The Associated Press

CHARLESTON, Ore. - Beachgoers at Sunset Bay State Park near Coos Bay have seen signs warning of bacterial contamination in the water in recent years.

But now the Oregon Department of Environmental Quality is working with researchers from the South Slough National Estuarine Research Reserve and Oregon State University to determine where it comes from and how long it lasts.

The signs go up when monthly tests show excessive levels of fecal coliform bacteria, which can cause illness.

Part of the federally funded project began last month when marine biologist Steven Rumrill and research assistant Ben Grupe placed a device in Big Creek to measure the amount of fresh water that enters the bay from the creek and to monitor its salinity, temperature, acidity and conductivity.

Grupe said it's the first step to understanding potential factors behind the contamination. The device will track flow and water quality during a variety of weather conditions.

The two researchers have several ideas about the cause, including feces from sea gulls and sea lions on the beach, or from elk living along the Big Creek or from homes near Lighthouse Beach.

andquot;If it's mostly from ... birds and sea lions, there isn't much we can do about that,andquot; Rumrill said. andquot;If it turns out it's mostly coming from the stream, then the state will determine what steps to take.andquot;

When levels are high, the public generally is advised to stay out of the water for about 30 days. But nobody knows for sure how long it takes the tide to cycle out the bacteria, Grupe said.

There have been andquot;well-documented cases of people getting sick from these pathogens, just not here at Sunset Bay,andquot; Rumrill said.

Pamela Blake, DEQ's South Coast Basin coordinator, said the yearlong project will allow state officials to take a different approach to the problem that could mean shorter, if not fewer, beach advisories.

andquot;The hope is [to work] with the source to reduce bacterial pollution,andquot; she said.

andquot;Everybody wants to know, [but] we may find out that it's a source we can't manage, and in that instance, we'll just be able to provide more information to people,andquot; she said.

In 2000, Congress passed an act establishing criteria for testing, monitoring and notifying the public of possible contamination, Blake said.

But it did not fund or require tracing the source.

andquot;None of it talked about the 'whodunit' of the mystery here,andquot; Blake said.

Blake said she doesn't expect the bacteria to be from a single source.

Beaches themselves remain safe even if signs advise staying out of the water, she added.

Ben Fisher, the manager of Sunset Bay State Park management unit for the state, said advisories have been posted there four or five times in the past 17 months but that the number of visitors has not faltered.