Continuous Water Level, Salinity, and Temperature Data from Monitoring Wells in Herring River Wetlands, Cape Cod, Massachusetts, 2020-2021

Well Installation: PVC wells were installed by USGS at five of the six sites; the Dry Forest well was previously installed by collaborators at the National Park Service (NPS). USGS wells consisted of two pre-manufactured sections of 1 inch (2.54 cm) diameter well casing that were threaded together: a length of slotted screened casing and a solid well casing that stuck above the sediment surface. The slot size was 0.010 inch (~ 0.3 mm). The length of slotted section was 2.5 feet (~0.762 meters) for the deeper HROC and HRHK wells and about 0.5 feet or between 20 and 30 centimeters for the wells installed at HRP Impounded in 2020. USGS wells were installed by pushing the well section into the sediment by hand or lightly tapping the top of the well with a mallet. The tip of the slotted screened well section was pushed about 1 meter below the land surface for deep wells and about 0.3 meters below land surface for shallow wells; the threaded portion (connecting the slotted length with the solid length) was below the sediment surface. Enough well casing remained above the sediment surface to ensure the groundwater well was not over-topped with surface water (0.3 meter - 1 meter). A vent hole was drilled near the top of the solid well casing. An eye-bolt was drilled into the inward facing edge of the threaded well cap; water level loggers were hung by aircraft cable threaded through the eye-bolt and through the logger cap and secured on both ends using crimped stainless-steel oval sleeves. Exact well heights and sensor deployment lengths are summarized in a separate entity and attribute section (HR_WellSensorDeploymentHeights_20_2021.csv).
The NPS Dry Forest well was a 1.5 inch diameter PVC well (0.010 inch slotted screen) loosely capped with a PVC cap socket. The water level logger was hung using the same aircraft cable used in the other wells; however it was not attached to the cap, it hung from a bolt between holes drilled approximately 4 cm from the top of the well casing.
In June 2020 we removed previously installed wells at the Phragmites site and redeployed the loggers in wells at sites newly established for greenhouse gas flux measurements (Sanders-DeMott and others 2022; both the cross referenced journal article and data release in this metadata record). The process date represents the latest process date.

Well Logger Deployments: All well loggers for this data release were In-Situ, model type Aqua TROLL 200 (30 psi maximum pressure; "a" indicates an absolute pressure sensor that is not vented to the atmosphere). The manufacturer's accuracy specification for this sensor is +/- 0.05 percent full-scale from -5 to 50 degrees Celsius, long-term stability is less than 0.1 percent full-scale; the manufacturer's specification for resolution is 0.005 percent full-scale or better. For specific logger serial numbers used at each site, refer to the file HR_WellSensorDeploymentHeights_2020_2021.csv included with this data release.
Well data loggers were initially deployed at two sites in September 2015; in subsequent years, additional sites, wells, and sensors were added to the study and this data was released in O'Keefe Suttles and others 2020 (previously cross referenced in this metadata record). The present data release begins with data logged between 1/8/2020 and November 2021. Data loggers were periodically downloaded in the field using instrument manufacturers' software (WinSitu); data were inspected for general accuracy. Further data processing and calculation steps are described in the next process steps. Dates of site visits are listed as follows, Typha: 1/8/2020, 5/4/2020, 5/15/2020, 9/23/2020, 12/07/2020, 12/11/2020, 4/15/2021, 5/07/2021, 9/17,2021. Dry Forest: 1/8/2020, 7/16/2020, 9/23/2020, 12/07/2020, 12/11/2020, 4/15/2021, 5/07/2021, 11/02/2021. Wet Shrub: 1/8/2020, 7/16/2020, 9/23/2020, 12/07/2020, 12/11/2020, 4/15/2021, 5/07/2021, 11/02/2021. Phragmites Shallow: 1/8/2020, 4/29/2020, 5/21/2020, 6/18/2020. Phragmites_Restricted_LowSal: 6/18/2020, 7/16/2020, 7/28/2020, 8/12/2020, 8/25/2020, 9/23/2020, 10/19/2020, 11/20/2020, 12/07/2020, 12/11/2020, 4/14/2021, 5/07/2021, 7/13/2021, 8/12/2021, 9/17/2021, 11/17/2021. Phragmities_Restricted_HighSal: 6/18/2020, 7/16/2020, 7/28/2020, 8/12/2020, 8/25/2020, 9/23/2020, 10/19/2020, 11/20/2020, 12/07/2020, 12/11/2020, 4/14/2021, 5/07/2021, 7/13/2021, 8/12/2021, 9/17/2021, 11/17/2021.
The process date represents the most recent end date for this process step.

A barometer (In-Situ BaroTroll 500; serial number 427140) was deployed in air (~1.5 meters from soil surface) near to the HRP well sites for the duration of the time-series measurements. The manufacturer's accuracy specification for this sensor is +/- 0.05 percent full-scale from -5 to 50 degrees Celsius, long-term stability is specified as less than 0.1 percent full-scale; the manufacturer's specification for resolution is 0.005 percent full-scale or better.
Logged atmospheric pressure from this barometer was used to correct logged pressure data from the non-vented water level sensors deployed in wells around the Herring River study sites using manufacturer software (WinSitu BaroMerge). Corrected pressure was converted to sensor depth assuming a brackish water density for all sites (WinSitu: 1.012 grams per cubic centimeter). Barometric pressure and density corrections were processed throughout the deployment period and checked while finalizing the data report. Corrected pressure and barometric pressure are reported in this data release.
Data from all continuous monitoring sensors were exported from manufacturers' software as a .csv file and compiled using MATLAB (R2020b). Water elevation calculations were performed in MATLAB as described in the following process steps. Data resulting from erroneous measurements (malfunctioning sensors or insufficient water within a well) were excluded from the final dataset. Data were processed throughout the deployment period and checked while finalizing the data report; the process date represents the latest date of data processing.

Field measured deployment heights for specific time periods are summarized in a comma separated text file (HR_WellSensorDeploymentHeights_2020_2021.csv) included with this data release. These deployment heights were used to convert sensor depth (calculated from pressure in the manufacturer's software; described in previous process step) to water depth below land surface (dbs) and water elevation with respect to NAVD88 (WL_NAVD88). Calculations were processed throughout the deployment period in MATLAB (R2020b). Positive dbs indicates water above the land surface; negative dbs indicates water below the land surface. The following parameters are used for these two calculations (units for all measurements are in meters): a: depth of sensor as calculated in manufacturer's software (see previous process step for description of measured pressure data and assumptions of density constants; positive value when sensor pressure is greater than barometric pressure) b: land surface elevation (in the NAVD88 datum) at deployment location measured by RTK (land_surface_elevation; positive above (elevation) and negative below the datum) c: deployment well height above land surface measured periodically in the field using a meter stick (height_above_land_surface; always positive) d: total length of the deployment cable and water level sensor measured in the field using a meter stick (deployment_length; always positive)
Well water elevation is calculated as: WL_NAVD88 = a+b+c-d
Well water depth below land surface is calculated as: dbs = a+c-d
Calculations were processed throughout the deployment period; the process date represents the latest date of data processing.