Mount St. Helens volcanic-ash fall in the Bull Run watershed, Oregon, March-June 1980

M.V. Shulters; Daphne G. Clifton

doi:10.3133/cir850A

Mount St. Helens volcanic-ash fall in the Bull Run watershed, Oregon, March-June 1980

Circular 850-A

By: M.V. Shulters and Daphne G. Clifton

https://doi.org/10.3133/cir850A

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Document: Report (pdf)
NGMDB Index Page: National Geologic Map Database Index Page (html)
Superseded Publications:

Mount St. Helens ash fall in the Bull Run watershed, Oregon, May-June 1980(1980)

Mount St. Helens ash fall in the Bull Run watershed, Oregon, March-April 1980(1980)

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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

Shulters, M., Clifton, D.G., 1980, Mount St. Helens volcanic-ash fall in the Bull Run watershed, Oregon, March-June 1980: U.S. Geological Survey Circular 850, iii, 15 p., https://doi.org/10.3133/cir850A.

ISSN: 2330-5703 (online)

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Additional publication details
Publication type	Report
Publication Subtype	USGS Numbered Series
Title	Mount St. Helens volcanic-ash fall in the Bull Run watershed, Oregon, March-June 1980
Series title	Circular
Series number	850
Chapter	A
DOI	10.3133/cir850A
Year Published	1980
Language	English
Publisher	U.S. Geological Survey
Contributing office(s)	Oregon Water Science Center
Description	iii, 15 p.
Country	United States
State	Washington
Other Geospatial	Bull Run watershed, Mount St. Helens