Skip to main content
U.S. flag

An official website of the United States government

The USGS works in partnership with more than 1,885 Federal, regional, State, Tribal, and local agencies or organizations to maintain and manage a multipurpose network of streamgages that monitor streamflow and (or) water level.

The USGS works in partnership with more than 1,885 Federal, regional, State, Tribal, and local agencies or organizations to maintain and manage a multipurpose network of streamgages that monitor streamflow and (or) water level. Approximately 8,500 of the more than 11,300 USGS streamgages in the network continuously monitor streamflow year-round and are collectively referred to as the National ‘Streamflow’ Network (NSN). Approximately 40% of the NSN are part of the Federal Priority Streamgages network (FPS), which was designed at Congress request to support national needs and serve as a backbone network that is not vulnerable to changing local priorities and resources and that is ‘hardened’ against extreme events. USGS streamgage data are made available online and are used by governmental organizations, private industries, and the general public. The data form the scientific basis for decision making related to protection of life and property from water-related hazards, such as floods; cost-effective management of freshwater that is safe and available for drinking, irrigation, energy, industry, recreation, and ecosystem health; and national, State, Tribal, and local economic well-being. In addition to maintaining and managing a national network of streamgages, the GWSIP ensures the integrity and quality of the data and information produced by its streamflow monitoring program by investing in quality assurance, and research and development.


Below, please find several highlights of recent streamflow monitoring accomplishments and planned activities.

  • In 2020, approximately 3,500 of the targeted 4,760 FPS sites were operational and 3,460 provided near real-time data to the public. GWSIP (FPS Base Funds) fully supports 35% of active FPS gages, while the remaining 65% are jointly funded by GWSIP (FPS Base Funds or Cooperative Matching Funds) and USGS partners. FPS base funding for these streamgages was has remained at $24.7 million since 2016 and several sites were discontinued in 2020 to cover the flat funding
  • As of 2021 there are 760 active Centennial streamgages that have been operational for 100 or more years. 
  • Real-time data from more than 6,780 streamgages allow NOAA’s National Weather Service (NWS) river forecasters to model watershed response, project future streamflows, forecast monthly to seasonal water availability, and issue appropriate flood watches and warnings. In 2020 the USGS National Water Information System received 52.3 million visits and responded to over 887 million human and automated requests for streamflow and water level information. These data are used for a variety of activities, such as managing flood or water scarcity risk to humans, designing bridges, roads and water-treatment plants, and supporting freshwater biodiversity conservation.
  • In 2020 the USGS continued to roll out the Next Generation Water Observing System (NGWOS) to leverage emerging breakthroughs in technical and computational capabilities to deliver high fidelity, comprehensive water data for critical needs. In November 2020 the Illinois River Basin is being added to the NGWOS (2020) to fill monitoring gaps and data needs to advance nutrient delivery and harmful algal bloom prediction.
  • In October 2020 the USGS unveiled a new mobile tool that provides real-time information on water levels, weather and flood forecasts all in one place on a computer, smartphone or other mobile device. The new USGS National Water Dashboard provides critical information to decision-makers, emergency managers and the public during flood events, informing decisions that can help protect lives and property. The National Water Dashboard is a much-needed advancement that will help keep communities across the country safe during extreme weather conditions,” said Tim Petty, Ph.D., Department of the Interior Assistant Secretary for Water and Science
  • The USGS WaterAlert service sends e-mail or text messages when real-time data for user-selected parameters exceed user defined thresholds. In 2020 WaterAlert sent more than 1.5 million alerts per month to about 120,000 subscribers.
  • In 2018, published revision to Guidelines for Determining Flood Flow Frequency--Bulletin 17C.
  • In 2019-2020, the USGS responded to several hurricanes and worked closely with the National Weather Service, Federal Emergency Management Agency, State Emergency Management Divisions and Department of Transportation, U.S. Army Corps of Engineers, and local law enforcement to provide information needed to inform response decisions related to the hurricane. USGS installed 56  rapid deployment gages, 160 storm-tide sensors, flagged over 300 high-water marks (access and download the data) and have made more than 140 high-flow streamflow measurements to provide information vital to people making decisions about public safety.

Stakeholder Quotes

“The independent, science-based streamflow information that we obtain from USGS gages is paramount to assuring compliance under our various interstate compacts with our neighboring states.”
Julie Cunningham, Oklahoma Water Resources Board

“I wanted to thank your team for their stellar work yesterday moving/installing new instruments at both dams [Barker and Addicks reservoirs]. It allows us to continue to use our assets and monitoring systems of the dams in the way we intended, allowing us to do more intensive monitoring elsewhere. The professionalism and skill your team displayed should make all taxpayers proud. Truly above and beyond.”
Coraggio Maglio, P.E., U.S. Army Corps of Engineers Galveston District