A Truthout investigation has confirmed that federal regulators approved at least two hydraulic fracturing, or "fracking," operations on oil rigs in the Santa Barbara Channel off the coast of California since 2009 without an updated environmental review that critics say may be required by federal law.

The offshore fracking operations are smaller than the unconventional onshore operations that have sparked nationwide controversy, but environmental advocates are still concerned that regulators and the industry have not properly reviewed the potential impacts of using modern fracking technology in the Pacific outer continental shelf.

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