Investigating hydraulic connections and the origin of water in a mine tunnel using stable isotopes and hydrographs

Applied Geochemistry
By:  and 



Turquoise Lake is a water-supply reservoir located north of the historic Sugarloaf Mining district near Leadville, Colorado, USA. Elevated water levels in the reservoir may increase flow of low-quality water from abandoned mine tunnels in the Sugarloaf District and degrade water quality downstream. The objective of this study was to understand the sources of water to Dinero mine drainage tunnel and evaluate whether or not there was a direct hydrologic connection between Dinero mine tunnel and Turquoise Lake from late 2002 to early 2008. This study utilized hydrograph data from nearby draining mine tunnels and the lake, and stable isotope (δ18O and δ2H) data from the lake, nearby draining mine tunnels, imported water, and springs to characterize water sources in the study area. Hydrograph results indicate that flow from the Dinero mine tunnel decreased 26% (2006) and 10% (2007) when lake elevation (above mean sea level) decreased below approximately 3004 m (approximately 9855 feet). Results of isotope analysis delineated two meteoric water lines in the study area. One line characterizes surface water and water imported to the study area from the western side of the Continental Divide. The other line characterizes groundwater including draining mine tunnels, springs, and seeps. Isotope mixing calculations indicate that water from Turquoise Lake or seasonal groundwater recharge from snowmelt represents approximately 10% or less of the water in Dinero mine tunnel. However, most of the water in Dinero mine tunnel is from deep groundwater having minimal isotopic variation. The asymmetric shape of the Dinero mine tunnel hydrograph may indicate that a limited mine pool exists behind a collapse in the tunnel and attenutates seasonal recharge. Alternatively, a conceptual model is presented (and supported with MODFLOW simulations) that is consistent with current and previous data collected in the study area, and illustrates how fluctuating lake levels change the local water-table elevation which can affect discharge from the Dinero mine tunnel without physical transfer of water between the two locations.

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Publication type Article
Publication Subtype Journal Article
Title Investigating hydraulic connections and the origin of water in a mine tunnel using stable isotopes and hydrographs
Series title Applied Geochemistry
DOI 10.1016/j.apgeochem.2009.09.015
Volume 24
Issue 12
Year Published 2009
Language English
Publisher Elsevier
Contributing office(s) Colorado Water Science Center, Toxic Substances Hydrology Program
Description 17 p.
First page 2266
Last page 2282
Time Range Start 2002-01-01
Time Range End 2008-12-31
Country United States
State Colorado
City Leadville
Other Geospatial Turquoise Lake
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