Real-time data are time-series (recorded at fixed intervals) data from automated equipment and represent the most current hydrologic conditions. Measurements are commonly recorded at 5-60 minute intervals and transmitted to the NWIS database every 1-4 hours. Real-time data are available online for 31 days.

Daily values are summarized from time-series data for each day for the period of record and may represent the daily mean, median, maximum, minimum, and/or other derived value. Daily values include approved, quality-assured data that may be published, and more recent provisional data, whose accuracy has not been verified. Example.

Statistics are computed from approved daily mean time-series data at each site. These links provide summaries of approved historical daily values for daily, monthly, and annual (water year or calendar year) time periods.

Annual maximum instantaneous peak streamflow and gage height

Periodic manual measurements of streamflow and gage height. These measurements are often used to supplement and (or) verify the accuracy of the time-series measurements.

       The USGS in Washington State currently collects data for about 300 streamflow, reservoir, water-quality, meteorological, and groundwater sites, of which about 240 have satellite telemetry for real-time data, and another 20 have other communications equipment for near-realtime data.

       The USGS has operated about 1,000 continuous data collection sites since 1895 when the first streamgage on the Spokane River at Spokane. Additional information about the USGS data collection program is available from the Washington Water Science Center home page, along with links below to an array of other sources of water resources data for Washington.

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