This web page broadly identifies and describes the flood hazard that Oregon faces. It also highlights previous plans, assessment tools, and resources that have been developed to identify, profile, and assess the vulnerability of risk from earthquake events in Oregon.
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FLOODING OVERVIEW:
Floods are a common and widespread natural hazard in Oregon. The National Flood Insurance Program reports that 256 communities in Oregon are prone to flooding, including all 36 counties. Flooding typically results from large-scale weather systems generating prolonged rainfall and from “rain on snow” events that cause large amounts of snowmelt.
In Oregon, these conditions are most common from October through April when storms from the Pacific Ocean bring intense rainfall. Flooding can be aggravated when streams are altered by human activity, such as through channelization of streams or loss of wetlands. Many types of flood hazards exist in Oregon, including riverine floods, flash floods (resulting from locally intense thunderstorms, ice jams and dam failures), coastal floods, shallow area and urban flooding and playa flooding. Flood hazards can cause severe property damage and loss of life. Oregon’s largest economic loss from natural disasters has resulted from flooding.
Back to indexSUMMARY OF OREGON'S VULNERABILITY TO FLOODS:
Flooding is the most troublesome of the chronic disasters as it causes severe property damage, occasionally, loss of life, and has resulted in Oregon’s greatest economic losses from any of the natural hazards.
As mentioned previously, the entire State of Oregon is susceptible to flooding. However, some regions are more likely to experience this hazard than others. Different types of flooding occur from various sources depending on the region of the state. Flooding from winter storms is the most common, particularly in western Oregon. In eastern Oregon, flood events occur as flash floods, spring runoff, ice jam flooding, lake flooding associated with high winds, basin playa flooding, and flooding from the breaching of natural debris dams.
From a state perspective, 256 communities and all 36 counties in Oregon have experienced flooding. However, the areas of the state most vulnerable to flooding are Tillamook County and the South/Central Willamette Valley Counties. However, as a region, the Coast-Lower Columbia has not identified flooding as its greatest hazard. Based upon local hazard analysis the South/Central Willamette Region is most vulnerable to damage and loss associated with flooding. Individual counties in Oregon where flooding was identified as a major concern, are: Baker, Grant, Josephine, Linn, Malheur, Marion, Polk, Tillamook, Union, Wallowa, and Wasco.
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FLOODING STATE RESOURCES:
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FLOODING INTERNET RESOURCES:
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Planning for Natural Hazards: Oregon Technical Resource Guide
This document serves as a guide for Oregon communities to state, federal and Internet resources, as well as recommended publications for planning for flood hazards. The guide also explains laws related to flood risk and describes how communities can assess and reduce their risk.
Department of Land Conservation and Development (DLCD)
DLCD administers the State’s Land Use Planning Program. The program is based on 19 Statewide Planning Goals, including Goal 7, related to natural hazards. DLCD also serves as Oregon’s federally designated agency to coordinate floodplain management in Oregon. DLCD maintains contact with flood prone communities throughout the state in order to help them meet the requirements of the NFIP and to ensure that they are prepared in case of flood. DLCD offers information on the NFIP, CRS and other FEMA - related programs. They also offer training courses on various flood mitigation programs.
Oregon Water Resources Department - Estimation of Peak Discharges
A study of the magnitude and frequency of floods in Oregon has been completed by the Oregon Water Resources Department (OWRD) with financial assistance from the Federal Emergency Management Agency, Oregon Department of Transportation, and the Association of Oregon Counties and with the cooperation of the U.S. Geological Survey. The study was undertaken to provide engineers and land managers with the information needed to make informed decisions about development in or near watercourses.
Oregon Emergency Management (OEM)
OEM administers FEMA’s Hazard Mitigation Grant Program, which provides monies for acquisition, elevation, relocation, and demolition of structures located in the floodplain. OEM also administers FEMA’s Flood Mitigation Assistance Program. This program provides assistance for NFIP insured structures only. OEM also helps local jurisdictions to develop local hazard mitigation plans. OEM is heavily involved in flood damage assessment and works mainly with disaster recovery and hazard mitigation programs. OEM provides training for local governments through workshops on recovery and mitigation. OEM also helps implement and manage federal disaster recovery programs.
Oregon Department of Consumer & Business Services - Building
Codes Division
The Building Codes Division (BCD) sets statewide standards for design, construction and alteration of buildings that include resistance to seismic forces. BCD is active on several earthquake committees and funds construction related continuing-education programs. BCD registers persons qualified to inspect buildings as safe or unsafe to occupy following an earthquake and works with OEM to assign inspection teams where they are needed.
Oregon Regional Risk Assessment
The state’s risk assessment is divided into eight geographic regions to provide a locally appropriate analysis of risk. Included are: a regional profile and maps, event history, and an analysis of the probability of and vulnerability to future events. While the hazard assessments do not have sections to specifically cover the threat from dust storm events, some dust storm events are documented in the windstorm sections of these assessments.
Oregon's Regional Hazards Viewer
The interactive viewer visually displays perceived vulnerability per hazard for each county in Oregon, which allows communities and the state to compare the vulnerability of hazards across regions.
Flood Chapter: State Plan
The Flood chapter of the state Natural Hazards Mitigation Plan provides a characterization of the flood hazard in Oregon. Additionally, the chapter describes current state programs and strategies, highlights successes in mitigation, and proposes short and long-term actions for future mitigation in the state.
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Back to indexMaintained by: Oregon Partnership for Disaster Resilience
Community Service Center
University of Oregon
Last Updated 07/02/2007
