Channel conditions in the lower Toutle and Cowlitz Rivers resulting from the mudflows of May 18, 1980

R.E. Lombard; M.B. Miles; L. M. Nelson; D. L. Kresch; P.J. Carpenter

doi:10.3133/cir850C

Channel conditions in the lower Toutle and Cowlitz Rivers resulting from the mudflows of May 18, 1980

Circular 850-C

By: R.E. Lombard, M.B. Miles, L. M. Nelson, D. L. Kresch, and P.J. Carpenter

https://doi.org/10.3133/cir850C

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Abstract

During several periods of volcanic-ash eruption at Mount St. Helens, Wash., (March 30, May 25-26, May 30-June 2, and June 12-13, 1980) strong winds from the north occurred at high altitudes. As a result, the volcanic ash fell some 50 miles to the south in the Bull Run watershed, the principal water-supply source for the metropolitan area of Portland, Oreg. Water samples collected from three stream sites within the watershed were compared with samples collected during the same season in previous years. No detectable changes were noted in chemical characteristics. Precipitation samples collected immediately after the June 12-13 ash fall ranged in specific conductance from 20 to 41 micromhos per centimeter at 25C and in pH from 4.0 to 4.3 pH units. Stream samples collected during the May-June period ranged in specific conductance from 18 to 28 micromhos per centimeter at 25C and in pH from 6.7 to 7.5 pH units. Volcanic-ash samples were collected and analyzed for particle size, chemical composition, and weight. Significant differences in particle size of ash were found in samples from two separate eruptions. (USGS)

Suggested Citation

Lombard, R., Miles, M., Nelson, L.M., Kresch, D., Carpenter, P., 1981, Channel conditions in the lower Toutle and Cowlitz Rivers resulting from the mudflows of May 18, 1980: U.S. Geological Survey Circular 850, v, C1-C16 p. :ill., maps ;26 cm., https://doi.org/10.3133/cir850C.

ISSN: 2330-5703 (online)

Additional publication details
Publication type	Report
Publication Subtype	USGS Numbered Series
Title	Channel conditions in the lower Toutle and Cowlitz Rivers resulting from the mudflows of May 18, 1980
Series title	Circular
Series number	850
Chapter	C
DOI	10.3133/cir850C
Year Published	1981
Language	ENGLISH
Publisher	U.S. Dept. of the Interior, Geological Survey ; Free on application to Distribution Branch, Text Products Section, U.S. Geological Survey,
Description	v, C1-C16 p. :ill., maps ;26 cm.