This data set was compiled to support the development of a model of oxygen reduction rates in Wisconsin groundwater wells; a model which is part of a Groundwater Nitrate Decision Support Tool for Wisconsin. Data were compiled from previously published studies with data collection from 1987 to 2009. Only data describing redox condition, groundwater age, depth to water, and well construction were compiled, though a majority of these studies presented a broader suite of analytes. Parameters compiled include dissolved oxygen, nitrate, indicators of denitrification, and parameters used in estimating groundwater age including tritium and chlorofluorocarbon (CFC) concentration. Age estimates based on these data, where published, were also included in this data set. The compilation of this data set did not involve quality control evaluation of the data; rather any qualifiers indicating data quality that were reported as part of the source data set were included.