Water level data for four sites in the coastal marsh at Grand Bay National Estuarine Research Reserve, Mississippi, from October 2018 through January 2020

Four Solinst LTC Levelogger Edge (Model 3001) M10 or M20 sensors were used to record water levels, conductivity and temperature at Sites 5–8. Before deployment, each sensor was programmed to record at a continuous 30-minute interval over the course of the 3-month deployment. In October 2018, 1.5-m long wells were installed at each of the four study sites so approximately 0.5 m of the wells were sticking out of the marsh or estuary surface. At the start of each trip the loggers were wrapped in a protective coating (plastic wrap, nylon stockings, and tape) and tied onto the well cap. Measurements of the string and logger length were collected for post-processing of the data. The logger was slowly lowered into the well and the well cap was secured. GPS position and elevation data were collected (using a real time kinematic global positioning system) on the top of the well cap and at the marsh surface next to the well.

After the initial deployment in October 2018, the water level loggers were collected and redeployed quarterly along with sediment plate deployments (February 2019, May 2019, August 2019, and November 2019). Each collection consisted of gently removing the logger from the well and noting if there was sediment in the well. If there was sediment in the well, it was cleaned and moved to a new location, a new water level logger was then placed inside the well. Measurements at the new location were collected for the string and logger as well as GPS coordinates and elevation. In August 2019, the Site 8 well was removed due to a crack in the well casing. In November 2019 (FAN 20CCT01), the three remaining Solinst LTC loggers were swapped out for In-Situ Rugged Troll 100 loggers. Inspection of the wells located at Sites 5 and 6 revealed that both were full of sediment; consequently, they were removed, cleaned, and redeployed. Additionally, in November 2019, an In-situ Rugged BaroTroll was deployed at the GNDNERR to collect barometric readings, since the In-Situ Rugged Troll 100 loggers only recorded water level data.

Water level, temperature, and conductivity data were downloaded from the Solinst loggers as raw uncorrected data. Temperature and barometric pressure from two local meteorological stations were obtained from the National Estuarine Research Reserve System Centralized Data Management Office for use with the 18CCT10-19CCT04 data. The In-Situ loggers used in the 20CCT01 data file does not include conductivity as the logger only collects water pressure and temperature. The barometric pressure was obtained from the Rugged BaroTroll logger deployed during the same time frame. The raw water pressure, temperature, and meteorological data were run through an R Studio code to convert the date into Coordinated Universal Time (UTC), corrected the water level based on the sensor depth, converted the elevation data into the North American Vertical Datum of 1988 (NAVD88), and clipped the data to a specified date range. Barometric pressure was used to correct level logger pressure data. For the Solinst loggers, the barometric data were generated from the NOAA meterological stations, whereas the In-Situ loggers had barometric corrections (barometric data collected by the BaroTroll logger) automatically completed within the In-Situ software. Data were then adjusted using elevation information and compared to NOAA tide and currents station 8740166 and/or 8739803. Elevation adjustment values include: 19CCT01 (Site 5 (-1.02 m), Site 6 (-0.92 m), Site 7 (-1.09 m), and Site 8 (-1.09 m)), 19CCT02 (Site 5 (-1.06 m), Site 6 (-0.82 m), Site 7 (-0.92 m), and Site 8 (-0.92 m)), 19CCT03 (Site 5 (-1.09 m), Site 6 (-1.02 m), Site 7 (-0.87 m), and Site 8 (-1.02 m)), 19CCT04 (Site 5 (-0.96 m), Site 6 (-0.93 m), and Site 7 (-0.92 m)), and 20CCT01 (Site 5 (-0.86 m), Site 6 (-0.61 m), and Site 7 (-0.82 m)). The final data output format was a CSV file. The final 19CCT04 Site 7 elevations were corrected by 0.14 m to account for field measurement error (data were not collected prior to moving well). The 19CCT02 Site 5 and 8 raw logger data showed sensor drift and were corrected and published as both corrected and uncorrected data. To ensure consistency with USGS publication standards, uncorrected data (raw water level or conductivity data that could not be corrected through sensor level or detrending adjustments) were also included in this publication. Both conductivity and water level data should be checked before use. For additional information about data corrections and detrending, please contact the authors.

Added keywords section with USGS persistent identifier as theme keyword.