This U.S. Geological Survey (USGS) Data Release provides analytical data from samples and measurements completed at the National Crude Oil Spill Fate and Natural Attenuation Research Site near Bemidji, Minnesota (Site) between 1984 and 2010. Included are inorganic and organic chemistry data from water, oil, and sediment samples, hydraulic conductivity data from well slug tests, and sediment grain-size distribution data from core samples. Most of these data sets have been described in previously published peer-reviewed reports, however the tabular data sets were not available with these publications. This data release provides the data in a tabular, database-ready format. Each result value in the data sets is coded to describe the kind of sample collected, the material that was analyzed, the method of analysis, and the publication where the value was originally published. Some sample codes are taken from the U.S. Geological Survey's National Water Information System (NWIS, https://waterdata.usgs.gov/nwis) and the remaining codes were developed specifically for Site data. Data dictionaries containing code definitions are available at a companion data release titled "Sampling site information, well construction details, and data dictionaries for data sets associated with the National Crude Oil Spill Fate and Natural Attenuation Site near Bemidji, Minnesota", available at https://doi.org/10.5066/F7736PDR.
In 1979, a high-pressure pipeline carrying crude oil burst near the city of Bemidji, Minnesota and spilled approximately 1.7 million liters (10,700 barrels) of crude oil into glacial outwash deposits. Since 1983, scientists with the U.S. Geological Survey, in collaboration with scientists from academic institutions, industry, and the regulatory community have conducted extensive investigations of multiphase flow and transport, volatilization, dissolution, geochemical interactions, microbial populations, and biodegradation with the goal of providing an improved understanding of the natural processes limiting the extent of hydrocarbon contamination. Long-term field studies at Bemidji have illustrated that the fate of hydrocarbons evolves with time, and a snap-shot study of a hydrocarbon plume may not provide information that is of relevance to the long-term behavior of the plume during natural attenuation. The research at the site has been supported primarily by the U.S. Geological Survey's Toxic Substances Hydrology Program.