The Federal Emergency Management Agency (FEMA), with input from local agencies, is working to update area flood maps for Alameda County and the cities of Oakland and Alameda California. The proposed maps more accurately identify flood hazards using current mapping processes and data, which will help planning and permitting officials, business owners, and residents make their communities more resilient from flooding. The preliminary maps identify revised flood hazards along Peralta Creek and the Byron Tract delta.
Before the new Flood Insurance Rate Maps (FIRMs) become effective, there is a 90-day appeal period from March 29, 2025 to June 28, 2025. During that time, residents or businesses with supporting technical and scientific information, such as detailed hydraulic or hydrologic data, can appeal the flood risk information on the preliminary maps, which can be viewed at hazards.fema.gov/femaportal/prelimdownload/.
Flood hazards are dynamic and change frequently for many reasons, including weather patterns, erosion, and community development. Officials from FEMA and Alameda County worked together to provide updated information that accurately reflects the flood risk. These changes may also affect future building standards or insurance requirements.
The local mapping project is part of a national effort led by FEMA to increase local knowledge of flood risks and support actions to address and reduce the effects of flooding on new and improved structures. FEMA encourages residents to review the preliminary flood maps to learn about local flood risks, potential future flood insurance requirements, and identify any concerns or questions about the information provided.
Risk of flooding affects almost every corner of the nation. In total, 98% of counties have experienced a flood event, which makes floods the most common and widespread of all weather-related natural disasters.
For questions about map changes in the Peralta Creek Watershed, contact the City of Oakland Public Works Department at watersheds@oaklandca.gov.
For questions about development in flood plain areas, contact the City of Oakland Planning & Building Department at lbutler@oaklandca.gov.