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Help using the NWISWeb water-quality data retrieval system

Help home page Navigation help Search criteria help
Output formats help Codes help Parameter help

This page introduces the water-quality data base, and guides new users through example data retrievals. Although a few definitions are provided herein, more complete definitions are provided on the main NWISWeb help page.

Outline:

Recent updates

There have been changes to parameter names in the National Water Information System (NWIS) Parameter Code Dictionary (PCD). These changes have been incorporated in NWISWeb this May 2003.

Description: The changes affect the parameter short name, long name, and column headings. They include

In some cases, the chemical names have been changed to nomenclature recommended by the International Union of Pure and Applied Chemistry (IUPAC).

Background

The NWISWeb water-quality data base is a compilation of the USGS district data bases. It is very large (about 3.5 million samples), with many types of measurements for many different environmental media, from many agencies. Search criteria are necessary to focus your search. There often is more than one way to locate desired data. The examples provided below are meant to familiarize new users with the system.

Brief explanation of data base

Understanding of a few key elements of the data base is essential to understanding what kind of data you retrieve. Technical data analyses often require more detailed information and coding

Site type describes whether the site is a surface-water, ground-water, precipitation-monitoring, or other site type.

Site name describes the location of the site. Often, the site type can be inferred from the site name. Requesting "list of sites" output formats allows users to view basic information for each site.

Medium type or medium code defines what kind of sample was collected for analysis. This question is particularly important for surface-water sites, which can have samples for several media (water, biological tissue, stream-bottom sediments, suspended sediments, etc.).

Parameter codes are used to identify the water-quality values stored in the data base. Each code is linked to a definition. Parameter-code definitions typically contain information about what was analyzed, what units are associated with the numerical data, and sometimes, how the sample was processed prior to analysis (filtering, for examples). Definitions for each retrieved parameter are provided in the heading of each output.

Data retrievals-general guidance

Retrieving data from this site consists of the following steps (starting from the main NWISWeb water-quality sample page).

Some hints:

Example data retrievals

Additional information for technical data analysis

Data retrievals-precautions


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Water Quality Samples for USA: Sample Data
http://waterdata.usgs.gov/nwis/qwdata?

Retrieved on 2004-11-01 04:39:49 EST
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