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Water Quality of San Francisco Bay
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There are two different ways to query this database:

Easy Query Button or Expert Query Button
Click on the Easy button if you would like help and guidance to create a meaningful query. All parameters are defined and process is split into 3 simple steps.
Use the Expert button to go to a single page containing all of the query options, without guidance.

If you intend to use any data for any publication, please cite.
Let us know about your usage via email, as your publication supports us keeping this database going.

In order to use the database properly and understand the limits of the data, please review:


  • CTD and discrete measurements are added to the database monthly and available from 1969 through the most recent cruise displayed on the site - see the bottom of the homepage for most recent cruise date.
  • Nutrient data (NO2, NO3+2, NH3, PO4 and Si) are added to the database quarterly and are available for 1969 through 8/22/19.

    Known data exceptions:

  • 2014-2018 Si were corrected 0-10% October 2019
  • Si not available for 2011-Feb 2014
  • NO2 is not available for 2005 - 2011
  • Light attenuation is not available for 2002-2006
  • Time of day values for cruise data sampled 1981 through 1987 are estimates and accurate to within +/- 30 minutes
  • Nutrient data are not collected all stations or depths,see STRUCTURE below

    The database is divided into 2 tables: the CTD table contains sensor data from the CTD and non-nutrient discrete data (chlorophyll a, dissolved oxygen, and SPM), and the nutrient table contains only discrete dissolved inorganic nutrient data.
    If your query contains both CTD and nutrient data, your results will include all of the CTD data and only nutrient data collected at the same time/location as CTD data. This is the majority of nutrient data. Nutrient water samples are usually collected at a small subset stations of the CTD data collection on any particular date, but there are rare occasions when nutrient data are collected at times/locations where CTD data were not collected. If you wish to view these data, only choose nutrient parameters and do not include CTD data in your query. If you wish to include CTD data only where nutrient data were collected, refine your query to select your nutrient ">0".

    Discrete data
    Discrete water grab samples (chlorophyll a, dissolved oxygen, and SPM) occur at a subset of CTD stations on any particular cruise. Since 1988, these data are listed at the 2m and bottom depth bins where collected. Light extinction coefficient is listed on the 1m line. Prior to 1988 when CTD use began, light attenuation is on the 0.5m line and other discrete parameters were collected at variable depths (commonly 0.5m, 1m, and 2m).

    To best inform your query, view the data table for your respective cruise to determine where data were collected. You can start at Data Visualization, choose the year of interest year, then choose the cruise to view. For each cruise date's data plot page there is a button in the upper right hand corner that links to the data table. Review the data table to understand the data from that date.

    Please review this page and the query help page, if you are unable to complete the data query you requre, contact Tara Schraga

    Please let us know if you are using our data in ANY publication (email It helps us keep this database going!

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