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.