Irrigating crops with oil field wastewater

Here in California's thirsty farm belt, where pumpjacks nod amid neat rows of crops, it's a proposition that seems to make sense: using treated oil field wastewater to irrigate crops. Oil giant Chevron recycles 21 million gallons of that water each day and sells it to farmers who use it on about 45,000 acres of crops, about 10 percent of Kern County's farmland.

State and local officials praise the 2-decade-old program as a national model for coping with the region's water shortages. As California's four-year drought lingers and authorities scramble to conserve every drop, agricultural officials have said that more companies are seeking permits to begin similar programs. The heightened interest in recycling oil field wastewater has raised concern over the adequacy of safety measures in place to prevent contamination from toxic oil production chemicals.

Until now, government authorities have only required limited testing of recycled irrigation water, checking for naturally occurring toxins such as salts and arsenic, using decades-old monitoring standards. They haven't screened for the range of chemicals used in modern oil production.

No one knows whether nuts, citrus or other crops grown with the recycled oil field water have been contaminated. Farmers may test crops for pests or disease, but they don't check for waterborne chemicals. But experts say that testing of both the water and the produce should be expanded.

Last month, the Central Valley water authority, which regulates the water recycling program, notified all oil producers of new, broader testing requirements and ordered the companies to begin checking for chemicals covered under California's new fracking disclosure regulations. The law requires oil companies to tell the state which chemicals they use in oil-extraction processes. "We need to make sure we fully understand what goes into the wastewater," said Clay Rodgers, assistant executive officer of the Central Valley Water Quality Control Board.

One environmental group has tested the irrigation water for oil field chemicals. Over the past two years, Scott Smith, chief scientist for the advocacy group Water Defense, founded by actor Mark Ruffalo in 2010, collected samples of the treated irrigation water that the Cawelo Water District buys from Chevron. Laboratory analysis of those samples found compounds that are toxic to humans, including acetone and methylene chloride — powerful industrial solvents — along with oil.

Sarah Oktay, a water testing expert, reviewed Smith's methods. "I wouldn't necessarily panic, but I would certainly think I would rather not have that," she said, referring to the chemicals identified in the water samples.

State Sen. Fran Pavley, D-Agoura Hills, is sponsoring legislation that would require expanded testing of water produced in oil operations. Pavley said it is "obviously unacceptable" that oil contaminants are found in irrigation water. "Anyone would be extremely concerned."