About the USGS Water Data for the Nation site

About USGS Water Data

The United States Geological Survey (USGS) has collected water-resources data at approximately 1.5 million sites in all 50 States, the District of Columbia, Puerto Rico, the Virgin Islands, Guam, American Samoa and the Commonwealth of the Northern Mariana Islands.

The types of data collected are varied, but generally fit into the broad categories of surface water and groundwater. Surface-water data, such as gage height (stage) and streamflow (discharge), are collected at major rivers, lakes, and reservoirs. Groundwater data, such as water level, are collected at wells and springs.

Water-quality data are available for both surface water and groundwater. Examples of water-quality data collected are temperature, specific conductance, pH, nutrients, pesticides, and volatile organic compounds.

This web site serves current and historical data. Data are retrieved by category of data, such as surface water, groundwater, or water quality, and by geographic area. Subsequent pages allow further refinement by selecting specific information and by defining the output desired.

Not all water-resources data collected by the USGS are provided on this web site. To inquire about the availability of additional hydrological data, as well as other USGS information such as reports, visit the USGS Water Resources Home Page at http://water.usgs.gov.

About this web site

This site is the public web interface to the USGS National Water Information System, a system that is based on several development efforts that were established in our water science centers. This system became an operational production system in 2001.

Technical specifications of our national system

• Web Servers (8 instances)
  • Operating system is Red Hat Linux
  • Processors - 2 quad core @ 2.53 GHz
  • Pages served by the Apache web server
  • Perl and CGI is used to display all pages
  • Graphics are created by Gnuplot and we are licensed to create GIF images from Unisys
• Database Servers (3 instances)
  • Operating system is Red Hat Linux
  • Processors - 2 quad core @ 2.53 GHz
  • MySQL is used to run our database
• Connectivity
  • 1 GHz direct connection between the web servers and the database servers

System Architectural Notes

• Most data collected by automated equipment in the field is held on site and transmitted to a GOES satellite at scheduled intervals, generally once an hour. This accounts for most delays between the data recording time and its arrival on this system.
• Data is received at NOAA's Wallops Command and Data Acquisition Station at Wallops Island, Virginia. Backup receivers are located at the EROS Data Center in Sioux Falls, SD. Data is then sent to USGS Water Science Centers for processing. When processing is completed, it is rapidly transmitted for posting on the web. In most cases it takes only a couple of minutes to process data once it is received and post it on the web.
• Current condition data is replicated between database servers in three geographic locations: Reston VA, Menlo Park CA and Sioux Falls SD.
• Historical data is maintained in Reston, VA with a backup server in Sioux Falls, SD.
• Our Analog web statistics are publicly available. On a typical month, this site ranks as the second most accessed USGS web site, behind earthquake.usgs.gov