Code dictionary
Code dictionary introduction
The USGS Code Dictionary is designed as a user-friendly way to cross reference various USGS codes or terms to other data related to that code or term.
For example, if you needed to know the relationship between a USGS parameter code and an observed property, you can look in the section of Code dictionary tools relating to Observed Properties.
Within the Observed Properties and Parameter Codes section, there are prompts to help you find the answers you need.
Code dictionary tools
Observed Properties and Parameter Codes
The easiest way to start is to look at the similarities between Observed Properties and Parameter Codes.
Parameter Codes and Observed Properties
- Both are US Geological Survey (USGS) specific terms used with USGS water data.
- Both describe the data being collected.
Now let’s look at the differences.
Parameter Codes
- Are always five numerical digits
- Are used for instantaneous data and discrete sample data
- Represent the data collected to the unit level (such as centimeters)
- Require a cross reference to a text description for the user to understand the code
- Can be correlated to exactly one observed property
- There are more than 28,000 parameter codes.
- See all 15,500 parameter codes that have discrete sample data as an array of codes and names. (opens in new tab)
Observed Properties
- Are only used to describe discrete sample data collected by USGS
- Are text descriptions of indeterminate length
- The unit value (such as centimeters) is not part of the observed property; the unit value is part of the data described by the observed property.
- Observed properties can relate to several parameter codes. For example, the observed property ‘Gage height, above datum’ is related to five parameter codes: 62618 - Lake or reservoir stage, above datum, meters, 00072 - Stream stage, meters, 99065 - Gage height, above datum, meters, 00065 - Gage height, feet, and 30207 - Gage height, above datum, meters.
- There are more than 14,400 observed properties.
- See all observed properties (names only) as an array. (opens in new tab)
Putting the pieces together
While the USGS has been using parameter codes for many years and they have advantages in conciseness and specificity, numeric codes are difficult for the public to understand and make USGS data less comparable to data being collected by other agencies.
The concept of observed properties is an attempt by the USGS to bridge these barriers. The USGS has transitioned to use observed properties to describe discrete sample data we've collected. For users accustomed to the parameter code system and those interested in better understanding observed properties, tools are provided in the following sections to help connect parameter codes to an associated observed property or an observed property to its associated parameter code or codes.