The U.S. Geological Survey's (USGS) National
Water Information System (NWIS) is a comprehensive and distributed
application that supports the acquisition, processing, and long-term
storage of water data. NWISWeb serves as the publicly available portal
to a geographically seamless set of much of the water data maintained
within NWIS (additional
background).
Nationally, USGS surface-water data includes more
than 850,000 station years of time-series data that describe stream
levels, streamflow (discharge), reservoir and lake levels,
surface-water quality, and rainfall. The data are collected by
automatic recorders and manual field
measurements at installations across the Nation.
Data are collected by field personnel or relayed
through telephones or satellites to offices where it is stored and
processed. The data relayed through the Geostationary Operational
Environmental Satellite (GOES) system are processed automatically in
near real time, and in many cases, real-time
data are available online within minutes.
Once a complete day of readings are received from a
site, daily summary data are generated and
made available online. Annually, the USGS finalizes and publishes the
daily data in a series of water-data reports. Approved daily data and
peak data are updated annually following
publication of the reports.
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