Surface and Groundwater Chemistry of Western WI : Establishing an Environmental Baseline

Abstract

The expansion of silica sand mining and concentrated animal feeding operations in western WI over the past decade has generated concerns about potential contamination of surface water and groundwater systems. However, the baseline chemical characteristics of the regional hydrologic system have never been documented. This investigation represents the first comprehensive analysis of surface water and groundwater chemistry throughout western WI, an area that encompasses sampling sites in the northeastern upper Mississippi River watershed between Barron and Tomah. The dissolved metal content of surface water sites (n=54) and municipal groundwater wells (n=13) has been quantified with each site sampled multiple times over the past 4 years to evaluate temporal variations in water chemistry. Geochemical analysis of Paleozoic stratigraphy (n~50) constrains trace metal concentrations in regional aquifers. Initial results demonstrate that surface water and groundwater in the region is very clean, with virtually all trace metals well below EPA drinking waters standards. The single exception is phosphorous, which exceeds applicable standards in both surface water and groundwater and is an important component of regional lake eutrophication events. This environmental baseline is vital to the development of reasonable and responsible environmental safeguards that will facilitate economic growth and sustainable development while protecting water resources in western WI.