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Remapping the 100-year Floodplain for Johnson Creek

Photo shows an open space holding flood water with dry winter grasses and split-rail fencing
Environmental Services is working to reconnect Johnson Creek to its historic floodplain, reduce flooding on private property, restore habitat, and improve water quality in the creek. This work is revising the 100-year floodplain maps, which may cause changes to property insurance requirements.
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About Floodplain Maps

The Federal Emergency Management Agency (FEMA) is the national government agency that coordinates federal aid and relief following a disaster. According to FEMA, flooding is one of the most common and costly environmental disasters. Flood risk can change over time due to climate change, development, or restoration activities within the floodplain.

FEMA maps flood risk around the country. Flood maps help show how likely an area is to flood. Learn more about flood maps on FEMA’s website.

The 100-year floodplain is an area that FEMA has mapped as having a one percent chance or greater of flooding in one year. Flood Insurance Rate Maps are the official maps showing the boundaries of the 100-year floodplain near the region's creeks, rivers, and streams.

Properties within the 100-year floodplain have special regulations and require flood insurance. Within the term of a 30-year loan, there is at least a 25 percent chance that a structure in the 100-year floodplain will flood. Some of these properties flood often, while others only flood during very large storms.

The City’s Role

Community Rating System Lowers Insurance Costs

The City participates in a voluntary FEMA incentive program called the Community Rating System (CRS). The City’s work to reduce flood damage, map flood risk, and educate the community about flooding and how to prepare for potential flooding qualifies Portland as a CRS community. As a CRS community, properties in Portland are eligible for flood insurance discounts.

Restoration Work to Reduce Flooding Impacts

Environmental Services has been working for more than 25 years to reduce the risk of flooding and lessen its impacts while improving habitat for wildlife like salmon and birds. Restoration projects in Portland’s watersheds restores natural floodplains to help protect human health, property, and the environment.

Changes to the Floodplain Maps for Johnson Creek

In the Johnson Creek watershed, Environmental Services has completed several major restoration projects since 1998. Learn about completed projects on our restoration and monitoring map found on this page about watershed restoration. Future projects include Springwater Wetlands, Brookside Wetlands, West Lents, and Johnson Creek Oxbow.

Map of the Johnson Creek watershed shows completed and upcoming projects with fish icons.

As our restoration work informs and changes the flood risk along Johnson Creek, FEMA requires us to update the FEMA Flood Insurance Rate Maps for the area. Once FEMA certifies these maps, certain properties may be required to get flood insurance under the National Flood Insurance Program.

Environmental Services is remapping the 100-year floodplain for Johnson Creek in the Lents and Powellhurst-Gilbert neighborhoods because of new data gathered for the Springwater Wetlands project. This work will also help fulfill commitments made to the local community during the Lents Collaborative Oregon Solutions project.

What’s Next for Floodplain Map Changes for Johnson Creek

FEMA is currently reviewing floodplain map revisions. Environmental Services plans to begin outreach to residents in 2024 when revisions are complete. FEMA may finalize revised maps in 2026.

Property Owner Notifications

If you received a floodplain remapping letter from Environmental Services in the mail, then your property will be impacted by a remapping effort. People in the project area may also receive regular project update mailers. The floodplain letters are on Environmental Services letterhead with the heading: Important Floodplain Remapping Information. If you receive a floodplain remapping letter, please carefully review it.

If you have questions or would like to learn more, please contact the floodplain remapping team. Contact information is on this page.

How will the changes to the floodplain maps affect you?

  • If you have a mortgage or home loan: Changes to floodplain maps on your property may change flood insurance requirements from your mortgage lender. If your property is in the mapped 100-year floodplain, then flood insurance is usually legally required. Federally-backed flood insurance is available through your property insurance provider. Learn more at
  • If you do not have a mortgage or home loan: Even if you don’t have a mortgage and your property is mapped in the 100-year floodplain, purchasing flood insurance could help protect you from the financial impacts of flooding. Homeowner’s insurance policies do not usually provide coverage for flood damage.
  • Some properties will no longer be within the mapped 100-year floodplain. If your property has been removed from the mapped 100-year floodplain, you may want to discuss your insurance needs with your insurance provider.
  • Construction and development. If you plan to build on your property, the new flood risk information may change your building permit requirements. For information on building in the floodplain, please contact the Bureau of Development Services.

More Information and Resources