogenic contaminant from low permeability zones and their potential impact on maintaining groundwater as a potable water resource within Wisconsin.