Continuous Water Level, Salinity, and Temperature Data from Monitoring Wells in Herring River Wetlands, Cape Cod, Massachusetts, 2021-2024

Well Installation: PVC wells were installed by USGS at seven of the eight sites; the High Toss 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 centimeters) 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 millimeters). The length of slotted section was 2.5 feet (~0.762 meters) for the HRUPD well installed for drought mitigation, HRDHF, HRHK and three of the five HRTLP wells. For all other wells the length of the slotted section was about 0.5 feet or between 20 and 30 centimeters. 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 (except for the HRTLP-Creek_174cm, HRTLP-Upland_110cm, and HRTLP-Upland_114cm wells that were screened 120-200 cm below land surface) and 0.3-0.7m 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 (0.3-1m). 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_2021_2024.csv).
The NPS High Toss 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.
One sand-packed well was installed at the Duck Harbor B site after examining logged CTD data from the initial well installation. To avoid the possibility of clogging the slotted screen section with very fine mud from this site, a second well was installed into a pre-dug shallow hole and backfilled with sand to aid in porewater exchange with the surrounding sediment.
The process date represents the latest process date.

Surface water CTD measurements at an experimental salt marsh study site, the Herring River Thin Layer Placement (HRTLP), were logged over two different time periods. From May to October 2022, a CTD was deployed in the river directly offshore from the salt marsh study site (refer to site_name "HRTLP-River"). The CTD was installed inside of a stilling well affixed to a sign post driven about 1 meter into the sediment. Deployment heights were measured upon initial deployment and when the sensor was retrieved at the end of the field season; the sensor was deployed about 10 cm from the sediment surface. Water level (NAVD88) calculations were based on deployment measurements made at the end of the deployment period 10/20/22 because they were made concurrently with RTK elevation measurements. A few centimeters of uncertainty over the course of the time series (due to the apparent slight movement of the stilling well from its initial deployment position or from sand infilling around the deployment post) is not corrected for in these calculations. In September 2023 a CTD was deployed on the marsh surface (refer to site_name "HRTLP-Marsh") at the HRTLP-Creek edge well site; a CTD was deployed horizontally along the marsh surface and affixed to adjacent wells. The last download date for this logger was November 2023. Data were excluded from the final dataset during periods when the sensors were not completely covered by site water. Description of elevation calculations are detailed in following process descriptions.
The process date represents the latest process date.

Logger Deployments: 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 previously released in two ScienceBase publications cross referenced in this metadata record (O'Keefe Suttles and others, 2020; O'Keefe Suttles and others, 2022). The present data release includes well data logged between 8/12/2021 and November 2024. Data loggers were periodically downloaded in the field using instrument manufacturers' software (WinSitu for CTDs and HOBOPro for temperature loggers); data were inspected for general accuracy. In May 2022 a new well at the Herring River Phragmites (HRP) site was installed closer to the eddy co-variance flux tower deployment. CTD data from the previous HRP well ends 5/18/2022 and data from the new well begins 5/25/2022; soil and air temperature data is reported from both sites from 5/18/2022 - 12/30/22 and then only from the new site until 9/1/2023.
Soil or air temperature sensors were co-deployed at some sites as needed for specific research purposes. Soil temperature sensors were attached to a wooden stick and pushed by hand so that the bottom of the temperature sensor was 10 cm below the land surface; at one site, HRTLP-Creek, we also installed a soil temperature sensor 100cm below the land surface. The air temperature sensor was inserted into a draft shield and attached to the groundwater well about 1 meter above the land surface. Site specific temperature sensor manufacturer make, model, serial numbers, and dates of deployment are as follows: HRTLP-Upland Onset HOBO MX2303 serial number 21079739; 5/12/2022-12/12/2022 (logged: temp_air and soil temp_10cm). HRTLP-Creek Onset HOBO MX2303 serial number 21058593; 5/12/2022-12/12/2022 (logged: soil temp_10cm and soil temp_100cm). HRDHA Onset HOBO U23-003 serial number 10897046; 4/27/2023-3/22/2024 (logged soil temp_10cm). HRDHB Onset HOBO U23-003 serial number 10897045; 4/27/2023-12/13/2023 (logged: temp_air and soil temp_10cm). HRDHC Onset HOBO U23-003 serial number 10897053; 4/27/2023-12/09/2023 (logged soil temp_10cm). HRP (41.9377049, -70.0546965) Onset HOBO U23-003 serial number 10897045; 5/18/2022-12/30/2022 (logged: temp_air and soil temp_10cm). HRP (41.9378776, -70.0549772) Onset HOBO MX2303 serial number 21058594; 5/18/2022-9/1/2023 (logged: temp_air and soil temp_10cm).
Dates of site visits are listed as follows: HR Bound Brook: 8/12/2021, 9/17/2021, 10/14/2021, 5/17/2022, 8/16/2022, 12/12/2022, 5/25/2023, 10/19/2023, 5/14/2024, 12/3/2024. HR Duck Harbor Forest: 8/12/2021, 9/17/2021, 10/14/2021, 5/26/2022, 12/12/2022, 2/17/2023. HR Duck Harbor Wetland: 8/12/2021, 9/17/2021, 10/14/2021, 5/26/2022, 5/26/2022, 8/25/2022, 1/27/2023, 4/27/2023. HR Duck Harbor A: 4/27/2023, 5/25/2023, 6/12/2023, 7/25/2023, 9/27/2023, 12/12/2023, 3/22/2024, 4/23/2024, 11/27/2024. HR Duck Harbor B: 4/27/2023, 5/25/2023, 6/12/2023, 7/25/2023, 8/16/2023, 9/27/2023, 12/12/2023, 3/22/2024, 4/23/2024, 11/27/2024. HR Duck Harbor C: 4/27/2023, 5/25/2023, 6/12/2023, 7/25/2023, 9/27/2023, 12/12/2023, 3/22/2024, 4/23/2024, 11/27/2024. HR Hopkins Wet Shrub: 11/02/2021, 5/19/2021, 6/15/2022, 8/8/2022, 12/12/2022, 5/25/2023, 10/19/2023, 4/23/2024, 12/3/2024. HR Upper Pole Dike: 10/1/2021, 10/14/2021, 12/7/2021, 5/23/2022, 8/8/2022, 8/16/2022, 12/12/2022, 6/12/2023, 10/19/2023, 4/23/2024, 12/3/2024. HR Phragmites: 11/17/2021, 5/18/2022, 5/25/2022, 7/14/2022, 12/12/2022, 3/16/2023, 5/25/2023, 9/19/2023, 10/19/2023, 5/14/2024, 12/3/2024. HR High Toss Dry Forest: 11/02/2021, 5/19/2021, 6/15/2022, 8/8/2022, 12/12/2022, 5/25/2023, 10/19/2023, 4/23/2024, 12/3/2024. HR Old County Typha: 9/17/2021, 11/2/2021, 11/17/2021, 5/12/2022, 5/18/2022, 6/28/22, 7/14/22, 8/8/22, 8/16/22, 12/12/2022, 3/16/2023, 5/25/2023, 7/25/2023, 9/19/2023, 11/16/2023, 3/22/2024, 5/14/2024, 11/27/2024. HRTLP-Creek_33cm: 5/12/2022, 6/21/2022, 6/28/2022, 8/16/2022, 10/21/2022, 9/11/2023, 11/16/2023, 4/23/2024. HRTLP-Creek_174cm: 5/12/2022, 6/21/2022, 6/28/2022, 8/16/2022, 10/21/2022, 9/11/2023, 11/16/2023, 4/23/2024. HRTLP-River: 5/23/2022, 7/25/2022, 10/21/2022. HRTLP-Upland_38cm: 5/12/2022, 6/21/2022, 6/28/2022, 8/16/2022, 10/21/2022. HRTLP-Upland_114cm: 6/21/2022, 6/28/2022, 8/16/2022, 10/21/2022. HRTLP-Upland_110cm: 8/29/2022, 10/21/2022. HRTLP-Marsh: 9/11/2023, 11/16/2023.
The process date represents the most recent end date for this process step.

A barometer was deployed in air (~1.5 meters from soil surface) in two locations over the course of the data collection time period; the first deployment was at the Herring River well sites (In-Situ BaroTroll 500; serial number 427140) until 5/25/2023 when a new logger was installed at the Old County Typha site (In-Situ BaroTroll 500; serial number 970997). Logged atmospheric pressure data from this barometer were 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 (R2021a). 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.

Well water level calculations: Field measured deployment heights for specific well logger deployment time periods are summarized in a comma separated text file (HR_WellSensorDeploymentHeights_2021_2024.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 (R2021a). Positive dbs values indicate water above the land surface; negative dbs values indicate 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 at deployment location measured by RTK (land_surface_elevation; positive above and negative below the NAVD88 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.

HRTLP-River and HRTLP-Marsh surface water level calculations: Field measured deployment heights are listed below for the two different deployment installations. These deployment heights were used to convert sensor depth (calculated from pressure in the manufacturer's software; described in previous process step) to water elevation with respect to NAVD88 (WL_NAVD88). Calculations were processed throughout the deployment period in MATLAB (R2021a).
HRTLP-River (In-Situ AquaTroll 200 serial number 845249): a: depth of sensor as calculated in manufacturer's software b: -0.178337 meters elevation (NAVD88) measured at the of the top of the stilling well at deployment location. Measured by RTK; negative elevation is below the datum. d: 0.375 meters measured distance from the top of the stilling well to the bottom of the stilling well/bottom of logger. e: 0.02 meters measured distance from the depth sensor to the bottom of the stilling well/bottom of the logger. Surface water elevation as measured from the CTD deployed in the river is calculated as: WL_NAVD88 = a+b-d-e
HRTLP-Marsh (In-Situ AquaTroll 200 serial number 845250): a: depth of sensor as calculated in manufacturer's software b: 0.2737 meters land surface elevation (NAVD88) at deployment location. Measured by RTK; positive elevation is above the datum. Surface water elevation as measured from the surface of the marsh is calculated as: WL_NAVD88 = a+b
Calculations were processed throughout the deployment period; the process date represents the latest date of data processing.