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National Water Information System (NWIS) Water-Quality Web Services

USGS and USEPA are working together to provide scientists and policy-makers an easier way to discover and acquire water-quality data from their large water-quality databases. A common suite of web services allow for the automated sharing of water monitoring data via a common format and terminology. A Water Quality Portal is now (2012) available at for downloading monitoring location information and associated water-quality results that are automatically linked and integrated from both USGS and USEPA databases.

A web service is a computer-to-computer protocol that allows for the direct sharing of information. The services provide the ability to combine data from USGS's NWIS and EPA's STORET systems. The services produce data formatted according to the Water Quality Exchange (WQX) Outbound XML schema, which has been developed collaboratively by USEPA and USGS. Applications such as internet portals can use the web services to access data from both NWIS and the STORET Warehouse without needing an authorized database connection.

The web services provide two core methods for accessing the information in these systems. Each of these web services share common input parameters and have pre-defined output formats (or schema). Monitoring location information and associated water-quality results will be served through these two services. The Station Web Service provides information for all monitoring locations within a given geographic area and the Results Web Service retrieves water-quality results (measurements) by site.

The NWIS Water-Quality Web Services serve data from the NWISWeb database. All publicly available data are not available through the web services at this time. The web services include results for USGS parameters represented in the crosswalk. At this time this accounts for approximately 92% of water-quality data available from NWISWeb.

Please Note: Changes to this page occurred on Sept 5, 2012 to reflect the availability of the new collaborative USGS/USEPA Water Quality Portal. While web service calls developed using the older USGS “Mini Portal” interface ( continue to be supported, we encourage users to update software and scripts to reflect the updated URLs from the USGS/USEPA Water Quality Portal (

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Page Last Modified: September 5, 2012 08:35 CDT