The owner of three Tucson carwashes must pay more than $300,000 in back pay to workers who were taken off the clock when there were no cars to wash.

The U.S. Department of Labor crackdown involves the franchise operator who owns the Thornydale Octopus Car Wash, the 22nd Street Octopus Car Wash, and the Valencia Octopus Car Wash.

The employees were on the job nearly 40 hours each week, but they were paid for just 25 to 30 hours apiece, said Jesus Olivares, community outreach coordinator for the Labor Department.

The difference, he said, was time waiting for customers to arrive.

Olivares said it would have been one thing had the workers been allowed to go home during slack periods. But that was not the case, he said.

“The employer was still controlling the time,” he said. “The employees were not allowed to leave the establishment. The employees were told, ‘You’re going to wait here until more cars arrive, and then we’ll put you back on the clock.’ ”

Olivares said the company was subject to a routine review his agency does of places like carwashes and other establishments with a large percentage of low-wage workers. The review — and the back wages — cover a two-year period beginning in August 2010.

He said that the company, informed by the Department of Labor of the problems, has corrected its practices.

The review also turned up three teens — one 14 and two age 15 — who were working at one of the sites more than eight hours a day. Olivares said that violates federal labor laws, which limit anyone in that age group to eight hours of work on non-school days, and less than that on days when school is in session.

According to Olivares, the company already has paid $313,333 to the Labor Department to be distributed to nearly 300 workers.

He said about 200 of these employees have not yet been located. Olivares said anyone who worked at any of the locations during the affected period should contact either the Labor Department or the Mexican Consulate.