Flood Maps

A Flood Insurance Rate Map (FIRM), Flood Boundary and Floodway Map (FBFM), and Flood Hazard Boundary Map (FHBM) are all flood maps that have been produced by FEMA. The FIRM is the most common map and is the one used by most communities. At a minimum, flood maps show flood risk zones and their boundaries, and may also show floodways and Base Flood Elevations (BFEs).

More recent flood map products include digital FIRMs, which are created using digital methods and can be incorporated into a community's Geographic Information System (GIS). FEMA has also produced Q3 Flood Data, which includes certain features of the FIRM, and may be used for insurance purposes and planning activities.

Flood Insurance Rate Map

Changes to Flood Zone Designations

If you believe your property was incorrectly included in a National Flood Insurance Program (NFIP) identified Special Flood Hazard Area (SFHA), you may submit an application to FEMA for a formal determination of the property's location and/or elevation relative to the SFHA. The SFHA is the area that has a 1-percent or greater chance of flooding in any given year; this area is also referred to by some as the 1-percent-annual-chance floodplain, base floodplain or the 100-year floodplain. After FEMA reviews the map change request, it will issue a Determination Document, either approving or denying the map change. If FEMA grants the map amendment or revision request, the property owner may no longer be required to pay flood insurance. The property owner may send the Determination Document to their lender and request that the federal flood insurance requirement for the structure be removed.

Current and Historical Maps

Current FIRM dated September 26, 2008 (PDF)
FIRM dated January 3, 1990 (PDF)
FIRM dated November 10, 1981 (PDF)
FIRM dated August 1, 1979 (PDF)
FHBM dated September 26, 1975 (PDF)

Flood Mapping Update

The current Flood Insurance Rate Map (FIRM) for Stanislaus County does not reflect protection by levees along the San Joaquin and Tuolumne Rivers from the 1% annual chance (100-year) flood. FEMA has issued preliminary (draft) FIRM panels for communities that are affected by this map revision. These panels reflect the latest engineering analyses, base data and topographic information available. Approximately 25 revised FIRM panels are expected for Stanislaus County: two of them for the city of Patterson. In addition to the updated FIRM panels, local officials will receive an updated Flood Insurance Study (FIS) report that includes a narrative description of the study for the San Joaquin River, the Tuolumne River and Dry Creek. These changes do not impact any urban areas within the city, only those next to the San Joaquin River such as the Water Quality Control Facility. This facility is considered within city limits and is now in the Special Flood Hazard Area (SFHA). In addition to adopting the flood maps, the city must also revise its flood code to reflect the most recent changes to the state’s Flood Model Companion Ordinance (Model Code). A public hearing will be held on July 6, 2021 at 7:00pm for the introduction and first hearing of the city's flood ordinance update. The second reading and adoption is scheduled for July 20, 2021.

Draft Title 17-Flood Hazard Areas Ordinance                                                                                                                                      Revised FIRM                                                                                                                                                                                      Revised Flood Insurance Study                                                                                                                                                            Public Hearing Notice

For the city to stay in the National Flood Insurance Program (NFIP), it must adopt these maps and proposed changes to the municipal code and be fully enforceable by August 24, 2021.This includes the 30-day post adoption period. These changes have been reviewed by FEMA, NFIP and the Department of Water Resources. 

If you have any questions regarding the ordinance updates or map changes, please call Maria Encinas at (209) 895-8061 or email mencinas@ci.patterson.ca.us.