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 stage could rise to 15 or 20 feet, sometimes very quickly. This is important because past records might tell us that when the stage hits 21 feet, the water will start flowing over its banks and into the basements of houses along the river -- time to tell those people to move out! With modern technology, the USGS can monitor the stage of many streams almost instantly.

Hydrologists are also able to convert stage height into streamflow volume by determining a rating curve for each site.

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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...

Why does the USGS use the spelling "gage" instead of "gauge"?

The spelling of “gage” is part of our very rich USGS history. In 1888, USGS Director John Wesley Powell met a very forward-thinking man named Frederick H. Newell. Powell was so impressed that he made Newell the first full-time appointee to the new Irrigation Survey, which was created to investigate the potential for dams and canals in the western...

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...

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,...

Where can I find flood maps?

FEMA is the official public source for flood maps for insurance purposes: FEMA’s Flood Map Service Center NOAA is responsible for producing flood forecast maps that combine precipitation data with USGS streamflow data: National Flood Forecasts Interactive Flood Information Map USGS flood map products include: USGS Flood Information : Maps and...
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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: February 26, 2013

Stay Current on Your Rivers with USGS WaterNow

For the first time, anyone can find out the current conditions on thousands of rivers and streams across the country, right from their phone, using USGS' latest system WaterNow.WaterNow makes the water conditions monitored by more than 16,000 streamgages and other sites across the country available via text or email. 

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Outside stream stage of Bull Lake Creek abv Bull Lake
December 13, 2017

Reading stream stage at Bull Lake Creek above Bull Lake streamgage

The wire weight is lowered to determine stage of Bull Lake Creek above Bull Lake

Large ruler-like instrument under a bridge standing up in the river water
February 11, 2017

USGS staff gage measuring the height of the water in the Carson River

USGS staff gage (ruler) measuring the height of the water, on the Carson River, near Brunswick Canyon, Nevada.

Photo of a cork line from a crest-stage gage
April 17, 2016

Cork line from a crest-stage gage

Photo of a cork line from a crest-stage gage. As waters rise inside the crest-stage gage, the cork floats on the top of the surface. When waters recede, the cork line is deposited as the water inside the gage begins to fall, marking the highest water level. (From Identifying and preserving high-water mark data

Photo of a staff gage on a Wisconsin stream
April 17, 2016

Staff gage on a Wisconsin stream

Staff gages, like this one, are attached to fixed structures. Field crews visually read and record the water-level height (stage) of the stream periodically.

Image: Staff Gage at Bonnet Carré Spillway
January 11, 2016

Staff Gage at Bonnet Carré Spillway

A staff gage at the Bonnet Carré Spillway, which is managed by the U.S. Army Corps of Engineers.

In late 2015/early 2016, unusually large rainfall in the Upper Mississippi River Valley led to flooding throughout Arkansas, Illinois, Louisiana, Mississippi, Missouri, and Tennessee. USGS water science centers responded to the flooding by measuring the streamflow,

Photo of USGS streamgage measures flooding in the lower Trinity River
March 31, 2015

USGS streamgage measures flooding in the lower Trinity River

A USGS streamgage measures flooding in the lower Trinity River, Texas. 

For the first time, USGS scientists are now collecting real-time sediment and water-quality information on water traveling into Galveston Bay. A better understanding of sediment and freshwater flow into Galveston Bay is now available from a new USGS report, done in cooperation with the Texas

December 11, 2012

Streamflow Gaging Station and Measurement on San Pedro River, AZ

USGS employee, Hanna Coy, talks about stream gauging.

November 13, 2012

Stage Discharge Ratings Class

USGS employees talk about the importance of getting accurate data from stream gauging and the benefit of the stage discharge ratings class.

Image: USGS Red River of the North at Fargo Streamgage
April 9, 2011

USGS Red River of the North at Fargo Streamgage

Water level measurement from the USGS Red River of the North at Fargo streamgage in downtown Fargo, ND. The water level peaked at around 39 feet at this streamgage on April 9. Real-time water level and streamflow data from this gage can be accessed online.

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.

An explanation of River Stage, which is the water level measured in feet above a point, usually somewhere below the river bed.

USGS Storm Words: River Stage

The USGS has many missions before, during and after a major storm. Here is an explanation of a word we commonly use with our science.

River Stage: Is the water level measured in feet above a point, usually somewhere below the river bed. The USGS’ real-time streamgage network is able to indicate when a monitored river reaches a stage where the water will start

An explanation of rating, which Is the relationship between river stage and discharge.

USGS Storm Words: Rating

The USGS has many missions before, during and after a major storm. Here is an explanation of a word we commonly use with our science.

Is the relationship between river stage and discharge. For many rivers, as stage rises so does the discharge, therefore, ratings are necessary because USGS scientists cannot always be at the 8,200+ nationwide streamgages to measure