Today marked the third consecutive day that people are being warned to stay out of the water at Kailua Beach after heavy rains caused 5,000 gallons of rain-diluted raw sewage to overflow from a manhole on Wana'ao Road Saturday night and enter Ka'elepulu Stream.

State health department spokeswoman Laura Lott said test results from Sunday's water-quality samples showed bacteria levels remained high. She said daily sampling is continuing and officials will continue to monitor.

"They are hopeful," Lott said that the water quality will improve by tomorrow in time to remove the warning signs for Thursday's Veterans Day holiday.

Meanwhile, at nearby Marine Corps Base Hawai'i, heavy rains combined with grease build-up in the sewer system forced the wastewater treatment plant to skip a step in the treatment process yesterday for 67,000 gallons of wastewater and release partially treated sewage through the outfall off Mokapu peninsula.

Marine officials said the bypass of some treatment occurred so that the plant could make mechanical repairs. State health officials were notified.

While the Mokapu release is considerably bigger than the one at Ka'elepulu Stream, it is considered less hazardous because it was partially treated and because the outfall is far from the beach, officials said.

State engineer Libby Stoddard, of the health department's Clean Water Branch, said bacteria counts generally remain high in shoreline waters for several days after heavy rains because of urban runoff — even when no sewage spills occur.

Runoff from the heavy rains turned the nearshore waters brown across the island, Stoddard said.

The city has spent millions of dollars in recent years to help prevent rainwater from getting into the sewage system. The infiltration of rain across O'ahu has caused chronic problems with wet-weather sewage spills. The city is under court order to reduce the number of spills.

The Kailua spill occurred from about 9:30 to 10:15 p.m. Saturday from a manhole near 429 Wana'ao Road. City wastewater crews notified the health department, and on Sunday city workers posted 125 signs along the beach, the stream and much of Kailua Bay.