Exploration of diffuse and discrete sources of acid mine drainage to a headwater mountain stream in Colorado, USA

Mine Water and the Environment
By: , and 

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Abstract

We investigated the impact of acid mine drainage (AMD) contamination from the Minnesota Mine, an inactive gold and silver mine, on Lion Creek, a headwater mountain stream near Empire, Colorado. The objective was to map the sources of AMD contamination, including discrete sources visible at the surface and diffuse inputs that were not readily apparent. This was achieved using geochemical sampling, in-stream and in-seep fluid electrical conductivity (EC) logging, and electrical resistivity imaging (ERI) of the subsurface. The low pH of the AMD-impacted water correlated to high fluid EC values that served as a target for the ERI. From ERI, we identified two likely sources of diffuse contamination entering the stream: (1) the subsurface extent of two seepage faces visible on the surface, and (2) rainfall runoff washing salts deposited on the streambank and in a tailings pile on the east bank of Lion Creek. Additionally, rainfall leaching through the tailings pile is a potential diffuse source of contamination if the subsurface beneath the tailings pile is hydraulically connected with the stream. In-stream fluid EC was lowest when stream discharge was highest in early summer and then increased throughout the summer as stream discharge decreased, indicating that the concentration of dissolved solids in the stream is largely controlled by mixing of groundwater and snowmelt. Total dissolved solids (TDS) load is greatest in early summer and displays a large diel signal. Identification of diffuse sources and variability in TDS load through time should allow for more targeted remediation options.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Exploration of diffuse and discrete sources of acid mine drainage to a headwater mountain stream in Colorado, USA
Series title Mine Water and the Environment
DOI 10.1007/s10230-017-0452-6
Volume 36
Issue 4
Year Published 2017
Language English
Publisher Springer Berlin Heidelberg
Contributing office(s) Colorado Water Science Center
Description 16 p.
First page 463
Last page 478
Country United States
State Colorado
City Empire
Other Geospatial Lion Creek