Officials assure residents health risks are low
Residents of 860 homes and businesses in the Green Valley area of Solano County, Calif., have been told that their water violates new government purity standards, but that they don't need to boil water or take other action while the problem is fixed during the next 18 months, the San Francisco Chronicle reported.
Residents expressed concern after Vallejo's Green Valley Water Treatment Plant, which pulls water from three nearby lakes, alerted them that during tests last year it found that its drinking water contained excessive byproducts, called trihalomethanes, of its chlorination process.
Vallejo officials and industry experts stressed that research on trihalomethanes suggested that the short-term risks of exposure to the substances were extremely low.
If 100,000 people drank two liters of contaminated water a day every day for 70 years, just one might get cancer, said Dave Spath, chief of the California Department of Health Services' Division of Drinking Water and Environmental Management.
"What I've been telling people is that the water is the same as it was last week, last month and last year, and if people were comfortable drinking it then, they should be comfortable now," said Joe Lennen, acting laboratory chemist at the Green Valley plant.
"Any water you chlorinate will have (trihalomethanes) in it," he said. "It's just a matter of the level."
According to the report, the plant near the outskirts of Fairfield and Suisun City is among many small surface-water treatment systems nationwide, from Coalinga in the Central Valley to Cibolo, Texas, and Floral City, Fla., that is notifying residents about the trihalomethanes.
The State of California last year required for the first time that plants serving less than 10,000 customers test for trihalomethanes; larger plants have tested for them since 1980.
Residents "have every right to be concerned," said Slawomir Hermanowicz, a UC Berkeley associate professor of environmental engineering who follows efforts to limit disinfectant byproducts in water. He said people needn't change their habits if their water providers take action.
"I would worry if they said it wasn't a problem and didn't do anything about it," he said. He said that many water providers, including the East Bay Municipal Utility District, had abandoned chlorine as a disinfectant to address the problem of trihalomethanes and that some were using ozone or ultraviolet light to purify water.
Lennen said Thursday that water samples taken from four different households last February, May, August and November found trihalomethanes at an average of 113 parts per billion -- exceeding the federal standard of 80 parts per billion.
Vallejo officials said they had held community meetings in Green Valley late last year to alert residents. The City Council last month approved spending $820,000 on a system to remove organic compounds from water that, when chlorinated, yield the potentially harmful byproducts.
The upgrades will be in place by December, and the plant will meet the water standards by the following July, the city said.
Officials on Jan. 12 sent an advisory to residents alerting them to the violations. It said residents didn't need to take corrective actions but should consult a doctor if they had concerns. Infants, the elderly and people with compromised immune systems "may be at increased risk," the letter said.
Information about water filtration products is available on the Web site of the California Department of Health Services. Some reportedly can drastically reduce levels of trihalomethanes.
Water treatment has long been costly in Green Valley. The $7 million plant was built in 1998 because the existing facility wasn't meeting water standards. Green Valley residents pay roughly three times as much for water as Vallejo residents, said Erik Nugteren, the city's deputy water superintendent of engineering.
"The state has put the regulations in, and we are required to meet that, and we're diligently trying to meet that," he said. "Unfortunately, it will cost money, and it will come back to the residents."