9 cows die at Delmoe Lake

By Nick Gevock, of The Montana Standard - 09/13/2007

Nine cows died after drinking from a recreational lake east of Butte, prompting federal officials to warn people to stay out of the water.

Witnesses reported watching the cows drink water from Delmoe Lake, then walk a mere few feet before falling over dead, said Terry Sexton, Whitehall district ranger for the Beaverhead-Deerlodge National Forest. Officials suspect the cause could have been a blue-green algae bloom and are warning people to stay out of the lake.

“Don’t drink the water, don’t get in the water,” Sexton said in a press release.

Delmoe Lake is located east of Butte, north of the Homestake exit on Interstate 90. The area is a popular recreation site for people from Butte and Whitehall.

Forest Service officials are working to keep the public away from the water, said Jack de Golia, Beaverhead-Deerlodge spokesman.

“We’re posting signs and trying to get the word out,” he said.

He added that a similar algae bloom has been recorded at nearby Homestake Lake, although it didn’t result in any animal deaths. But Delmoe Lake hasn’t had any such blooms.

The recent warm weather is likely a factor, de Golia said.

Blue-green algae when in the bloom growth phase can produce a cyanotoxin that is incredibly lethal, said Dr. Joe Hartley, a large animal veterinarian in Dillon. He studied blooms in lakes in northern Idaho while in veterinary school and said they could kill animals quickly.

“When it blooms in certain times of the year it’s very toxic,” he said. “We would take a cc of water, give it to mouse and it would kill it almost instantly.” To be lethal, the toxin has to be ingested, he said. But that’s possible for a person or animal just swimming in the water.

The Forest Service doesn’t plan to test the water because the results would likely take a while to come back, de Golia said. The suspected toxin gets killed by a hard frost, so officials are hoping to get a cold night to take care of the problem.

“Certainly we can’t chlorinate the lake,” he said. “We’re just going to keep people away from it until the cold weather sets in.” Reporter Nick Gevock may be reached at nick.gevock@mtstandard.com.