Ocean water samples collected over the last two days met state standards for acceptable water quality, the department announced.
In an abundance of caution, the Department of Public Health will continue to sample affected beaches through Thursday.
The beaches that have been reopened are:
-- Dockweiler State Beach at Water Way Extension;
-- Dockweiler State Beach at Hyperion Plant;
-- El Segundo Beach; and
-- Grand Avenue Storm Drain.
The Hyperion Water Reclamation Plant discharged 17 million gallons of untreated sewage through its one and five-mile outlets Sunday, prompting the beach closures.
RELATED: 17-million-gallon sewage spill prompts closure of beaches from Dockweiler to El Segundo
Hyperion Executive Plant Manager Timeyin Dafeta issued a statement Monday afternoon saying that on Sunday afternoon, the plant "became inundated with overwhelming quantities of debris, causing backup of the headworks facilities. The plant's relief system was triggered and sewage flows were controlled through use of the plant's one-mile outfall and discharge of untreated sewage into Santa Monica Bay.''
Dafeta said the 17 million gallons of sewage -- about 6% of a daily load -- was discharged as an emergency measure through the one-mile outfall to prevent the plant from going offline and discharging more raw sewage. Normally, treated sewage is discharged through the five-mile outfall.