The BP refinery in Whiting, Indiana, discharged nearly five times more industrial waste into Lake Michigan than legally allowed on Monday.

The refinery has been dealing with an "operational issue" since Friday, according to BP spokesperson Michael Abendhoff.

BP notified the Indiana Department of Environmental Management that it discharged 8,932 pounds of total suspended solids on Monday, according to IDEM spokesperson Courtney Arango.

The refinery is legally permitted to discharge 5,694 pounds per day, Arango confirmed. Another test on Tuesday indicated that the amount of total suspended solids rose to 26,621 pounds, nearly five times that limit.

"The BP Whiting Refinery is responding to an upset at the refinery’s wastewater treatment facility," Abendhoff said in an emailed statement. "BP has notified the Indiana Department of Environmental Management that this upset has resulted in exceedances of BP’s daily permit limit for total suspended solids. This is a wastewater issue; there has been no leak or discharge of any hydrocarbons into Lake Michigan."

Total suspended solids are solid particles of industrial waste that can be trapped in a filter during wastewater treatment. Arango said after IDEM was notified, the agency sent its deputy director to investigate the issue and further action is pending the findings of that ongoing investigation, which is scheduled to continue through Thursday.

"We know BP is doing some operational adjustments and we believe that is the cause," Arango said. "Tomorrow's inspection, the second in a week, will help us determine more. We're also relying on the company to inform us on the changes in their process."

"BP is working to safely return the refinery to normal operations as soon as possible," Abendhoff said.

Arango said the discharge does not affect drinking water or marine life, and should not be a cause for concern for patrons of nearby Whihala Beach. All beaches remain open, and visitors can check water quality on the IDEM's website.