(85 sites)
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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. |
(144 sites)
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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. |
 (131 sites)
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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. |
(24,958 sites)
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Manual measurements of depth to water in wells. These measurements are
often used to supplement and (or) verify the accuracy of the instantaneous measurements.
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The USGS National Water Information System (NWIS) contains extensive water data for the Nation. Public access to many of these data is provided via NWISWeb (additional background).
The Ground-Water database consists of
more than 850,000 records of wells, springs, test holes, tunnels,drains, and
excavations in the United States. Available site descriptive information
includes well location information such as latitude and longitude,
well depth, and aquifer.
The USGS annually monitors ground-water levels in thousands of
wells in the United States. Ground-water level data are
collected and stored as either discrete field-water-level measurements or as
continuous time-series data from automated recorders. Data from
some of the continuous record stations are relayed to USGS
offices nationwide through telephone lines or by satellite
transmissions providing access to realtime ground-water
data. 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.
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