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Science After the Volcano Blew

Research near Mount St. Helens proceeded despite bureaucratic hurdles, limited funding and an extremely hazardous environment

Douglas Larson

An Uncommon Scientific Challenge

Various factors contributed to what became a limited effort to assess Spirit Lake: chiefly bureaucratic hindrance and inertia, a lack of funding, and unreliable logistical support in an incredibly challenging location. At the beginning, scientific efforts were spotty. The initial research on the eruption’s effects on Spirit Lake and other blast-zone lakes was suspended only four months after the eruption. Studies didn’t resume for nearly two years, when an emergency required them. Starting in late October 1980, with the onset of winter, Spirit Lake began rapidly filling with water. By April 1981, lake volume had increased by almost 30 percent, and its surface elevation had risen to roughly 1,017 meters. According to estimates by the Corps and the USGS, there was a high probability that the debris dam blocking the lake’s outlet would fail if lake levels rose above 1,055 meters. Failure of the dam would cause catastrophic flooding downstream, an event that would seriously threaten tens of thousands of people.

2010-07LarsonF4.jpgClick to Enlarge ImageIn November 1982, as a temporary solution, the Corps started pumping water from the lake to stabilize its surface elevation. Barge-mounted pumps removed lake water at the rate of 307 cubic meters per minute, discharging it across the debris dam through a pipeline 1,100 meters long that emptied into the North Fork Toutle River. Pumping during the first year held the lake level at just about the crucial 1,055 meters. Had the lake not been pumped, its surface elevation would have reached 1,079 meters by August 1983, causing the lake to overtop the debris dam or breach it at a lower elevation. Meanwhile, as a permanent solution, the Corps began constructing a tunnel outlet connecting Spirit Lake to the North Fork Toutle River via South Coldwater Creek.

But before any water could be released, the Corps was required to monitor the lake’s water quality. Post-eruption water-quality assessments had made it clear that Spirit Lake’s waters contained unusual biological and chemical pollutants. Releasing great amounts could contaminate public water supplies, disrupt fish that migrate from the ocean to freshwater to spawn, and imperil other valuable resources downstream. The U.S. Environmental Protection Agency, the U.S. Forest Service and the U.S. Public Health Service recommended that the Corps develop and maintain a long-term water- quality program at Spirit Lake to monitor the discharges.

In January 1983, three months after pumping commenced, I was assigned the task of developing and implementing the Corps’ Spirit Lake water- quality assessment. I was instructed to produce a “basic” program, one in which discharged water was simply collected periodically for bacteriological and chemical analyses. I argued that in order to comply with multiple federal directives, the Corps had to conduct wider limnological studies to systematically define the lake’s physical, chemical and biological properties for the purpose of tracking lake recovery, and to identify potentially hazardous chemical and biological constituents.

Yielding to these directives, the Corps finally approved the program, which was launched in April 1983. By then, unfortunately, lake conditions had already shifted substantially toward recovery, meaning that major post-eruption chemical and biological transformations had occurred without being thoroughly documented. Prior to 1983, Spirit Lake had been visited approximately 20 times for limnological data. But because of paltry logistical and funding support, these surveys were brief, lasting only a few hours and produced limited information. All visits but two were made in the summer and provided little data about seasonal differences in lake conditions.

Before more comprehensive research could begin at Spirit Lake, considerable planning was required. The eruption had created an immensely challenging set of geophysical obstacles, health hazards and dangerous lake conditions, all of which made for a unique limnological experience. The research required unorthodox logistics and sampling techniques that were sometimes more experimental than the lake science itself. Lake visits were needed year-round, with winter month surveys staged in deep snow, strong winds and icy waters.

During the early phase of lake research, 1980 through 1982, researchers used small rubber dinghies to collect water samples and deploy various recording instruments in situ. These fragile craft proved to be inadequate, for several reasons: They were too small to safely accommodate personnel and equipment; they lacked a cabin, exposing people to rain, wind, sun and blowing ash; they were unstable and difficult to control, especially in rough waters; and they could easily be pushed—even crushed—by the massive log rafts that drifted unpredictably across the lake.

2010-07LarsonF5.jpgClick to Enlarge ImageIn early 1983, I argued for a boat sturdy enough to resist collisions with floating logs and with sufficient engine power to avoid the logs or push them out of the way. Instead, I was furnished with a much-used fiberglass cabin cruiser (5.8 meters long) equipped with a castoff outboard motor. The only thing missing was a set of water skis. During a lake survey in May 1983, the boat struck a partially submerged log that produced a two-meter-long crack in the hull, causing the boat to slowly fill with water. While three fellow limnologists bailed frantically, I managed to steer the boat to shore before it could sink. The boat was deemed “unserviceable” and trucked out for disposal.

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