California Flood Preparedness Week

While rain may seem like a welcome event after more than five years of drought, drought effects actually increase the risk of dangerous flash flooding and debris flow. The U.S. Geological Survey California Water Science Center, the National Weather Service, the California Department of Water Resources, and others work together to make sure public officials have access to reliable, real-time weather and water data to make informed, flood management decisions during rain events.

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The CAWSC is on the job, monitoring rivers and streams closely with an extensive Streamgage Network. The USGS network collects real-time data from more than 500 streamgages throughout the State.

Many of these gages are Automated Local Evaluation in Real-Time (ALERT) streamgages, meaning they are designed to send warnings when water levels reach a predetermined level or change rapidly. High water levels or sudden changes in flow may be indicative of an increased risk of debris flow and flash flooding, which can pose a significant hazard to downstream communities. Data from ALERT gages are used by the National Oceanic and Atmospheric Administration (NOAA) National Weather Service (NWS) to assess the need for emergency preparedness or early warning systems that can help protect life and property.

Monitoring the rise and fall of water levels is important throughout the State, particularly in areas affected by wildfires. Burn areas have increased risk of both flash flooding and debris flow, and CAWSC is on the job carefully watching the potential of these hazards through the USGS streamgaging network.

In 2015, the USGS installed 11 new ALERT streamgages in the Valley and Butte wildfire burn areas in Northern California. CAWSC chose these areas specifically to monitor and assess hazards associated with post-fire risks.

"[The sites] were strategically located in conjunction with the NWS to ensure that the best locations were chosen that would give emergency managers the data needed for the issuance of flood warnings," says Al Caldwell, CAWSC Deputy Associate Director for Data. "Debris flows are expected in the steep areas of these burns, and sites with high probability of landslides were also considered in the siting of these gages with the help of the USGS Landslides Hazards group."

What does this mean to you? All USGS streamgaging data is publically available online in various locations. Consider the sources below for water, streamgaging, and flood activity data:

California Water Data
View real-time USGS streamgaging data at sites across the state

USGS WaterNow
Subscribe to have data sent directly to your phone or email

California Flood Activity
Project Alert Notices include response summaries of USGS streamgaging network activity during storm events in California

Watches, Warnings or Advisories for California
Access current alerts from NOAA

Communities throughout California also provide early alert systems, where you can subscribe to have important hazard warnings sent directly to you. These resources are essential to avoiding potential flash floods, debris flow, or other hazards that may affect your community.