FEMA Flood Information: Maps and Information

Rosemarie Gaglione, Director, Public Works

Contact Information

Public Works
Land Development Counter

Marin County Civic Center
3501 Civic Center Drive, Suite 308
San Rafael, CA 94901
Phone: (415) 473-3755
TTY: (415) 473-3232
Email: DPWLandDevEngineer

The Federal Emergency Management Agency (FEMA) is responsible for the preparation of Flood Insurance Rate Maps for the National Flood Insurance Program. The panels on this page contain information about the FEMA studies which are underway in Marin County, how to locate the various flood zones in Marin County, answers to frequently asked questions and additional links for more information.

The County of Marin administers the Federal Emergency Management Agency (FEMA) flood insurance program in unincorporated areas of Marin County. For information on flood insurance within the limits of any Marin Communities, please contact them directly.


Flood Insurance Maps

The Federal Emergency Management Agency (FEMA) is responsible for the preparation of Flood Insurance Rate Maps for the National Flood Insurance Program. Two separate FEMA studies have been completed in Marin County that have resulted in revised Flood Insurance Rate Maps for residents in unincorporated Marin and certain cities/towns. In summary, this is the status of the two studies:

  1. The San Francisco Bay Coastal study became effective 3-17-16. This study affected all low lying areas along the Eastern Marin County San Francisco Bay shoreline.
  2. The Open Pacific Coast study, which is studying the flood risk along the Marin County Pacific Ocean coast became effective 8-15-17.

Some property owners have acquired letters of Map Change (LOMC) for their properties. A list of valid LOMCs is available.

For more information on these studies, visit this FEMA Region IX website.

As there have been significant changes to these flood zone maps the following information is important for property owners:

  • If you wish to visit FEMA FIRM's please go to the FEMA Flood Map Service Center website and enter your address.
  • For the County of Marin's Geographical Information System (GIS) maps, please go to the Marin Map website.
  • If you are unable to get a map, please feel free to come into the Marin County Department of Public Works, Room 308 at the Civic Center, call (415) 473-3755 or email us and we will be able to give you the same map.
  • Federally backed mortgage lenders will very likely require property owners that are partially or fully within a SFHA to purchase flood insurance. We recommend printing the FEMA FIRM's and the Marin GIS maps. Show the flood hazard area maps to your mortgage lender to get a determination from them if you are required to get flood insurance. For general FEMA flood insurance information, please visit the FloodSmart website. The County and cities are not involved in any way with the administration or provision of flood insurance. We want to advise you, however, that in the past, as part of FEMA’s authority to administer flood insurance, they have subsidized or ‘grandfathered’ lower insurance rates for property owners that obtained flood insurance policies prior to their property being added to a Special Flood Hazard Area. This is still the case, but FEMA advises that this grandfathering is being phased out over the next few years. For more information on flood insurance, you can visit the National Flood Insurance Program website, operated by FloodSmart.gov or contact your insurance agent.
  • For an overview of the Homeowner Flood Insurance Affordability Act of 2014, visit this FEMA website.

Frequently Asked Questions

Below you will find a listing of commonly asked questions and their answers. If you don't find your question listed, Marin County can provide one-on-one flood information at the permit Counter located in the Marin County Civic Center, Room 308.  There are Land Development Engineers available to answer questions about flood maps, flood zones, base flood elevations (BFE), elevation certificates and to determine whether your property is located in a Special Flood hazard Area (SFHA).

Click on a question to see the answer, or Open All Questions.

  • Why is flooding dangerous?

    Floods are one of the most common hazards in the United States. Flooding can be local, impacting a neighborhood or community, or larger, affecting entire river basins and multiple states. However, all floods are not alike. Some floods develop slowly, sometimes over a period of days and weeks. But other kinds of flooding known as flash floods can develop quickly, sometimes in just a few minutes and without any visible signs of rain. Flash floods often have a dangerous wall of roaring water that carries rocks, mud, and other debris and can sweep away most things in its path. Overland flooding occurs outside a defined river or stream, such as when a levee is breached, but still can be destructive. Flooding can also occur when a dam breaks, producing effects similar to flash floods. Just a few inches of water from a flood can cause tens of thousands of dollars in damage. Each year, more deaths occur due to flooding than from any other severe weather related hazard.

    Be aware of flood hazards no matter where you live, but especially if you live in a low-lying area, near water or downstream from a dam. Even very small streams, gullies, creeks, culverts, dry streambeds, or low-lying area that may appear harmless in dry weather can flood. Every state is at risk from this hazard.

    For more information, see FEMA's flood web page.

  • What are my flood risks?

    Anywhere it rains, it can flood. A flood is a general and temporary condition where two or more acres of normally dry land or two or more properties are inundated by water or mudflow. Many conditions can result in a flood: hurricanes , overtopped levees, outdated or clogged drainage systems and rapid accumulation of rainfall.

    Just because you haven't experienced a flood in the past, doesn't mean you won't in the future. Flood risk isn't just based on history, it's also based on a number of factors: rainfall, river-flow and tidal-surge data, topography, flood-control measures, and changes due to building and development.

  • Why do I need to buy flood insurance?

    Standard homeowners insurance doesn't cover flooding. It is important to have protection from the floods associated with hurricanes, tropical storms, heavy rains and other conditions that impact the U.S.

    In 1968, Congress created the National Flood Insurance Program (NFIP) to help provide a means for property owners to financially protect themselves. The NFIP offers flood insurance to homeowners, renters, and business owners if their community participates in the NFIP. Participating communities agree to adopt and enforce ordinances that meet or exceed FEMA requirements to reduce the risk of flooding. Marin County participates in the NFIP.

    • Find out more about the NFIP and how it can help you protect yourself by visiting Floodsmart.gov.
  • How do I find out if I am in a flood zone?

    You can contact the Land Development Division of the Department of Public Works for FEMA flood zone information. They can be reached by phone at (415) 473-3755, by email to the Department of Public Works Land Development Engineer, or in person in Room 308 at the Marin County Civic Center.

  • How do I obtain an elevation certificate?

    Elevation Certificates can only be completed by a licensed land surveyor, engineer, or architect who is licensed by the State to perform such functions. Copies of completed elevation certificates that have been submitted to the County are available at the Land Development office in Room 308 at the Marin County Civic Center.

    To find a licensed professional land surveyor in your area, please go to the California Land Surveyors Association website.

  • What is a Special Flood Hazard Area (SFHA)?

    The Special Flood Hazard Area (SFHA) is defined by FEMA as the area that will be inundated by the flood event having a 1-percent chance of being equaled or exceeded in any given year (sometimes called the “100-year” flood). Flood-hazard maps or flood insurance rate maps (FIRMs) have been created by FEMA to show the flooding risk for your community, which help determine the cost of flood insurance. The lower the degree of risk, the lower the flood insurance premium. Properties in the SFHA may be subject to the mandatory flood insurance purchase requirements of the National Flood Insurance Program (NFIP). A good source of flood information is the Homeowner FAQs. You can also contact the Land Development Division of the Department of Public Works for FEMA flood zone information. They can be reached by phone at 415-473-3755, by email, or in person in Room 308 at the Marin County Civic Center.

  • Can I change my flood zone determination?

    It depends on the reason for the change in flood zone. If a property owner thinks their property has been inadvertently mapped in a Special Flood Hazard Area or is now out of the flood zone due to elevating the structure or another reason, they may submit a request to FEMA for a Letter of Map Change or Amendment (LOMA). The requirements of the LOMA depend upon the reason for the requested change in flood zone and may require the applicant to hire a licensed surveyor or engineer. 

    If the request is granted, property owners may be eligible for lower flood insurance premiums, or the option to not purchase flood insurance.

    If an elevation certificate is required to support the change in flood zone, the elevations must be certified by a Registered Professional Engineer or Licensed Land Surveyor.

    A Letter of Map Change (LOMC) reflects an official revision/amendment to an effective Flood Insurance Rate Map. If the LOMC request is granted, property owners may be eligible for lower flood insurance premiums, or the option to not purchase flood insurance.

    A Letter of Map Amendment (LOMA) is a letter from FEMA stating that an existing structure or parcel of land that is on naturally high ground and has not been elevated by fill, would not be inundated by the base flood. Applicants can now use the Online LOMC, an Internet-based tool, to easily request a Letter of Map Amendment. The Online LOMC tool is available to any applicant who would like to submit a LOMC request directly to FEMA and does not require a surveyor or engineer to submit.

    A Letter of Map Amendment-Out As Shown (LOMA-OAS) is a determination made by FEMA for the property and/or buildings as to whether it is located with the SFHA. Only use this method if it is clear, visually, that the structure is not in the SFHA. Instructions are available Instructions for LOMA-OAS are available online.

  • How high should I build my home above the Base Flood Elevation (BFE)?

    If your home is in a Special Flood Hazard Area (SFHA) you must build your home so that the finished flood elevation is at least one (1) foot above the FEMA Base Flood Elevation (BFE). FEMA updates their maps and BFE regularly so it can be assumed that the BFE for your structure will change over time. It may be prudent to build, remodel, or elevate your home more than one foot above the BFE to protect yourself, your family, and your possessions.

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