Suspended sediment concentrations from water samples collected in south San Francisco Bay, California, 2023-2024

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Frequently anticipated questions:

What does this data set describe?

Title:
Suspended sediment concentrations from water samples collected in south San Francisco Bay, California, 2023-2024
Abstract:
Water samples were collected in south San Francisco Bay between August 2023 and August 2024 to measure suspended sediment concentration. The water samples were collected near USGS instrument platforms (see time-series data page) with a peristaltic pump. The suspended sediment concentrations of the samples were determined at the USGS Pacific Coastal and Marine Science Center sediment lab. Measured suspended sediment concentrations were used to calculate calibration coefficients that can be used to convert time series of turbidity data to time series of suspended sediment concentrations. These calibration coefficients can be found in file: DMP23_Turbidity_to_SSC_calibration_constants.csv, one of the support files for the time-series data section of this data release.
Supplemental_Information:
Information about the data collection field activities can be found at: https://cmgds.marine.usgs.gov/fan_info.php?fan=2023-655-FA Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  1. How might this data set be cited?
    McGill, Samantha C., and Tan, Angela C., 20250820, Suspended sediment concentrations from water samples collected in south San Francisco Bay, California, 2023-2024: data release DOI:10.5066/P14D723N, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    McGill, Samantha C., Lacy, Jessica R., Stevens, Andrew W., Allen, Rachel M., Dartnell, Peter, Thede, Joanne C., Tan, Angela C., and Hatcher, Gerald A., 2025, Oceanographic and hydrographic monitoring data of a shallow-water placement of dredged sediment in south San Francisco Bay, California, 2023-2025: data release DOI:10.5066/P14D723N, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    Other_Citation_Details:
    Suggested Citation: McGill, S.C., Lacy, J.R., Stevens, A.W., Allen, R.M., Dartnell, P., Thede, J.C., Tan, A.C., and Hatcher, G.A., 2025, Hydrodynamic, bathymetric, and sediment transport data spanning dredge material placement in south San Francisco Bay, California, 2023-2025: U.S. Geological Survey data release, https://doi.org/10.5066/P14D723N.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -122.18533
    East_Bounding_Coordinate: -122.14645
    North_Bounding_Coordinate: 37.61126
    South_Bounding_Coordinate: 37.57592
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 10-Aug-2023
    Ending_Date: 13-Aug-2024
    Currentness_Reference:
    ground condition at time sample was collected
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Comma-separated values
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      Indirect_Spatial_Reference: Data were collected in San Francisco Bay, California
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Point (220)
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 1.0E-5. Longitudes are given to the nearest 1.0E-5. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is World Geodetic System 1984 (WGS84).
      The ellipsoid used is WGS84.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
  7. How does the data set describe geographic features?
    DMP23_SSC.csv
    Table containing attribute information associated with the dataset (Source: Producer defined)
    Sample_ID
    Sample identifier in XYY format where X identifies the data series (W for water sample) and YY indicates the number in the series. Identical Lab IDs indicates replicate samples processed by the sediment lab. (Source: Producer defined) Unique identifier for samples; assigned in the sediment lab.
    Date_Collected
    Date in MM/DD/YYYY format of sample collection. (Source: Producer defined)
    Range of values
    Minimum:08/10/2023
    Maximum:08/13/2024
    Units:Date in month/day/year format
    Time_UTC
    Time of sample collection, in hh:mm:ss format, Coordinated Universal Time (UTC) (Source: Producer defined)
    Range of values
    Minimum:15:06:00
    Maximum:21:20:00
    Units:hours:minutes:seconds format, Coordinated Universal Time (UTC)
    Latitude
    Latitude of sample location in decimal degrees, north. (Source: Producer defined)
    Range of values
    Minimum:37.57592
    Maximum:37.61126
    Units:Decimal degrees
    Longitude
    Longitude of sample location in decimal degrees, east. (Source: Producer defined)
    Range of values
    Minimum:-122.18533
    Maximum:-122.14645
    Units:Decimal degrees
    Sample_Height_MAB
    The height in meters above the seabed where sample collection occurred. MAB stands for Meters Above Bed. (Source: Producer defined)
    Range of values
    Minimum:0.15
    Maximum:2.65
    Units:meters
    Method
    Method of sample collection. (Source: Producer defined)
    ValueDefinition
    pumpSamples were collected using a peristaltic pump
    Total_Depth_m
    Water depth in meters at time of sampling, determined from the ships echosounder. (Source: Producer defined)
    Range of values
    Minimum:0.8
    Maximum:3.4
    Units:meters
    Aliquot_Volume_ml
    The volume of sample in milliliters used for the analysis. (Source: producer defined)
    Range of values
    Minimum:80.0
    Maximum:250.0
    Units:milliliters
    Sediment_Weight_mg
    The weight of the dried sediment captured by the filter. (Source: producer defined)
    Range of values
    Minimum:0.82
    Maximum:16.37
    Units:milligrams
    Suspended_Sediment_Concentration_mg/l
    The suspended sediment concentration in milligrams per liter from the sample. Calculated by dividing the dried sediment weight (in milligrams) by the liquid volume of sample filtered (in liters) to estimate the concentration of suspended sediments. (Source: producer defined)
    Range of values
    Minimum:3.56
    Maximum:118.38
    Units:milligram per liter
    Entity_and_Attribute_Overview: The first line of the csv file is a header line.
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Samantha C. McGill
    • Angela C. Tan
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Attn: PCMSC Science Data Coordinator
    2885 Mission Street
    Santa Cruz, CA

    831-460-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

These data were collected to calibrate turbidity data from optical backscatter sensors to suspended-sediment concentration. These data were collected as part of a collaborative study with USGS Western Ecological Research Center monitoring the pilot project conducted by U.S. Army Corps of Engineers San Francisco District. The study investigated the transport, impacts, and evolution of strategically placed dredged material in a shallow subtidal region adjacent to a marsh. Goals of this study were to assess the potential use of shallow-water placement for marsh management and restoration while gaining insight into local sediment transport adjacent to marshes in the shallows of south San Francisco Bay. These data are intended for researchers, students, policy makers, and the general public.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 13-Aug-2024 (process 1 of 2)
    Water samples were collected periodically between August 2023 and August 2024 using a peristaltic pump. Tubing extended from the pump to a metal frame of a known height, that was lowered off the side of the ship to a desired elevation below the water surface (after determining the total water depth from the ships echosounder). The frame was held at the desired depth until a 1-liter plastic bottle was filled. Sampling positions were recorded using the ships navigation system. Samples were placed in cold storage until processed.
    Date: 19-Aug-2024 (process 2 of 2)
    The suspended sediment concentrations of the samples were determined in the USGS Pacific Coastal and Marine Science Center sediment lab. Suspended sediment concentrations were determined by filtering a known, subsampled volume of sample through a pre-weighed 0.45 micrometer nitrocellulose membrane filter, which is then dried and reweighed to determine the mass of suspended sediment caught on the filter. The mass of the suspended sediment in the water sample was calculated by subtracting the weight of the clean filter from the weight of the dried filter with captured sediment. This dried sediment weight (in milligrams) is divided by the liquid volume of sample filtered (in liters) to estimate the concentration of suspended sediments.
  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Data values are within the expected value range and have been used to calibrate coincident turbidity measurements in the file: DMP23_Turbidity_to_SSC_calibration_constants.csv. This file can be found in the support files for the time series data section of this data release.
  2. How accurate are the geographic locations?
    All other horizontal positions were derived from ship navigation systems, which included: Garmin GPSMAP 7610 and a Garmin GPS19x antenna, Garmin GPSmap XSV chartplotter and a Garmin GPS19x antenna, and Garmin Echomap UHD2 64sv w/ inbuilt GPS antenna; all were WAAS-capable, and had location to within 3 m.
  3. How accurate are the heights or depths?
    No formal positional accuracy tests were conducted. Pumped samples were collected with the intake valve at a fixed height on the sampling frame either resting on the seabed or suspended from the vessel.
  4. Where are the gaps in the data? What is missing?
    Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. Specific field notes were retained in the file to support further use of the data.
  5. How consistent are the relationships among the observations, including topology?
    Data values are within the expected values for suspended sediment in south San Francisco Bay.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints No access constraints
Use_Constraints USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey (USGS) as the originator of the dataset and in products derived from these data.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - CMGDS
    2885 Mission Street
    Santa Cruz, CA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov
  2. What's the catalog number I need to order this data set? These data are available in csv format (DMP23_SSC.csv) accompanied by CSDGM FGDC-compliant metadata.
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.
  4. How can I download or order the data?
    • Availability in digital form:
      Data format: file contains the csv table in format comma-delimited text (version Microsoft Excel 2002 (12527.20988) 64-bit) Size: 0.0155
      Network links: https://doi.org/10.5066/P14D723N
    • Cost to order the data: None.

  5. What hardware or software do I need in order to use the data set?
    The data are available in comma-separated values (CSV) spreadsheet format. Text editing software can be used to open the file, as well as spreadsheet programs, such as Microsoft Excel.

Who wrote the metadata?

Dates:
Last modified: 20-Aug-2025
Metadata author:
PCMSC Science Data Coordinator
U.S. Geological Survey, Pacific Coastal and Marine Science Center
2885 Mission Street
Santa Cruz, CA
United States

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/DataReleases/CMGDS_DR_tool/DR_P14D723N/DMP23_SSC_metadata.faq.html>
Generated by mp version 2.9.51 on Tue Sep 2 13:32:13 2025