Organic milk sometimes costs twice as much as the rest of the milk you’ll find in the supermarket dairy aisle, but you get what you pay for, right? A new report about one of the largest suppliers of store-brand organic milk casts some doubts on the standards of some products.

The Washington Post looked into Aurora Organic Dairy, a company that isn’t a household name, but which supplies milk to companies like Walmart, Whole Foods, and Costco for their store-brand products. Aurora’s High Plains complex is a massive farm where more than 15,000 cows live on 6,000 acres of land.

Aurora has been accused of this exact thing in the past, with the now-defunct Rocky Mountain News reporting on the issue back in 2007, and the company settling a class action over allegations that the milk wasn’t as organic as advertised in 2012.

One of the selling points of organic dairy products is that cows are grass-fed, which is supposed to provide health benefits for consumers and a more pleasant life for the cows. Cows are supposed to spend a certain amount of time outside grazing every day as long as grass is available.

The Post noticed something about Aurora’s cows when visiting the farm: They weren’t in the pastures. In satellite photos taken in July, which should be peak grazing season, only a few hundred of the 15,000 cattle were hanging out in the pastures. The Post flew by the property with drones as well as examining satellite photos.

A company spokeswoman said that the Post’s cow counts were “anomalies,” though the reporters visited the farms during and after grazing season, for as long as 10 hours at a time.

The popularity of organic food means that massive farming operations have popped up to fill the demand, which in turn means that the food doesn’t come from the rolling hills of beautiful family farms that we imagine. Defenders of small organic farms argue that big organic operations hurt smaller farmers.

“About half of the organic milk sold in the U.S. is coming from very large factory farms that have no intention of living up to organic principles,” Mark Kastel of the Cornucopia Institute, a group that represents smaller-scale organic farms, told the Post.

The Post sent samples of milk known to come from Aurora, as well as milk from small local farms, to the dairy science department at Virginia Tech. The scientists tested it for the two beneficial fats known to be present in milk from grass-fed cows.

Organic milk should have elevated levels of conjugated linoleic acid and alpha-linolenic acid, and lower levels of linoleic acid. Milk from Aurora that was tested had levels of these fats comparable to conventional milk, but came with USDA Organic certification labels and price tags.

When asked for comment, the company dismissed the results and wouldn’t comment to the Post on them, claiming that there were multiple variables at play, and maybe the fats in the milk were the result of different grasses that grazing animals eat in the Rockies. (That isn’t the case.)

Here’s the thing with USDA organic certification: The current system is that farms and companies hire and pay their own inspectors, who have been approved by the USDA. This system isn’t perfect: The inspectors that Aurora hired, from the Colorado Department of Agriculture, visited the farm complex after grazing season was over, making it impossible for them to tell whether the animals were given the opportunity to graze.

Check out the whole investigation, including aerial cow grazing footage, at the Washington Post.

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