Acid rock drainage in the upper Snake River: The presence of heavy metals in a mineralized watershed
Other: University of Colorado Boulder honors thesis, 2012.
The coupled environmental impact of acid rock and acid mine drainage is a problem facing countless waterways across the Rocky Mountains. Here we examine the Snake River watershed, located near the former mining boomtown of Montezuma. Over the three decades, researchers for numerous government agencies, the Institute of Arctic and Alpine Research, and graduate students at the University of Colorado have closely monitored changes here in water chemistry and heavy metal contamination present in its contributing streams, resulting from both over a hundred and fifty years of mining activities and the natural weathering of pyrite-laden rock.
The purpose of this project, funded in large part by an Undergraduate Research Opportunity Grant, is to test the dissolved metals present in the upper Snake River, an undisturbed portion of the reach that is naturally acidified and loaded from both surface and subsurface flow. Augmenting this data are field measurements of stream flow, pH, and total dissolved solids collected at a one-week interval between September 22nd and 28th, 2012. The follow-up lab analysis of samples was performed by the Laboratory for Environmental and Geologic Studies using Inductively Coupled Plasma Mass Spectrometry to determine concentrations of aluminum, cadmium, copper, iron, manganese, sulfate and zinc present at 15 sites distributed among the Upper Snake; the headwaters, 3 main tributaries and their conflux, and the confluence downstream with the pristine Deer Creek. Certain sites were chose due to availability of water chemistry data going back over 30 years, with others chosen because of their reflection of similar climate conditions at the time of sampling. By choosing sites which have been heavily studied and measured over a large temporal scale, it is therefore possible to correlate these new results with pre-existing data to draw new conclusion regarding the presence of heavy metals in the upper Snake River as to whether these levels have increased, further enrichment is occurring, and how these change in relation to drivers such as climate.Download thesis (78 MB)