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 weeks or less to maintain equipment and make required adjustments. NWS technicians have a separate maintenance schedule. In either case, data retrieved from remote sensors is always considered provisional and subject to revision after quality control and analysis. Differences between remotely reported and field-measured data are usually small and within tolerances required for water resources management and control.

Learn more: From the River to You

Related Content

Filter Total Items: 9

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 graduate student named Frederick Haynes 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...

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...

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,...

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,...
Filter Total Items: 4
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.

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. 

Filter Total Items: 12
Snowmibiles needed to get to Blackrock Creek streamgage
January 4, 2018

Snowmibiles needed to get to Blackrock Creek streamgage

Snowmibiles needed to get to Blackrock Creek streamgage

Image shows a USGS scientist in a PFD servicing a streamgage
August 29, 2017

Servicing the Streamgage at Addicks Reservoir

USGS scientist Tom Pistillo services the streamgage at Addicks Reservoir to ensure that accurate reservoir water-level data are being measured, which are critical for helping the U.S. Army Corps of Engineers and Harris County Flood Control District make informed reservoir operation decisions.

A USGS Hydrologic Technician installs a new streamgage
February 23, 2017

A USGS Hydrologic Technician installs a new streamgage

U.S. Geological Survey Hydrologic Technician Patrick Anzman installs a new streamgage February 23 over the Schuylkill River in the Philadelphia neighborhood of Manayunk. Photo by Mason Manis, USGS. 

Image: USGS Scientist Inspects Streamgage During Flooding Event
October 3, 2015

USGS Scientist Inspects Streamgage During Flooding Event

USGS scientist Matt Jennings inspects streamgage number  02136361 at Turkey Creek near Maryville, South Carolina, the morning of October 4, 2015. The discharge they measured was 6,000 cfs.

These instruments form the backbone of our National Streamgage Network, which in turn feeds valuable information on water level, streamflow and sometimes water quality to various

Image: Streamgage Inspections on the Big Thompson River
September 18, 2013

Streamgage Inspections on the Big Thompson River

Ben Glass of the USGS Colorado Water Science Center inspects a USGS rapid deployment streamgage on the Big Thompson River in Loveland, Colo. The river is one of many that flooded during a significant September 2013 rain event along Colorado's Front Range, damaging or destroying several USGS streamgages.

December 11, 2012

Streamflow Gaging Station and Measurement on San Pedro River, AZ

USGS employee, Hanna Coy, talks about stream gauging.

Image: Souris River Streamgage
June 25, 2011

Souris River Streamgage

As the Souris River flooded during the early summer of 2011, it overcame levees in the city of Minot, N.D., causing about 11,000 people to evacuate their homes. The record-breaking flood crested on July 25 at over 26,000 cubic feet per second (cfs) and 24 feet - nearly 13 feet over flood stage - according to U.S. Geological Survey streamgages in the area.

"An above

Attribution: Water Resources
Image: James River at Huron, SD Streamgage
March 1, 2011

James River at Huron, SD Streamgage

USGS hydrologic technicians Tyler Meyer and Jesse Rigge document the river stage and ensure that the streamgage on the James River at Huron, SD is working properly. A streamflow measurement of 17,500 cubic feet per second was made during the site visit.

Attribution: Water Resources
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.

Image: Working on Streamgage
June 11, 2008

Working on Streamgage

USGS personnel working at a "century" streamgage constructed in 1913