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September 1, 2021

To learn more about USGS’s role in providing science to decision-makers before, during and after Hurricane Ida, visit

For information on what the Department of Homeland Security and FEMA are doing, visit:

For more on what the U.S. Government is Doing, visit: or for Spanish.

Editor’s Note: This story was updated September 2 to reflect ongoing USGS field work.

A USGS hydrologic technician sits on the bank of a stream and uses an Acoustic Dopler Current Profiler to measure streamflow
Dakota Robey, a USGS hydrologic technician, uses an Acoustic Dopler Current Profiler to measure elevated streamflow caused by the remnants of Ida at Beaver Run in Carroll County, Maryland. USGS photo. (Public domain.)

U.S. Geological Survey crews are in the field today in multiple states responding to the flooding and high water caused by Ida. The Category 4 hurricane made landfall August 29 in Louisiana hurricane with powerful storm surge, heavy rains and 150+ mph winds.

In Louisiana, crews are making high flow measurements to capture how much water is flowing in several rivers and streams impacted by Ida. There are also crews in West Virginia, Maryland, Delaware, Pennsylvania, New Jersey, New York and New England making water measurements from rains received from the remnants of Ida. Several places in the Northeast received severe flooding from Ida. For instance, New York City and surrounding areas was hit with catastrophic flash flooding from torrential rainfall of up to 9 inches falling on areas already saturated by several inches of rain from Hurricane Henri last week.

A USGS hydrologic technician stands on a bridge using a computer to processes a completed high water measurement.
Ian Lynch, a USGS hydrologic technician, processes a completed streamflow measurement taken September 1 on Chartiers Creek in Carnegie, Pennsylvania. USGS photo by Celeste Huss. (Public domain.)

More than 130 USGS streamgages are measuring water levels at flood stage from the rains Ida dropped across the country, with more than 30 gauges showing rivers and streams that are in major flood stage. The public can track changing water levels at locations of interest by checking out the USGS National Water Dashboard, which has data from approximately 11,400 real-time USGS streamgages across the nation.

Crews in Louisiana, Maryland, New Jersey and Pennsylvania have begun repairing USGS streamgages damaged or destroyed by Ida. This work is vital to ensuring the data USGS streamgages provide on river levels and flow continues to reach emergency managers, flood forecasters and anyone threatened by potential flooding caused by Ida. The National Weather Service uses the data to track floodwaters in real-time as they develop flood forecasts that are used to protect lives and property, and the U.S. Army Corps of Engineers use it to manage flood control at dams and reservoirs across affected regions.

“Most of our damaged streamgages in Louisiana are in the marsh areas or along the coast and we aren’t going to be able to get to those for some time due to road closures and flooding,” said Aub Ward, USGS Lower Mississippi Gulf Water Science Center Data Chief of Operations. “Our plan is to get crews out to repair equipment as soon as it can be done safely so those streamgages can get back to transmitting their critical data.”

Because streamgage and post-storm floodwater data informs decision-makers as they work to help protect the public, USGS crews will be in the field over the coming days continuing this work as needed.

Crews in Louisiana and Mississippi are also working to collect USGS storm tide sensors, which were installed before Ida made landfall to measure the storm’s coastal waves and storm tide. Storm tides are increases in ocean water levels caused by extreme storms and include the storm generated surge plus changes to water levels from local tide cycles. Storm tides are among the most dangerous natural hazards unleashed by hurricanes. They can destroy homes and businesses, wipe out roads, bridges, water and sewer systems, and profoundly alter coastal landscapes.

However, due to downed trees and flooded roads, it will take time to collect all of the sensors.

A USGS civil engineer finds and measures a high water mark left behind by flooding cause by Ida.
Brandon Anderson, a USGS civil engineer, locates a highwater mark left by flooding from Hurricane Ida. This high water mark was found at a USGS streamgage site on the Tchoutacabouffa River near White Plains, Mississippi. Photo by Trent Baldwin, USGS. (Public domain.)

“Many of our sensors in South Louisiana were installed in the hardest hit parts of the state so it will take some time to get down there,” said John Storm, a USGS hydrologist. “Today and tomorrow we hope to be able collect some sensors in Mississippi and in Western Louisiana and we will collect the rest as we can get to them.”

In the coming weeks, the data obtained from the storm tide sensors can help the Federal Emergency Management Agency tell the difference between wind and water damage – important information for property owners and insurers. The data can also improve coastal change forecast and storm surge models and provide information used by FEMA to update the nationwide flood zone maps that underpin the federal flood insurance program. 

Storm tide sensor deployment locations for Ida can also be found on the Flood Event Viewer, although the data from those instruments aren’t available in the viewer until the sensors are collected and the data processed.

For more than 125 years, the USGS has monitored flow in selected streams and rivers across the U.S. The information is routinely used for water supply and management, monitoring floods and droughts, bridge and road design, determination of flood risk and for many recreational activities. 

Access current flood and high flow conditions across the country by visiting the USGS WaterWatch website. Receive instant, customized updates about water conditions in your area via text message or email by signing up for USGS WaterAlert.

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