FEMA Floodplain Management Program


The Contra Costa County Floodplain Management Program is for unincorporated County areas only. Engineering Services Division coordinates the program and provides floodplain information for existing structures and proposed projects within the Special Flood Hazard Area (SFHA).

In July 1987, the Federal Emergency Management Agency (FEMA) produced a Flood Insurance Study (FIS) and printed Flood Insurance Rate Maps (FIRMs). These watersheds are re-studied and re-mapped periodically, showing areas with a one percent chance of flooding each year. These areas are commonly referred to as "100-year floodplains," and are shown as SFHAs on the FIRMs. Flood insurance is mandatory for residential, commercial, and industrial developments within SFHAs, and for federally-backed mortgages. Flood insurance may also be required by lenders.

In compliance with the National Flood Insurance Program (NFIP), the County adopted a Floodplain Management Ordinance. This Ordinance requires that the lowest floor, including basement, for all new structures or substantial improvements to existing structures within a SFHA, shall be elevated one to two feet above the 100-year Base Flood Elevation (BFE) for that area. Lower insurance rates are available when the lowest floor is above the BFE.

Visit the FEMA website and the FloodSmart website for information on the NFIP. These websites offer information on floodplains, flood insurance coverage for residential and commercial structures, and flood preparation and recovery. 

FEMA Flood Zone Determination

Visit the FEMA website to determine if you property is within the SFHA.

Public Works staff can determine your flood zone designation using available Assessor's Parcel Map, County base maps, FEMA information, and other documents or maps. The fee for this written determination is $50 per parcel. If a site visit is warranted, there will be an additional $250 fee.

For the Flood Zone Determination (PDF), please have the address and/or parcel number, as well as the phone number, for the property in question available. The information provided in response to your request includes the FIRM designation, community number, panel number and effective date, base flood elevation (if available on the FIRM), and average depth of inundation. 

Floodplain Permit and Elevation Certificate

If you are constructing improvements within the SFHA, you are required to apply for a Floodplain Permit (PDF) from the Public Works Department, at the Application and Permit Center. Elevation Certificate (EC) will be required for new and substantial improvements.

Elevation Certificates (EC) provide elevation information on the structure. Copies of the form and instruction are available on FEMA's website. The County maintains ECs for all new and substantially improved structures in the SFHA. To obtain a copy of the EC, please contact our Floodplain Management team at (925) 646-1623. 

Floodplain Map Change 

(Letter of Map Amendment and Letter of Map Revision)

Letter of Map changes are in the forms of Letter of Map Amendment (LOMA), Letter of Map Revision (LOMR), or in an official republication of the map to reflect the changesThe LOMA or LOMR application is submitted directly to FEMA by you as the property owner or your agent. Before submitting the application, FEMA requires the community to review the application for certain LOMA application and all LOMR application.

LOMA amends the FIRM by letter and is usually issued because a property was inadvertently mapped in the SFHA, but is actually above the BFE on high ground. If a property is located within the regulatory floodway, FEMA requires the community to review the application before submitting it to FEMA.

LOMR revises the FIRM and sometimes the FIS. FEMA requires a community to review the application before submitting it to FEMA.

Review by the community is acknowledged by signing the Community Acknowledgement section of the application. Staff will review your application for compliance with local ordinance, regulations, and permits; and reasonableness and accuracy, given the knowledge of local conditions. FEMA will review the application and supporting technical data. The cost for this review is based on time and material, with an initial deposit of $500. The deposit will need to be included with the Community Acknowledgement form, a copy of the application to FEMA, and any other applicable supporting documents to Public Works Department, Engineering Services Division.

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CRS Rating 

Contra Costa County has earned a Class 5 community rating from FEMA's National Flood Insurance Program (NFIP). As a result, current and new policyholders will save 25% percent on the annual premium on each flood insurance policy in identified high-risk areas and 10% percent in lower risk areas.


Contra Costa County Riverine Physical Map Revision (PMR)

Contra Costa County Riverine PMR includes new flood studies being performed along the following flooding sources in Contra Costa County:

  • Portions of Brushy Creek
  • Frisk Creek
  • Kellogg Creek
  • Marsh Creek
  • Mount Diablo Creek

The update also includes a new study of the 10-, 50-, 100-, and 500-year flood events, as well as the creation of floodways for the reaches.

The Flood Insurance Rate Map (FIRM) panels, Flood Insurance Study (FIS) report, are available from FEMA FloodMap Service Center.