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March 16, 2023

U.S. Geological Survey streamgages provide vital information to the public and decision-makers for a diverse set of needs.

The First USGS Streamgage 

In the late 1800s, John Wesley Powell, second Director of the U.S. Geological Survey, had a vision for the Western United States. After exploring the West, Powell recognized that the availability of water was key to the settlement of the region. 

Powell proposed to inventory all streams in the West to evaluate the potential for irrigation in the region. The essential first step in this process was to gage the flow of those streams.  

A hydrographer in a wooden cable car lowers a current meter into the stream below.
A hydrographer taking a cableway streamflow measurement at the first USGS streamgage in Embudo, New Mexico.

A few cities in the Eastern United States had already begun using streamgages, as early as the 1870s, to collect data needed for the design of their water supply systems. Their methods generally involved constructing channels and dams to enable accurate gaging; however, these methods were not feasible in the West. 

In January 1889, the first USGS streamgage was established along the Rio Grande near Embudo, New Mexico. The Rio Grande at Embudo streamgage was developed to handle the unique challenges of the Rio Grande: shallow, fast-moving water and soft, mobile channel beds. 

The equipment and techniques developed at the Embudo site became the foundation of USGS streamgaging methods. 

The USGS Streamgaging Network 

Today, the USGS operates one of the largest streamgaging enterprises in the world, with more than 11,800 streamgages operating in all 50 states, the District of Columbia, Puerto Rico and Guam. Most USGS streamgages are funded in partnership with one or more of about 1,500 Federal, state, local and Tribal agencies and organizations. Each streamgage provides vital information that can help protect lives and property, as well as ensure adequate water supply for the future.  

A streamgage contains equipment that measures, stores and transmits data on water levels and streamflows. Most USGS streamgages transmit data via satellite to USGS computers on an hourly basis, or more frequently during emergency situations. The data are then made available online in near real-time through the USGS National Water Dashboard. Customizable updates about water conditions can also be received on the go by subscribing to USGS WaterAlert

Image: USGS Streamgage at Baton Rouge
A USGS streamgage on the Mississippi River in​​ Baton Rouge, Louisiana. 

USGS streamgage information can be used to meet diverse needs, including uses for water supply and management, monitoring floods and droughts, bridge and road design, determination of flood risk and many recreational activities. 

During the flooding that occurred in California between late December 2022 and January 2023, USGS streamgages provided vital information to the public and decision-makers. Multiple atmospheric rivers swept across California, causing periods of heavy rainfall for most of the state. During this time, the San Francisco Public Utilities Commission utilized USGS streamgage data to plan flood response activities.  

“The SFPUC relies on accurate and real-time hydrology information for our water supply system and watershed land operations, particularly during storm events,” said Tim Ramirez with the San Francisco Public Utilities Commission. “Information regarding reservoir levels, and streams flowing into and from the reservoirs are critical data we use to make operational decisions, and we are grateful for the USGS staff out in the field during these storm events who are an important part of our team.”   

While the current streamgage network provides vital information, the network covers less than 1% of rivers and streams across the country. Additionally, while this information is useful to many, the current spatial and temporal resolution of streamgages are not sufficient to address challenging questions, such as the long-term and short-term risks of floods and droughts.  

Looking to the Future 

USGS scientists are currently working on the next generation of streamflow monitoring technologies.  

The USGS’s Next Generation Water Observing System is a new initiative aimed at developing innovative water monitoring instruments and techniques. NGWOS provides enhanced real-time water quantity, quality and use data that are necessary to support modern water prediction, emergency and water management decision-making and daily water operations.   

Large-scale particle-image velocimetry
The USGS is advancing the use of large-scale particle-image velocimetry (LSPIV), a method that uses innovative video analyzation techniques to measure streamflow.

One example of an innovative streamflow monitoring technology includes the utilization of Large-Scale Particle Image Velocimetry. With LSPIV technology, downward-facing video of moving water can be processed to estimate the velocity of water in the stream. This technology is beneficial for collecting measurements at sites where flow conditions are rapidly changing or difficult for standard streamgaging techniques.  

NGWOS technologies will be primarily tested in USGS’s Integrated Water Science basins, which are medium-sized watersheds (10,000-20,000 square miles) and underlying aquifers that are representative of larger hydrologic regions across the country. The most promising technologies tested in the IWS basins will be transitioned into USGS national network operations to improve the efficiency and accuracy of data collection. 

To date, NGWOS activities are underway in the Delaware, Upper Colorado and Illinois River Basins. USGS began planning for NGWOS activities in the Willamette River Basin in 2022 and will begin implementing new monitoring assets in the basin later this year. USGS will begin planning for NGWOS implementation in a fifth IWS basin, the Trinity-San Jacinto River Basin, later this year. 

The development of new streamgaging technologies and methods through the NGWOS program continues the USGS’s 134-year legacy of providing reliable and relevant scientific information to decision-makers and the public. Learn more about NGWOS:

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