Concerned about test results showing high levels of chromium 6 in north Los Angeles County water wells, the Board of Supervisors on Tuesday ordered officials to devise a plan to remove the contamination.
The motion by Supervisor Mike Antonovich, approved unanimously, gives the Public Works Department a month to report on ways to remove chromium 6 and other chemical contaminants from the wells.
Supervisors voted in the wake of tests showing that 32 of 44 county-owned wells tested positive for chromium 6, with concentrations reaching as high as 17.6 parts per billion.
Although that falls within current state standards, the concentrations are up to 90 times the level of chromium 6 that has been recommended by a state agency for optimum safety.
County public works officials have said levels of chromium 6 in tap water could be lower than the amounts found in the wells because the well water may be blended with other water sources.
The tests found 14 wells that registered above 10 parts per billion for chromium 6, all of them in the Antelope Valley.
County officials said the 32 wells that had detectable levels of chromium 6 serve about 44,000 homes and businesses, and are all operated by the county Public Works Department.
County officials asked for the well tests last month after a test of drinking water at 110 county buildings showed levels of up to almost 9 parts per billion. Tests are continuing at other county buildings and wells.
California has no specific standard for chromium 6, but the state Office of Environmental Health Hazard Assessment has called for a new public health goal of 2.5 parts per billion for total chromium, which officials say would reduce chromium 6 concentrations to 0.2 parts per billion.
The current standard for total chromium is 50 parts per billion.
David Spath, state Department of Health Services drinking water chief, was not available for comment on the county well tests. But Spath, whose agency is reviewing the assessment office's recommendation, has in the past recommended against closing water wells that meet current state standards, saying there is not an acute risk to public health.
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Chromium 6 in Water Wells
Thirty-two of 44 Los Angeles County wells operated by the Public Works Department tested positive for chromium 6, with one registering as high as 17.6 parts per billion. The 14 county wells listed below all had chromium 6 levels at or exceeding 10 parts per billion:
Source: Los Angeles County