Ten groundwater piezometers and lake-level stilling wells were deployed in Upper Klamath Lake (UKL), Oregon during May through October 2017. Piezometers and stilling wells were deployed in pairs so that water levels could be measured relative to a common measuring point (MP) at each location. Piezometers were installed in the lakebed sediment, with screens from 3.92 to 4.92 feet below the sediment-water interface (lakebed). Stilling wells were screened open to the lake. Continuous water-level data were collected at nine locations using submerged pressure transducers. One barometric pressure transducer was deployed so that continuous water-level data could be barometrically compensated. Discrete depth-to-water check measurements were collected at all ten locations at about two-week intervals using a calibrated electric water-level tape. Continuous water-level data from submerged pressure transducers were corrected for shifts and converted to values of water level below MP using discrete depth to water-level measurements. Any data that were determined to be unrepresentative (effects from waves or field measurements) or erroneous (logger malfunction) were discarded. Continuous groundwater and lake water-level data were used to calculate vertical hydraulic gradient (VHG).