The City of Simi Valley is in the second year of an estimated four-year project to update its official flood maps. These maps are being updated through a FEMA program called Physical Map Revision (PMR). The current maps were made using information from the early 1990s. Since then, the City has grown significantly, and new technology now helps experts study flood risks more carefully and accurately.

In the past, small studies were completed for different parts of the City but were not connected to each other. The City is now creating one overall, up-to-date map using the best available data and tools. This will help people know their true flood risk. Many homes that are now shown in flood zones could be removed, which means some people may no longer have to buy flood insurance. But in some other areas, property owners might be shown to have flood risks that were not previously known.

To create this new floodplain map, the City is working with a local engineering firm with extensive experience in stormwater flow analysis throughout Ventura County. Over the past year, the team has completed the following tasks:

• Studied about 65% of the City’s flood channels (around 28 miles) using new computer tools that make better flood models.

• Built a new Citywide hydrology model. This model shows that stormwater flows are smaller than before, which means the flood zones will be smaller, and fewer people will need to buy flood insurance.

• Built a Citywide watershed model to find areas that could flood after big wildfires, like the Easy Fire in 2019 or the Woolsey Fire in 2018. These maps show how deep and where water might flow if storm drains are blocked by fire debris.

• Created detailed flood models for major watersheds like Arroyo Simi, Bus Canyon, Dry Canyon Las Llajas, North Simi Drain, Sycamore Canyon, and Tapo Canyon. These models help predict how flooding is expected to happen during big storms.

Next year, the City will finish studying the rest of the flood channels and add more details to the maps. This includes adding both public and private storm drain systems. These new maps will give a much clearer picture of what might happen during a big flood.

After the modeling is done, FEMA will check the results and create new official flood maps. These maps will be open for the public to review for feedback before they are approved.

The project is moving forward on schedule, and the City will keep sharing updates as the work continues.

If you have any questions or concerns about the remapping project or its effect on your property, you may contact the City’s Floodplain Manager at (805) 583-6786.