August 22, 2016 | David F. Coppedge

Spirit Lake Threatens Megaflood

36 years after Spirit Lake was destroyed by a volcano, it has come back with its own threats of destruction.

Spirit Lake, a Pacific northwest gem, was almost unrecognizable at noon on May 18, 1980. The eruption of Mt. St. Helens in Washington State covered it with logs and debris swept into the lake by the blast. It took years to recuperate, its bottom 64 meters higher than before, its waters fouled with toxic fumes and clogged with sinking tree trunks. Yet soon after the catastrophic mudflows that threatened everything downstream to the Columbia River, a new danger loomed. Robert F. Service recounts what happened next for Science Magazine:

Thirty-six years ago, the mountain erupted, killing 57 people and blowing a cloud of ash 20 kilometers high. It also sent an avalanche of rock, sand, and gravel down its north slope that crashed into Spirit Lake, blocking the river that drained it. In 1984, engineers bored a 2.6-kilometer-long tunnel to drain the lake so it wouldn’t rise high enough to bust through the debris dam. If that happened, it would likely wipe out whole towns downstream, potentially killing tens of thousands of people.

Problem solved? No. The artificial tunnel was a stopgap measure. The fears of 36 years ago are back with a vengeance.

In January [this year], emergency crews raced to save an engineered tunnel built 3 decades ago to keep nearby Spirit Lake from breaching a natural dam of volcanic debris. A rupture could send a wall of water and mud downstream that would likely wipe out several towns and kill tens of thousands of people. The 2.6-kilometer-long tunnel, which had begun to collapse, was closed for 10 weeks so engineers could rebore a 10-meter-long section and bolster it with steel ribs. During the closure, Spirit Lake rose 6 meters, about halfway to a dangerous level where water could start cutting through the soft top of the dam.

This means that without human intervention, Spirit Lake would breach its dam within months. How bad could that be? You don’t want to think about it.

With no outlet, rain and snowmelt swelled Spirit Lake, raising fears of a breach that would launch, in hours or minutes, a surge of water five times the average flow of the mighty Columbia River. “It would cause a flood so big you just don’t want to know,” says Thomas Dunne, a panel member and geomorphologist at the University of California, Santa Barbara.

Just look at evidence of past flooding, Service says, to see how massive the damage could be.

In fact, it has happened before. Spirit Lake has repeatedly punctured debris dams from earlier eruptions, says Jon Major, a hydrologist with the U.S. Geological Survey in Vancouver, Washington. One such event some 3350 years ago appears to have inundated the area where the towns of Kelso, Castle Rock, and Longview now sit, more than 60 kilometers away in the Cowlitz River valley, under 20 meters of water and mud.

Service delves into the political infighting going on about what to do. Each solution has problems. The tunnel is not natural; it alters fish habitats downstream, but it also reduces sediment load that benefits lower catchment basins. Digging a “natural” channel (as engineers dug at nearby Coldwater Lake) would increase sediment loads in the Columbia River channel, requiring more dredging. Everybody seems to agree, though, that doing nothing is not an option.

All this from one “little” lake beside one relatively puny volcano. How much could a bigger volcano do? How much could a bigger dam breach do? You don’t have to look far. Megafloods carved the Channeled Scablands farther east in Washington (7/25/08). Even secular geologists propose historic megafloods in China (8/08/16), the Black Sea, and the English Channel. The Yellowstone fossil forests, once thought to be a slow-and-gradual deposit, are now believed to have been deposited in one or more catastrophic mudflows (9/28/15), just like at Mt. St. Helens. Some think breached dams carved the Grand Canyon. After all, a mudflow in 1982 carved a similar canyon at Mt. St. Helens at 1/40th the scale of the Grand Canyon. After years of indoctrination into uniformitarianism, geologists are warming up to the idea of catastrophic megafloods (12/19/13, 6/21/10).

The power of moving water is underappreciated by many people. With sufficient volume and energy, flood water initiates processes like plucking and cavitation that can carve solid rock like butter, causing enormous change in a matter of minutes. You can scale it up to any size. Imagine what a global flood could do. Why, it might deposit sediments all over the world, loaded with remains of plants and animals. These sediments might be flat on top of each other as water directions shifted, covering large areas and even crossing continents. Later, impounded lakes might breach their dams and create huge canyons through the sediments while they were still soft.

You don’t have to imagine. That’s what we observe. Lyell-inebriated geologists have long opposed large floods due to the power of the gradualist paradigm (4/30/09; see Steve Austin on YouTube discuss Darwin’s wrong interpretation of the big Santa Cruz River Canyon in Argentina). We need to see the geological evidence with new eyes and minds—minds not trained to dismiss evidence just because it happens to coincide with a certain historical account.

 

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