Sunny Jiang, assistant professor of environmental studies at the University of California, Irvine, tested water samples at 12 major river mouths in southern California for the human adenovirus, a potentially harmful pathogen (a cousin of the hepatitis A virus). She found adenovirus at four of the 12 sites: the Los Angeles, San Gabriel, Santa Ana, and Tijuana river mouths. Of these, however, only the Los Angeles river mouth also had high fecal bacteria counts, the standard criterion for evaluating water quality, closing beaches, and monitoring compliance with federal clean water laws. The Los Angeles River had one of the highest bacteria counts when Jiang took her water samples in February and March 1999. Malibu Lagoon and Moonlight Creek in San Diego County also ranked high on bacteria counts, but she found no adenovirus there.

Jiang’s study did not determine whether the adenoviruses were alive or infectious. Their presence, however, does definitively indicate that human waste is polluting our waterways. Because some viruses can live as long as 130 days in seawater, Jiang said that even dead adenoviruses may point to the presence of other virulent viruses.

“We need to reconsider our monitoring and coastal water standards,” Jiang concluded. “The current open and closed beach status does not indicate the human health risk.”

Steve Weisberg, the executive director of the Southern California Coastal Water Research Project, said Jiang’s work has two take-home messages: “For one, we know the bacteria that we see are not due entirely to things like birds or cats. The second message is that the weak correlation (between bacterial and viral contamination) means we should rethink how much reliance we place on bacterial measurements.”

Epidemiological studies have established a link between bacterial counts and illness, but no similar studies have shown that viral contamination is associated with an increased chance of illness. “We don’t have a way to translate the number of viruses you find to a health risk,” said Mitzy Taggart, staff scientist at Heal the Bay in Santa Monica.

Viral detection methods are also unwieldy and expensive. Jiang, for instance, must take 20-liter water samples to capture enough viruses to run her tests. Taggart said: “The science behind monitoring for viruses is in its infancy. [Jiang’s] work is moving us toward the time when we will be able to use viral-detection methods at the beaches.”

Jiang’s study was funded by California Sea Grant. She is currently working with the Public Facilities and Resources Department in Orange County to track viral contamination in the chronically polluted waters of the Aliso Creek watershed. She is also working with other UC Irvine professors on a project to study the impact of the Santa Ana River on beach pollution in Huntington Beach, which was closed most of the summer in 1999 and 2000.

Jiang theorizes that Huntington Beach pollution could be originating from wastewater discharged four miles offshore by an outfall pipe. Tides, ocean currents, and warm water released by a nearby power plant may be sweeping the wastewater ashore, she said. She plans to test this hypothesis by tracking human contaminants as they drift from the outfall pipe toward shore.

Christina S. Johnson works for California Sea Grant, within the National Sea Grant College Program, National Oceanic and Atmospheric Administration, U.S. Department of Commerce