This data release includes time series data collected at the Bremerton Naval Complex, Bremerton WA. Groundwater levels and water quality parameters in two monitoring wells were recorded every 15 minutes during a 7-month deployment. Time series data were collected from June 29, 2018, to February 26, 2019. Field deployment details and quality assurance methods are included in the following paragraphs. Groundwater monitoring well MW-709 was monitored using two data loggers. The first data logger is a non-vented pressure transducer (In-Situ Rugged TROLL 100) that was deployed resting on the well bottom (BOT). The well measurement point (MP) elevation is 16.86 feet above NAVD88 with a total depth from MP of 30.00 feet and the transducer rested at -14.14 feet below NAVD88. Data collected at this location is referenced by National Water Information System (NWIS) site ID 473324122382202. Temperature and depth were recorded every 15-mintes for the entire deployment. Time-series data from this data logger are located in the text file “MW-709_BOT_time-series_data.txt”. Temperature ranged from 12.1 to 18.8 degrees Celsius. Pressure transducers, which measure the pressure above the transducer, were programmed in feet for all loggers used in this data set. The collected depth data was corrected for changes in barometric pressure by subtracting the atmospheric (barometric) pressure (feet of water) from pressure transducer measurements for each 15-minute value, with due consideration of units. Barometric-corrected depth data was converted to water level altitude by adding an -13.41 feet offset to each 15-minute value to reference the North American Vertical Datum of 1988 (NAVD88). Water level altitude ranged from 1.75 to 6.71 feet. The second data logger is a non-vented pressure transducer (Solinst LTC Levelogger) programmed to record temperature, depth, specific conductance and salinity. The data logger was suspended from a buoy with a deployment depth of 1.55 feet below the water surface (TOP). Data collected at this location is referenced by NWIS site ID 473324122382201.The buoy system was intended to maintain a constant deployment depth below the well water surface as tidally-influenced monitoring well water levels change. There was a lag in the buoy system response to well water level changes caused by the 150 mL plastic bottle getting stuck moving up and down inside the well casing resulting in water depth fluctuation ranging from 2.77 to 8.75 feet. Temperature readings during the calibration check procedures were determined less than poor (greater than one degree Celsius lower than a NIST-certified thermistor at five temperatures); therefore, the time-series data did not meet USGS publication criteria. Specific conductance readings during the calibration check procedures were determined less than poor (greater than 15 percent lower than a calibration standard); therefore, the time-series data did not meet USGS publication criteria. Water level altitude time-series data from this data logger are located in text file: “MW-709_TOP_time-series_data.txt”. Groundwater monitoring well MW-412 was monitored using two data loggers. The first was a non-vented pressure transducer (In-Situ Rugged TROLL 100) that was deployed resting on the well bottom (BOT). The well measurement point (MP) elevation is 14.66 feet above NAVD88 with a total depth from MP of 24.00 feet and the transducer rested at -9.34 feet below NAVD88. Data collected at this location is referenced by NWIS site ID 473323122382902. Temperature and depth were recorded every 15-minutes for the entire deployment. Time-series data from this data logger are located in the text file “MW-412_BOT_time-series_data.txt”. Temperature ranged from 11.1 to 14.8 degrees Celsius. Barometric-corrected depth data was converted to water level altitude by adding an -9.40 feet offset to each 15-minute value to reference the North American Vertical Datum of 1988 (NAVD88). Water level altitude ranged from -0.06 to 2.86 feet. The second data logger is a non-vented pressure transducer (In-Situ Aqua TROLL 200) programmed to record temperature, depth, specific conductance and salinity suspended from a buoy and deployed 1.55 feet below the water surface (TOP). Data collected at this location is referenced by NWIS site ID 473323122382901. The buoy system was intended to maintain a constant deployment depth below the well water surface as tidally influenced monitoring well water levels change. There was a lag in the buoy system response to well water level changes caused by the 150 mL plastic bottle getting stuck moving up and down inside the well casing resulting in water depth fluctuation ranging from 0.95 to 4.36 feet. Time-series data from this data logger are located in the text file: “MW-412_TOP_time-series_data.txt”. Survey of MW-412 and MW-709 top-of-casing altitudes was completed on 4/26/2019. Vertical (altitude) position data was collected with RTN-GPS at each monitoring well measurement point (MP). MW-412 measured MP altitude is 14.66 feet and MW-709 MP is 16.86 feet above the North American Vertical Datum of 1988 (NAVD88). Depth to water (DTW) measurements recorded on the 15-minute interval and altitude of MP was used for calculating the offset applied to 15-minute time-series barometric corrected depth data. Offset calculation used is: Offset = (MP - Altitude - DTW - 15-minute depth). Hourly barometric pressure data from 06/01/2018 to 03/30/2019 was acquired from the Bremerton Naval Airport weather station. Missing data was flagged as not available (NA). All groundwater data was recorded at 15-minute intervals, so 15-minute time-steps were generated from barometric hourly data by keeping each hour data point constant for the remaining three 15-minute time steps within that hour. Barometric pressure in units of hectopascals at mean sea level was first converted to millimeters of mercury (conversion factor 0.7500616827) then converted to feet of water (conversion factor 0.04460334762). Depth data was corrected for barometric pressure effects by subtracting barometric pressure from each 15-minute depth data. Time-series data of barometric pressure are located in the text file: “Barometric Pressure.txt”. Tidal water level 15-minute time-series data was acquired from the National Oceanic and Atmospheric Administration (NOAA) Tide Station: 9445958 Bremerton, WA. The NOAA Tides and Currents website (https://tidesandcurrents.noaa.gov/stationhome.html?id=9445958#tides) for this station was accessed on 07/02/2019 for download of 15-minute tidal data referenced to NAVD88 from June 2018 to February 2019. Data time series was adjusted for consistent Pacific Standard Time step. Tidal water level altitude ranged from -6.02 to 11.29 feet. Time-series data of tidal levels are located in the text file: “Tidal_WL_Altitude_time_series_data.txt”. Quality assurance and control measures for continuous water-quality data were performed per USGS protocols (Wagner and others, 2006), which included temperature checks at five temperatures against a NIST-certified thermistor and specific conductance checks against calibration standards spanning the range of environmental values. Other than the temperature and specific conductance readings that were outside of publication criteria from the logger at the top of well 709, all other parameters met quality control criteria for publication and no corrections were applied. During site visits, discrete measurements of water level and water-quality data were collected, including vertical profiles to identify changes in temperature and specific conductance associated with a seawater-groundwater interface. Discrete water-quality data are published in the USGS National Water Information System database by Site ID (https://nwis.waterdata.usgs.gov/usa/nwis/qwdata).