This data release reports the concentration results for organic compounds (disinfection byproducts [DBP], pesticides, per- and polyfluoroalkyl substances [PFAS], pharmaceuticals and volatile organic compounds [VOC]), cyanotoxins, microbiological indicators, as well as radon-222 analyzed in samples collected from private well and public supply sourced tapwater samples from a community in Montana. A total of 26 samples were collected, plus one quality-control field blank, from 18 residences with private wells and 8 locations who receive their water from public supply sources. Pesticide and DBP compounds were analyzed at the U.S. Geological Survey (USGS) Organic Chemistry Research Laboratory in Sacramento, California; radon-222, PFAS and VOC were analyzed at the USGS National Water Quality Laboratory in Denver, Colorado; pharmaceutical compounds were analyzed at the USGS Organic Geochemistry Research Laboratory in Lawrence, Kansas; microbiological indicators were analyzed at the USGS Michigan Bacteriological Research Laboratory in Lansing, Michigan. Estrogenicity samples were analyzed at the USGS Eastern Ecological Science Center, Leetown, West Virginia. Trace elements and rare earth elements were also analyzed for this study. The results and associated information can be found here: Schreiner, M.L., Romanok, K.M., Bradley, P.M., Smalling, K.L., Meppelink, S.M., McCleskey, R.B., and Roth, D.A., 2024, Concentration results for inorganic constituents in discrete tapwater samples, Montana, 2024: U.S. Geological Survey data release, https://doi.org/10.5066/P1DQ7ZFQ.

Toxic harmful algal blooms are caused by cyanobacteria and can pose a threat to freshwater ecosystems, including the western basin of Lake Erie. Bloom toxicity can be influenced by variation of biosynthetic repertoires of toxic cyanobacteria but is not well studied beyond microcystins. Water samples collected by the National Oceanic and Atmospheric Administration from July 2016 through October 2022 were filtered and extracted to be analyzed qualitatively by liquid chromatography/high resolution mass spectrometry to help determine spatiotemporal patterns of cyanobacteria, cyanopeptides, and biosynthetic gene clusters by providing metabolomic data. The data files included in this data release describe a sample's identifying information, the chromatographic peak areas detected in a sample during qualitative analysis that indicates a potential compound match to a chemical structure within Thermo Fisher's Compound Discoverer 3.3 database, and a numerical peak rating used to identify the metabolic peaks within a sample. The peak rating combines peak quality and peak reproducibility and ranges from 0 to 10 with 10 being the best rating.

With mortalities of avian wildlife sometimes inferred to be associated with exposure to harmful algal bloom events, the need for clarifying diagnostic parameters for helping to justify case diagnoses is needed. Hence, adult female mallard ducks (Anas platyrhynchos) were exposed to a controlled administration of microcystin-LR, and their liver cells were studied for biomarkers of exposure and effect by using flow cytometric and microscopic methods, and an enzyme assay.

The EPA National Coastal Condition Assessment (NCCA) is a nation-wide survey of coastal and estuarine water quality. During the 2015 EPA NCCA, samples were collected for analysis of algal toxins and cyanotoxins at the Organic Geochemistry Research Laboratory (OGRL) at the U.S. Geological Survey Kansas Water Science Center (KSWSC) by liquid chromatography triple quadrupole mass spectrometry (LC/MS/MS). The 542 samples collected from the Great Lakes were analyzed for anatoxin-a, cylindrospermopsin, domoic acid, 10 microcystin congeners, nodularin, and okadaic acid. A subset of samples were also analyzed for dinophysistoxin-1, dinophysistoxin-2, gymnodimine, pectenotoxin-2, and 13-desmethyl spirolide c.

The U.S. Environmental Protection Agency (EPA) National Coastal Condition Assessment (NCCA) is a nationwide survey of coastal and estuarine water quality. During the 2015 EPA NCCA, samples were collected at 732 sites for analysis of algal toxins and cyanotoxins at the Organic Geochemistry Research Laboratory (OGRL) at the U.S. Geological Survey Kansas Water Science Center (KSWSC) by liquid chromatography triple quadrupole mass spectrometry (LC/MS/MS). Samples from the Atlantic, Gulf, and Pacific coasts of the conterminous U.S. were analyzed for anatoxin-a, cylindrospermopsin, domoic acid, dinophysistoxin-1, dinophysistoxin-2, gymnodimine, 10 microcystin congeners, nodularin, okadaic acid, pectenotoxin-2, and 13-desmethyl spirolide c.

This dataset contains algal identification and enumeration data for phytoplankton samples collected by the U.S. Geological Survey (USGS) between July 2019 and November 2019 at seven reservoirs across the United States. Reservoirs sampled included Lake Koshkonong, Wisconsin, Pelican Lake, Minnesota, Lake Ida, Minnesota, Pomme de Terre, Minnesota, Lake Emily, Minnesota, Milford Lake, Kansas, and Jordan Lake, North Carolina. The samples were analyzed at the Caribbean - Florida Water Science Center (CFWSC) Phycology Laboratory using morphology-based microscopy methods. This data is part of a larger multi-agency project between the U.S. Environmental Protection Agency, the National Aeronautics and Space Administration, the National Oceanic and Atmospheric Administration, and USGS called the Cyanobacteria Assessment Network (CyAN). The goal of the CyAN project is to develop a satellite-based, early warning system to detect harmful algal blooms (HABs) in freshwater systems.

Microcystins (MC) are a class of cyanotoxins produced by many cyanobacteria taxa. Although toxic to metazoans, the evolution of microcystin pre-dates the appearance of metazoans, and so MC did not originate as a toxin to potential metazoan grazers. One hypothesized functional role of microcystin is the management and acquisition of metals, several of which form complexes with MC intracellularly. Metals are often used to build enzymes within the cell that allow cyanobacteria to use non-preferred nitrogen (N) and phosphorus (P) sources, such as nitrate, urea and organic P. If trace metals are in low supply, primary producers may become limited because of their inability to access these non-preferred N and P forms. Furthermore, if MC are used for metal acquisition and management, we would expect that as demand for these trace metals varies, so will the production of MC. We performed 7 mesocosm experiments in triplicate on naturally occurring phytoplankton communities from two nearshore habitats that experience annual cyanobacterial blooms (Green Bay, Lake Michigan and Maumee Bay, Lake Erie). In these experiments, we provided natural communities with amendments of labile nutrients (NH4+ and/or PO43-) and trace metals (Fe, Zn, Ni and Mo) and measured growth (as chlorophyll a), the relative abundance of MC-producing genes (mcyE gene copies), the relative abundance of MC-producing RNA and the MC concentration. Experiments were performed by James H Larson and Sean W Bailey at the Upper Midwest Environmental Sciences Center (UMESC). Genetic measurements were performed by Erin A. Stelzer (Ohio-Indiana-Kentucky Water Science Center) on samples collected at UMESC. Cyanotoxin measurements were performed by Keith A. Loftin (Kansas Water Science) on samples collected at UMESC.

The Bonnet Carré Spillway (BCS), located about 28 miles northwest of New Orleans, Louisiana, was constructed in the early 1930s as part of an integrated flood-control system for the lower Mississippi River Plain. The BCS is designed to divert water from the Mississippi River (MSR) into Lake Pontchartrain (LP), which then flows into Lake Borgne and the Mississippi Sound (MS Sound), thus relieving pressure on levees downstream. Opening of the spillway occurs when measured streamflow in the MSR at New Orleans exceeds approximately 1.25 million cubic feet per second, which normally occurs once a year in late spring. In 2019, for the first time, the spillway opened twice in one year; the first opening occurred between February 27th and April 11th and the second occurred between May 10th and July 22nd (U.S. Army Corps of Engineers, 2022). Monitoring the quality of estuary surface waters that receive inflows from the MSR diverted through the BCS is of vital importance to public and natural resource managers in Louisiana and Mississippi. These waterbodies provide habitat for many species of fish, shellfish, crabs, seagrass, and marine mammals, and are used for recreational activities and commercial fishing (U.S. Geological Survey, 2020). During the 2008–2020 BCS openings, MSR water entered LP and changed the brackish-estuarine system to a freshwater-dominated system, with some areas maintaining low salinity for 2 to 3 months. The introduction of nutrient-rich fresh river water into nutrient-poor brackish LP is known to substantially change the chemistry and ecology of the lake (Mize and Demcheck, 2009). Except for large openings during 2011 and 2019, algae blooms appear to be generally relegated to LP, particularly the northwest part of the lake, and in some instances, originating from Lake Maurepas.  Although not normally an acute health hazard, these blooms can substantially limit the use of lake and sound waters for commercial and recreational activity. The U. S. Geological Survey (USGS), Lower Mississippi-Gulf Water Science Center, in cooperation with the U.S. Army Corp of Engineers (USACE) New Orleans District, sampled water from LP and the western MS Sound prior, during, and after the seven BCS openings that occurred between 2008 and 2020. Water samples were analyzed for major ions, nutrients, inorganic plus organic particulate carbon, total suspended solids, chlorophyll a, and algal toxins; results are available on the USGS National Water Information System (NWIS; U.S. Geological Survey, 2022). Vertical water column profiles of field water quality parameters, phytoplankton community sample results from 2008, 2011, 2013, 2016, 2018, 2019, and 2020, and oxygen and hydrogen stable freshwater isotopic composition sample results from 2019 and 2020 are reported in this data release. Field water-quality measurements were collected using a water quality sonde equipped with a depth transducer for measuring water depths and sensors for measuring water temperature, specific conductance (salinity), pH, dissolved oxygen, and oxygen percent saturation. Profile measurements were collected from 0.5 m above the water-sediment interface at the bottom, at mid-depth, and 0.5 m below the approximate water surface to help determine whether any water quality stratification is occurring, including salinity stratification and hypoxia in bottom waters that serve as habitat for bottom dwelling organisms, such as oysters. In addition, near-surface habitats, those found at the top of the water column, can exhibit elevated pH and oxygen saturation during the day when phytoplankton blooms are concentrated near the surface in the euphotic zone. Maximum depths in the euphotic zone, where photosynthesis occurs, were estimated from Secchi depth measurements. These measurements were used to guide sample collection depths for chlorophyll, phytoplankton, and algal toxins. Phytoplankton samples were collected using National Water Quality Assessment Program protocols (Moulton II et al., 2002). Samples collected in 2008 and 2011 were preserved with a 1% Lugol’s solution and sent to the Academy of Natural Sciences in Philadelphia, PA for taxonomic analysis, according to Charles et al. (2002). Samples collected in 2013, 2016, 2018, 2019, and 2020 were preserved with a 0.25-0.50% glutaraldehyde solution and sent to Phycotech, Inc. in St. Joseph, MI for taxonomic analysis. Research-grade microscopes ranging from 40-1,000x magnification were used to identify phytoplankton in samples to the most practical taxonomic levels (normally, species or genus level). Oxygen and hydrogen stable isotopic (? 18O and ?D) compositions were determined from samples collected in 2019 and 2020. The combination of salinity and isotope results were used to distinguish proportions of MSR water, water from local drainages, and seawater in LP and MS Sound throughout the sampling period. Water samples and salinity measurements were collected from the surface of the water column and filtered with a 0.45 µm syringe filter and stored in glass amber bottles with lids that were securely covered with parafilm to prevent evaporation. Isotopic analysis was performed using isotopic ratio infrared spectroscopy (Sanial et al., 2019). This data set provides profile measurement, phytoplankton, and oxygen and hydrogen stable freshwater isotopic composition data for Lake Pontchartrain and the Mississippi Sound collected between 2008 and 2020. "Table_1_Station_Data.txt" contains profile data (latitude, longitude, station name, etc) for all sites sampled and an overview of data available for each site by year. "Table_2_Field_physiochemical_profile_data_2008_2019.txt" contains physiochemical data (temperature, specific conductance, salinity, etc) for all sites sampled. "Table_3_Phytoplankton_Community_Data_2008_2020.txt" contains taxonomic data for all sites sampled. "Table_4_Salinity_and_stable_water_isotope_2019_2020.txt" contains oxygen and hydrogen stable isotopic composition data for all sites sampled.

This U.S. Geological Survey (USGS) data release provides discretely measured cyanotoxin, chlorophyll-a, and cyanobacterial toxin genetic data for samples collected from twelve large river sites throughout the United States, from June through October 2019. Discrete water-quality samples were analyzed for cyanotoxins (anatoxin, cylindrospermopsin, microcystin, and saxitoxin), chlorophyll-a, and cyanobacterial toxin genetics as part of a National Water-Quality Assessment Project pilot study to describe cyanobacteria and cyanotoxin occurrence in the Nation's large rivers.The data release contains the genetic data (in .csv and .xlsx formats), qPCR standard curve information (in .csv and .xlsx formats), and a readme file explaining the data headers for the genetic and standard curve files.

This U.S. Geological Survey (USGS) Data Release provides phytoplankton data for samples collected from twelve large river sites throughout the United States, from June through October 2019. All data are reported as raw calculated values and are not rounded to USGS significant figures. The dataset includes all routine and quality assurance/quality control samples collected as part of a National Water Quality Assessment Project pilot study to describe cyanobacteria and cyanotoxin occurrence in the Nation's large rivers. Phytoplankton were identified to the lowest possible taxonomic level with both abundance (reported as both natural units and cells) and biovolume reported.