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

Open-File Report 80-593

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Abstract

On May 25-26, May 30-June 2, and June 12-13, 1980, strong, high-altitude winds from the north occurred during periods of volcanic-ash eruption at Mount St. Helens in southwestern Washington. As a result, ash fell in the Bull Run watershed, Oregon, some 50 miles to the south, the principal water-supply source for the Portland area. Samples from precipitation collectors and from stream sites in the Bull Run watershed were collected on several dates during May and June 1980. Analyses were made and are tabulated for pH, conductivity, acidity, sulfate, and nitrate plus nitrite. Field pH values of the precipitation ranged from 4.0 to 5.6 pH units and the stream samples from 6.7 to 7.5 units. Particle-size analyses for ash samples collected in the Bull Run watershed and Portland, Oregon , are also shown. Volcanic events, precipitation and high-altitude speeds for northerly winds are given for May 18-June 15, 1980. (USGS)

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Mount St. Helens ash fall in the Bull Run watershed, Oregon, May-June 1980
Series title:
Open-File Report
Series number:
80-593
Edition:
-
Year Published:
1980
Language:
ENGLISH
Publisher:
U.S. Geological Survey,
Description:
11 p. :ill., map ;27 cm.