National Flood Insurance Program

Everyone faces the risk of natural disaster and no plan to protect property can be complete without insurance coverage against potential damage and loss. It is important to know exactly what coverage you may need and what coverage is available to protect your property against all of the natural hazards it may be exposed to so that you are not underinsured or not insured at all. Check with your insurance company or local insurance agent.

Flooding is the most prevalent and costly natural hazard in Oregon, and a component in 90% of the nation’s disasters.

National Flood Insurance Program

The City of Lake Oswego has been a Participating Community of the National Flood Insurance Program (NFIP) since 1977.

The NFIP is a Federal program enabling property owners in participating communities to purchase insurance protection against flood related property damage.  Participation in the NFIP is an agreement between cities and the Federal Government that makes flood insurance available to communities that adopt and enforce floodplain management standards in Special Flood Hazard Areas (SFHA). The SFHA is defined as an area of land that would be inundated by a flood having a 1-percent chance of occurring in any given year (also referred to as the base flood or 100-year flood).

A number of laws have been passed to strengthen the National Flood Insurance Program (NFIP), ensure its fiscal soundness and inform its mapping and rate-setting through expert consultation, reports and studies. These include:

  • The Biggert-Waters Flood Insurance Reform Act of 2012
  • The Consolidated Appropriations Act of 2014
  • Homeowner Flood Insurance Affordability Act of 2014

Historical Background

In 1987, the Federal Emergency Management Agency (FEMA) completed a Flood Insurance Study (FIS) and prepared Flood Insurance Rate Maps (FIRM) that delineated local flood hazard areas and established Base Flood Elevations (BFE) for communities proximate to water bodies subject to flooding.

In 2000, FEMA embarked on a nation-wide effort to modernize the outdated FIS and related floodplain maps.   Shortly after, prompted in part by the significant flooding that occurred in 1996 and 1997, the City of Lake Oswego, in partnership with Clean Water Services and several communities along the Tualatin River, participated in an expanded study of the Tualatin River drainage basin.

The results of these efforts have produced an updated Flood Insurance Study (FIS) and associated floodplain maps.  The FIS and maps take advantage of 20 years of advancements in digital mapping technology, rainfall data, stream flow data and data gathered from the 1996 and 1997 flood events and thus represent the Best Available Science (BAS) upon which new floodway and flood elevation information was developed.

In 2008 FEMA completed, and the City adopted the new FIS and Digital Flood Insurance Rate Maps (DFIRM). The results of the study reflect and increase in BFE's and floodway widths for the Tualatin River Oswego Lake, the main canal and the interconnected bays. These increases in the BFE and floodway widths affected properties located at elevations slightly higher than floodwater elevations seen during the 1996 flood event.

More recently, following the completion of the Oswego Lake Dam Spillway project, a study was conducted and a Letter of Map Revision (LOMR) was issued by FEMA. This LOMR is FEMA's acknowledgment and official recognition of the lowering of the BFE. The lower BFE applies to properties on Oswego Lake, Blue Heron Canal, Lakewood Bay and West Bay. There are no changes to the floodplains along the main canal, Springbrook Creek, Tualatin River or the Willamette River.

To view the 2008 Flood Insurance Study (FIS) for Clackamas County and Incorporated Areas or the August 24, 2012 Letter of Map Revision, click on the appropriate links on the right. 

The Digital Flood Insurance Rate Maps (DFIRM) for Lake Oswego are under construction, 

More information

Talk to your insurance agent about how rate changes may affect your flood insurance policy.

For more specific information, contact the following specialists:

FEMA guidance about reform of NFIP program:
Christine Shirley, Oregon Dept. of Land Conservation and Development, at 503-373-0050 ext. 250

Floodplain maps, zoning and elevation certificates:
Rob Amsberry, City of Lake Oswego – Engineering Department, 503-635-0268

Flood Hazard Mitigation options:
Jay Wilson, Clackamas County Disaster Management, at 503-723-4848



  • Lake Oswego Natural Hazard Mitigation Plan (Flood, pg 33) - adoption expected in May 2024
  • 2024 Natural Hazard Risk Report for Clackamas County - (DOGAMI, O-24-XX, September 2023 Draft), Table A-23.) - provides hazard analysis summary tables that identify populations and property countywide that are vulnerable to the flood hazard.
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