17 million gallons of raw sewage was discharged into the ocean. Why’d it take so long to alert the public?

Dockweiler and El Segundo beaches are still closed after 17 million gallons of raw sewage from the Hyperion Water Reclamation Plant ended up in the ocean on Sunday. Public health officials waited until Monday evening to reveal news of the sewage dump. The plant’s manager says an investigation into the spill is underway. Officials have been testing the water, and beaches may be able to open on Thursday.