DNA tests incriminate foul fowl

Investigators find geese, not dairy cattle, contaminated local stream

By MITCH LIES

Capital Press

DNA evidence has been used to solve a mystery on an Oregon dairy in a case of mistaken manure identity.

It turns out the cows weren't the culprit. It was the geese all along.

Wym Matthews, head of the state program that regulates dairies, turned to DNA after state investigators were stumped as to why waters running adjacent to a dairy had high bacteria counts.

"We couldn't see any visual indication on the dairy that they were discharging," Matthews said.

"Their facility seemed tight. All the typical things we do on an inspection did not reveal what was going on," Matthews said.

The farmers, Ron and Nellie Bem, meanwhile, began to suspect that the geese that graze their pasture during much of the year could be the cause of the high bacteria counts.

"There were high counts and just no explanation for them," Nellie Bem said.

"That's why we decided to sample for that," Matthews said. "We wanted to see what is the contribution from regulated animals versus unregulated animals."

The case marked the first time the ODA turned to DNA evidence to solve a question on the origin of surface water pollution. The findings relieved the Bems.

"It is kind of what we've been saying all along, that we're not contaminating the water," Nellie Bem said. "It is the birds and the geese that are all around.

"Just because the E. coli count is high, it isn't necessarily the bovine causing it," she said.

DNA has been used to determine the source of bacteria in watersheds for more than a decade, Matthews said. But rarely has it been used to clear a dairy of pollution claims.

Matthews chose to employ the technology at the Bems' Hoodview Dairy after a neighbor complained that the dairy was polluting a creek, and after state investigators failed to uncover the origin of the bacteria.

State investigators took performed a dye test, where they put colored dye in the dairy's manure tank, and spread dye around the dairy to determine if fecal matter was leaving the premises.

"Every hour we walked around the outside of the dairy, looked at all the drainages, and didn't see anything," Matthews said. "A day later we didn't see anything. And a week later we didn't see anything.

"So that appeared to tell us there is not a leak that (the Bems) don't know about," he said.

Investigators continued to have these samples that every once in a while would go above 400 colony forming units per 100 millimeters of sample," Matthews said.

Oregon's water-quality standard calls for no pollutants above 406 colony forming units per 100 millimeters of sample.

At that point, Matthews decided to employ the DNA technology that he had heard of but never used.

The process involves taking two samples, running one for bacteria and running the other sample through a filter. The filter then is frozen with bacteria stuck on it and transported to a lab in Corvallis that does DNA testing.

Lab technicians compare DNA on the filter with a library of markers to determine if it is from humans, dogs, horses, birds or bovines.

"It helped a lot," Matthews said. "The one set of samples that we got back from the dairy showed that from this particular drainage, this particular day, there was no cow DNA. None. And there were birds that day.

"That time it was a violation of the water-quality standard, but it doesn't look like cows were to blame," Matthews said. "There was no human, there was no dog, and there was no cow DNA. The only hit we got on that particular drainage were birds."

Matthews said the state plans to use the technology sparingly in the future.

"It is fairly expensive," he said, costing $200 per sample.

But it is available, and could be used in future unsolved mysteries.