The state Department of Health Services has found another 101 contaminated drinking-water wells in Southern California, most of them in Los Angeles County, state officials said Friday. The major chemicals found were pesticides and industrial solvents, including tricholoroethylene (TCE), a suspected cancer-causing agent.
Only last November, the state identified 190 contaminated wells in the Southland as part of a year-old, ongoing statewide investigation ordered by the Legislature. The initial phase, which is now completed, focused on the larger public water systems serving 200 customers or more.
Final figures obtained on Friday show a total of 291 contaminated wells in Southern California--221 of them in the San Fernando, San Gabriel and central water basins of Los Angeles County.
Virtually all such wells have either been shut down or are having their water diluted to bring contamination levels within acceptable limits, said state Health Services toxicologist David Storm. In the other cases, customers are being provided drinking water.
Report Being Worked On
The report is still under preparation, and it was not immediately clear just what percentage of Los Angeles County's water supply comes from the contaminated wells.
Since November, state investigators have found 94 additional contaminated wells in Los Angeles, and about half of them had concentrations exceeding recommended state safety levels, according to Storm.
On a statewide basis, 18.2%, or 538, of the 2,947 wells tested were found to have some levels of contamination and a third of those had concentrations exceeding the recommended safety levels.
But in Los Angeles County, 41%, or 221, of the 535 wells tested were found to have some levels of contamination and 46% had concentrations higher than recommended by the state.
535 Wells Sampled
The 535 wells sampled in Los Angeles County represent about half of the estimated 1,000 wells in public drinking water systems, Storm said. Each of the systems serves more than 200 customers.
He said the investigation of ground-water contamination turned up 13 chemicals, such as herbicides and solvents, for which no health safety standards have been developed either by state or federal authorities. Thus, a well found to contain those chemicals would not have to be shut down.
The U.S. Environmental Protection Agency and the state have come under criticism from various environmental and public health interests for their failure to establish standards for more chemicals.
In the final data, no additional contaminated wells were found in Orange County; four were reported last November, but they did not exceed the recommended safety levels.
In San Diego County, only one well was found to be slightly contaminated. Three more contaminated wells have been found in Riverside County, bringing that county's total to 20, five of which exceed recommended safety levels. Another four contaminated wells have been found in San Bernardino County, bringing its total to 43, of which 11 exceed action levels. There were only two contaminated wells in Ventura County, both of which exceed recommended safety levels.