Savage North Winter Brings Runoff Floods

All winter long, the monster snow sat, 109 inches of it, the most in memory, congealing in backyards like enormous albino hedgerows and sprouting like whalish toadstools in shopping mall parking lots. Trudging inside 8-foot-high tunnels carved out of sidewalk slush, desperate Dakotans wondered if the worst snowfall on record would ever melt away.

Now, in the first flush of a Great Plains spring, they worry it is melting too fast. From the upper tip of the Red River Valley to the lower tributaries that spill into the Mississippi and Missouri rivers, the ice-capped waterways of the northern Plains are starting to shed their frozen skins in a rapid-paced runoff that anxious weather forecasters and civil engineers fear could accelerate into the most devastating spring flood in decades.

When floods come, like the disastrous wash that surged over the Ohio River Valley a month ago, they usually mount so quickly that emergency planners have little time to prepare.

But the lingering snowpack that buried the Dakotas has stayed long enough to give state and federal disaster officials more than a month’s cushion--not only time to plan, but to test new methods of flood management that may well become standard practice in coming years. In one closely watched experiment known as “ice dusting,” helicopters have dumped hundreds of tons of sand and dirt on the frozen Red River in North Dakota and the Platte in Nebraska in an attempt to control the melting of ice flows before they jam up and flood at river bends.

Last week, North Dakota National Guard troops working along an oxbowed stretch of the Red River just north of Grand Forks pitched sandbags into waiting Huey helicopters at the frenzied pace of a ton every five minutes.

“We can’t guarantee it’ll work, but if it saves a bridge or a life, terrific,” said Warrant Officer Neal Jacobsen over the roar of rotor blades.

New Storm Sends Red River Surging

There was no time to rest. Ice-caked soybean and sugar beet fields from Grand Forks to Fargo were already brimming with melted snow. The Red River was rising more than a foot a day under its pale green icecap. And after a brutal winter in which meteorologists recorded six separate blizzards, yet another storm this weekend brought rain that would hasten the melt-off and more snow to confuse matters further.

The steady rain that fell Saturday sent the Red River to a record-tying level of 18 feet at Wahpeton, N.D., with a forecast crest of up to 19 1/2 feet by Monday.

“This is nuts,” said computer programmer Doug Dean as he shoveled a trough through a 2-foot field of snow in his backyard. The temperature was 45 degrees. “I don’t know whether to shovel or sandbag.”

In Dean’s neighborhood in the small town of Dilworth, just east of Fargo in Minnesota, lawns and roofs were still piled high with snow. But several houses down, a playground was underwater and township workers were manning industrial pumps and bolstering a wall of sandbags to turn away the relentless runoff pouring in from melting fields.

“The weather gods are playing with our heads,” said Fargo city operations director Dennis Walaker as he drove around his city at dusk, barking instructions over two cellular phones as he checked over-stressed drainage sluices and waterlogged lots.

Fargo merchants had been planning to honor Walaker’s work crews last week for their heroic work in plowing the drifts that threatened to bury the city all winter. But the crews were too busy delivering sandbags and pumping out low-lying neighborhoods to attend their own award ceremony. “Maybe they should reschedule this thing to next August,” Walaker muttered.

The winter’s savagery stunned Dakotans, who thought they were inured to the extremes that come with living near the Canadian border. Biting winds whipped drifts over rooftops. The subzero cold killed thousands of cattle. Whole neighborhoods were forced to contract with earth-moving firms to haul away tons of compacted snow. Some ice piles will not melt away until June.

“Nobody in Fargo liked the way the movie ‘Fargo’ made us sound like slow-talking idiots,” said Linda Fjellanger, who lives in the Fargo suburb of Moorhead, Minn. “But they sure got all that snow right.”

Emergency Planners on Alert for Flooding

Now all that snow is turning to water. Last week, every street in Fargo, it seemed, was puddled over from melting slush.

North Dakota’s emergency planners have been on alert for the runoff since Feb. 14, when National Weather Service officials warned of record floods with river stages that could be the highest in a century. It was not only the record amounts of snowfall that caused concern, said Lee Anderson, chief meteorologist in the Weather Service’s Grand Forks station. The snow was “exceedingly wet,” with “a high volume of water packed into the snow cover,” Anderson said. And when winter came, the Dakota soil was already heavily saturated by autumn rains.

“Most of the variables are pointing to heavy flooding,” Anderson said. The only unknown factor was whether inclement weather will add to the record snow melt. This weekend’s storm “sure won’t help,” Anderson said.

There was a heightened sense of urgency last week as the first flood waters began seeping into outlying towns like Dilworth and lapping at muddy new subdivisions of tract housing on Fargo’s fringes.

“Everybody cursed all that snow, but it did have one silver lining. It gave us time,” said Lonnie Hoffer, an official with the North Dakota Division of Emergency Management.

In the last month, the U.S. Army Corps of Engineers has spent more than $3.5 million, distributing tens of thousands of sandbags to riverfront towns and adding height to earthen levees in selected spots along upper Plains rivers. “It’s a luxury we don’t usually get,” said Dave Christensen, chief of the readiness branch in the Corps’ St. Paul region.

Some towns have taken advantage of new technology, buying mechanized sandbaggers to augment the teams of volunteers that already have begun showing up in flood-threatened neighborhoods. Grand Forks bought a $20,000 machine, which is now churning out a targeted 1.5 million sandbags. Fargo bought three smaller $6,000 machines to fill 90,000 bags. “They improve your sandbagging capacity 10 times over,” Walaker said.

North Dakota officials decided not to rely on sandbags and levee-building alone. Three weeks ago, National Guard helicopters began the ice dusting along the Red and Sheyenne rivers, a rarely used tactic aimed at managing the rate of flooding.

Last week, three helicopters made repeated sorties over the Red River north of Grand Forks, darting over a 55-mile stretch of oxbows to drop their loads. Inside the hovering choppers, North Dakota guardsmen spilled 40-pound bags of sand down two chutes. Roaring off after each five-minute drop, they left dirty trails along the ice that wound along the river like chicken tracks.

The thermal principle underlying the effort is simple but hard to control. The dark sand dumped on the lighter-colored ice is designed to attract sunlight and heat like a black suit worn in the summer, Hoffer said. As the ice melts, the gritty sand works its way down into the ice pack, forcing the ice to crumble instead of breaking off in large sheets, which often jam at river bends and near bridges.

Nature always adds its own variables. “The key in ice dusting,” said the Corps’ Christensen, “is that timing is critical. The sun needs to be out, and there has to be enough time for sand to melt down through the ice cover. If you put the sand on too late, you really can’t affect the jams that cause the really big headaches. And if you put the sand on too soon and you get snow on top of that, it loses its effectiveness”--a problem that could crop up this weekend as more snow fell in the Dakotas.

Experimenting With Ice Dusting Concept

Until recently, ice dusting had been tried regularly only in Alaska, where river icing is an annual problem. North Dakota officials embraced the concept after the tactic was used during the last two years on small rivers in Nebraska, Wisconsin and Idaho.

“What we don’t know is whether it can be successful after the kind of harsh winter we had,” Hoffer said. Officials said ice dusting on the narrower Sheyenne River appeared to work, but there was still too much ice clogging the Red last week to declare victory.

In Fargo, as the newest storm approached, Walaker drove near the city’s southern edge, pointing out how nature can frustrate even the most well-planned flood defense. He knows every weak spot in the city’s topography where melting snow and river water could pose a danger. His work crews had been monitoring the low areas for weeks.

But the melt was almost at flood stage, and despite all their knowledge and preparation, despite all the river dusting, Walaker knew there were only so many places where the town could deploy its tractors, sand spreaders and teams of volunteers.

“The frustrating thing is we’ve taken every precaution, done everything we can think of not to get nailed,” Walaker said. “And after all that, we can still get nailed.”