Flood Information

The Federal Emergency Management Administration (FEMA) manages the National Flood Insurance Program (NFIP) to help reduce the cost and impact of floods. NFIP maps show where floods have happened and are likely to happen again.



We can request a Conditional Letter of Map Revision (CLOMR) from FEMA for projects that will change a flood area. This letter is a comment from FEMA about the changes the one of our projects will make.

The CLOMR does not revise a NFIP map. It only indicates whether the proposed project will be recognized by FEMA. Building permits cannot be issued based on a CLOMR, because a CLOMR does not change the NFIP map. 

We can request a revision to the Flood Insurance Rate Map (FIRM) to reflect a finished project. "As-built" designs and other data is used to support the revision request.



We can request a Letter of Map Revision (LOMR) when a project is complete. This is a formal process to change FEMA's Flood Insurance Rate Map (FIRM), or Flood Boundary and Floodway Map (FBFM), or both. 

LOMR are based on physical changes that impact the way water flows and the location or course of a river or stream. These changes may impact flood elevations and hazard areas. 

Projects seeking a CLOMR/LOMR


Glossary of terms

Flood Resources


Frequently Asked Questions


  1. What does a CLOMR mean for my particular property?

    In most cases, it means that your property should see a reduction in the frequency and magnitude of flooding associated with nearby creeks during larger storm events.
  2. Does this mean I will no longer need to pay for flood insurance?

    In most cases, yes. But that change will not be effective until after the construction is complete. We will then need to submit a LOMR to FEMA to update the current Flood Insurance Rate Maps (FIRMS).

    In come cases, property owners may still need to carry flood insurance if improvements do not relieve all the flooding impacts to nearby properties.
  3. How long after the LOMR is submitted and the new FIRMs issued and become effective?

    It could take FEMA several years to review the improvements, perform analysis, and prepare new FIRMs.
  4. My property was not in a flood zone before, but now it appears it is. Why, and what does this mean for my property?

    Some properties not previously in a flood zone could be in a flood zone following construction. This is due to more accurate topographical survey data incorporated into the hydraulic model and is not related to the recent or upcoming improvements.
  5. Who can I contact with questions about the flood maps?

    Please email or call 503-846-8761.

  6. Who can I contact with questions about previous and/or upcoming projects? 

    Please email your questions to staff.