The data herein are geochemical (from X-Ray fluorescence spectrometry), grain size (percent clay, silt, sand), lithological (loss on ignition data), bathymetric, reconstructed IVT, and radioactive isotopes (14-C, 210-Pb, 226-Ra, and 137-Cs). These data were collected from sediments from Leonard Lake, Mendocino County, California, USA starting in 2014. Together, these data provide evidence for a record of extreme precipitation going back three millennia, showing regional pluvial and drought cycles.

These data are the geochemical (from X-ray fluorescence spectrometry), grain size, lithological (loss on ignition), diatom assemblages (taxa counts), bathymetric, and radioactive isotopes (210-Pb, 137-Cs) from sediments from Wildcat Lake, Point Reyes National Seashore, California, USA starting in 2021. Taken together, they provide evidence for extreme precipitation events linked to atmospheric rivers. They also indicate anthropogenic involvement in the watershed.

These data are the geochemical (from X-ray fluorescence spectrometry), grain size, lithological (loss on ignition), diatom assemblages (taxa counts), bathymetric, and radioactive isotopes (210-Pb, 137-Cs) from sediments from Wildcat Lake, Point Reyes National Seashore, California, USA starting in 2021. Taken together, they provide evidence for extreme precipitation events linked to atmospheric rivers. They also indicate anthropogenic involvement in the watershed.

Sediment samples, including marsh and estuarine surface samples and marsh push and peat-auger cores, were collected from Point aux Chenes, Mississippi from October 23-26, 2018, and August 4, 2021. Marsh surface samples (top 1 centimeter (cm) of sediment; sample names appended with S), marsh push cores (core names appended with M) and peat-auger cores (core names appended with R) were collected along 50-meter (m), shore perpendicular, transects identified as sites 5, 6, 7, and 9. All samples in the dataset are referred to by alternate field activity number (FAN) 18CCT09 (FAN 2018-358-FA) and alternate FAN 21CCT02 (FAN 2021-320-FA). Estuarine PONAR grab samples (sample names appended with G), marsh surface samples, and push cores were collected and brought back for sedimentological analyses including dry bulk density, organic content, grain-size for the development of a sedimentological baseline, and gamma spectroscopy for the development of geochronologies. Peat augers were collected, described for depth to peat, and discarded in the field. Marsh and estuarine surface and core sediment samples are part of the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center's (SPCMSC) Estuarine-MaRsh Geology (EMRG) and Sea-level and Storms Impacts on Estuarine Environments and Shorelines (SSIEES) research projects which study how and where short- and long-term marsh and estuarine coastal process interact in order to identify and evaluate geologic and geomorphic variables influences on marshes and their resiliency under different storm and sea-level scenarios, determine marsh-upland boundary change rates, and sediment accumulation and erosion rates. Note: This data release was revised on August 2, 2021, and versioned on August 23, 2023. Please see the Suggested Citation section on the data release webpage for more details.

Sediment samples, including marsh and estuarine surface samples and marsh push and peat-auger cores, were collected from Point aux Chenes, Mississippi from October 23-26, 2018, and August 4, 2021. Marsh surface samples (top 1 centimeter (cm) of sediment; sample names appended with S), marsh push cores (core names appended with M) and peat-auger cores (core names appended with R) were collected along 50-meter (m), shore perpendicular, transects identified as sites 5, 6, 7, and 9. All samples in the dataset are referred to by alternate field activity number (FAN) 18CCT09 (FAN 2018-358-FA) and alternate FAN 21CCT02 (FAN 2021-320-FA). Estuarine Ponar grab samples (sample names appended with G), marsh surface samples, and push cores were collected and brought back for sedimentological analyses including dry bulk density, organic content, grain-size (for the development of a sedimentological baseline), and gamma spectroscopy (for the development of geochronologies). Peat augers were collected, described for depth to peat, and discarded in the field. Marsh and estuarine surface and core sediment samples were collected by the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center's (SPCMSC) to study how and where short- and long-term marsh and estuarine coastal process interact in order to identify and evaluate geologic and geomorphic variables influences on marshes and their resiliency under different storm and sea-level scenarios, determine marsh-upland boundary change rates, and sediment accumulation and erosion rates. Note: This data release was revised with additional data. Please see the data release webpage for more details.

Sediment samples, including marsh and estuarine surface samples and marsh push and peat-auger cores, were collected from Point aux Chenes, Mississippi from October 23-26, 2018, and August 4, 2021. Marsh surface samples (top 1 centimeter (cm) of sediment; sample names appended with S), marsh push cores (core names appended with M) and peat-auger cores (core names appended with R) were collected along 50-meter (m), shore perpendicular, transects identified as sites 5, 6, 7, and 9. All samples in the dataset are referred to by alternate field activity number (FAN) 18CCT09 (FAN 2018-358-FA) and alternate FAN 21CCT02 (FAN 2021-320-FA). Estuarine Ponar grab samples (sample names appended with G), marsh surface samples, and push cores were collected and brought back for sedimentological analyses including dry bulk density, organic content, grain-size (for the development of a sedimentological baseline), and gamma spectroscopy (for the development of geochronologies). Peat augers were collected, described for depth to peat, and discarded in the field. Marsh and estuarine surface and core sediment samples were collected by the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center's (SPCMSC) to study how and where short- and long-term marsh and estuarine coastal process interact in order to identify and evaluate geologic and geomorphic variables influences on marshes and their resiliency under different storm and sea-level scenarios, determine marsh-upland boundary change rates, and sediment accumulation and erosion rates. Note: This data release was revised with additional data. Please see the data release webpage for more details.

Sediment samples, including marsh and estuarine surface samples and marsh push and peat-auger cores, were collected from Point aux Chenes, Mississippi from October 23-26, 2018, and August 4, 2021. Marsh surface samples (top 1 centimeter (cm) of sediment; sample names appended with S), marsh push cores (core names appended with M) and peat-auger cores (core names appended with R) were collected along 50-meter (m), shore perpendicular, transects identified as sites 5, 6, 7, and 9. All samples in the dataset are referred to by alternate field activity number (FAN) 18CCT09 (FAN 2018-358-FA) and alternate FAN 21CCT02 (FAN 2021-320-FA). Estuarine PONAR grab samples (sample names appended with G), marsh surface samples, and push cores were collected and brought back for sedimentological analyses including dry bulk density, organic content, grain-size for the development of a sedimentological baseline, and gamma spectroscopy for the development of geochronologies. Peat augers were collected, described for depth to peat, and discarded in the field. Marsh and estuarine surface and core sediment samples are part of the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center's (SPCMSC) Estuarine-MaRsh Geology (EMRG) and Sea-level and Storms Impacts on Estuarine Environments and Shorelines (SSIEES) research projects which study how and where short- and long-term marsh and estuarine coastal process interact in order to identify and evaluate geologic and geomorphic variables influences on marshes and their resiliency under different storm and sea-level scenarios, determine marsh-upland boundary change rates, and sediment accumulation and erosion rates. Note: This data release was revised on August 2, 2021, and versioned on August 23, 2023. Please see the Suggested Citation section on the data release webpage for more details.

This dataset includes field measurements and laboratory analyses of surface water, bottom water (sediment-water interface), surficial (0-2 cm) sediment, pore water (0-2 cm), and biota collected in Lake Combie, California, from September 2017 through August 2021. The study area includes six sites within the reservoir where discrete samples of surface water, bottom water, sediment, and pore water were taken along the length of the reservoir at the following distances from the spillway: 0.07 miles, 0.5 miles, 0.9 miles, 1.2 miles, 1.3 miles, and 1.4 miles. The within-reservoir sites were sampled during September 2017, February 2018, and May 2018, prior to a large sediment removal operation, and again during September 2019, February 2020, and June 2020 following the removal operation. Zooplankton samples were collected at four of the six sites during the sampling period. Fish were collected from within two regions of the lake: in the Wooley Creek arm of the lower reservoir, and in the upper reservoir near the targeted area for sediment removal operations. Vertical profiles of water quality were measured with a multi-parameter sonde during water collection events and during one zooplankton event. Thirty-six surface water and thirty-six bottom water samples were collected at each site and analyzed for total mercury (filtered and particulate), methylmercury (filtered and particulate), total suspended solids, sulfate, chloride, selected dissolved nutrients, particulate 13-C/12-C and 15-N/14-N isotopic ratios, total particulate carbon and nitrogen, particulate carbon to nitrogen molar ratio, dissolved organic carbon, and dissolved organic-matter properties (absorption and fluorescence). Thirty-six bed-sediment samples were analyzed for total mercury, methylmercury, total reduced sulfur, and organic content. Pore water extracted from bed sediment was analyzed for filtered total mercury, filtered methylmercury, sulfate, chloride, selected dissolved nutrients, and dissolved organic carbon. Surface water, bottom water, and sediment collections included an additional four field replicates each for analysis - pore water had six replicates. One hundred six zooplankton samples and twenty-three replicates were analyzed for total mercury, methylmercury, 13-C/12-C isotopic ratio, and 15-N/14-N isotopic ratio. Two hundred ninety fish samples were analyzed for total mercury, methylmercury, 13-C/12-C isotopic ratio, 15-N/14-N isotopic ratio, and total mass carbon and nitrogen. Water-quality field measurements made with a multi-parameter sonde included water temperature, barometric pressure, specific conductance, dissolved oxygen, pH, and turbidity. The within-reservoir data includes seven data tables given as both machine readable tab-delimited text (*.txt) and Excel formats (*.xlsx): 1) DataDictionary_LCR17-21, the data dictionary, which provides definitions and details related to the six other data tables, and includes citations of analytical methods; 2) SurfWater_Field-Lab_LCR17-20, the surface water and bottom water data table; 3) Sediment_LCR17-20; 4) PoreWater_LCR17-20; 5) Zooplankton_LCR17-20; 6) Fish_LCR18-21; and 7) SurfWater_Profiles_LCR17-20.

This dataset includes field measurements and laboratory analyses of surface water, bottom water (sediment-water interface), surficial (0-2 cm) sediment, pore water (0-2 cm), and biota collected in Lake Combie, California, from September 2017 through August 2021. The study area includes six sites within the reservoir where discrete samples of surface water, bottom water, sediment, and pore water were taken along the length of the reservoir at the following distances from the spillway: 0.07 miles, 0.5 miles, 0.9 miles, 1.2 miles, 1.3 miles, and 1.4 miles. The within-reservoir sites were sampled during September 2017, February 2018, and May 2018, prior to a large sediment removal operation, and again during September 2019, February 2020, and June 2020 following the removal operation. Zooplankton samples were collected at four of the six sites during the sampling period. Fish were collected from within two regions of the lake: in the Wooley Creek arm of the lower reservoir, and in the upper reservoir near the targeted area for sediment removal operations. Vertical profiles of water quality were measured with a multi-parameter sonde during water collection events and during one zooplankton event. Thirty-six surface water and thirty-six bottom water samples were collected at each site and analyzed for total mercury (filtered and particulate), methylmercury (filtered and particulate), total suspended solids, sulfate, chloride, selected dissolved nutrients, particulate 13-C/12-C and 15-N/14-N isotopic ratios, total particulate carbon and nitrogen, particulate carbon to nitrogen molar ratio, dissolved organic carbon, and dissolved organic-matter properties (absorption and fluorescence). Thirty-six bed-sediment samples were analyzed for total mercury, methylmercury, total reduced sulfur, and organic content. Pore water extracted from bed sediment was analyzed for filtered total mercury, filtered methylmercury, sulfate, chloride, selected dissolved nutrients, and dissolved organic carbon. Surface water, bottom water, and sediment collections included an additional four field replicates each for analysis - pore water had six replicates. One hundred six zooplankton samples and twenty-three replicates were analyzed for total mercury, methylmercury, 13-C/12-C isotopic ratio, and 15-N/14-N isotopic ratio. Two hundred ninety fish samples were analyzed for total mercury, methylmercury, 13-C/12-C isotopic ratio, 15-N/14-N isotopic ratio, and total mass carbon and nitrogen. Water-quality field measurements made with a multi-parameter sonde included water temperature, barometric pressure, specific conductance, dissolved oxygen, pH, and turbidity. The within-reservoir data includes seven data tables given as both machine readable tab-delimited text (*.txt) and Excel formats (*.xlsx): 1) DataDictionary_LCR17-21, the data dictionary, which provides definitions and details related to the six other data tables, and includes citations of analytical methods; 2) SurfWater_Field-Lab_LCR17-20, the surface water and bottom water data table; 3) Sediment_LCR17-20; 4) PoreWater_LCR17-20; 5) Zooplankton_LCR17-20; 6) Fish_LCR18-21; and 7) SurfWater_Profiles_LCR17-20.

This dataset holds data associated with the stratigraphic descriptions and grain size analyses and the radiocarbon age dating for the journal article "Stratigraphy and eruption history of maars in the Clear Lake Volcanic Field, California"