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Descriptions of the Animas River-Cement Creek confluence and mixing zone near Silverton, Colorado, during the late summers of 1996 and 1997

Open-File Report 2005-1064

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Abstract

Acidic waters from Cement Creek discharge into the circum-neutral Animas River in a high-elevation region of the San Juan Mountains near Silverton, Colorado. Cement Creek is acidic and enriched in metals and sulfate because it is fed by discharges from abandoned mines and natural mineral deposits. Mixing with the Animas River raises the pH and produces precipitates of iron and aluminum (oxy)hydroxides, which in turn can adsorb other metals. This confluence was studied in 1996 and 1997 to better understand mixing and sorption processes which are common during the neutralization of acidic streams. The photographs in this report show flow braiding and other features that influenced the way the two streams mixed during the late summers of the two years. They also show 'banding' due to incomplete mixing and 'opalescence' due to chemical reactions and the formation of colloidal-size particles in the mixing zone.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Descriptions of the Animas River-Cement Creek confluence and mixing zone near Silverton, Colorado, during the late summers of 1996 and 1997
Series title:
Open-File Report
Series number:
2005-1064
Edition:
-
Year Published:
2005
Language:
ENGLISH
Description:
8 p. online; 5 p. report (ill.)
Scale:
100000