(FULTON COUNTY, Ga.) — Officials now say it was a large volume of chemicals -- not a sewer spill, that caused high levels of E. coli in the Chattahoochee River over the busy holiday weekend.

WSB-TV′s Ashli Lincoln was at the Fulton County Water Treatment Plant on Monday, where officials said a chemical malfunction in the system prevented sewage from being thoroughly cleaned and sanitized before it was released back into the river.

Officials are still working to determine which chemical malfunctioned. Eleven miles of the river are currently closed between the Chattahoochee Nature Center and White Water Park.

David Clark, the Executive Director of Fulton County Public Works, said the normal process of treating water involves sewage being filtered and disinfected and then released back into the river.

In this case, a chemical did not trigger safety mechanisms to stop the release back into the river, which resulted in wastewater material that was not thoroughly clean being released.

The county is now diverting five to seven million gallons of sewage to neighboring Cobb County.

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