US Army Corps of Engineers
Portland District Website

The Christmas Flood of 1964: Learn from the past. Prepare for the future.

Economic impacts from the Flood of '64

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Damages would have been much worse without the seven Corps reservoirs in the Willamette Valley. The Corps calculated that these 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).  

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

Without the reservoirs, 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).”

We were flood ready in 1964; we are flood ready today.

Geomorphic impacts of the flood

The floods of winter 1964 (Dec. 19, 1964–Jan. 31, 1965) were some of the largest flood events ever recorded for many rivers in western Oregon. Heavy rain fell directly on high elevation snowpack, melting the snow and increasing the floodwaters to levels 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, nearly 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 of the 1964 floods. Another legacy of the 1964 floods is the use of extensive gravel bars deposited by the flood 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