FEMA Updates Flood Maps in Alameda County

OAKLAND, Calif. – The Federal Emergency Management Agency (FEMA) has delivered preliminary flood maps for Alameda County and the cities of Alameda, Oakland, and Piedmont, California. The maps identify revised flood hazards along Peralta Creek and the Byron Tract delta. The new maps will help building officials, contractors and homeowners make effective mitigation decisions, thereby contributing to safer and more disaster resilient communities.

Before the new Flood Insurance Rate Maps (FIRMs) become effective, a 90-day appeal period will run from March 29, 2025, to June 28, 2025. During this time, residents and businesses with supporting technical and scientific data—such as detailed hydraulic or hydrologic studies—may appeal the flood risk information. The preliminary maps are available for review at hazards.fema.gov/femaportal/prelimdownload/.

Flood hazards are dynamic and change over time due to factors such as weather patterns, erosion, and community development. FEMA and Alameda County officials worked together to provide updated information that accurately reflects the flood risk. These updates may also impact future building standards and insurance requirements.

This local mapping project is part of FEMA’s nationwide effort to increase flood risk awareness and support actions that reduce the impact of flooding on new and existing structures. FEMA encourages residents to review the preliminary flood maps to understand local flood risks, potential future insurance requirements, and to raise any concerns about the information provided.

Flooding is the most common and widespread weather-related natural disaster in the United States. Ninety-eight percent of counties have experienced a flood event, highlighting the importance of understanding and preparing for flood risks.

For more information, contact Moses Tsang at Alameda County Public Works Agency at (510) 670-5553 or moses@acpwa.org. 

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FEMA’s mission is helping people before, during, and after disasters. Follow FEMA Region 9 online at x/femaregion9.