Mary Clare Weatherwax, wetlands program manager for the tribe, told the Great Falls Tribune (http://bit.ly/uO8y9e) that water samples from four locations in a creek in the pasture where the cattle were found show levels of salinity far above the maximum recommended limit.

She said the finding of sodium sulfate indicates the salt came from groundwater soils and bedrock that likely came to the surface in a saline seep.

“And that was the only water that was available to those cattle,” Weatherwax said. “Sodium sulfate was the primary salt that was found. That's indicative that it was locally derived from groundwater soils and bedrock.”

Weatherwax said the salty water wasn't caused by oil and gas activity on the reservation.

She said that sodium sulfate is an indication of a saline seep, which she said was different from sodium chloride, which would come from a deeper source and indicate oil drilling activities if it reaches the surface.

Maureen Kiely of the Environmental Protection Agency in Helena said “everything was indicative of a natural saline seep.”

Veterinarian Bar Gustafson, who examined the cattle, said he tasted the water and found it salty. He said, like humans, cattle can't survive drinking salt water.

“You'll die,” he said.

Aerial photos of the site taken when the cattle were found show areas of white in the soil indicating high levels of salt.

Experts at the Montana Salinity Control Association in Conrad said this year's higher precipitation levels resulted in a higher water table and the most saline seep the state has seen in a decade. Water seeps to the surface and evaporates, leaving behind naturally occurring salts.