FRESNO, Calif. — Sales of organic milk are soaring, but watchdogs say some of the dairy products shoppers are consuming may not be as earth-friendly as the labels purport.

A large dairy in Tulare County recently became the first in California to have its organic certification suspended because it violated organic standards — a move consumer advocates claimed as a victory.

"People should be able to buy organic milk with confidence," said Mark Kastel, co-director of the Cornucopia Institute, a Wisconsin-based consumer watchdog group. "Our hope is that this is the first salvo in a crackdown against these industrial farms that are masquerading as being organic."

The Case Vander Eyk Jr. Dairy, a 10,000-cow operation in the San Joaquin Valley, can no longer produce or sell milk labeled as organic in the United States unless it is recertified, said Joan Shaffer, a spokeswoman for the U.S. Department of Agriculture's National Organic Program.

Officials at Vander Eyk, whose dairy cows produce both organic and conventional milk, did not return calls seeking comment.

Horizon Organic — a brand of Texas-based Dean Foods Co. that sells about 45 percent of the nation's organic milk — stopped buying milk from Vander Eyk in December because it wasn't satisfied with the quality of the organic milk, spokeswoman Molly Keveney said.

On May 16, investigators working with a company that certifies organic dairies for the USDA found that Vander Eyk did not meet federal organic requirements. For dairies, that means proving that the herd eats organic feed, has not been dosed with hormones and has access to pasture.