Minnesota Pollution Control Agency officials say their monitoring equipment has recorded 42 exceedances of safe hydrogen sulfide levels over a one week period that ended Monday.
That comes as no surprise to Jeff Brouse, who lives about 800 yards from the farm. Brouse says the fumes continue to make neighbors sick.
"The smell was coming right towards my house last night," he said. "I woke up at 4:48 this morning from smell in my home with all the windows closed. I had a headache, nauseous. Now today, I still feel like somebody just beat me."
Hydrogen sulfide is the gas that smells like rotten eggs. It's coming from three large manure basins on the Excel farm.
Late last week, the EPA sent notice to the owners of Excel Dairy that they're in violation of Minnesota state law and the federal Clean Air Act. An EPA spokesman says the EPA will meet with the company in August to discuss the violations.
Meanwhile, federal inspectors have set up their own hydrogen sulfide monitors around the farm.
State law says hydrogen sulfide levels are supposed to be below 30 parts per billion outside the diary farm's property line. PCA officials say their monitoring equipment is only capable of detecting up to 90 parts per billion, and twice last week the levels exceeded that.
Neighbors have been doing their own air quality monitoring. They say on Monday, they detected levels as high as 600 parts per billion.
That's unsafe, according to Minnesota Department of Health toxicologist Rita Messing. Messing is the one who suggested people evacuate their homes back in June.
She says the hydrogen sulfide levels recently detected by the PCA can make people sick. However, more concerning she says, is that longterm affects from repeated exposure are undocumented.
Messing says the Health Department is watching the data and could recommend another evacuation. But for now, she says those dairy farm neighbors are on their own.
"People on the ground need to decide how they're going to protect themselves given the levels that we see," Messing said. "They are of concern, there's no question about that, and it's not just that they've seen it a few times. They've been seen over the last several months, and that's very concerning."
Excel Dairy is operated by a South Dakota company called Prairie Ridge Management, which owns a dozen dairies in Minnesota and the Dakotas.
Minneapolis attorney Jack Perry represents the company and says the odors are a direct result of work ordered by the Pollution Control Agency.
Perry says the PCA required them to do repair work on one of the manure basins. He says that work is complete, but the dairy is unable to resume use of the basin until the PCA inspects it and gives the go-ahead. Perry claims that until then, there's nothing they can do about the smell.
Excel Dairy has not followed through on a request from the MPCA to put a straw cover over the manure beds to cut down on the smell, according to Regional Division Director Gaylen Reetz.
Excel contends it can't do that until the repaired basin gets inspected. Reetz says that inspection was scheduled to happen Wednesday.
Reetz says regulation and enforcement of dairy operations is a slow process. But he says things are moving forward.
"We're working to find a solution to provide relief to the neighbors of the facility," he said. "That's our goal. At some point, if we can't find something that works, ultimately, there could be a revocation of the permit. But there's a fairly high test for us to get to that point."
Last month the PCA and the state Attorney General's office filed a lawsuit against Excel Dairy, alleging the company isn't doing enough to meet state air quality standards. A judge is expected to rule on the suit in the coming weeks.