California aquifers contaminated by fracking waste, water board confirms

California aquifers are contaminated with high levels of arsenic, thallium and nitrates, as three billion gallons of wastewater from the oil industry have been dumped into the surrounding water-supply wells, according to a report by California State Water Resources Board.

The report submitted to the US Environmental Protection Agency (EPA) said that at least nine of the 11 fracking wastewater injection wells, which were shut down earlier this year, have contaminated aquifers supplying water for drinking and farm irrigation purposes.

In July, the Division of Oil, Gas and Geothermal Resources closed 11 oilfield injection wells in Kern county and began testing almost 100 others in the region for their potential to contaminate the aquifers.

The EPA then ordered the state water board to provide an assessment of the water-contamination risk within 60 days.

The report found that the water wells protected under federal and state laws contain arsenic, nitrate and thallium beyond the permissible limits.

Conservation organisation Center for Biological Diversity, which has obtained the water board’s report, said: "While the current extent of contamination is cause for grave concern, the long-term threat posed by the unlawful wastewater disposal may be even more devastating.

"Benzene, toluene and other harmful chemicals used in fracking fluid are routinely found in flowback water coming out of oil wells in California, often at levels hundreds of times higher than what is considered safe, and this flowback fluid is sent to wastewater disposal wells.

"Underground migration of chemicals such as benzene can take years."

Arsenic is a well-known carcinogen that weakens the human immune system and thallium is a toxin component used in rat poisons.

The enquiry by the water board revealed that another 19 oil wells may have contaminated the protected aquifers and "dozens more have been injecting waste into aquifers of unknown quality."

Center for Biological Diversity attorney Hollin Kretzmann said: "Clean water is one of California’s most crucial resources and these documents make it clear that state regulators have utterly failed to protect our water from oil industry pollution.

"Much more testing is needed to gauge the full extent of water pollution and the threat to public health, but Governor Brown should move quickly to halt fracking to ward off a surge in oil industry wastewater that California simply isn’t prepared to dispose of safely."

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Image: Aerial view of California Aqueduct. Photo: courtesy of Ikluft / Wikipedia.