Water-Quality Data in and near Groundwater Flow-Through Kettle-Hole Lakes, Western Cape Cod, Massachusetts, 2003 - 2018

This U.S. Geological Survey (USGS) data release provides a comprehensive dataset of water-quality results, physical-parameter measurements, hydrologic measurements, and site information collected to study the nature and extent of water quality along groundwater flow paths adjacent to glacial-kettle lakes on Cape Cod, Massachusetts.

Water-quality samples were collected in 2003, 2005, and 2012 through 2018 in and near seven kettle lakes located on western Cape Cod, with most of the data collected in 2015-2017 from Ashumet Pond, which is located in the towns of Falmouth and Mashpee. Data were also collected at other lakes to compare the lake-specific influences of geochemistry and hydrology on the downgradient groundwater systems.  Samples were collected over the course of multi-day and multi-month sampling events to capture the influence of annual and diel changes in the lakes. Water-quality results are presented for groundwater samples collected from monitoring wells and multilevel samplers (MLS) located downgradient from the lakes; shallow groundwater samples from beneath the lake bottoms (also referred to herein as porewater samples) collected near shore by using microwells, also known as pushpoints (manufactured by M.H.E. Products1), installed 5-100 centimeters below the lake-bottom surface into known groundwater upwelling and lake-water downwelling zones near the lake shore; grab samples of lake water collected in conjunction with the near-shore groundwater samples; and profiles of the lake water column collected in deeper parts of the lake basins.

The data include field water-quality measurements of specific conductance, pH, dissolved oxygen, temperature, and alkalinity (incremental field titration method) using single-parameter field probes as well as multiprobe sondes; concentrations of samples collected for selected organic and inorganic solutes, including major cations and anions, minor elements, nitrate, nitrite, ammonium, total dissolved nitrogen, dissolved organic carbon, and dissolved inorganic carbon; concentrations of dissolved gases, including nitrous oxide and methane, absorbance of ultraviolet/visible light; stable isotopic ratios of carbon (delta 13C, d13C) measured in dissolved inorganic carbon; isotope ratios of oxygen (d18O) and hydrogen (d2H) measured in water; isotope ratios of oxygen (d18O) and nitrogen  (d15N) measured in nitrate plus nitrite; and isotope ratios of oxygen (d18O) measured in dissolved oxygen gas.

The data release also includes results from analyses of sediment-core material collected from the sediment surface to 30 centimeters below the lake bottom, and analyses of aquatic vegetation and biofilms on pebble surfaces in Ashumet Pond. The sediment-core results include total carbon and nitrogen content of dried organic material scraped from the pebbles, d13C and d15N of carbon and nitrogen of the organic matter, extractions of ammonium, and carbon dioxide and oxygen measurements used to estimate potential respiration rates from incubation experiments.

The data are compiled into ten Excel (.xlsx) tables: (1) A summary of all the sampling event names and dates (Summary Sampling Events.xlsx), (2) sample information, field measurements, and results from laboratory water-quality analyses for environmental samples collected from monitoring wells, MLSs, lake-basin profiles, and near-shore pushpoints (Water Quality Samples.xlsx), (3) results from selected water-quality analytes for laboratory duplicates, laboratory blanks, and equipment rinseate samples (QAQC Samples.xlsx), (4) distance from shore and lake-stage measurements for Ashumet Pond pushpoint site ASHPD-GWOUT-R-N at select times used in a regression equation to estimate distance to shore, and measured distances between pushpoint, MLS, and well locations relative to site ASHPD-GWOUT-R-N (Distance Calculations.xlsx), (5) approximate water-level altitudes at monitoring well and MLS sites calculated from water-level measurements made at water-table wells concurrent to water-quality sampling (Approximate Well Water Level.xlsx), (6) carbon and nitrogen concentrations and d13C and d15N of  sediment cores, aquatic vegetation, and pebble scrapings collected at Ashumet Pond (ASHPD Sediment.xlsx), (7) d18O of dissolved oxygen and water in selected groundwater samples (O2 Isotopes.xlsx), (8) details of experiments to measure potential rates of carbon dioxide and oxygen production and consumption in selected groundwater samples (CO2 & O2 Rates.xlsx), (9) sediment extractions of ammonium using potassium chloride in selected groundwater samples (KCl Extractions.xlsx), and (10) field water-quality measurements made using multiprobe sondes at Ashumet, Santuit, and Shubael Ponds (Continuous Sonde Data.xlsx).

A data dictionary file describes the entities, attributes, reporting limits, uncertainties, minimum and maximum values, analytical instruments, methods, and citations for the tables (1-10) in the dataset (Data Dictionary.xlsx).

This dataset is complemented by surface-water and groundwater temperature records and lakebed seepage data from in and near several western Cape Cod lakes, which are documented in the following data release:

Hull, R.B., Briggs, M., LeBlanc, D.R., Armstrong, D.A., McCobb, T.D., Temperature and seepage data from the lake-bottom of groundwater flow-through kettle hole lakes, western Cape Cod, MA, 2015 - 2018: U.S. Geological Survey data release, https://doi.org/10.5066/P9QLIFWV.
 
1 Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.