(CN) - Federal regulators relied on outdated data in approving air-quality standards for California's San Joaquin Valley, the 9th Circuit ruled Friday.
The Environmental Protection Agency spent six years studying a California's 2004 State Implementation Plan governing ozone levels in portions of the valley. But by the time it approved the plan in 2010, environmental groups such as the Sierra Club said the new model was already outdated.
The federal appeals panel in San Francisco agreed, granting environmentalists' petition for review and sending the EPA back to the drawing board.
In 2007, a new generation of computer-modeling technology gave an emissions level estimate that presented a significant gap from estimates used in the 2004 plan. And yet EPA made no attempt to explain the discrepancy, the three-judge panel found.
"Our role is not to substitute our conclusions based on the facts presented for those of the agency, and we express no opinion as to what conclusion EPA should have reached, with respect to the validity of the 2004 SIP, upon consideration of the 2007 data," Judge Ronald Gould wrote for the court. "But we should not silently rubber stamp agency action that is arbitrary and capricious in its reliance on old data without meaningful comment on the significance of more current compiled data. We hold that EPA's failure to even consider the new data and to provide an explanation for its choice rooted in the data presented was arbitrary and capricious."
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