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).
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In 2000, FEMA embarked on a nation-wide effort to modernize the outdated FIS and related floodplain maps.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, the 2008 Digital Flood Insurance Rate Maps (DFIRM) for Lake Oswego, or the August 24, 2012 Letter of Map Revision, click on the appropriate attachment below.
The link to the Digital Flood Insurance Rate Maps (DFIRM) is under construction.