The Environmental Protection Agency is putting the Lehigh Cupertino’s cement plant on notice.

For years some residents living near the plant have complained about toxic pollutants coming from the facility. Now, the EPA has just issued what is called a "notice of violation" against Lehigh.

"What it underscores is all of our concerns, all our prior concerns are validated," Quarry No spokesperson Bill Almon said.

The EPA is accusing Lehigh of making physical changes to its plant operations between 1996 and 1999. The agency says those changes could have resulted in increased emissions of greenhouse gases from that point forward.

The EPA says Lehigh’s actions violated the Clean Air Act.

"They didn’t obtain the proper permits to do that or install the additional air pollution control measures that they were required to do," EPA spokesperson Mary Simms said.

Lehigh’s current owners say the plant was under different management during the mid to late 90’s. It is now looking into exactly what happened and if excessive emissions have ever taken place.