Cattle deaths in Caribou Co. attributed to selenium poisoning 

Eighteen head of cattle grazing near the abandoned Lanes Creek phosphate mine in Caribou County died earlier this month from acute selenium poisoning, the USDA’s poisonous plant research lab in Logan, Utah confirms. Sheep and cattle have died from selenium poisoning in the past after feeding on selenium-tainted vegetation in the phosphate mining region, but cows were thought to be less susceptible to it. Selenium is a toxic byproduct of phosphate that can leach and be absorbed by plants.

IDEQ Regional Administrator Bruce Olenick said his Pocatello office received a telephone call on Aug. 11 from Simplot, alerting it to the cattle deaths east of Monsanto’s South Rasmussen Ridge Mine and north of Simplot’s Smoky Canyon Mine. Simplot officials met with grazing association members on Aug. 10.

“Sheep are more susceptible. We always thought cows were more immune and had higher tolerances for selenium,” Olenick said, speculating the plants were eaten later in the year when they had more time to mature and gain higher toxicity.

Kip Panter, the lab's research leader, said the Bear Lake Grazing Association cattle were moved into the area on Aug. 2 and died about three days later. “It doesn’t take long. Acute selenium is very toxic. It affects the heart and lungs,” Panter said.

A range rider provided liver, kidney and blood samples from the cows, which were analyzed by the Utah State Diagnostic Laboratory on the Utah State University campus. The samples tested positive for high levels of selenium, Panter said.

While water samples from a nearby creek were normal, Purple Aster showed 4,000 parts per million of selenium, which is relatively high, he said, adding lots of rain caused vegetation to grow more lush and high this season.

The Lanes Creek Mine was run by the Alumet Partnership many years ago. Alumet sold the property to the Bear Lake Grazing Association in 1997. The J.R. Simplot Co. leases mineral rights, but has never mined there.

Simplot spokesman David Cuoio stated: “The area where the 15 to 20 cattle died is not near any present or past Simplot phosphate mining operations.”

It was discovered in 1997 that horses and sheep grazing near Southeast Idaho phosphate mining operations were dying of selenium poisoning. As a result, Monsanto, Simplot, Agrium, FMC/Astaris and Rhodia each spent $1 million to conduct an area-wide study in conjunction with the Idaho Department of Environmental Quality.

Several horses died near Agrium’s Mabey Canyon Mine in Caribou Canyon on pasture at the base of a mine dump. Sheep fatalities also occurred near Simplot’s Conda mine.

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