The USGS maintains and monitors hundreds of streamgages across California, as well as across the Nation. Nearly all data collected by the USGS is made public and most in near real-time. Cities can use the data for flood mitigation and water supply.
To help emergency managers and others protect life and property due to floods and other water-related hazards, the USGS delivers a continuous source of streamflow information. The U.S. Geological Survey has been measuring streamflow in the U.S. for over 120 years. We operate more than 7,500 streamgages in the U.S. and nearly 500 in California that collect data to determine the amount of water flowing in rivers and streams. Automatic alerts are transmitted when water levels change rapidly and/or reach flood stage. These alerts help emergency managers assess potential hazardous conditions near the gage or for downstream locations.

California Streamgage Network
Streamgage sites provide continuous scientific data such as water level (stage) and flow rate, chemistry, and temperature in the Nation’s rivers. This critical information is used for many purposes, from flood forecasting to recreational planning. Water agencies rely on this information to assess the availability and quality of water supplies. It also helps us understand how streams are affected by human activities and by climate change.
See Current California Water Conditions >>
Automated Local Evaluation in Real-Time (ALERT) Gages
Many of the USGS streamgages in California are Automated Local Evaluation in Real-Time (ALERT) gages. ALERT gages are designed to send an automated warning when water levels reaches predetermined levels or change rapidly.
These water levels can signify potentially hazardous conditions for downstream locations. ALERT data are streamed in real-time to the National Water Information System (NWIS-web), and are used by the National Weather Service for model forecasting and to issue flood warnings.
The USGS California Water Science Center recently added several ALERT gages and precipitation stations in the burn areas of the Valley and Butte Wildfires to help monitor the potential for mudslides and debris flows, and to provide early flood warning to downstream areas.
Below are other science projects associated with this project.
Floods in California
Flood Inundation Mapping Science
Flood Inundation Mapping (FIM) Program
Below are data or web applications associated with this project.
California Flood Activity Alerts
USGS Flood Event Viewer - Network
National Water Information System web interface (NWISweb)
Below are multimedia items associated with this project.

The USGS maintains and monitors hundreds of streamgages across California, as well as across the Nation. Nearly all data collected by the USGS is made public and most in near real-time. Cities can use the data for flood mitigation and water supply.
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.
Below are data or web applications associated with this project.
Runoff Estimates for California
National Water Information System (NWIS) Mapper
Drought & Surface Water in California
Below are news stories associated with this project.
To help emergency managers and others protect life and property due to floods and other water-related hazards, the USGS delivers a continuous source of streamflow information. The U.S. Geological Survey has been measuring streamflow in the U.S. for over 120 years. We operate more than 7,500 streamgages in the U.S. and nearly 500 in California that collect data to determine the amount of water flowing in rivers and streams. Automatic alerts are transmitted when water levels change rapidly and/or reach flood stage. These alerts help emergency managers assess potential hazardous conditions near the gage or for downstream locations.

California Streamgage Network
Streamgage sites provide continuous scientific data such as water level (stage) and flow rate, chemistry, and temperature in the Nation’s rivers. This critical information is used for many purposes, from flood forecasting to recreational planning. Water agencies rely on this information to assess the availability and quality of water supplies. It also helps us understand how streams are affected by human activities and by climate change.
See Current California Water Conditions >>
Automated Local Evaluation in Real-Time (ALERT) Gages
Many of the USGS streamgages in California are Automated Local Evaluation in Real-Time (ALERT) gages. ALERT gages are designed to send an automated warning when water levels reaches predetermined levels or change rapidly.
These water levels can signify potentially hazardous conditions for downstream locations. ALERT data are streamed in real-time to the National Water Information System (NWIS-web), and are used by the National Weather Service for model forecasting and to issue flood warnings.
The USGS California Water Science Center recently added several ALERT gages and precipitation stations in the burn areas of the Valley and Butte Wildfires to help monitor the potential for mudslides and debris flows, and to provide early flood warning to downstream areas.
Below are other science projects associated with this project.
Floods in California
Flood Inundation Mapping Science
Flood Inundation Mapping (FIM) Program
Below are data or web applications associated with this project.
California Flood Activity Alerts
USGS Flood Event Viewer - Network
National Water Information System web interface (NWISweb)
Below are multimedia items associated with this project.

The USGS maintains and monitors hundreds of streamgages across California, as well as across the Nation. Nearly all data collected by the USGS is made public and most in near real-time. Cities can use the data for flood mitigation and water supply.
The USGS maintains and monitors hundreds of streamgages across California, as well as across the Nation. Nearly all data collected by the USGS is made public and most in near real-time. Cities can use the data for flood mitigation and water supply.
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.
Below are data or web applications associated with this project.
Runoff Estimates for California
National Water Information System (NWIS) Mapper
Drought & Surface Water in California
Below are news stories associated with this project.