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Water-Quality Data for the Nation

Real-time water-quality data

Real-time water-quality data are returned directly from field instruments. Instantaneous data are recorded at 5-minute to 1-hour intervals and uploaded to the data base every 4 hours.

Discrete water-quality data

Retrieve water-quality data from field and/or laboratory analysis of water, biological tissue, stream sediments, and other environmental samples.


Tutorial explaining how to perform a water quality retrieval and understand the results


The USGS collects and analyzes chemical, physical, and biological properties of water, sediment and tissue samples from across the Nation. The NWISWeb discrete sample data base is a compilation of over 4.2 million historical water quality analyses in the USGS district data bases through September 2003. The discrete sample data is a large and complex set of data that has been collected by a variety of projects ranging from national programs to studies in small watersheds. Users should review the help notes and particularly the Data retrieval precautions before beginning any retrieval or analysis of data from this data set. Additions of more current data, modifications to ancillary information, and enhanced retrieval options to help users find and appropriately use the data they need are planned for a future release of NWISWeb.

At selected surface-water and ground-water sites, the USGS maintains instruments that continuously record physical and chemical characteristics of the water including pH, specific conductance, temperature, dissolved oxygen, and percent dissolved-oxygen saturation. Supporting data such as air temperature and barometric pressure are also available at some sites. At sites where this information is transmitted automatically, data are available from the real-time data system.

You may find additional water-quality data of interest in EPA STORET.

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Water-Quality Data for USA

Retrieved on 2004-10-14 17:27:17 EDT
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