FAQ: Sauvie Island Flood Map

1. Why are portions of Sauvie Island getting new flood hazard maps?

Flood hazard maps, also known as Flood Insurance Rate Maps (FIRMs), are important tools in the effort to protect lives and properties in Multnomah County. They indicate the risk for flooding throughout the County. However, the current maps are out of date. Some areas were never mapped in detail, and other areas haven’t been re-mapped in years.  

New digital mapping techniques provide more detailed, reliable and current data on Multnomah County flood hazards. The result: a better picture of the areas most likely to be impacted by flooding and a better foundation from which to make key decisions.

2. Who is responsible for revising the maps?

Currently, there is a nationwide collaborative effort across all levels of government to update the nation's flood hazard data and provide it in a detailed, digital format, in accordance with a multi-year plan created by the Federal Emergency Management Agency (FEMA). The effort evolved as a growing number of industries were impacted by out-of-date flood data. 

Multnomah County’s map modernization project is a joint effort with FEMA in cooperation with local associations and private sector partners. The flood hazard maps must present flood risk information that is correct and up to date to ensure that they provide a sound basis for floodplain management and insurance rating. FEMA relies heavily on communities to provide notification of changing flood hazard information and to submit the technical support data needed to reflect the updated flood hazards on the NFIP maps. Although revisions may be requested to change any of the information presented on the NFIP maps, FEMA generally will not revise an effective map unless the changes involve modifications to Special Flood Hazard Areas (one percent annual chance floodplains or flood elevations). 

More detailed information on flood risk has been developed as part of the required engineering assessments to determine if the Sauvie Island Levee met all necessary safety standards. It is the local government’s responsibility to share this data and revise flood hazard maps to increase public safety. 

3. What is a Flood Hazard Map?

Flood hazard maps, also called “Flood Insurance Rate Maps” or “FIRMs” are used to determine the flood risk to your home or business. The low- and moderate-risk zones are represented on the maps by the letter “X” or an “X” that is shaded. The high-risk zones will be labeled with designations such as “A”, “AE”, “AO” or “AH”.

  • Zone A: Areas with a 1% annual chance of flooding and a 26% chance of flooding over the life of a 30-year mortgage. Because detailed analyses are not performed for such areas; no depths or Base Flood elevations are shown within these zones.
  • Zone AE: Flood prone areas where Base Flood elevations are provided. AE Zones are now used on new format FIRMs instead of A1-A30 Zones.
  • Zone X: Areas outside of the special flood hazard area.

4.  What is a Letter of Map Revision (LOMR)?

A Letter of Map Revision (LOMR) is the Federal Emergency Management Agency’s (FEMA's) official modification to an effective Flood Insurance Rate Map (FIRM). LOMRs can result in a physical change to the existing regulatory floodway, the effective Base Flood Elevations (BFEs), or the Special Flood Hazard Area (SFHA). LOMR reviews take up to 90 days to process, are subject to an appeal period, and usually become effective within six months after they are issued. Because a LOMR officially revises the effective FIRM, the flood hazard updates shown are used to rate flood insurance policies and enforce flood insurance and development requirements. 

5. What are the benefits of revising flood hazard maps?

Flood hazard maps revised to show the most currently available data will benefit numerous groups of people in different ways: 

  • Community planners and local officials will gain a greater understanding of the flood hazards and risks that affect Multnomah County and can therefore improve local planning activities. 
  • Builders and property owners will have access to more detailed information for making decisions on where to build and how construction can affect local flood hazard areas. 
  • Insurance agents, insurance companies, and lending institutions will have easy on-line access to updates and upcoming changes in order to serve their customers and community more efficiently. 
  • Home and business owners will have the ability to make better financial decisions about protecting their properties.

6. What is a floodplain and how do I determine if my property is located in this area?

A floodplain is the part of the land where water collects, pools, and flows during the course of natural events. Such areas are classified as Special Flood Hazard Areas (SFHA), and are located in a 100-year flood zone. The term "100-year flood" is a little confusing. It is the flood elevation that has a 1- percent chance of being equaled or exceeded each year; it is not the flood that will occur once every 100 years. The likelihood of a flood occurring within a 100-year stretch of time is very, very high, but there’s no way to predict when the next flood will occur – or the one after that. The redrawn maps indicate the floodplain as a “high-risk” area. Low- and moderate-risk areas will be designated as X zones and shaded X zones on the new maps. 

7. How will the new flood hazard maps affect me?

The lands inside of the Sauvie Island levee will be affected differently by these map changes. There will be some properties that aren’t affected – their risk remains the same. Other properties will now be mapped into a higher-risk area and/or show a new Base Flood Elevation.   

Base Flood Elevation: The height of the base flood—or area of land that has a 1 percent chance of flooding in a given year—in feet, in relation to the North American Vertical Datum of 1988.

8. What will happen if I move from a low- or moderate-risk area to a high-risk area?

If the new maps—once adopted—indicate the building on your property is now at a higher risk for flooding, you will be required to purchase a flood policy if you carry a mortgage from a federally regulated lender. If you do not have a mortgage, it is still recommended that you purchase flood insurance. Over the life of a 30-year loan, there is about a 3 times greater chance of having a flood in your home than having a fire. And most homeowner’s insurance policies do not provide coverage for damage due to flooding. 

9. How might the new flood maps affect me financially?

When new maps are officially adopted, if your structure is mapped into a high-risk area and you have a mortgage with a federally-regulated lender, you will need to purchase flood insurance.  If your property is mapped into a low-or moderate-risk area, you are not required to purchase or maintain insurance, but are strongly encouraged to do so.  The cost of properly protecting your home and contents from flood damage is far less expensive than the cost to repair or replace it after a flood has occurred.

Through the National Flood Insurance Program, coverage can often be obtained at significant savings. The average cost for a flood insurance policy is around $500 per year. Further, homeowners may qualify for a Preferred Risk Policy that covers both a structure and its contents for as little as $112 per year. Coverage for renters starts at just $39 a year. Talk to your insurance agent to determine the appropriate level of protection you need and the money savings options that are available.

10. What if my home or business is mapped into a high-risk area, but I believe the designation is in error?

Flood map designations are always based on the best data available to engineers and local officials at the time areas within a community are surveyed and assessed. Every effort is made to ensure that the maps reflect the most accurate and reliable information about the flood risk for all properties. However, re-examining and updating flood hazard information for an entire community is often a multi-year process, and you may feel that you have more accurate data about your property when new maps are eventually completed and released to the public.  

As a mechanism to ensure that residents’ questions or concerns about the new map designations are addressed, a 90-day “Public Comment Period” is in place which will start after the LOMR application has been reviewed by FEMA.  Affected landowners will be sent another notification letter at that time. During this period, citizens will have the opportunity to submit technical and/or scientific data to support a claim that their property has been improperly placed in a high-risk area. If you have better information, such as an elevation certificate, topographic map or detailed hydraulic or hydrologic data, then you may be able to protest or appeal the flood risk indicated by the new maps. More information on the Protest and Appeal process is available online.

11. When do the new maps become effective?

Multnomah County estimates final map adoption in 2023 and there are many steps in the process that will occur prior to map adoption. Multnomah County plans to submit a Letter of Map Revision (LOMR) to FEMA in 2023 to consider the FIRM revisions based on new interior flood data. FEMA has 90 days to review the LOMR application and may request additional data. Once a determination of the LOMR application is made, FEMA will then officially release the revised flood maps (FIRMs), in preliminary form, to county officials and the public. A 90-day Public Comment Period will then be provided. The final adoption process will conclude following the closure of the comment period. Once the maps are adopted by Multnomah County, new flood insurance requirements will become effective. Impacted property owners will be invited to attend and participate in the Planning Commission hearing prior to map adoption.

For an updated timeline of the FIRM revision process, visit the project webpage which will be updated throughout the project timeline.

12. How can I learn more about the flood map revision process and how it could affect me?

Website Resources:

Contact Information: