Accession Number : ADA182837

Title :   Spirit Lake, Mount St. Helens, Washington: Limnological and Bacteriological Investigations. Volume 2.

Descriptive Note : Final rept. 1983-1986,

Corporate Author : ARMY ENGINEER DISTRICT PORTLAND OREG

Personal Author(s) : Larson,Douglas W. ; Glass,Michael W.

Report Date : MAR 1987

Pagination or Media Count : 143

Abstract : The cataclysmic eruption of Mount St. Helens, Washington, on 18 May 1980, filled nearby Spirit Lake with timber and volcanic debris and completely blocked the lake's natural outlet. The lake, which the outlet had previously kept in hydrological balance, was hence forth impounded in a closed, hydrologically unstable basin by a debris dam 150-180m thick. This event greatly altered the limnology of Spirit Lake and resulted in extremely poor water quality. Some post-eruption water quality characteristics included whole-lake anoxia, which persisted for months; and extraordinarily high concentrations of sulfides, methane, reduced iron and manganese, phosphorus, and dissolved organic matter. Concentrations of total bacteria reached 1X10 cells/ml, thought to be unprecedented for natural lakes. This report describes the post-eruption limnological recovery of Spirit Lake, Washington, 1980 to 1986. Other topics of discussion include the limnological impacts of lake drawdown, the effects of Spirit Lake release flows on receiving waters in the North Fork Toutle River basin, and the bacteriology of lakes and rivers in the Mount St. Helens blast zone. Keywords: Limnology; Water quality; Bacteriology; Biogeochemical processes; Volcanic effects; Lakes.

Descriptors :   *LAKES, *WATER QUALITY, BACTERIA, DISSOLVING, ORGANIC MATERIALS, BALANCE, HYDROLOGY, LIMNOLOGY, METHANE, PHOSPHORUS, BACTERIOLOGY, CONCENTRATION(COMPOSITION), HIGH RATE, SULFIDES, MANGANESE, IRON, WASHINGTON(STATE), RIVERS, BASINS(GEOGRAPHIC), TREES, WOOD, DEBRIS, VOLCANOES, WATER

Subject Categories : Hydrology, Limnology and Potamology

Distribution Statement : APPROVED FOR PUBLIC RELEASE