Upper Snake River

Confluence of the Upper Snake River (left) and Deer Creek (a non-ARD/AMD stream on the right). The reddish coloring evident in the Upper Snake River and in the mixing zone below the confluence is due to iron oxide precipitates. Photo by: Garrett Rue.

The Upper Snake River (USR) drains a mineralized watershed in the Rocky Mountains of central Colorado east of Keystone Ski Resort and south of the Arapahoe Basin Ski Area. The watershed produces acid rock drainage resulting in naturally acidic and metal rich waters in the river. Despite considerable mining within another tributary of the Snake River (i.e. Peru Creek), the watershed of the Upper Snake River is essentially undeveloped, and naturally-occurring land disturbances are also lacking. An approximately 30-year (1979-2011) stream chemistry record for the USR thus provided a unique opportunity to examine climate-driven trends in water quality in the region.

USGS and INSTAAR researchers found that during most of the low flow months from August to April, the months when metal concentrations are highest, both zinc and manganese concentrations have increased between 350% and 400% over the 30-year timeframe. One possible mechanism for the increase in metal concentrations is that a decrease in the extent and duration of snow cover is allowing for increasing ground temperatures and rock weathering. Another potential mechanism is that higher evapotranspiration rates are leading to decreased overall groundwater recharge and the lowering of water table levels. This could result in increased sulfide oxidation in soil volumes more newly exposed to air. Rising metal concentrations in the Upper Snake River have a variety of implications. Marginal fish habitats may become uninhabitable. The use of USR water for water supply, fishing, or snowmaking may become unsafe. In addition, shifting baseline metals concentrations may also make assessment of remediation efforts more complicated.

For more information contact: Dr. Andrew Todd, (atodd@usgs.gov)

Citation

Todd, A. S., Manning, A. H., Verplanck, P. L., Crouch, C., McKnight, D. M., & Dunham, R. (2012). Climate-change-driven deterioration of water quality in a mineralized watershed.Environmental science & technology, 46(17), 9324-9332.  DOI: 10.1021/es3020056

Related publications

Crouch, C. M., McKnight, D. M., & Todd, A. S. (2013). Quantifying sources of increasing zinc from acid rock drainage in an alpine catchment under a changing hydrologic regime.Hydrological Processes.  DOI: 10.1002/hyp.9650

Manning, A. H., Verplanck, P. L., Caine, J. S., & Todd, A. S. (2013). Links between climate change, water-table depth, and water chemistry in a mineralized mountain watershed.Applied Geochemistry, 37, 64-78.  DOI 10.1016/j.apgeochem.2013.07.002

Todd, A., McKnight, D., & Wyatt, L. (2003). Abandoned mines, mountain sports, and climate variability: implications for the Colorado tourism economy. Eos, Transactions American Geophysical Union, 84(38), 377-386.  DOI: 10.1029/2003EO380002