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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

Bacteria in Polluted Waters

Not all of the hazards encountered in the blast zone were readily perceived. The black, toxic waters of lakes and rivers harbored potentially pathogenic bacteria including Klebsiella pneumoniae, Pseudomonas aeruginosa, and Legionella pneumophila. L. pneumophila had caused the mysterious pneumonia epidemic at an American Legion convention in Philadelphia in July 1976. Called Legionnaires’ disease, the illness sickened 211 people, 34 of whom died.

2010-07LarsonF12.jpgClick to Enlarge ImageIn April 1981, the State of Washington’s Department of Social and Health Services (WDSHS) was notified that eight scientists had become ill with fever, cough and sore throat after working around the lakes and rivers in the blast zone. Further inquiry found that among 250 scientists who had visited the blast zone between June 1980 and June 1981, 28 reported developing headaches, sore throat and high fever (103–104 degrees Fahrenheit) within a week after visiting the blast zone. All recovered within a few days.

Field scientists suggested that the puzzling illness was Legionnaires’ disease. John Kline of the USGS reported that several members of his agency’s research teams had gotten sick with flulike symptoms soon after visiting lakes and rivers in the blast zone. He indicated that water samples collected from Spirit Lake and the North Fork Toutle River contained “extremely high concentrations” of Legionella bacteria, with one sample yielding 1.3 × 108 organisms per liter. Spirit Lake and other blast-zone waters provided an ideal medium for explosive bacterial growth, most likely due to nutrient enrichment, increased water temperatures from geothermal springs and other factors such as the waters’ exposure to volcanic debris.

Subsequent research by David Tison of Oregon State University and colleagues lent credence to allegations that the mysterious illness was Legionnaires’ disease. They found relatively large numbers (up to 1.3 × 107 organisms per liter) of potentially virulent L. pneumophila in Spirit Lake and other blast zone waters during the spring and summer of 1981. Michael Glass, a WDSHS microbiologist, reported that L. pneumophila was present in 52 percent of samples—numbering in the hundreds—collected from Spirit Lake between 1983 and 1986. Glass identified six other Legionella species, two of which (L.gormanii and L. longbeachae) are also human pathogens. Two new species were named: Legionella sainthelensi and L. spiritensis.

2010-07LarsonF13.jpgClick to Enlarge ImagePublic health investigators noted that people who contracted the illness were mostly scientists working in close proximity to blast-zone lakes and rivers. They hypothesized that mists generated at these sites by turbulent streams and waterfalls and, especially, the rotor blasts of nearby helicopters enabled exposure to the disease organisms. Legionnaires’ disease is not caused merely by the presence of Legionella, but by contact with bacteria-bearing aerosols in mist-filled air that people breath in.

The occurrence of Legionnaires’ disease was never proven, although the WDSHS conceded that the illness could have been a “mild form” of the disease, which the agency called “Red Zone Fever.” Had Legionnaires’ disease been confirmed, state and federal health authorities would have closed the blast zone for months or longer until the disease threat had abated. Closure would have put the Corps at loggerheads with its Congressional mandate in the blast zone—that is, to control flooding and mudflows, remove sediment blocking navigable rivers, repair or replace bridges and roads and provide damage assessments, all without delay to protect lives and property. Ironically, the threat of Legionnaires’ disease was a major hook that got us more money for lake research.

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