Slime Atop Water Still a Mystery : Ventura Keys: The city has posted warnings to swimmers on the beaches that dot this posh residential community.

Ventura County health officials on Thursday took water samples for the third time in three weeks from the Ventura Keys after Keys residents called to complain about a thick, greenish-brown slimy substance atop the waterways in front of their residences.

City officials also were called and took their own set of samples, but neither they nor county inspectors were able to determine immediately either the cause of the problem or the nature of the substance. Nor were they able to determine to what degree, if any, the substance was contaminating the waterways.

Both county and city officials said they must wait three to five days for lab test results before reaching any conclusions.

But Barbara Fosbrink, the city’s coastal project manager, said a preliminary study from the city lab chemist showed that the substance “could be largely algae and protozoas,” which are harmless.

Meanwhile, the small beaches that dot this posh, upscale neighborhood of waterfront residences near the Ventura Harbor remained posted with warnings by the city alerting prospective swimmers to “exhibit caution/discretion in any bodily contact with the channel waters.”

Those signs were put up after samples taken by county health officials July 25 indicated a “higher-than-normal coliform count” in the channel waters. Coliform concentrations usually signal contamination from decaying materials such as raw sewage or dead animals, officials said.

Only a single water sample was taken on that occasion, and county officials returned last Tuesday for more extensive tests, the results of which are expected today.

The city took responsibility for that problem last week after determining that it was caused by a storm drain discharge. In an unsigned statement, the city said remedial steps had been taken and pronounced the problem all but solved.

So when Keys residents Ray Russum and his next-door neighbor, David Lawhorn, awoke Thursday morning to discover a pool of slime in front of their homes, they were upset.

“This looks like the Exxon Valdez!” said Russum, referring to the giant oil spill off the coast of Alaska.

“I don’t know what this is, but I . . . am not going to touch it,” Lawhorn said.

Russum and representatives from the county and city, however, surveyed the mouths of several storm drain channels that empty into the Keys in separate expeditions and could find no obvious signs of contamination.

And representatives from both the city and county said the substance found Thursday did not appear to pose a threat to the residents’ health.

“The high levels of bacteriological materials appear to be localized, and there’s no reason to believe at this point that they pose a hazardous problem,” said Bob Williamson of the Ventura County office of environmental health.

Fosbrink said the “frothy mess” the residents complained about could be natural living organisms from the channel bottom that were raised to the surface by “respiratory gas” or carbon monoxide that accumulates at night beneath the surface and rise in the morning with the high temperatures.

The news from the city brought some relief to Russum. “I’m glad to hear that, but until I read the reports from the city and the county, I won’t be sure,” he said.