How to Use Water Quality Goals Online

Available Documents

You can search for numeric water quality thresholds on over 860 chemicals and water quality parameters:

This information is intended to help you interpret water quality data to assess impairments and threats to beneficial uses of water resources and to derive assessment thresholds based on California's water quality standards. Also included is information to help you use the thresholds contained in the database.

To avoid improper use of the numeric thresholds contained in the database, users are strongly encouraged to carefully review the Water Quality Goals Staff Report.

Using the Database

Go to the search screen, shown below. In the box, enter a chemical or parameter name, portion of a name, abbreviation, or Chemical Abstracts Service (CAS) Registry Number, then click the “Submit” button.

The search tool will present you with a list of chemicals and parameters that matches your entry, as in the example below. Click on the one of interest to view a table of numeric thresholds for that chemical or parameter.

Each table of numeric thresholds contains a number of live links:

  • Click on the Source & References blue underlined headings on the left to see descriptions of and original references for each type of numeric threshold. If the reference is available on the internet, you will be presented with live links to these materials.
  • Click on the blue underlined Footnote1 and Footnote 2 links to view additional information on the numeric thresholds presented in the table. Note: Applicable footnotes also appear at the bottom of the table.
  • Where numeric thresholds vary with hardness, pH and other parameters, you will find “see page...” links in the Notes column of the table. Clicking on one of these blue underlined links opens a new window that presents an Excel table and graph of the relationship. (You may need to close the Sources & References window to be able to open these tables and graphs.) The formulas that control the relationship between the parameter and the numeric threshold are built into these Excel tables, allowing the user to easily calculate the numeric threshold associated with any value of the parameter that is entered by the user.

At the top and bottom of the table:

  • The New Search link takes you to a new search screen
  • The Return to Previous Search Results link takes you back to the list of chemicals and parameters that satisfied your last search
  • The Print link allows you to print the table

Other information included in the table:

  • Synonyms for the chemical or parameter
  • Chemical Abstracts Service (CAS) Registry Number, if available
  • Units for each threshold (the default units is micrograms per liter or “ug/L”, equivalent to parts per billion or “ppb”)
  • Explanatory Notes with corresponding symbols at the bottom of the table
  • Adoption Date for most numeric thresholds
  • Limiting Threshold to indicate recommended assessment thresholds to protect specific beneficial uses in specific water body types (see corresponding symbols at the bottom of the table). An explanation of how these assessment thresholds are selected may be found in the Water Quality Goals Staff Report.

The Water Quality Goals database is periodically updated to reflect newly released and revised numeric water quality thresholds.

Questions or Comments about Water Quality Goals?