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 storm. How bad was it? So bad they made a movie about it – watch the 1964 newsreel. The graph represents conditions at Government Camp, Ore.

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).”

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).

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/.

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.

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). 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.