People choose to pay a premium for organic food because they know it is produced following strict rules that prioritize healthy soil, crop diversity and animal welfare.

Except when it isn’t.

The misinterpretation of a rule governing organic livestock by some certification agencies has allowed a few dairy farms to produce milk inconsistent with national standards. It has put those dairy farms who follow the rule the way it was intended — including all the organic dairy producers in Maine — at a disadvantage.

The U.S. Department of Agriculture should close this loophole to put all dairy producers on level ground — and to maintain the integrity of the department’s organic certification.

The problem concerns “origin of livestock” rules for when conventional dairy cows can be transitioned into organic herds. The intention of the rule was to allow each farm a one-time transition, to smooth the path from conventional to organic.

However, some USDA-accredited organic agents — though not the Maine Organic Farmers and Gardeners Association, the only agent in Maine — interpret the rule as allowing for continuous conversions.

Organic agriculture advocates say this interpretation is a boon to some large-scale dairy farms, which can raise calves under cheaper conventional methods, then convert them to organic standards when time comes to produce milk.

As a result, Maine’s organic dairy farms, which raise their calves using organic methods from the start, spend $600-$1,300 more per calf than those who skirt the rules, according to the state agriculture officials, who along with Gov. Janet Mills are asking the USDA to act.

What’s more, by allowing dairy products that are not fully organic to be sold under that label risk diminishing the USDA certification in the eyes of consumers, which in the long run will hurt all organic operations.

That’s no small thing. Maine’s dairy farms are hurting — mostly small family farms, dozens have been lost in just the last few years. Of the 231 left, more than 25 percent sell to organic processors.

And generally, organic farming is booming in Maine, where total organic product sales increased almost 65 percent from 2012 to 2017, to $60 million. Though organic farming still makes up only a tiny fraction of national and statewide agricultural production, it is growing — and represents an important part of Maine’s farming future.

And that future could be very bright, as long as Maine farms are allowed a level playing field, and to sell their goods under a certification that consumers trust.

Certified organic products are popular because that certification means something. The health and environmental differences between organic and nonorganic goods are complex and often depend on individual producers. But consumers know that when they buy something that is USDA-certified organic, it was made under certain conditions that they wish to support with their own dollars.

The misinterpretation of the livestock rule undermines that understanding. It hurts not only dairy producers who are following the rules, but all organic farmers as well.

The U.S. House of Representatives has passed a bill ordering the USDA to finalize the proposed rule that would end this loophole. If the Senate passed the same bill, the department would have to act.

Better yet, the USDA should stand up for its own rule, and make sure its organic certification keeps its meaning.