/ Mount St. Helens 25th Anniversary

01:15 PM PDT on Wednesday, May 11, 2005

By SUSAN WYATT / KING5.com

USGS

The eruption turned the once crystal clear Spirit Lake, at the base of the volcano, into a bubbling basin of toxic sludge.

When Mount St. Helens exploded on May 18, 1980, more than 150 square miles of forestland was instantly turned into a gray wasteland. Avalanches of rock, mud and ice swept down the mountain, choking rivers and streams with debris.

"It kind of looked like a melting bowl of ice cream out here, a lot of quicksand material in the low spots. Pretty much a brown and gray landscape, and very little, no signs of plant life," said Peter Frenzen, a scientist with the U.S. Forest Service. "People compared it to the moon."

The eruption turned the once crystal clear Spirit Lake, at the base of the volcano, into a bubbling basin of toxic sludge. The water temperature on May 18 was nearly 90 degrees, more than 30 degrees higher than normal, and most of the dissolved oxygen was depleted.

USGS scientists said the water "looks and smells very much like the effluent liquor from a pulp mill."

The lake increased in area, decreased in depth, and rose about 240 feet in altitude as a result of the eruption. The surface of the lake was covered with logs blown down in the blast.

Slide show: Life returns

In September of 1980, the surface of the lake was emitting large quantities of gas, some of it in "boils" 2 to 3 feet in diameter and some of it in almost continuous "streamers" of gas bubbles. Many of the gases identified were toxic, and some were flammable.

Spirit Lake was essentially dead.

The heavy Northwest rains flushed the lake and by 1982, scientists noticed key changes in the ecosystem, including the discovery of algae and aquatic insects.

In 1993, fish were discovered in the lake, though how they got there is a mystery. Perhaps they were survivors that traveled to the lake via streams or maybe a fisherman illegally stocked the lake.

KING

One of the most successful trees has been the alder, which disperses easily and is capable of rapid growth on the nutrient-poor, volcanic deposits.

The Washington State Department of Game estimated that nearly 7,000 deer, elk and bear were killed in the eruption, as well as birds and small animals.

Of the 32 species of small mammals thought to be living near the volcano, only 14 were known to have survived. These animals suffered either directly through injury or death, or indirectly through the reduction in availability of food, water or cover.

Bird survival was confined to areas on the margins of the blast zone where ashfall was the only disturbance.

Bees, whose dense body hairs act as a trap for dust, were among the insects hardest hit by the abrasive ash. In fact, there was a noticeable lack of insects in the blast zone in the first few years after the eruption. Volcanic ash affects insects in much the same way as powder-based insect sprays used by homeowners to kill them. The sharp ash particles wear away at the thick cuticle that protects them from dehydration.

Scientists entering the blast zone shortly after the eruption were surprised to find that many organisms managed to survive in what appeared to be a lifeless landscape. Plants sprouted from the pre-eruption soil surface and signs of activity by gophers indicated that animals living below ground had survived beneath the volcanic ash.

"Once we discovered that plants survived on the blast zone hill slopes we realized that recovery was going to be a relatively rapid process," said Frenzen.

KING

A tiny frog is among the amphibians that live in ponds around Mount St. Helens.

The most common plant survivors were weedy plants such as fireweed and pearly everlasting, which sprouted where they could reach the ash surface, either through cracks or in gullies where buried soil was exposed by erosion.

Isolated patches of Pacific silver fir and mountain hemlock survived the eruption intact, bent over beneath heavy snow banks. Huckleberry and salmonberry bushes managed to survive on snow-covered north slopes or in isolated pockets on the backside of mountain ridges that deflected the full force of the blast.

Birds were able to return to the blast zone within days or weeks because of their exceptional mobility and because some food, such as seeds and some insects, were available. Helicopter pilots working in the crater said hummingbirds dive-bombed their bright orange flight suits and the red plastic markers of scientists.

Birds such as the mountain bluebird that nest in cavities in standing dead trees prospered in the blast zone.

Deer and elk were seen in the blast zone within days of the eruption. By 1994, elk populations had returned to near pre-eruption levels and prospered on clover and grasses that had been planted to stabilize the land.

But the herd eventually grew too large for the area to support, and in the winter of 1999, more than 100 elk starved in the Toutle Valley because of heavy snowfall. In 2004, the herd was thinned through relocation and 10 hunting permits were issued.

KING

Elk are seen grazing among the trees.

These days, tourists flock to the Weyerhaeuser Forest Learning Center each summer to watch the elk on the valley floor 1,300 feet below.

The 110,000-acre Mount St. Helens National Volcanic Monument in the Gifford Pinchot National Forest was established by Congress in 1982 to preserve the unique natural features created by the 1980 eruption for the benefit of future generations.

The eruption of Mount St. Helens in 1980 demonstrated that even after a large-scale, catastrophic disturbance, plants and animals can survive in the midst of apparent total devastation. The spread of trees and shrubs will continue and the developing forest will mask the evidence of the 1980 eruption.

Within a few decades, scattered coniferous trees such as Douglas fir, Western hemlock and Lodgepole pine will begin to emerge. By 2100 these scattered groups of trees will begin to converge and the area will take on the appearance of a young forest. By the year 2200 much of the area will be covered in mature forest as it was before the blast of May 18, 1980.

"The speeding up of the recovery process is increasing over time. There is more and more life out here," said Frenzen. "This mountain is only 2,500 years old, and there have been multiple forests that have grown on multiple layers from past eruptions so we were just lucky to see what Mount St. Helens has been doing for thousands of years," said Frenzen.