A week after heavy rains spurred massive flooding, runoff and sewage spills, brown water advisories remain in effect for O'ahu and Kaua'i beaches, and health officials are asking swimmers to steer clear of murky, debris-laden waters as a precaution at least through tomorrow.

"The water is still pretty murky in some areas," said Watson Okubo, director of the Department of Health's Clean Water Branch. "We ask people to use their common sense. If it looks dirty, why go in?"

Meanwhile, shark warning signs were again posted at Makaha Beach Park yesterday after a shark sighting. Okubo said sharks are attracted to the murky water and could also be coming into Makaha because of animal carcasses, including feral pigs, dogs and goats, that were swept into the ocean during the rains.

On Tuesday, the Health Department said, signs at beaches warning swimmers of contamination from sewage spills were taken down when levels of fecal-born bacteria dropped to acceptable levels. But Okubo said that many near-shore waters are still brown and full of debris, from tree branches to household items.

In addition to attracting sharks, brown water can carry leptospirosis and other contaminants.

"If you don't have to recreate in the water, don't," Okubo said.

But at Kailua Beach yesterday, brownish, murky waters weren't keeping many people out.

One Toronto couple said lifeguards warned them to steer clear of the water and so they watched the waves mournfully from shore. But others said they didn't see a need to stay out, since there were no signs posted.

"It looked pretty decent to us, so we just got in," said Josette Mills, who is visiting from Dallas. She was at the beach with her three children, ages 14, 10 and 7. "There were no warnings. No warnings at all."

A LOT OF RUNOFF

Nearby, Brian McNeely, 51, of Colorado, was wading in the water.

He said he and his family stayed out of the water on the Leeward Coast earlier this week because it was very brown and full of debris. But he said the brownish tinge to the Kailua water yesterday didn't scare him.

"It's just a casual day at the beach," he said.

Experts say the waters on O'ahu and Kaua'i are taking so long to clear up because of the sheer magnitude of runoff that was washed into the ocean in last week's rains and because the downpours followed a period of prolonged dryness, when streambeds were allowed to build up with debris.

The wet weather has also stuck around in places, sending more runoff into the ocean. Intermittent downpours were seen yesterday on O'ahu, and National Weather Service forecasters say scattered showers should be expected through tomorrow. Drier weather is in the forecast for the weekend, though.

Last Thursday, O'ahu was pummeled with more than 14 inches of rain in a 12-hour period. The downpours flooded homes, pushed debris and waste into the ocean and spurred several sewage spills, which sent nearly 400,000 gallons of treated and untreated sewage into waterways islandwide.

Carl Evensen, an environmental quality specialist and chairman of the Natural Resource and Environmental Management department at the University of Hawai'i-Manoa, said streambeds that had been dry or nearly dry for months were "flushed out" in the torrential showers.

"That's why there is so much debris and why there is so much sediment and turbidity in the water," he said yesterday.

The rains "were so intense" and followed a "long dry period."

He added that the Health Department's warnings about brown water are important to heed.

"When the ocean doesn't look inviting, stay away," he said.

Evensen said leptospirosis in brown ocean water is a real concern.

But he said it's unclear how long leptospirosis can remain a danger in ocean water.

Over time, the organism will die with exposure to salt and light.

RISK OF ILLNESS

Officials don't look for the presence of leptospirosis in the ocean because there is no "good environmental test," Evensen said, adding that those with low immune systems are most at risk of getting sick from brown water. People with open wounds are also at higher risk.

On top of brown ocean water, health officials are also warning residents about the presence of leptospirosis in floodwaters, which swept through homes across O'ahu. The Health Department has not heard of any cases of leptospirosis in the wake of the recent rains but, Okubo said, the "conditions are ripe."

Leptospirosis is endemic in freshwater streams in Hawai'i.

The state saw two cases of leptospirosis after flooding in Manoa in 2004.

Okubo said those cleaning out flooded homes should wear boots and gloves.

People who contract leptospirosis complain of vomiting, muscle pain and fever. These symptoms generally appear seven to 14 days after someone has had contact with contaminated fresh water and can result in mild to severe illness. Without treatment, leptospirosis can lead to hospitalization or death.