How often are real-time streamflow data updated?

USGS real-time streamflow data are typically recorded at 15-minute intervals, stored onsite, and then transmitted to USGS offices once every hour, depending on the data relay technique used.

Recording and transmission times might be more frequent during critical events (floods, for example). Data from current sites are relayed to USGS offices via satellite, telephone, and/or radio telemetry and are available for viewing within minutes of arrival.

Water-quality measurements are recorded in time intervals typically as small as 5 minutes to hourly.

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Is there a way to get alerts about streamflow conditions?

Yes! The USGS offers two services: WaterAlert - automated emails or text messages are sent to you whenever certain parameters (that you define) are exceeded at one of our gaging stations. WaterNow - Send an email or text message to WaterNow@usgs.gov containing the USGS Site Number of the gage you want to query (optionally add parameter codes to...

How can I obtain river forecasts (flood forecasts)?

River forecasts (flood forecasts) are made by the National Weather Service River Forecast Centers and released through local Weather Service Offices. The NOAA Web site has a map showing the location of the forecast centers, their areas of responsibility, and the location of the gages they use. The vast majority of current streamflow data used for...

Does "stage" tell you how much water is flowing in a stream?

Not directly. You cannot say that because a stream rises (doubles) from a 10-foot stage to a 20-foot stage that the amount of flowing water also doubles. Think of a cereal bowl with a rounded bottom. Pour one inch of milk in it. It doesn't take much milk to make it up to the one inch level because the bowl is at its narrowest near the bottom. Now...

Why are there sometimes differences between USGS and National Weather Service river stages?

At some USGS stream-gage installations, NOAA’s National Weather Service (NWS) maintains a separate stage sensor that is serviced by NWS technicians. Calibration of any sensing device can occasionally drift from a "true" value, so there might be differences between USGS and NWS data reports. USGS personnel visit installations on an interval of 6...

What does the term "stream stage" mean?

Stream stage is an important concept when analyzing how much water is moving in a stream at any given moment. "Stage" is the water level above some arbitrary point in the river and is commonly measured in feet. For example, on a normal day when no rain has fallen for a while, a river might have a stage of 2 feet. If a big storm hits, the river...

What is a rating curve? Why does it change over time?

In order to convert water height (or “stage”, usually expressed as feet) into a volume of water (or “discharge”, usually expressed as cubic feet per second), USGS hydrographers must establish a relationship between them. This stage-discharge relationship is called a rating curve. It’s developed by making frequent direct discharge measurements at...

Why might USGS streamflow data be revised?

Real-time USGS streamflow data are PROVISIONAL, meaning that the data have not been reviewed or edited. These data might be subject to significant change and are not official until reviewed and approved by the USGS. Real-time streamflow data can be affected by: backwater from ice or debris such as log jams algae and aquatic growth in the stream...

Sometimes the USGS real-time stage data seems too high (or too low). Are the USGS data inaccurate?

There can be occasional equipment or database problems where erroneous data are reported for short periods of time until corrections can be made. This is why it is important to look at a record of streamflow (like the 7-day hydrograph plots) rather than a single point in time. However, most of the time the USGS has a high level of confidence in...

Where can I get real-time and historical streamflow information?

The best starting point for USGS streamflow data is the interactive National Water Information System (NWIS): Mapper website. Zoom in to your area of interest or use the search options in the left navigation window. The map displays active surface-water sites by default, but you can change the type of water site (surface-water, groundwater,...

Why do some real-time streamgaging stations stop transmitting data for extended periods of time?

The USGS usually corrects any equipment or station problems within a few days of their occurrence. Occasionally, replacement parts or equipment might not be readily available, or a station might be inaccessible due to weather conditions. Most USGS stream-gaging stations are operated in cooperation with other agencies. At some stations, the stage...

How do we benefit from USGS streamgages?

Information on the flow of rivers is a vital national asset that safeguards lives, protects property, and ensures adequate water supplies for the future. The USGS is the federal agency responsible for operating a network of about 7,000 streamgages nationwide. Data from this network are used by water managers, emergency responders, utilities,...
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Date published: February 1, 2017

The Vital Nature of Streamgaging

Gary Moore spent the last three days of 2015 stacking hefty bags of sand in front of a fellow church member’s brick home. With only 1,000 feet between the house and the swelling Mississippi and Meramec Rivers, Moore and other volunteers worked quickly, in frigid temperatures, to assemble a 10-foot high, 1,000-foot-long sandbag wall to ward off floodwaters.

Date published: August 22, 2016

Fighting the Floods

The USGS response to the Louisiana floods is part of the larger USGS flood science mission...

Date published: March 22, 2016

Follow Your Stream to Learn About Water

Explore America's streams and rivers from your computer or mobile device.

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Measuring streamflow using bridge crane, Powder River at Sussex
May 25, 2017

Measuring streamflow using bridge crane, Powder River at Sussex

Measuring streamflow using bridge crane and AA meter, Powder River at Sussex

Measuring Streamflow
November 7, 2016

Measuring Streamflow

USGS National Flood Coordinator, Bob Holmes, conducts a live Skype interview with The Weather Channel while measuring streamflow on the Mississippi River at St. Louis on New Year's Eve in 2015. Photograph credit: Jennifer LaVista, USGS

Measuring Streamflow
November 7, 2016

Measuring Streamflow

USGS crews had two research vessels out measuring streamflow on the Mississippi River at St. Louis on New Year's Eve. Eric Looper and Jason Cannon and many other USGS field crews were out in the floodwater over the holiday. Photograph credit: Jennifer LaVista, USGS

Measuring Streamflow
November 7, 2016

Measuring Streamflow

USGS scientist Chris Rowden drives a research vessel measuring streamflow alongside another field crew on the Mississippi River at St. Louis. Photograph credit: Jennifer LaVista, USGS

A U.S. Geological Survey hydrologic technician, uses an Acoustic Doppler Velocimeter to measure stream flow on a Florida creek.
September 2, 2016

Measuring streamflow

Neil Yobbi, U.S. Geological Survey hydrologic technician, uses an Acoustic Doppler Velocimeter to measure stream flow on Curlew Creek in Tampa, Florida. While Hurricane Hermine might have made landfall almost 200 miles away in St. Marks, Florida, a USGS rain gauge in Pinellas County, Florida, still measured more than 16 inches of total rain during the past three-day storm

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Measuring streamflow from a cableway, Green River blw Fontenelle Resv
April 18, 2016

Measuring streamflow from a cableway, Green River blw Fontenelle Resv

Measuring streamflow from a cableway using an ADCP, Green River blw Fontenelle Reservoir, WY

Image: Hydrologist Measuring Streamflow
April 10, 2014

Hydrologist Measuring Streamflow

USGS hydrologist Greg Clark measures streamflow on Government Gulch Creek, a tributarty to the Coeur d'Alene River in northern Idaho. Streamflow data collected are included in the Coeur d'Alene Basin Environmental Monitoring Program the USGS conducts in cooperation with the Environmental Protection Agency.

December 11, 2012

Streamflow Gaging Station and Measurement on San Pedro River, AZ

USGS employee, Hanna Coy, talks about stream gauging.

Image: Measuring Streamflow
October 5, 2010

Measuring Streamflow

USGS hydrologic technician measuring streamflow in the Merced River, near Happy Isles stream gage in Yosemite Valley.

October 14, 2009

Streamgages: The Silent Superhero

Whether you drink water from your tap, use electricity or canoe down your local river, chances are you benefit from USGS streamgage information. So what is a streamgage and what does it do for you? This CoreCast episode gives you the inside scoop on your silent superhero.

Transcript and captions available soon.