500-year wait for next flood not likely
Grand Forks, N.D. (AP)
Though the flooding here and in neighboring East Grand Forks, Minn., has been dubbed a once-in-500-years event, experts say the next flood could be worse, and sooner than expected.

"There’s nothing in the books that says it can’t go higher next year," said Leon Osborne, director of the Regional Weather Information Center at the University of North Dakota.

"I honestly believe, both scientifically and personally, that we cannot start soon enough preparing for next year’s flood," he said.

Some confusion has come from a misunderstanding of what the 500-year flood label means.

"One-hundred-year floods and 500-year floods have absolutely nothing at all to do with 100 and 500 years," Osborne said.

References to a 500-year flood mean there is a 0.2 percent chance the Red River will exceed this year’s 54.1-foot record in any given year. It does not mean 500 years will pass before that happens.

"Next year has the exact same chance as this year," said Pat Foley of the Army Corps of Engineers.

Experts at the university, the corps and the National Weather Service all agree this year’s Red River flooding was not a once-in-500-years event. "Not even close," Foley said.

University geologist Paul Todhunter said Grand Forks and East Grand Forks residents need to start rebuilding dikes "pronto."

"Because the soil is so wet, it is more than likely that we will have a higher-than-usual flood next year," he said. "In fact, if we get a lot of rain the next two or three months, we could have another flood before the summer is over."

Until two weeks ago, the worst-known floods in Grand Forks struck in 1824, 1825 and 1826. There also was severe flooding in 1848, 1851, 1852 and 1853.

When big floods come around, they tend to revisit two or three years in a row, Todhunter said.

"The soil has been very wet for the past year. Unless we have an exceptionally dry summer, that soil will stay wet," he said. "Next year, even average rainfall and snowmelt would produce a significantly large runoff event."

Rita Kepner, a public relations officer for the Federal Emergency Management Agency, said she has been dispatched to places where several disasters strike in a short period of time.

"I’m not going to give away my North Dakota map when I leave here," she said.