The West braces for the big melt

  • Heavy spring runoff erodes a stretch of the Snake River

    Robert Bower/Post Register

The West is shaking off one of the wettest winters ever, and the snow keeps falling. Instead of April showers, a spring blizzard hit Wyoming early in the month, killing thousands of cattle and sheep trapped in fence-line snowdrifts.

Record snowpacks are piled up in the high country, aided by late April storms: Parts of Washington's Cascades hold more than twice as much snow as usual, Idaho's sitting on a snowpack that's 60 percent above average, and snow depths measure near 150 percent of average across the Western states.

May's warmth now brings a new worry: Record snowpacks could melt too fast and cause massive floods. As the nightly news fills homes with the devastation of flood-ravaged Grand Forks, N.D., Westerners watch with apprehension.

The West's heavy snow and saturated soil could lead to "the most widespread flooding in a decade," the National Weather Service warned in March. Towns such as Hailey, Idaho, are stockpiling rock, sand and burlap bags while anxiously keeping an eye on the rising local river.

Daryle James, Hailey's city administrator, says residents are being notified of evacuation procedures: "We're still actively preparing for the worst-case scenario."

Idaho farmers are also scrambling to protect their land, armoring the banks of the Salmon and other rivers with rock riprap, and building current-deflecting underwater stone walls called "barbs."

Such work deserves expert advice, and legally requires permission from the Army Corps of Engineers. But the water won't wait for bureaucracy, the farmers say; at least 20 are changing the river on their own. The landowners could be fined, says Corps program manager Matt Bilodeau, although the agency evaluates emergency cases individually.

Just outside Wyoming's Grand Teton National Park, wealthy homeowners are poised to spend $2 million to protect multimillion-dollar estates from the rising Snake River. Five property owners, including James Wolfensohn, the president of the World Bank, are digging gravel out of the river and building levees hundreds of feet long on the banks. Their drastic river alterations are beyond the control of the Army Corps of Engineers, which can regulate bank stabilization only below the normal high-water line, says Chandler Peter, a Corps program manager.

There are some who say people who knowingly build in a floodplain should expect to be flooded - even millionaires. Perhaps, Peter muses, local governments "would want to decide whether someone can build in the floodplain or not." But the bottom line, he says, is protection of private property. "The houses are here, the potential flood is coming. The threat is very real."

Other areas have already been inundated. Western Nevadans, just drying out from a New Year's flood (HCN, 1/20/97), are especially leery of a repeat episode. Northeastern Montanans watched the Milk River overflow its banks last month, and across the state, Montanans are gearing up for more floods. Late April saw residents of Logan, Utah, holding back the usually tame Blacksmith Fork River with sandbags, and Idaho's Henry's Fork River was nudging flood stage at the same time. Fed by four days of heavy rainfall in late March, several rivers in western Washington poured over their banks, destroying nearly 30 homes and damaging 500 more. A sudden thaw in mid-May could push those rivers over their banks again.

To make room for the coming spring runoff, dam managers are dumping as much water as possible from reservoirs across the West. The massive drawdowns, however, create different problems. Some irrigation channel inlets are left high and dry above the waterline until the snowmelt arrives to raise pool levels. Biologists worry that lowering the reservoirs too far could decimate fish populations. And then there's gas bubble disease, an often fatal fish malady. When tons of water are sent churning through spillways, large amounts of oxygen and nitrogen are mixed into the froth. Fish absorb the gases through their gills, and when they swim to the surface, the gases form bubbles that block blood vessels and burst through the fishes' skin and eyes. The dam-related disease is a problem for endangered salmon and steelhead populations in Oregon's Snake and Columbia rivers.

This big water year does have its bright side.

"There's going to be a great water supply this year," says Tony Tolsdorf, a hydrologist with the Natural Resources Conservation Service (NRCS) in Colorado. "The agricultural community's going to love it. People can water their lawns. And it reduces spring wildfires."

Recreational boaters are thrilled, too: Idaho's Salmon and Payette rivers are expected to run with 100-year highs, and the Colorado River's Cataract Canyon will probably top 55,000 cubic feet per second by the end of May, says Paul Henderson, chief of interpretation at Utah's Canyonlands National Park. At 55,000 cfs, he says, the river becomes "the biggest whitewater in North America," with standing waves 25 to 30 feet tall: "It could be a wild spring."

Despite the flurry of preparation, the floods of 1997 are not a sure thing. "It all depends on how (the snow) comes off," says Scott Pattee, a NRCS water supply specialist.

"If it will stay cool and come off slowly, maybe there might not be much flooding." This spring in the West, he adds, "we're pushing our luck pretty heavily."

* Danielle Desruisseaux, HCN intern

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