This dataset contains information from groundwater monitoring wells at the National Crude Oil Spill Fate and Natural Attenuation Research Site near Bemidji, Minnesota, USA. The information includes field and laboratory methods, site locations, and inorganic and organic chemistry data. Samples were collected between 2009 and 2023, and analyzed for inorganic anions: F (fluoride), Cl (chloride), Br (bromide), NO3 (nitrate), PO4 (phosphate), SO4 (sulfate), and cations: Ca (calcium), Na, (sodium), Mg (magnesium), K (potassium), Si (silicon), Sr (strontium), Al (aluminum), Fe (iron), Mn (manganese), Ba (barium), B (boron), Li (lithium), Ag (silver), As (arsenic), Be (beryllium), Bi (bismuth), Cd (cadmium), Ce (cerium), Co (cobalt), Cs (cesium), Cr (chromium), Cu (copper), La (lanthanum), Mo (molybdenum), Ni (nickel), Pb (lead), Rb (rubidium), Sb (antimony), Se (selenium), Sn (tin), Th (thorium), Tl (thallium), U (uranium), V (vanadium), W (tungsten), and Zn (zinc). Additionally, samples were analyzed for benzene, toluene, ethylbenzene, o, m, p-xylene, total VHC (30 volatile hydrocarbons), NVDOC (non-volatile dissolved organic carbon), methane, ammonia as nitrogen, alkalinity as HCO3 (bicarbonate), and LMWOA (low molecular weight organic acids; lactate, acetate, propionate, formate, butyrate, pyruvate, and benzoate). The following analyses were performed during a select number of years: delta 13C of DIC (dissolved inorganic carbon) delta 13C of DOC, (dissolved organic carbon) and delta 2H in H2O, delta 18O in H2O. Field measurements for specific conductance, pH, and dissolved oxygen were measured daily. Water levels were measured during the sampling events. The supporting metadata files contain site information, field and laboratory methods, water chemistry, and quality-control results. There are three tables.

The U.S. Geological Survey (USGS) collected porewater samples from nine suction lysimeters in 2018, 2019, and 2021 for analysis of organic and inorganic constituents from the National Crude Oil Spill Fate and Natural Attenuation Research Site near Bemidji, MN. In August of 1979, approximately 1,700,000 L (liters), or 10,700 barrels, of crude oil spilled onto a glacial outwash aquifer. Sampled lysimeters included L310-1.5, L310-4.5, L1802-1.8, L9014-1.5, L9014-3.0, L9014-4.5, L9017-1.3, L9017-2.5, and L9017-3.7. This data release presents data on analytes that are important indicators of biodegradation processes. Some of these analytes, if present in elevated concentrations, can be a concern regarding potential effects on human health and the environment. There is one tabulated data set containing concentrations of non-volatile dissolved organic carbon (NVDOC), ammonium (NH3-N), orthophosphate, alkalinity as bicarbonate (HCO3-), major inorganic anions, cations, and trace elements. The supporting metadata file contains site information, field and laboratory methods, water chemistry, and quality-control results. Samples were analyzed in the Reston Biogeochemical Processes in Groundwater Laboratory (RBPGL) in Reston, VA, and by a contract lab, Meadowlands Environmental Research Institute (MERI) in Lyndhurst, NJ.

The U.S. Geological Survey (USGS) collected porewater samples from nine suction lysimeters in 2018, 2019, and 2021 for analysis of organic and inorganic constituents from the National Crude Oil Spill Fate and Natural Attenuation Research Site near Bemidji, MN. In August of 1979, approximately 1,700,000 L (liters), or 10,700 barrels, of crude oil spilled onto a glacial outwash aquifer. Sampled lysimeters included L310-1.5, L310-4.5, L1802-1.8, L9014-1.5, L9014-3.0, L9014-4.5, L9017-1.3, L9017-2.5, and L9017-3.7. This data release presents data on analytes that are important indicators of biodegradation processes. Some of these analytes, if present in elevated concentrations, can be a concern regarding potential effects on human health and the environment. There is one tabulated data set containing concentrations of non-volatile dissolved organic carbon (NVDOC), ammonium (NH3-N), orthophosphate, alkalinity as bicarbonate (HCO3-), major inorganic anions, cations, and trace elements. The supporting metadata file contains site information, field and laboratory methods, water chemistry, and quality-control results. Samples were analyzed in the Reston Biogeochemical Processes in Groundwater Laboratory (RBPGL) in Reston, VA, and by a contract lab, Meadowlands Environmental Research Institute (MERI) in Lyndhurst, NJ.

The dataset consists of 30-year percentage depletion calculations, hydrocarbon group compositions, organic carbon mass fractions and hydrocarbon concentrations for 16 locations sampled at the Bemidji (MN) oil spill study site. Also included in the dataset are concentrations for 33 individual volatile hydrocarbons from the aforementioned sampling locations.

These data were collected in cooperation with the U.S. Geological Survey Hydrogeophysics Branch for the National Crude Oil Spill Fate and Natural Attenuation Research Site. Water-quality data were collected using an Ecomapper Autonomous Underwater Vehicle (AUV) and measured parameters include temperature, specific conductance, salinity, water density, pH, dissolved oxygen, total chlorophyll, and blue-green algae. These data are provided in two formats: a CSV file named AUV_WQ_North.csv, and in the Environmental Systems Research Institute (ESRI) shapefile format consisting of a group of files that have been compressed into a zip archive that is named AUV_WQ_North_shapefile.zip.

The National Crude Oil Spill Fate and Natural Attenuation Research Site is located near Bemidji, MN, USA. A high-pressure oil pipeline ruptured in 1979 releasing ~1.7 million liters of light crude oil, which sprayed over an area of ~6500 square meters and collected in topographic depressions. Approximately 75% of the spilled oil was recovered. Much of the remainder reached the water table, where it is distributed into three residual oil bodies (the north, middle, and south oil pools). Groundwater flows east-northeast toward a small lake roughly 300 m downgradient from the original spill site. Secondary reactions of sediments with byproducts from anaerobic degradation of the oil plumes cause increases in total dissolved solids, which are transported in groundwater and raise the electrical conductivity of the groundwater above background levels, presenting a potential monitoring target for electrical geophysical methods. This data release contains electromagnetic induction (EMI), ground penetrating radar (GPR), electrical resistivity tomography (ERT), and specific conductance (SpC) data collected over and within the lake where it is believed high SpC groundwater associated with degradation of the oil plume is discharging. Direct measurements of lake sediment specific conductance and temperature, as well as pore water specific conductance, are also included. The current release (ver. 3.0) contains data from 2018, 2019, and 2021. Previous versions of this data release contained only data from 2018 (version 1.0), and data from 2018 and 2019 (version 2.0). The interested user can contact Neil Terry (nterry@usgs.gov) or the USGS Hydrogeophysics Branch to obtain a copy of the original release. A revision history is also included on this root page.

The Bemidji crude oil spill site is a long-term USGS study site to understand the fate of crude oil in the shallow subsurface. A description of the site can be found at https://mn.water.usgs.gov/projects/bemidji. In 2014 concentrations of non-volatile dissolved organic carbon (NVDOC) were three times higher than diesel range organics (DRO) in the contaminant plume*. This is important because most of the NVDOC in the plume is composed of partial transformation products of compounds from the crude oil that are not reflected in a DRO analysis. In 2016 we conducted a campaign to determine if DRO values continue to reflect only a fraction of the NVDOC. These data are the results of that campaign. A total of 25 wells were sampled for DRO and NVDOC in August, 2016. Three wells with long term records were included in the sampling: 530B, 515B, and 9316D. Wells sampled in 2016 but not in 2014 include two wells located 14 m from a down gradient lake (1217B and 1217C) and one well in the zone sprayed by oil (956). *Bekins, B. A., Cozzarelli, I. M., Erickson, M. L., Steenson, R. A., and Thorn, K. A., 2016, Crude Oil Metabolites in Groundwater at Two Spill Sites: Groundwater, v. 54, no. 5, p. 681-691.

This digital dataset contains historical geochemical and other information for 255 samples of groundwater from 41 wells located within 3-miles of the San Ardo Oil Field in Monterey County, central California. Data were compiled from preexisting datasets into two separate data files described as follows: 1) a summary data file identifying each well, it's location, basic well construction, the number of chemistry samples and period of record, and data sources; and 2) a data file of geochemistry analyses for selected water-quality indicators, major and minor ions, nutrients, and trace elements, plus parameter code and (or) method, reporting level, reporting level type, and supplemental notes. A data dictionary was created to describe the geochemistry data file and is provided with this data release.

This digital dataset contains historical geochemical and other information for 271 samples of produced water from 143 sites in or near the San Ardo Oil Field in Monterey County, central California. Produced water is a term used in the oil industry to describe water that is produced from oil wells as a byproduct along with the oil and gas. The locations from which these historical samples have been collected include 101 wells; three wells (DataSet_ID 118 ,125, and 130) are located outside of the administrative boundary, but closer to San Ardo (within 3 miles) than any other oil field, and therefore they were included in this dataset. Well depth, perforation depths, and (or) depths referred to on geochemistry reports as interval of zone produced, are available for 97 of these wells. Additional sample sites include 11 storage tanks, and 31 unidentifiable sample sources. Designated well use and sample descriptions provide further insight about what the samples represent. The well use designation of most of the wells (79) is OG (oil/gas) and the samples (188) associated with these wells represent produced water. Samples from two wells (Dataset ID 28 and 130) are described as formation water. One well (Dataset ID 30) was drilled as a water-source well (WS) and used to supply groundwater in support of oil production at the time it was sampled, but later converted to an injection well. Another well (Dataset ID 103) was originally drilled as an oil well, but later abandoned and converted to an irrigation well prior to sampling. Eighteen wells have a site type designation of "injectate" based on the sample description combined with the designated well use at the time of sample collection (SF, steam flood; WD, water disposal; or WF, water flood). Most of the historical samples associated with injectate sites may represent water that originated from sources other than the wells at which they were collected. However, samples from two of these wells (Dataset ID 16 and 76) likely represent produced water as they were sampled prior to the wells being used for injection. Limited information is available about historical samples from storage tanks and unidentifiable sample sources, but these may represent pre- or post-treated composite samples of produced water from single or multiple wells. The numerical water chemistry data were compiled by the U.S. Geological Survey (USGS) from scanned laboratory analysis reports available from the California Geologic Energy Management Division (CalGEM). Sample site characteristics, such as well construction details, were attributed using a combination of information provided with the scanned laboratory analysis reports and well history files from CalGEM Well Finder. The compiled data are divided into two separate data files described as follows: 1) a summary data file identifying each site by name, the site location, basic construction information, and American petroleum Institute (API) number (for wells), the number of chemistry samples, period of record, sample description, and the geologic formation associated with the origin of the sampled water, or intended destination (formation into which water was to intended to be injected for samples labeled as injectate) of the sample; and 2) a data file of geochemistry analyses for selected water-quality indicators, major and minor ions, nutrients, and trace elements, parameter code and (or) method, reporting level, reporting level type, and supplemental notes. A data dictionary was created to describe the geochemistry data file and is provided with this data release.

The Wilcox Oil Company Superfund site (hereinafter referred to as “the site”) was formerly an oil refinery in northeast of Bristow in Creek County, Oklahoma. Historical refinery operations contaminated the soil, surface water, streambed sediments, alluvium, and groundwater with refined and stored products at the site. The Wilcox and Lorraine process areas are where the highest concentrations of volatile organic compounds, semivolatile organic compounds, polycyclic aromatic hydrocarbons, and trace elements (including metals) (collectively hereinafter referred to as “contaminants”) were measured in a local shallow perched groundwater system within the alluvium (hereinafter referred to as the “alluvial aquifer”) at the site during previous site assessments. In order to understand the potential migration of contaminants through the soil and groundwater in these areas, the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, investigated aquifer characteristics of the alluvial aquifer in the Wilcox and Lorraine process areas of the site to (1) document hydraulic conductivity and other aquifer characteristics of the alluvial aquifer that govern contaminant fate and transport, (2) describe the geospatial extent and concentration of the contaminants in the alluvial aquifer in the Wilcox and Lorraine process areas, and (3) describe the geochemical controls pertaining to oxidation and reduction governing the fate and transport and the degradation potential of contaminants in the groundwater. This data release documents the data that were collected and briefly describes how they were used to characterize the hydrogeologic framework, groundwater-flow system, geochemistry, and aquifer hydraulic properties of the shallow groundwater system. Refer to the companion larger work citation (Teeple and others, 2025) for the complete description and data analyses.