LONGVIEW – Charlie Crisafulli zipped himself into a dry suit, splashed into Spirit Lake and explored a world only a handful of researchers have seen in the past quarter century.
He pushed through thick beds of vegetation and counted the chunky trout that swam up and peered into his face mask.
“Spirit Lake is a complex world, like an underwater forest,” Crisafulli, a Forest Service ecologist, said after the swim. “It teems with life. It’s fascinating. It’s very complex.”
A quarter century after the eruption of Mount St. Helens turned the lake into a murky cauldron devoid of oxygen, the lake water is clearer than before the eruption.
“It’s a remarkable lake,” said Doug Larson, a lake scientist who has surveyed Spirit Lake since soon after the eruption, most recently last summer.
The lake has been off-limits to the public since the eruption. This year, because of the heightened seismic and eruptive activity at the volcano a few miles to the south, even the trails near the lake are closed to the public.
But Crisafulli wasn’t deterred from continuing his research at Spirit Lake last summer, despite thunderous rockfalls nearly every day in the crater a couple of miles away.
Earlier this month, Crisafulli and fellow researcher Eric Lund returned on a windy day when the air and water temperatures were both in the mid-50s. A fresh layer of snow sparkled atop Mount Margaret and Coldwater Peak north of the lake, and a plume of steam vented steadily from the expanding lava dome inside the volcano’s crater.
Geese in “V’ formations honked overhead, and a herd of about 50 elk rambled over the pumice plain near the lake.
“It’s a great day for a swim in Spirit Lake!” Crisafulli said. “If three cups of coffee didn’t wake you up, this will.”
Actually, dry suits over a layer of fleece kept swimmers comfortable.
Crisafulli explored a cove on the lake’s southeast corner. The mat of logs that floats on the lake was conveniently on the other shore.
The underwater vegetation undulates in the wind-driven current. Plants and algae carpet the lake bottom in hues of green. Sunken trees appear almost black – though they host small plants. Crisafulli likens the scene to kelp forests off the coast of California.
Spirit Lake now hosts about 12 species of aquatic plants, dominated by pond weed, which roots in 12 to 15 feet of water. The underwater garden has spread rapidly in the past five years.
“Many of these were likely never in the lake” before 1980, Crisafulli said. Unlike most mountain lakes, Spirit Lake has an extensive shallow area on its south shore that’s a good environment for plant life.
“The top of the mountain slid into the lake and shoaled this part,” Crisafulli said.
Few plants have taken hold along the lake’s north shore, the site of the old youth camps.
“The whole opposite shoreline has little to no vegetation growing,” Lund said. “It drops off too quickly.”
Unfortunately, the plant list includes milfoil. The unwanted, invasive species can form a mat atop water, though it isn’t doing that in Spirit Lake. Crisafulli surmises that the milfoil, like other plants, was brought in by geese.
Last summer, Crisafulli and his fellow researchers had a boat helicoptered in to Spirit Lake and were able to motor around it regularly. Larson, who first researched lake water for the Army Corps of Engineers, made two trips.
“The water is very clear,” he said.
On one trip, he measured the visibility at 50 feet.
“That’s a record,” he said. “Even before the eruption it was about 45 feet.”
Soon after the eruption, visibility in the lake was only a few inches.
“If someone had asked me after the eruption what it would have looked like after 25 years, I would never have guessed it would have been like this,” Larson said. It’s a very different body of water. The lake’s bottom is at a higher elevation than the surface of the pre-eruption lake, and its surface area increased by 80 percent.
Because all the trees and vegetation around the lake were killed, Larson expected soil to erode into the lake. “You would think it would be a shallow and marshy.”
Crisafulli said pumice has washed into the lake, creating deltas, but it doesn’t create the marshy environment that soil would. During last summer’s boat excursions, Crisafulli discovered a line of submerged hummocks along the east shore, their tops about 3 feet below the surface.
“They’re like very steep, peaked mountains – and only the tops are vegetated,” Crisafulli said. He hopes to learn more about the hummocks and the extent of vegetation by surveying the underwater topography of the lake next summer. He needs $2,000 or $2,500 to fly in the boat again.
When last measured, the lake was 112 feet at its deepest point.
The Spirit Lake shoals are “lined with thousands and thousands of snails and teeming with insects,” Crisafulli said – a feast for the rainbow trout that are as big as 25 inches and 5 pounds. Crisafulli swims the same route each time so he can compare the number of fish spotted.
“I counted 35 fish,” Crisafulli said after about an hour in the water. “Thirty-five fish is a lot to see,” he added, about twice the normal count. The great majority were 3- and 4-year-old fish, 20 to 25 inches long, he said, though he’s also seeing more smaller fish.
On a trip to the lake earlier this fall, the fish were in a feeding frenzy on mayflies, Lund said. “There were no less than 100 fish jumping that day.” As you navigate over and around the remains of the old growth forest devastated by the eruption, part of which now lies littered along the shore, you’ll spot beaver-gnawed branches here and there. Though Crisafulli hasn’t seen an actual beaver yet, he pointed out how the critters are aiding revegetation by moving the branches.
He tugged at a foot-long section of willow that had sprouted tiny roots into the sand.
“This is going to become a plant,” he said.
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