State health officials are investigating potential contaminated storm water runoff into the ocean from the city’s Waimanalo Gulch landfill in Waianae.

State health spokeswoman Janice Okubo said the discharge began on Sunday after heavy rainfall.

Okubo said the city is required to report discharges into the ocean and failure to notify the state about a discharge into the ocean is a violation.

“We are still investigating it,” she said.

A state health solid waste inspector discovered the water runoff on Thursday, she said.

The inspector notified state clean water branch officials who are conducting the investigation.

City spokesman Louise Kim McCoy said the landfill operator Waste Management of Hawaii followed protocol and notified the state solid waste branch on Monday about the discharge.

She said the state clean water branch visited the landfill on Tuesday.

“The health department did not raise any issues or concerns at that time,” she said.

Okubo said potentially contaminated storm water went into the ocean between Ko Olina and Kahe Power Plant from Sunday through yesterday.

She said the landfill will be conducting water sampling.

Okubo said at this time, health officials do not know how much potentially contaminated water entered the ocean nor do they know the concentration of any pollutants.

“There are a lot of unknowns,” she said.

She said no warning signs were posted because officials weren’t sure about the concentration of pollutants and felt the discharge had already dissipated in the ocean.

A spokeswoman for Honolulu Mayor Peter Carlisle said this afternoon that she would check into the incident.

No one from the operator of the landfill, Waste Management of Hawaii, was available for comment.