Shallow nearshore groundwater chemistry and estimates of groundwater seepage were collected across 21 locations along Lake Spokane, WA, beginning in October 2016 and ending in October 2019. Groundwater chemistry was collected using temporary mini-piezometers and seepage rates from Lee-type seepage meters. Sample locations are divided into two distinct types: Primary sites, where seepage data and groundwater chemistry were collected, and secondary sites, which were only sampled for groundwater chemistry. This data release includes two Comma Separated Value (CSV) files, one containing the individual seepage meter measurements, and a second that includes all groundwater chemistry. Included in the file of groundwater chemistry are estimates of vertical hydraulic gradients determined from sample piezometers using a field manometer. This data were collected to support an investigation of groundwater nutrient loading to Lake Spokane, WA (Sheibley and Foreman, 2020).