Vanport City Flood
At about 4:17 PM the western (railroad) dike burst, sending a 10 ft (3.0 m) wall of water into the area of Vanport College.
Because of the numerous sloughs and backwaters in the area, the progress of the flood was delayed about 30 minutes, giving residents more time to escape.
An emergency siren began to sound shortly after the initial breach, and residents began to head up Denver Avenue to higher ground.
At the time of the flood, the population of Vanport was down to about 18,500 people. Because of the holiday, many residents were away from their homes for the day. These factors contributed to the low loss of life: there were only 15 deaths. Nonetheless, the city was a complete loss.
DIKES ARE SAFE AT PRESENT.
YOU WILL BE WARNED IF NECESSARY.
YOU WILL HAVE TIME TO LEAVE.
DON'T GET EXCITED”— The Housing Authority of Portland
On May 30, 1948, at approximately 4:17 p.m., the railroad dike between Smith Lake and Vanport City gave way. Within moments a 10-foot-high wall of water rushed over lands north of the Columbia Slough and inundated the city of Vanport. Sixteen lives were lost and Vanport City was forever gone.
The Columbia River intervened on Memorial Day, May 30, 1948. Swollen by weeks of heavy rain, the river at Portland crested fifteen feet higher than its flood plain, held back only by dikes. At 4:17 p.m., the water breached the Northern Pacific Railway embankment and backfilled the low-lying community. While water filled sloughs and low spots, the community’s 18,500 residents had thirty-five minutes to escape. The rising water tumbled automobiles and swirled Vanport’s wooden apartment buildings off their foundations like toy boats. Fifteen residents died.