The Christmas flood of 1964 was a major flood in the United States' Pacific Northwest and some of Northern California between December 18, 1964, and January 7, 1965, spanning the Christmas holiday.
Considered a 100-year flood, it was the worst flood in recorded history on nearly every major stream and river in coastal Northern California and one of the worst to affect the Willamette River in Oregon. It also affected parts of southwest Washington, Idaho, and Nevada.
In Oregon, 17 or 18 people died as a result of the disaster, and it caused hundreds of millions of dollars in damage. The flooding on the Willamette covered . The National Weather Service rated the flood as the fifth most destructive weather event in Oregon in the 20th century.
California Governor Pat Brown was quoted as saying that a flood of similar proportions could "happen only once in 1,000 years," and it was often referred to later as the Thousand Year Flood. The flood killed 19 people, heavily damaged or completely devastated at least 10 towns, destroyed all or portions of more than 20 major highway and county bridges, carried away millions of board feet of lumber and logs from mill sites, devastated thousands of acres of agricultural land, killed 4,000 head of livestock, and caused $100 million in damage in Humboldt County, California, alone.
History
An atypical cold spell began in Oregon on December 13, 1964, that froze the soil, and it was followed by unusually heavy snow. Subsequently, an atmospheric river brought persistent, heavy, warm rain. The temperature increased by . This melted the snow, but left the soil frozen and impermeable. Some places received the equivalent of a year's rain in just a few days. Albany received of rain in December, almost double its average December rainfall of . Detroit recorded an extra of rain, and at Crater Lake, where the average normal December rainfall is , there was over of rain. As rivers and streams overflowed and the soil became saturated, mudslides occurred, roads closed, and reservoirs overflowed. Many towns were isolated. By the end of the flood, every river in Oregon was above flood stage, and more than 30 major bridges were impassable.
Late January
Heavy warm rain and melting snow caused more flooding in late January 1965, after the waters had begun to recede from the December flood. More mudslides occurred in places that had withstood the December flooding, and there were more deaths. Many streams in the northern San Joaquin Valley reached higher flows than they had in December.
Effects and aftermath
Oregon
The Christmas flood of 1964 was "the most severe rainstorm to ever occur over central Oregon, and among the most severe over western Oregon since the late 1870s", according to the National Weather Service office in Portland.
Some of the worst mudslides occurred in the Mount Hood Corridor, and one man died in a mud and debris avalanche near Rhododendron that destroyed 15 houses. Other deaths occurred from drowning and electrocution, and one man died when the new John Day bridge collapsed.
Yamhill County was severely affected. The Highway 219 bridge between Newberg and St. Paul, and Wilsonville Road between Newberg and Wilsonville were closed, trapping hundreds of people.
On the Oregon Coast, downtown Reedsport was flooded with of water, and in Coos Bay, a massive logjam contributed to severe flooding. The ports at Gold Beach and Brookings were destroyed.
At Oregon City, Willamette Falls was unrecognizable as a waterfall, and the city was flooded by several feet of water. In Portland, the lower deck of the Steel Bridge was underwater and had also been hit by a log raft consisting of around 1,000 logs. The impact of the raft severely damaged the Hawthorne Bridge, closing it for a year. At above flood stage, the flooding of the Willamette River at Portland in 1964 was second only to the 1948 flood that wiped out Vanport City. At its peak, the water was at the top of Downtown Portland's seawall.
Salem Memorial Hospital (now Salem Health) had to be evacuated after waters from nearby Shelton Ditch and Mill Creek flooded the hospital's basement. Hospital staff, parks department employees, and even inmates from the Oregon State Penitentiary placed sandbags around the hospital to prevent floodwaters from coming in. Eventually, the flooding coupled with a loss of power led to the decision to evacuate patients to Salem General Hospital on Center Street. 121 patients were evacuated from Salem Memorial by hospital staff, doctors, ambulance crews, and the National Guard. The hospital was able to reopen five days later after extensive work to repair the flooding damage.