Descriptions of the Animas River-Cement Creek Confluence and Mixing Zone Near Silverton, Colorado, During the Late Summers of 1996-1997
GEOLOGICAL SURVEY WASHINGTON DC
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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 oxyhydroxides, 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.
- Hydrology, Limnology and Potamology