The U.S. Geological Survey (USGS) now provides online, historical instantaneous streamflow discharge data—dating back to around 1990— through its Instantaneous Data Archive (IDA). In this new system, users can find streamflow information reported at the time intervals at which it is collected, typically 15-minute to hourly intervals.

The USGS has provided historical daily streamflow data on the Internet for more than a decade, but for many scientific and engineering proposes it is useful to have the historical data in shorter time increments. The instantaneous data has been available for many years, but was not accessible through the web. This new database gives users the information through a user-friendly automated process.

"A user-friendly archive of historical instantaneous streamflow data are important to many different users for such things as floodplain mapping, flood modeling, and estimating pollutant transport," said Robert Hirsch, USGS associate director of water. "The new IDA site should be very helpful to research scientists and engineers for a wide range of hydrologic analyses."

The IDA website currently has about 1.5 billion instantaneous data values from 5,500 streamgages in 26 states. The USGS says that populating this website takes effort and resources that are being provided "as available," and not all states and streamgages are available at this time. The number of states and streamgages with data will continue to increase. Additionally, the IDA database might expand in the future to include other variables such as temperature and pH.

The USGS, which has monitored flow in streams and rivers across the United States for more than 125 years, collects data from more than 7,400 streamgages, many of which provide real-time data in 15-minute increments. USGS streamflow data is routinely used for water supply and management, monitoring floods and droughts, bridge and road design, water availability and quality planning, and for many recreational activities.

Access an even larger variety of USGS data, such as for groundwater and water quality, through the National Water Information System Web Interface (NWISWeb), which contains more than 1.5 million sites.