Are the data from the Water Quality Portal (WQP) available through web services?

The WQP provides an easy way to access data stored in various large water quality databases through form-based queries as well as through standalone web services (A web service is a computer-to-computer protocol that allows for the direct sharing of information. Applications such as internet portals can use the web services to access data from the various databases without needing an authorized database connection). The WQP provides various input parameters on the form interface including location, site, result, and date parameters to filter and customize the output result set. Equivalent data retrievals can be performed using web services, which have the same input parameters and predefined output formats offered through the form. For more information see the Web Services Guide.

How often are the data refreshed?

The USGS services are refreshed every 24 hours, the STORET services are refreshed once a week on Thursday evening, and the STEWARDS data are refreshed once a week on Saturdays. 

How much data are available?

As of July 2015, over 265 million results from over 2.2 million monitoring locations are currently accessible through the portal. The portal reports samples and results collected from each location since the beginning of the databases.

Why do I have to add "USGS-" or other organization identifiers in front of my NWIS site id when searching?

Why do I have to add the Organization ID in front of my STORET site id when searching?

The site ids in the STORET and NWIS systems have not been harmonized (unlike the case with characteristics). Therefore, a site id may be duplicated across the two systems. Furthermore, the site id within STORET is unable to serve as a unique identifier for a site because STORET aggregates data from different organizations who have not harmonized their identifiers. Because of these reasons, the WQP has chosen to prefix the simple site id in order to make it a suitable unique identifier.

Why is the MonitoringLocationIdentifier not quite the same as the site ID?

The MonitoringLocationIdentifier is meant to be consistent within the WQP in the sense that any MonitoringLocationIdentifier you get back from the WQP can be re-input into the WQP as a site id search identifier. However, if you are used to using STORET or NWIS, this site id will not be consistent with the site id used by STORET or NWIS. For the reasons why the WQP site id is different from the STORET or NWIS site id, please see the answer to the question above.

Why will Google Earth display a lot more points than the Mapping tool when I download data in KML format?

KML files specify a set of sites that can be displayed in Google Earth, Google Maps, or any other 3D Earth browser compatible with KML. Due to technical limitations in web mapping technology, we have limited the maximum number of sites that can be mapped on the WQP Map tool to 250,000, which is large enough to encompass the vast majority of queries.

Why do some queries take longer than others?
How can I reduce the time it takes for the WQP to return my dataset?

Some queries take longer to return the resulting dataset than other queries for various reasons. Large datasets will take longer to return depending on file size and internet connection speed.  The "Sampling Parameter" section of the query page, which requires working through 100x more data that site-dependent queries, can ofter slow query response.   Using certain filters also affects query run time. Use the start date filters to reduce the size of the resulting dataset and to reduce query run time.