In this March 26, 2014 photo provided by the U.S. Geological Survey, a U.S. Geological Survey hydrologic technician measures streamflow in the Blackfoot River at the site of USGS stream gaging station in the Blackfoot River above Blackfoot Reservoir near Henry, Idaho. An 11-year state and federal study of selenium pollution in the southeastern Idaho watershed where some 700 sheep, cattle and horses have died over the last several decades after grazing in contaminated areas has found the toxin is likely moving through groundwater.