Distinguishing natural from mining-related metal sources by including streambank groundwater data in a stream mass loading study

Journal of Contaminant Hydrology
By: , and 

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Abstract

Distinguishing stream metal loading caused by mine features from that caused by natural background sources remains challenging, yet this distinction is essential for making effective remedial decisions at many legacy mine sites. We combine a stream tracer injection and synoptic sampling study with data from shallow near-stream groundwater wells to estimate left-bank versus right-bank metal loading contributions at the 100-m spatial scale. The study was performed in the East Mancos River, a mountain headwater stream in Colorado, USA. The dominant source of elevated stream metal concentrations could be either groundwater infiltration through right-bank Doyle Mine waste piles or natural acid rock drainage from hydrothermally altered bedrock located mainly on the left bank. For the five metals of concern (Cu, Al, Zn, Cd, and Mn), we find that 15 % of the load contributed by diffuse groundwater inputs in the section potentially influenced by Doyle mine waste originates from the right bank. This right-bank potential mine contribution equates to only 3 % of the total watershed instream load for these metals. Furthermore, apparent 3H/3He groundwater ages in segments contributing most of the right-bank metal loading are sufficiently old (9–12 yr) to suggest that infiltration through the waste piles, located only 140–180 m from the stream, is unlikely. Estimated potential Doyle mine loading contributions can therefore be considered maximum values. Study results thus indicate that Doyle mine waste piles are a minor source of metal loading under low-flow conditions, and streambank groundwater data can provide valuable additional information in stream mass loading studies.

Suggested Citation

Manning, A.H., Runkel, R.L., Morrison, J.M., Warix, S., Wanty, R.B., Walton-Day, K., Snook, M., 2026, Distinguishing natural from mining-related metal sources by including streambank groundwater data in a stream mass loading study: Journal of Contaminant Hydrology, v. 277, 104841, 15 p., https://doi.org/10.1016/j.jconhyd.2026.104841.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Distinguishing natural from mining-related metal sources by including streambank groundwater data in a stream mass loading study
Series title Journal of Contaminant Hydrology
DOI 10.1016/j.jconhyd.2026.104841
Volume 277
Publication Date January 05, 2026
Year Published 2026
Language English
Publisher Elsevier
Contributing office(s) Colorado Water Science Center, Geology, Geophysics, and Geochemistry Science Center
Description 104841, 15 p.
Country United States
State Colorado
Other Geospatial East Mancos River
Additional publication details