USGS hydrologic technician Aliesha Bradford measures streamflow on Warm Springs Creek near Mackay, Idaho. Photo by Ryan Moore, USGS.
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 its real-time stage data.
During low streamflow conditions, aquatic grasses, debris, or rocks near the gage can produce artificial increases in water level readings. During extreme cold weather, ice can affect stage and discharge determinations at some stations. Adjustment of data for ice effects requires detailed analysis.
Learn more:
- National Water Information System (NWIS) Mapper - Active USGS Surface Water sites with data
- Streamgaging Basics
Related
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...
Is there a way to get alerts about streamflow conditions?
Yes! The U.S. Geological Survey WaterAlert service provides notifications to your email or phone for changes in water conditions based on thresholds you choose.
How can I obtain river forecasts (flood forecasts)?
River forecasts (flood forecasts) are made by the National Weather Service - National Water Prediction Service. The overall map on the website uses color designations to give a quick overview of current conditions. A legend and other information can be selected in the right column. From the main map, click on a station to bring up a box which includes a graph showing current information and a...
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, pour in milk until it is two inches deep -- it...
What does the term "stream stage" mean?
Stream stage (aka gage height) 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...
Why are there sometimes differences between USGS and National Weather Service river stages?
At some USGS streamgage 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...
How is a rating curve used to convert gage height into streamflow?
In order to convert gage height (or "stage", usually expressed as feet) into streamflow (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 manual discrete discharge measurements at stream gaging stations. The rating curve depends on...
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 sediment movement malfunction of recording equipment...
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, springs, atmospheric) and select to show inactive sites...
Why do some real-time streamgaging stations stop transmitting data for extended periods of time?
The USGS usually corrects any equipment or station problems at our streamgages 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 streamgaging stations are operated in cooperation with other agencies. At some stations, the stage transmitting equipment is owned...
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, environmental agencies, universities, consulting firms...
Measuring Streamflow on Warm Springs Creek near Mackay, Idaho
USGS hydrologic technician Aliesha Bradford measures streamflow on Warm Springs Creek near Mackay, Idaho. Photo by Ryan Moore, USGS.
Measuring streamflow in fast moving floodwater.
USGS hydrographer measuring streamflow using a handheld Acoustic Doppler Velocimeter in fast moving floodwater Cajon Creek near Keenbrook, California.
USGS hydrographer measuring streamflow using a handheld Acoustic Doppler Velocimeter in fast moving floodwater Cajon Creek near Keenbrook, California.
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.
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.
Ice jam on Little Wind River (06235500)
Ice jam on Little Wind River Ice jam on Little Wind River (06235500), February 2017. Streamgage destoryed soon after photo taken.
Ice jam on Little Wind River Ice jam on Little Wind River (06235500), February 2017. Streamgage destoryed soon after photo taken.
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.
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.
Ice Jam at White River near Interior, SD (06446500)
Ice jam at White River near Interior, SD (USGS streamgage 06446500). More information on this site is available at https://waterdata.usgs.gov/sd/nwis/inventory/?site_no=06446500&agency_cd=USGS&.
Ice jam at White River near Interior, SD (USGS streamgage 06446500). More information on this site is available at https://waterdata.usgs.gov/sd/nwis/inventory/?site_no=06446500&agency_cd=USGS&.
Under The Ice
On February 26, Nick Stasulis and Charlie Culbertson visited USGS station 01054200 Wild River at Gilead, Maine to make a streamflow measurement through the ice. For these measurements, 20-30 holes are drilled through the ice and a current meter (the spinning yellow cups) is used to measure velocity. River depths and distance across the channel are also measured.
On February 26, Nick Stasulis and Charlie Culbertson visited USGS station 01054200 Wild River at Gilead, Maine to make a streamflow measurement through the ice. For these measurements, 20-30 holes are drilled through the ice and a current meter (the spinning yellow cups) is used to measure velocity. River depths and distance across the channel are also measured.
Measuring Streamflow on Big Thompson River
Jeff Bailes (foreground) of the USGS Colorado Science Center disassembles streamflow-measuring equipment on the Big Thompson River while Ben Glass (background) inspects a USGS rapid deployment streamgage. 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 streamg
Jeff Bailes (foreground) of the USGS Colorado Science Center disassembles streamflow-measuring equipment on the Big Thompson River while Ben Glass (background) inspects a USGS rapid deployment streamgage. 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 streamg
Streamflow Gaging Station and Measurement on San Pedro River, AZ
USGS employee, Hanna Coy, talks about stream gauging.
USGS employee, Hanna Coy, talks about stream gauging.
A rainbow over the USGS streamflow station gage house
A rainbow over the USGS streamflow station gage house at the outlet of Bass Harbor Marsh in Maine (monitoring location 010228955).
A rainbow over the USGS streamflow station gage house at the outlet of Bass Harbor Marsh in Maine (monitoring location 010228955).
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.
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.
Measuring Streamflow Through a Weir
Pew Creek below Johnson Road, Lawrenceville, Ga. The metal structure is a "V" weir. A sediment dam was built on either side of it to force the water through the weir. Scientists can calculate gallons per minute flow in the stream by timing how long the flow took to fill a bucket.
Pew Creek below Johnson Road, Lawrenceville, Ga. The metal structure is a "V" weir. A sediment dam was built on either side of it to force the water through the weir. Scientists can calculate gallons per minute flow in the stream by timing how long the flow took to fill a bucket.
Preparing to Measure Streamflow from a Bridge
USGS Oklahoma Water Science Center Hydrologic Technician Rick Hanlon prepares to conduct a streamflow measurement off of a bridge over the North Canadian River near Oklahoma City.
USGS Oklahoma Water Science Center Hydrologic Technician Rick Hanlon prepares to conduct a streamflow measurement off of a bridge over the North Canadian River near Oklahoma City.
Related
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...
Is there a way to get alerts about streamflow conditions?
Yes! The U.S. Geological Survey WaterAlert service provides notifications to your email or phone for changes in water conditions based on thresholds you choose.
How can I obtain river forecasts (flood forecasts)?
River forecasts (flood forecasts) are made by the National Weather Service - National Water Prediction Service. The overall map on the website uses color designations to give a quick overview of current conditions. A legend and other information can be selected in the right column. From the main map, click on a station to bring up a box which includes a graph showing current information and a...
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, pour in milk until it is two inches deep -- it...
What does the term "stream stage" mean?
Stream stage (aka gage height) 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...
Why are there sometimes differences between USGS and National Weather Service river stages?
At some USGS streamgage 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...
How is a rating curve used to convert gage height into streamflow?
In order to convert gage height (or "stage", usually expressed as feet) into streamflow (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 manual discrete discharge measurements at stream gaging stations. The rating curve depends on...
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 sediment movement malfunction of recording equipment...
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, springs, atmospheric) and select to show inactive sites...
Why do some real-time streamgaging stations stop transmitting data for extended periods of time?
The USGS usually corrects any equipment or station problems at our streamgages 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 streamgaging stations are operated in cooperation with other agencies. At some stations, the stage transmitting equipment is owned...
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, environmental agencies, universities, consulting firms...
Measuring Streamflow on Warm Springs Creek near Mackay, Idaho
USGS hydrologic technician Aliesha Bradford measures streamflow on Warm Springs Creek near Mackay, Idaho. Photo by Ryan Moore, USGS.
USGS hydrologic technician Aliesha Bradford measures streamflow on Warm Springs Creek near Mackay, Idaho. Photo by Ryan Moore, USGS.
Measuring streamflow in fast moving floodwater.
USGS hydrographer measuring streamflow using a handheld Acoustic Doppler Velocimeter in fast moving floodwater Cajon Creek near Keenbrook, California.
USGS hydrographer measuring streamflow using a handheld Acoustic Doppler Velocimeter in fast moving floodwater Cajon Creek near Keenbrook, California.
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.
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.
Ice jam on Little Wind River (06235500)
Ice jam on Little Wind River Ice jam on Little Wind River (06235500), February 2017. Streamgage destoryed soon after photo taken.
Ice jam on Little Wind River Ice jam on Little Wind River (06235500), February 2017. Streamgage destoryed soon after photo taken.
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.
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.
Ice Jam at White River near Interior, SD (06446500)
Ice jam at White River near Interior, SD (USGS streamgage 06446500). More information on this site is available at https://waterdata.usgs.gov/sd/nwis/inventory/?site_no=06446500&agency_cd=USGS&.
Ice jam at White River near Interior, SD (USGS streamgage 06446500). More information on this site is available at https://waterdata.usgs.gov/sd/nwis/inventory/?site_no=06446500&agency_cd=USGS&.
Under The Ice
On February 26, Nick Stasulis and Charlie Culbertson visited USGS station 01054200 Wild River at Gilead, Maine to make a streamflow measurement through the ice. For these measurements, 20-30 holes are drilled through the ice and a current meter (the spinning yellow cups) is used to measure velocity. River depths and distance across the channel are also measured.
On February 26, Nick Stasulis and Charlie Culbertson visited USGS station 01054200 Wild River at Gilead, Maine to make a streamflow measurement through the ice. For these measurements, 20-30 holes are drilled through the ice and a current meter (the spinning yellow cups) is used to measure velocity. River depths and distance across the channel are also measured.
Measuring Streamflow on Big Thompson River
Jeff Bailes (foreground) of the USGS Colorado Science Center disassembles streamflow-measuring equipment on the Big Thompson River while Ben Glass (background) inspects a USGS rapid deployment streamgage. 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 streamg
Jeff Bailes (foreground) of the USGS Colorado Science Center disassembles streamflow-measuring equipment on the Big Thompson River while Ben Glass (background) inspects a USGS rapid deployment streamgage. 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 streamg
Streamflow Gaging Station and Measurement on San Pedro River, AZ
USGS employee, Hanna Coy, talks about stream gauging.
USGS employee, Hanna Coy, talks about stream gauging.
A rainbow over the USGS streamflow station gage house
A rainbow over the USGS streamflow station gage house at the outlet of Bass Harbor Marsh in Maine (monitoring location 010228955).
A rainbow over the USGS streamflow station gage house at the outlet of Bass Harbor Marsh in Maine (monitoring location 010228955).
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.
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.
Measuring Streamflow Through a Weir
Pew Creek below Johnson Road, Lawrenceville, Ga. The metal structure is a "V" weir. A sediment dam was built on either side of it to force the water through the weir. Scientists can calculate gallons per minute flow in the stream by timing how long the flow took to fill a bucket.
Pew Creek below Johnson Road, Lawrenceville, Ga. The metal structure is a "V" weir. A sediment dam was built on either side of it to force the water through the weir. Scientists can calculate gallons per minute flow in the stream by timing how long the flow took to fill a bucket.
Preparing to Measure Streamflow from a Bridge
USGS Oklahoma Water Science Center Hydrologic Technician Rick Hanlon prepares to conduct a streamflow measurement off of a bridge over the North Canadian River near Oklahoma City.
USGS Oklahoma Water Science Center Hydrologic Technician Rick Hanlon prepares to conduct a streamflow measurement off of a bridge over the North Canadian River near Oklahoma City.
Updated Date: March 18, 2025