An aerial view of the Walt Disney complex.

An aerial view of the Walt Disney complex. (Times Community News / August 27, 2012)

The Los Angeles Regional Water Quality Control Board has concluded an investigation into contamination on the site of the Walt Disney Studios, a senior board official said.

The agency’s decision comes a day after the Los Angeles Times reported that the board, along with the U.S. Environmental Protection Agency, was investigating whether a vintage air conditioning system and cooling towers at Disney were the source of groundwater and soil contamination from chromium 6, a cancer-causing heavy metal.

Water board officials had indicated they were weeks away from completing a review of environmental tests conducted by a firm hired by Disney to test soil and groundwater on the Burbank property.

On Friday, Sam Unger, the board's executive officer, told the Times that the board had completed its review of soil tests and concluded that levels of chromium 6 were within regulatory guidelines.

Disney has denied using chromium compounds in its air conditioning system or cooling towers. The company said in a detailed response to the EPA on May 10, 2011, that it stored a small amount of chromium-based material used to clean equipment in film processing and that the hazardous waste was properly disposed of through the city of Burbank. Disney said tests of the wastewater discharge showed low levels of chromium that were “well within the effluent limitations allowed by the city of Burbank.”

The U.S. EPA recently added the Disney site to a list of facilities being investigated for possible chromium 6 contamination in the Burbank and Glendale area and announced plans to install monitoring wells to the east and west of the Disney site. A spokesman for the EPA said the agency's investigation was ongoing.

Richard Verrier is a Los Angeles Times staff writer