Federal authorities have won roughly $830,000 in back pay for more than 100 workers from four Mexican restaurants in southern Minnesota and Iowa operating as a single enterprise after finding that the owners violated various labor laws.

U.S. Labor Department investigators said the violations involved numerous schemes by the restaurants in Redwood Falls, Mankato and New Ulm, Minn., and Mason City, Iowa, to short their workers' pay.

Janete Alvarez Campos of New Ulm has an ownership stake in all four restaurants either as sole owner or partner. A message was left with her Thursday seeking comment about the federal findings.

"The employer has agreed to comply in the future" and to make back-pay payments by March 2020, said Scott Allen, a regional spokesman for the Labor Department.

The agreement comes under what is known as an administrative settlement and does not involve court action or any "concept of guilt or innocence," Allen said.

Among the tactics employed to the detriment of the workers, according to investigators:

• Some servers had to "kick back" their hourly wages to their employer and work solely for tips.

• Bussers, food runners, cooks and dishwashers were paid flat salaries regardless of how many hours they worked, leaving them short of the federally required $7.25 minimum hourly wage and, at times, depriving them of overtime pay.

• Pay deductions for uniforms pushed workers below the minimum wage.

"Employers must pay their employees the wages they have legally earned," David King, the Labor Department's Wage and Hour Division district director in Minneapolis, said in a statement.

According to the Labor Department, Plaza Garibaldi in Redwood Falls cheated 30 workers out of more than $150,000; La Terraza Mexican Grill and Bar in Mankato shorted 26 workers more than $160,000; Plaza Garibaldi Authentic Mexican Restaurant in New Ulm must pay 31 workers $390,000; and Las Palmas Mexican Restaurant in Mason City owes 26 workers nearly $130,000.

Anyone who suspects they are owed back wages may contact the Wage and Hour Division at dol.gov/whd.

"We encourage employers to make use of the many tools the Wage and Hour Division provides to help them understand their obligations, and to contact us for assistance," King said.