Spirit Lake (Washington)

Spirit Lake

(February 2005)
Location Mount St. Helens National Volcanic Monument, Skamania County, Washington, US
Coordinates 46°16′23″N 122°08′06″W / 46.27306°N 122.13500°WCoordinates: 46°16′23″N 122°08′06″W / 46.27306°N 122.13500°W
Primary inflows Precipitation, streams
Primary outflows Drainage tunnel
Basin countries United States
Surface elevation 3,406 feet (1,038 m)[1] (3,198 ft (975 m) before May 18, 1980)[2]

Spirit Lake is a lake north of Mount St. Helens in Washington State. The lake was a popular tourist destination for many years until the 1980 eruption of Mount St. Helens. Prior to 1980, there were six camps on the shore of Spirit Lake: a Boy Scout camp (Columbia Pacific Council), a Girl Scout camp, two YMCA camps (Longview YMCA camp Lowit, and Portland YMCA camp), Harmony Fall Lodge, and another for the general public. There were also a number of lodges catering to visitors, including Spirit Lake Lodge and Mt. St. Helens Lodge; the latter was inhabited by Harry R. Truman, who became one of the volcano's victims.[3]

Pre-1980 eruption

Prior to 1980, Spirit Lake consisted of two arms that occupied what had been the valleys of the North Fork Toutle River and a tributary. About 4,000 years ago, these valleys were blocked by lahars and pyroclastic flow deposits from Mount St. Helens to form the pre-1980 Spirit Lake. The longest branch of Spirit Lake was about 2.1 miles (3.4 km) long. A stable outlet channel flowed from the lake to the North Fork Toutle River across a natural dam composed of volcanic material. The level of Spirit Lake remained basically stable, at an altitude of about 3,198 ft (970 m).[2][4][5]

Mount St. Helens eruption

During the 1980 eruption of Mount St. Helens, Spirit Lake received the full impact of the lateral blast from it. The blast and the debris avalanche associated with this eruption temporarily displaced much of the lake from its bed and forced lake waters as a wave as much as 850 ft (260 m) above lake level on the mountain slopes along the north shoreline of the lake. The debris avalanche deposited about 350,000 acre-feet of pyrolized trees, other plant material, volcanic ash, and volcanic debris of various origins into Spirit Lake. The deposition of this volcanic material decreased the lake volume by approximately 46,000 acre-feet. Lahar and pyroclastic flow deposits from the eruption blocked its natural pre-eruption outlet to the North Fork Toutle River valley at its outlet, raising the surface elevation of the lake by between 197 ft (60 m) and 206 ft (60 m). The surface area of the lake was increased from 1,300 acres to about 2,200 acres and its maximum depth decreased from 190 ft (60 m) to 110 ft (30 m). The eruption tore thousands of trees from the surrounding hillsides and swept them into Spirit Lake. These thousands of shattered trees formed a floating log raft on the lake surface that covered about 40% of the lake’s surface after the eruption.[2][6]

After the eruption, Spirit Lake contained highly toxic water with volcanic gases seeping up from the lake bed. A month after the eruption, the bacteria-carrying water was devoid of oxygen. Scientists predicted that the lake would not recover quickly, but the reemergence of phytoplankton starting in 1983 began to restore oxygen levels. Amphibians such as frogs and salamanders recolonized the lake, and fish (reintroduced by fishermen) thrived.[7][8]

Current water level

The water level of Spirit Lake is maintained at about 3,406 ft (1,040 m) by draining water through a gravity-feed tunnel completed in 1985. The 2,500 ft (760 m)-long tunnel was cut through Harrys Ridge to South Coldwater Creek.[1][8] Had the lake level not been stabilized, the dam, which was composed of volcanic avalanche debris created by the 1980 eruption, would have been breached and caused catastrophic flooding within the Toutle River Valley.[9][10]

Gallery

References

  1. ↑ 1.0 1.1 Anonymous (2013) USGS Cascades Volcano Observatory: Spirit Lake. Mount St. Helens, Cascades Volcano Observatory.
  2. ↑ 2.0 2.1 2.2 Meyer, W, and PJ Carpenter (1983) Filling of Spirit Lake, Washington. Open-File Report no. 82-771. U.S. Geological Survey, Reston, Virginia.
  3. ↑ Anderson, DA (2013) Mount St. Helens. Arcadia Publishing, San Francisco, California. 126 pp. ISBN 9781467130554
  4. ↑ Hopson, CA (2008) Geologic Map of Mount St. Helens, Washington Prior to the 1980 Eruption. Scale 1:62,500, Open-File Report no. 2002-468. U.S. Geological Survey, Reston, Virginia.
  5. ↑ Lipman, PW., and DR Mullineaux, eds. (1981) The 1980 eruptions of Mount St. Helens, Washington. Professional Paper no. 1250. U.S. Geological Survey, Reston, Virginia. 844 pp.
  6. ↑ Lee DB (1993) Effects of the Eruptions of Mount St. Helens on Physical, Chemical, and Biological Characteristics of Surface Water, Ground Water, and Precipitation in the Western United States. Water-Supply Paper no. 2438. U.S. Geological Survey, Reston, Virginia.
  7. ↑ Dale, VH, FJ Swanson, and CM Crisafulli, eds. (2005) Ecological Responses to the 1980 Eruption of Mount St. Helens. Springer Science+Business Media, Inc., New York, New York, 342 pp. ISBN 978-0387238500
  8. ↑ 8.0 8.1 Larson, D (1993) The Recovery of Spirit Lake. American Scientist. 81(2):166-177.
  9. ↑ Swift, CH, and DL Kresch (1983) Mudflow hazards along the Toutle and Cowlitz Rivers from a hypothetical failure of Spirit Lake blockage. Water-Resources Investigations Report no. 82-4125. U.S. Geological Survey, Reston, Virginia.
  10. ↑ Kresch, DL (1992) Development and routing of mudflow resulting from hypothetical failure of Spirit Lake debris dam, Washington. Water-Resources Investigations Report no. 91-4028. U.S. Geological Survey, Reston, Virginia.

External links

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