San Francisco — Cleaning up after the Mt. St. Helens volcano -- a job that is costing much less than first anticipated -- is being helped considerably by unusual weather in the Pacific Northwest this winter.
Lower-than-average precipitation and almost nonexistent snowpacks at higher elevations mean less water runoff and, consequently, fewer problems from sedimentation and debris that can clog rivers and cause flooding.
Officials of the US Geological Survey (USGS) say that some 400 million cubic yards of material (mud, logs, rocks, and volcanic ash) still lie above the Washington towns down- stream from St. Helens. But they also note that the rate of flow in the Toutle and Cowlitz Rivers (which flow from the vicinity of the mountain into the Columbia River north of Portland, Ore.) is only about half the typical amount for this time of year.
"What it means is, we're going to have less of a sediment problem than we had estimated," said USGS hydrologist Larry Hubbard. "The potential is still there, but it's dependent on the number and intensity of rains we have this year."
"It's beginning to look like we're in a dry year, but these storms can bring you back up to normal real quick," adds US Army Corps of Engineers spokesman Jim Addison. "If we have seen the worst of the winter's rainstorms, then we should be in good shape for the rest of the year."
So far, the Corps of Engineers has dredged some 45 million cubic yards of material from the Toutle and Cowlitz Rivers and another 15 million tons from the Columbia River navigation channel. Shipping operations are back to normal. But another 35 million tons still need to be dredged from the Columbia, a job that will take several years and hundreds of millions of dollars. So far, the corps has spent $218 million of an estimated total cost of $350 million.
Overall economic losses since Mt. St. Helens erupted eight months ago have been $860 million, according to Washington State's department of Commerce and Economic Development, most of this in timber losses and cleanup. This is a considerable sum, but still only a fraction of the $2.6 billion figure that former Gov. Dixy Lee Ray (who was defeated in her bid for reelection last fall) had anticipated.
Agricultural losses in particular have been much lower than anticipated. The state in fact has just had its best apple crop ever.
As for the mountain itself, the most recent volcanic activity was in late December when a "swarm" of minor earthquakes shook St. Helens. Officials describe the mountain as being "in a holding pattern," but they expect continued volcanic activity there over many months and perhaps years. The last eruptive cycle at Mt. St. Helens lasted from 1800 to 1857, and earlier cycles lasted even longer.
"Based on the mountain's past behavior, I would say that we can expect intermittent explosive activity," said Stephen Harris, who teaches volcanology at California State University and is an authority on Cascade Mountain Range volcanos. This explosive activity, he adds, will include the venting of steam and ash to high altitudes, but not the kind of massive eruption that started the volcanic cycle.
A lava dome continues to grow within the St. Helens crater. Mr. Harris says it is "very likely" that, like two others formed since the initial eruption last may, this dome will be blown away. Beyond that, he predicts magma (molten rock within the mountain) will become less explosive and more free flowing, and that it will eventually rebuild the summit of Mt. St. Helens.