This dataset consists of sensor profile and water sample results from monitoring campaign to investigate the effects of two dredged pits in eastern Lake Pontchartrain on dissolved oxygen conditions within the water column in and surrounding the pits over a three-year period. The borrow pits were excavated to provide soil material to nourish three nearby protected marsh sites: Bayou Sauvage National Wildlife Refuge, Turtle Bayou Protected-Side Intermediate Marsh, and New Zydeco Ridge. The southern borrow pit occupies 418 acres and was monitored using a 9-point grid. The northern pit is 330 acres and was monitored using a 12-point grid. During 2021-2023, the U.S. Geological Survey, Lower Mississippi-Gulf Water Science Center, in cooperation with the U.S. Army Corp of Engineers New Orleans District collected data in the lake. Pit areas were sampled monthly in March, April, September, October, and November and twice a month during May, June, July, and August when possible. A multi-parameter water quality sonde was used to measure dissolved oxygen concentration, pH, specific conductance, and salinity to monitor for the formation of hypoxic conditions. At each grid location, a 3-point vertical profile was measured. When hypoxic conditions were encountered (dissolved oxygen <2 milligrams per liter (mg/L)) measurements were made at 1 foot intervals to define the extent of the hypoxic zone. During each sampling event, a surface and sub-surface water sample were collected at each pit to analyze for the presence of chlorophyll, phycocyanin, and microcystin at Auburn University. Sample water was first filtered through a glass fiber filter. To measure chlorophyll, filters were extracted with 90% aqueous ethanol for 24 hours at 4°C in the dark prior to being filtered through a glass fiber filter and analyzed with a fluorometer with a non-acidification chlorophyll module. To measure phycocyanin, filters were extracted while grinding in 50mM phosphate buffer and allowed to extract in the dark for 4 hours at room temperature before extract was purified using centrifugation and passing through a 0.2 um membrane filter and analyzed with a fluorometer. To measure microcystin, filters were extracted twice for 1 hour in acidic 75% aqueous methanol prior to pooling extracts, filtered through a glass fiber filter, dried on a sample concentrator, and redissolved in a phosphate buffer prior to analysis via enzyme-linked immunosorbent assay for intracellular microcystin content. Further information on these methods can be found in Belfiore and others, 2021. In 2022-2023, at a subset of locations at each pit, additional sensor measurements for chlorophyll and phycocyanin were collected and water was sampled to measure turbidity and monitor for the presence of cyanobacteria and microcystin toxins at Tulane University. Turbidity was measured using an turbidimeter. A handheld Harmful Algal Bloom indicator was used to determine a Phycocyanin:Chlorophyll-a ratio and a fluorometer was used to measure chlorophyll-a fluorescence. Samples to monitor for cyanobacteria and microcystin toxins were collected using sterile bottles and stored at -80°C until DNA extraction and quantitative real-time polymerase chain reaction (qPCR) was performed. Sample filtration followed protocol as described in Standard Methods for the Examination of Water and Waste Water, 19th edition. Further information on this method can be found in other published reports (Sipari and others, 2010, Rinta-Kanto and others, 2005, Rantala and others, 2004, and Doblin and others, 2007).

In cooperation with the Tennessee Wildlife Resources Agency (TWRA) and University of Tennessee Knoxville (UTK), the U.S. Geological survey (USGS) collected cyanobacterial toxin concentrations (i.e., microcystin, anatoxin, cylindrospermopsin, and saxitoxin) and water-quality field data at 4 sites on the Clinch River from November 2020 to December 2023. The goal for the sample data was to better understand the occurrence and distribution of cyanobacterial toxins in a section of the Clinch River. Sample collection was primarily during the growing season, when harmful algal blooms (HABs) are known to be most active. This data release documents the toxin concentrations and water-quality data produced from the study.

This U.S. Geological Survey (USGS) Data Release provides high-resolution, nearshore, spatial water-quality data collected from Owasco Lake, New York, on June 26 and October 8, 2019. All data are reported as raw measured values and are not rounded to USGS significant figures. Continuous water-quality monitors were mounted to a boat at approximately 0.5-meters below the water surface and used to measure water nitrate, chlorophyll fluorescence (fChl), fluorescent dissolved organic matter (fDOM), dissolved oxygen, specific conductance, phycocyanin fluorescence (fPC), turbidity, pH, and temperature.

This U.S. Geological Survey (USGS) Data Release provides high-resolution, nearshore, spatial water-quality data collected from Owasco Lake, New York, on June 26 and October 8, 2019. All data are reported as raw measured values and are not rounded to USGS significant figures. Continuous water-quality monitors were mounted to a boat at approximately 0.5-meters below the water surface and used to measure water nitrate, chlorophyll fluorescence (fChl), fluorescent dissolved organic matter (fDOM), dissolved oxygen, specific conductance, phycocyanin fluorescence (fPC), turbidity, pH, and temperature.

Blooms of nuisance and toxic cyanobacteria, referred to as cyanobacteria harmful algal blooms (cHABs), occur seasonally in Saginaw Bay, Lake Huron, and pose a threat to human health, affect the quality of life, and significantly degrade the ecosystem. NOAA Great Lakes Environmental Research Laboratory and the Cooperative Institute for Great Lakes Research (CIGLR), University of Michigan, started regular water quality monitoring of Saginaw Bay, Lake Huron in 2012. Since that time the monitoring effort has expanded to incorporate additional parameters and sample locations. Physical, chemical, and biological water quality data were collected during repeated sampling trips to a set of stations before, during, and after HAB events (from May - October). Data for these discrete sampling events include: Secchi disk depth, Conductivity, Temperature and Depth (CTD), CTD specific conductivity, CTD beam attenuation, CTD beam transmission, CTD dissolved oxygen, CTD photosynthetically active radiation, turbidity, particulate microcystin, dissolved microcystin, extracted phycocyanin, extracted chlorophyll-a, total phosphorus, total dissolved phosphorus, soluble reactive phosphorus, ammonia, nitrate + nitrite, urea, particulate organic carbon, particulate organic nitrogen, dissolved organic carbon, chromophoric dissolved organic material absorbance at 400 nm, total suspended solids, and volatile suspended solids. The bulk water quality parameters were analyzed via established techniques and procedures for routine water quality monitoring and analysis (APHA 1992, 1998, 2017). This research was funded by the Great Lakes Restoration Initiative (GLRI) to support the projects “Decision Support Tools to Link Predictions to HABs and Source Water Protection”, Synthesis Observation and Response (SOAR), and Real-time Environmental Coastal Observation Network (ReCON).

This U.S. Geological Survey (USGS) Data Release provides high-resolution, nearshore, spatial water-quality data collected from Seneca Lake, New York, on July 9-10 and October 9-10, 2019. All data are reported as raw measured values and are not rounded to USGS significant figures. Continuous water-quality monitors were mounted to a boat at approximately 0.5-meters below the water surface and used to measure water nitrate, chlorophyll fluorescence (fChl), fluorescent dissolved organic matter (fDOM), dissolved oxygen, specific conductance, phycocyanin fluorescence (fPC), turbidity, pH, and temperature.

This U.S. Geological Survey (USGS) Data Release provides high-resolution, nearshore, spatial water-quality data collected from Seneca Lake, New York, on July 9-10 and October 9-10, 2019. All data are reported as raw measured values and are not rounded to USGS significant figures. Continuous water-quality monitors were mounted to a boat at approximately 0.5-meters below the water surface and used to measure water nitrate, chlorophyll fluorescence (fChl), fluorescent dissolved organic matter (fDOM), dissolved oxygen, specific conductance, phycocyanin fluorescence (fPC), turbidity, pH, and temperature.

This U.S. Geological Survey (USGS) Data Release provides high-resolution, nearshore, spatial water-quality data collected from Seneca Lake, New York, on July 9-10 and October 9-10, 2019. All data are reported as raw measured values and are not rounded to USGS significant figures. Continuous water-quality monitors were mounted to a boat at approximately 0.5-meters below the water surface and used to measure water nitrate, chlorophyll fluorescence (fChl), fluorescent dissolved organic matter (fDOM), dissolved oxygen, specific conductance, phycocyanin fluorescence (fPC), turbidity, pH, and temperature.

Episodes of low dissolved oxygen are common during the summer in the bottom water of the central basin of Lake Erie. Dissolved oxygen and temperature observations at a high temporal frequency and a broad spatial extent provide the supporting data for the development of experimental hypoxia hindcast and forecast models and aid our understanding of the development and extent of hypoxia. Underwater sensor moorings were deployed across the central basin of Lake Erie to monitor oxygen conditions by the National Oceanic and Atmospheric Administration (NOAA) Great Lakes Environmental Research Laboratory and the Cooperative Institute for Great Lakes Research (CIGLR), University of Michigan. Moorings were deployed during the summer season beginning in 2017 to collect in situ data for the following parameters, water temperature, dissolved oxygen, water current speed and direction, specific conductivity, pH, turbidity, oxidation-reduction potential (ORP), chlorophyll, phycocyanin, dissolved organic matter, and phosphorus at hourly or sub-hourly time intervals.