According to the Summit Daily (http://tinyurl.com/9o7rlbm ), rising concentrations of zinc and other metals in the upper Snake River west of the Continental Divide near Keystone may be caused by falling water tables, melting permafrost and other problems caused by warmer air temperatures.

High concentrations of dissolved metals in the upper Snake River watershed are also being blamed on acid drainage from past and present mining activities.

The studies were led by the U.S. Geological Survey and the University of Colorado, Boulder.