This dataset contains historical data on concentrations of total and dissolved organic carbon in Massachusetts streams from the U.S. Geological Survey National Water Information System (NWIS) database. The data were compiled from NWIS using site and sample selection criteria to retrieve all publicly available data from surface-water samples that contained analysis of both total and dissolved organic carbon. The data set was screened, as much as possible from the site and sample description information in NWIS, to retain only routine environmental samples from stream sites. The final data set consists of 223 samples from 52 sites and were collected from 1978 to 2007.

This data release includes water-quality data collected at 38 sites in central and eastern Massachusetts from April 2018 through May 2019 by the U.S. Geological Survey to support the implementation of site-dependent aluminum criteria for Massachusetts waters. Samples of effluent and receiving surface waters were collected monthly at four wastewater-treatment facilities (WWTFs) and seven water-treatment facilities (WTFs) (see SWQ_data_and_instantaneous_CMC_CCC_values.txt). The measured properties and constituents include pH, hardness, and filtered (dissolved) organic carbon, which are required inputs to the U.S. Environmental Protection Agency's Aluminum Criteria Calculator version 2.0. Outputs from the Aluminum Criteria Calculator are also provided in that file; these outputs consist of acute (Criterion Maximum Concentration, CMC) and chronic (Criterion Continuous Concentration, CCC) instantaneous water-quality values for total recoverable aluminum, calculated for monthly samples at selected ambient sites near each of the 11 facilities. Quality-control data from blank, replicate, and spike samples are provided (see SWQ_QC_data.txt). In addition to data tables, the data release includes time-series graphs of the discrete water-quality data (see SWQ_plot_discrete_all.zip). For pH, time-series graphs also are provided showing pH from the discrete monthly water-quality samples as well as near-continuous pH measured at one surface-water site at each facility (see SWQ_plot_contin_discrete_pH.zip). The near-continuous pH data, along with all of the discrete water-quality data except the quality-control data, are also available online from the U.S. Geological Survey's National Water Information System (NWIS) database (https://nwis.waterdata.usgs.gov/nwis).

The sampling of 41 hydrologically diverse rivers that are monitored through the National Water Quality Network (NWQN) by the U.S. Geological Survey (USGS) took place during the water years of 2008 through 2018. Water samples were collected and filtered in the field (unless otherwise noted) using 0.45 micrometer pre-rinsed capsule filters (Versapor membrane), silicon tubing, and a peristaltic pump. Water samples were then shipped on ice to the USGS in Boulder, Colorado and chilled to approximately 4 to 6 degrees Celsius until analysis. Dissolved organic carbon (DOC) was measured on an OI700 Analytical total organic carbon analyzer by wet-oxidation; each sample was measured in replicate and the average was reported. Ultraviolet (UV) absorbance at the wavelength of 254 nanometers was measured with an Agilent HP8453 UV-visible spectrophotometer. Specific UV Absorbance (SUVA) at 254 nanometers is a calculated parameter defined as the UV absorbance at a wavelength of 254 nanometers in absorbance units per centimeter divided by the DOC concentration in milligram per liter and then multiplied by 100. SUVA at 254 nanometers is reported in units of liter per milligram carbon per meter and correlates with the percent aromatic carbon of the dissolved organic matter (DOM). Iron(III) absorbs light in the UV spectrum and, if present at appreciable concentration, can influence UV absorbance values at 254 nanometers and calculated SUVA values. For sites believed to exhibit iron(III) concentrations sufficient for the UV absorbance at 254 nanometers of the DOM to be influenced, the filter-passing total iron concentrations of whole water samples were determined using a Hach spectrophotometer and FerroVer method. SUVA values were calculated using iron(III)-corrected UV absorbance at 254 nanometers for samples that were determined to have filter-passing total iron concentrations greater than 0.02 milligram per liter. Utilizing the UV-visible absorbance spectral scans, spectral slopes at wavelengths 275 to 295 nanometers and at wavelengths 350 to 400 nanometers were determined. The spectral slope ratio is a calculated parameter defined as the spectral slope at wavelengths 275 to 295 nanometers divided by the spectral slope at wavelengths 350 to 400 nanometers. Fluorescence measurements were made on a Jobin-Yvon Horiba Fluoromax-3 fluorometer. Fluorescence measurements included the wavelength of peak emission intensity at 370 nanometers excitation and the fluorescence index (FI). FI is defined as the ratio of fluorescence emission at 470 nanometers divided by 520 nanometers at excitation 370 nanometers. Additional fluorescence indices determined included the humification index (HIX) and the freshness index (β:α). Humification index values increase with the proportion of humic substances. The humification index is defined as the area under the emission spectrum from 435 to 480 nanometers divided by the summation of areas under the emission spectrum at 300 to 345 nanometers and 435 to 480 nanometers, at an excitation of 254 nanometers. The freshness index increases with the proportion of recently produced DOM and is defined as the intensity of fluorescence emission at 380 nanometers divided by the maximum fluorescence emission intensity between 420 and 435 nanometers at excitation 310 nanometers. DOM was separated into fractions by an isolation method that passes aqueous sample at pH < 2 sequentially through Amberlite XAD8 and XAD4 resins using low pressure liquid chromatography. The hydrophobic organic acid (HPOA) fraction is the eluate from the XAD8 fractionation column, and the transphilic organic acid (TPIA) fraction is the eluate from the XAD4 fractionation column. The hydrophilic organic (HPI) fraction is the effluent of the sample passed sequentially through the XAD8 and XAD4 fractionation columns. The hydrophobic organic neutral (HPON) fraction is that retained on the XAD8 column after passing the sample through at pH < 2 and back eluting with

The dataset contains the analytical results for environmental and quality-control replicate sample sets and the computed relative percent differences (RPD) greater than 25 percent for the data collected during the surface-water sampling for the Triangle Area Water Supply Monitoring Project. The data are from samples collected during October 2013 through September 2015. Several study sites contained in this dataset were sampled for other USGS projects during the same time frame. Unless the samples at these sites were collected in conjunction with the Triangle Area Water Supply Monitoring Project, the data for other projects are not included in the dataset.

The dataset contains the environmental data collected for the Triangle Area Water Supply Monitoring Project. The data are from the samples collected during routine and storm-runoff sampling events during October 2015 through September 2017. Several study sites contained in this dataset were sampled for other USGS projects during the same time frame. Unless the samples at these sites were collected in conjunction with the Triangle Area Water Supply Monitoring Project, the data for other projects at these sites are not included in this dataset.

The dataset contains the environmental data collected for the Triangle Area Water Supply Monitoring Project. The data are from the samples collected during routine and storm-runoff sampling events during October 2017 through September 2019. Several study sites contained in this dataset were sampled for other USGS projects during the same time frame. Unless the samples at these sites were collected in conjunction with the Triangle Area Water Supply Monitoring Project, the data for other projects at these sites are not included in this dataset.

This file contains the water quality data summarized in the 1998 report entitled: Baseline Water Quality Inventory, John Muir National Historic Site. The data and locations existed in the United States Environmental Protection Agency's Storage and Retrieval (STORET) water quality database management system when the report was published.

This dataset provides the expected and determined concentrations of selected inorganic and organic analytes for spiked reagent-water samples (calibration standards and limit of quantitation standards) that were used to calculate detection limits by using the United States Environmental Protection Agency’s (USEPA) Method Detection Limit (MDL) version 1.11 or 2.0 procedures, ASTM International’s Within-Laboratory Critical Level standard procedure D7783-13, and, for five pharmaceutical compounds, by USEPA’s Lowest Concentration Minimum Reporting Level procedure. Also provided are determined concentration data for reagent-water laboratory blank samples, classified as either instrument blank or set blank samples, and reagent-water blind-blank samples submitted by the USGS Quality System Branch, that were used to calculate blank-based detection limits by using the USEPA MDL version 2.0 procedure or procedures described in National Water Quality Laboratory Technical Memorandum 2016.02, http://wwwnwql.cr.usgs.gov/tech_memos/nwql.2016-02.pdf. The determined detection limits are provided and compared in the related external publication at https://doi.org/10.1016/j.talanta.2021.122139.

This file contains the water quality data summarized in the 1997 report entitled: Baseline Water Quality Inventory, Hubbell Trading Post National Historic Site. The data and locations existed in the United States Environmental Protection Agency's Storage and Retrieval (STORET) water quality database management system when the report was published.

This file contains the water quality data summarized in the 1998 report entitled: Baseline Water Quality Inventory, Thomas Stone National Historic Site. The data and locations existed in the United States Environmental Protection Agency's Storage and Retrieval (STORET) water quality database management system when the report was published.