FEMA flood risk mapping is part of a national effort to increase local knowledge of flood risks and support actions to reduce flooding effects on existing, new, and improved structures.
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Flood risk changes over time. FEMA revises flood maps as risks are identified and new data and information becomes available. By using the latest flood mapping data, building officials, contractors, and homeowners can make informed decisions that contribute to a safer and more flood-resilient community.
There is no set timeline for revising flood maps. Revisions typically occur when more accurate engineering information becomes available through a FEMA-funded restudy or when a community makes new information available to FEMA.
FEMA’s Flood Risk Mapping Project covers the Santa Rosa Creek watershed. This includes Santa Rosa Creek and key tributaries, including Austin Creek, Brush Creek, Brush Creek Middle Fork, College Creek, Ducker Creek, Matanzas Creek, Paulin Creek, Peterson Creek, Forestview Creek, Piner Creek, Rincon Creek, Spring Creek, and Wendell Creek
A FEMA flood map, or FIRM, is revised through a multi-year process that includes distribution of preliminary mapping and a 90-day public appeal and comment period before adoption and effective date.
The SFHA is the area mapped on a Flood Insurance Rate Map (FIRM) by FEMA with a 1% annual chance of flooding. If a home or structure is in a SFHA, it has a 1-in-4 chance of getting flooded over a 30-year period.
FEMA relies heavily on communities to provide local flood risk information, including technical data. The City and Sonoma Water, Santa Rosa’s flood control district, are providing local hydrologic and hydraulic data to FEMA from the Santa Rosa Creek Flood Study completed in 2023. FEMA will use the local data and their own to develop Preliminary FIRMs and Flood Insurance Study (FIS).