Portland District and a history of floods

The Christmas Flood of 1964: Learn from the past. Prepare for the future.December 1964 started like many years before ... little did residents know they would suffer a devastating blow in the Pacific Northwest. Heavy snow followed by warm torrential rain created the 1964 Christmas Flood, one of the worst natural disasters Oregon has witnessed in modern history – for many communities it was even bigger than the 1996 flood. Residents, businesses and governments in Washington, Oregon, northern California and parts of Idaho and Nevada suffered nearly $500 million in damages in 1965 dollars; that's nearly $3.5 billion dollars today. 

Now it's 50 years later and we’re better able to detect and respond to such an event.  It's important to remember the potential for another flood like this remains, and the possible impacts on our state’s growing population and ever-developing landscape are enormous.

Do you know your risk?  Are you flood-ready?

On this site, learn about the weather conditions leading to the Christmas Flood of 1964 and the consequences to life, property and the economy of the region.  You can also find information and resources to help you understand your current flood risks and improve individual and community responses to a flood.

The December 1964 flood

Diagram illustrating the conditions behind the 1964 flood

The Christmas 1964 flood was one of the biggest floods experienced in the Pacific Northwest. Freezing temperatures and 3-4 feet of snow followed by a tropical storm’s warm air and torrential rain caused the flood. The damage extended through five northwestern states. Read the National Weather Service's detailed account of the stormHow bad was it? So bad they made a movie about it – watch the 1964 newsreel. The graph represents conditions at Government Camp, Ore.

Economic impacts from the flood

Businesses, agricultural and county, state and federal government agencies had to recover from devastating losses. 

Non-forestry and non-residential losses

Business Type

1964 dollars

2012 dollars


$ 50,634,243

$  364,566,549

Commercial business

$ 12,654,047

$    91,109,138


$ 60,963,889

$  438,940,000

Residential, personal property

$ 19,025,040

$  136,980,288


$   7,200,100

$    51,840,720


$   4,429,525

$    31,892,580


Public ownership


1964 dollars

2012 dollars


$ 56,993,100

$ 410,350,320


$ 12,583,313

$   90,599,853


$ 13,374,200

$   96,294,240


$   6,642,000

$   47,822,400


$      928,064

$     6,682,060


$      381,660

$     2,747,952

Damages would have been much worse without the seven Corps reservoirs in the Willamette Valley. A 1966 Corps report on the Christmas 1964 flood states, “It is probable that all the Willamette River bridges in Portland, except the St. Johns Bridge, would have been destroyed. (Even with the reduced [flood] stages observed, some of the bridges were closed at the peak of the flood because of the danger of sudden destruction, and only with the heroic efforts of the harbor patrol and tugboat operators in removal of accumulated logs and debris were the bridges saved from great damage or destruction).”

The Corps calculated the reservoirs prevented an estimated $540 million in 1965 dollars, or about $ 3.7 billion (2012 dollars) in flood damage in the Willamette River Basin. During the flood more than 7,000 homes were damaged or destroyed in Oregon, more than half the total for the region. Homes damaged or destroyed:

Oregon: 7,032

California: 5,090

Washington: 153

Idaho: 150

The total estimate of trailer and home losses by Oregon was about $245 million (about $1.8 billion in 2012 dollars).

Geomorphic impacts of the flood

The floods (Dec. 19, 1964–Jan. 31, 1965) were some of the largest flood events ever recorded for many rivers in western Oregon, and not seen since the historic floods of 1861. The excess water altered the landscape and substantially changed river channels throughout the region. Headwater streams in the mountains of the Cascades and Coast Range became choked with debris from landslides that were triggered across the steep terrain. Floodwaters scoured the previously stable sediment from the floodplain of valley-bottom streams, causing channels to widen and meander and new gravel bars to form. 

Today, more than 50 years after the flood, the geomorphic impacts of this flood can still be seen throughout western Oregon. The sediment that was deposited along many rivers during the flooding became seeded with cottonwood, willow, and alder trees, creating distinctive, even-aged modern forests. Many of the channel changes triggered by the 1964 floods have survived recent smaller floods, so that the habitats, ecosystems, and infrastructure still show the effects from 1964. Another legacy of the floods is the use of extensive gravel bars deposited by the event as a source of aggregate for construction of roads, including Interstate 5 and Highway 101. For more information on the geomorphology of the Willamette River floodplain, visit http://pubs.usgs.gov/of/2013/1246/.

Willamette Valley dams reduced damage

The flood was bad around the state, but it could have been much worse, at least in the Willamette Valley. Seven Corps flood control dams were in operation at the time and significantly reduced damage there. See how the Corps’ system of Willamette Valley dams works in this video.

How do these dams perform their water management mission?

Managing water is not the only goal during a flood. Emergency preparedness and response is everyone’s responsibility, and government agencies can provide assistance before, during and after natural disasters or other emergencies. Learn more about the Corps’ Emergency Management program.

It could have been worse - much worse

The Corps' seven flood-management dams significantly reduced flood damage to downstream communities. This graph shows three hydrographs at several USGS gages. The blue line represents the actual flow observed in the 1964 Christmas Flood. The red line is the estimated flow that would have occurred if no dams were in place. The green line is the estimated flow if all 11 of today’s Willamette Valley flood-control reservoirs were in place. Hydrograph showing Salem during the 1964 flood event

How much of a difference is that? For context, this picture shows Salem Memorial Hospital during the flood. The red line on the buildings shows how much higher the water would have been if no dams had been in place at the time of the flood - nearly 7 feet, or most of another story of the building. Picture of the Salem Hospital in Oregon from the 1964 Flood

Since 1964, the Corps added four more flood-control dams to our Willamette Valley Project, plus two in the Rogue River Basin, where none existed in 1964. We’ve also added Willow Creek Dam near Heppner, Ore.

Could flooding impact you?

Rivers make the Pacific Northwest a beautiful place to live, but if those rivers flood, they can destroy homes and businesses, causing millions of dollars’ worth of damage. It’s not if the next flood will happen – it’s when. 

While Corps dams, state and local actions have reduced flood risks for some downriver residents, the state’s growing population and continued development mean that many remain in harm’s way. Vast areas of agricultural land in historical floodplains around Oregon have been developed for residential use since 1964 (see image below). Six area maps; blue areas are safe building zones The Federal Emergency Management Agency’s Flood Map Service Center, https://msc.fema.gov/portal, is the official public source for flood hazard information produced in support of the National Flood Insurance Program. Use the MSC to find your official flood map, access a range of other flood hazard products, and take advantage of tools for better understanding flood risk. The Federal Emergency Management Agency designated the shaded land in these maps as vulnerable to certain levels of flooding.

There’s no law preventing development in these areas, but Federal regulations require that homeowners with federally-backed home loans in these areas purchase flood insurance. The properties bordered in white on these maps have all been developed since the 1964 Flood.

The Oregon Department of Land Conservation and Development has information about protection of people and property from natural hazards through sound land-use planning.

Flood preparedness, response and recovery partners


Office of Emergency Management: maintains an emergency services system.

Department of Land Conservation and Development: its natural hazards program addresses protection of people and property from damage caused by natural hazards.

Department of Geology and Mineral Industries: increases understanding of Oregon's geologic resources and hazards.

Water Resources Department: responsible for managing water in Oregon.


National Weather Service: provides weather, water and climate data, forecasts and warnings for the protection of life and property.

Natural Resources Conservation Service: provides assistance for many conservation activities.

U.S. Geological Survey: provides reliable scientific information to minimize loss of life and property from natural disasters.