Mar, 2018

Compare Three Thomas Fire Mudslide Risk Maps

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With another storm coming, the Ventura County Peace and Justice Network is offering three mudslide risk maps for our readers to compare. This might help you make the difficult decision to evacuate, or at least pick up extra sandbags.

US Geological Survey Debris Flow Hazard Map

The US Geological Survey (USGS) provides the most extensive background on how it gets its information.

The map pays special attention to river flows and explains how being beneath a creek during a rain might affect your safety.

It is detailed. For example, it classifies a small area on Fir Street and Poli in downtown Ventura as risky red and nearby areas as lower risk. 

It also considers areas around the 101 freeway between Ventura and Carpinteria, Ventura Avenue and parts of the Ojai Valley as risky. The Ventura County map does not include many of these areas in the mandatory or voluntary evacuation zone.

The US Geological Survey map is still preliminary at this publishing.

To view and interact with the USGS map click here

Gmap4 2018 Wildland Fire Debris Flow Risk Map

The Gmap4 borrows from USGS data, but it provides a different view of the data. The mapmaker does an excellent job showing creek flows.

Information about Joseph Elfelt, the mapmaker is here 

Open this map full screen.

Ventura County Map

The Ventura County map is drastically different from the USGS and Gmap4 maps.  The county may consider parts of downtown Ventura, Ventura Avenue, and huge swaths of the Ojai Valley as risky, but the simple map distributed on March 18, 2018 does not reflect this. This may lead county residents to prematurely think they are safe during a storm.

Out of the three maps the Ventura County shows less creek flow risks. 

If you zoom into the Ojai Valley you can see the Ventura County map is less conservative than the USGS map. The USGS explains why it classifies huge swaths of the Ojai Valley, and parts of the city of Ventura, in red. The county map does not classify many of these areas as either in the voluntary or mandatory evacuating zone.

Santa Barbara County switched to a new map that follows the creeks and actual geographic landscape of the community after critics charged the county’s evacuation plan and maps during the Montecito mudslide as inadequate. The January mudslide caused over 20 deaths.

Maybe Ventura County needs to switch the map it sends to its residents.

County website in Spanish here.

View map


Mudslides are life and death. We recommend using all the Ventura County resources. If you are not under mandatory evacuation, please consider the USGS map as well.

To view and interact with the USGS map click here

Check out county resources here

Thank you Lucas Zucker from Central Coast Alliance United for a Sustainable Economy (CAUSE) who let us know about the Gmap4 map.

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