A worker prunes trees in an orchard near Bakersfield, California Lucy Nicholson / Reuters To cope with super dry conditions, a lot of California farms over the last two decades have turned to using recycled water... from oil companies.

The Los Angeles Times reports that "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," or about 10% of the farmland in the southern part of California's Central Valley, Kern County.

While it has never been proven unsafe, the LAT reports that some scientists say there isn't enough testing on the water to really be sure.

Here's how it works:

In the Kern County program, Chevron's leftover water is mixed with walnut shells, a process the company says extracts excess oil. The water then flows to a series of treatment ponds. The treated water is launched into an eight-mile canal to the Cawelo Water District, where it is sometimes further diluted with fresh water. The water supplies 90 Kern County farmers with about half their annual irrigation water.

They get this water for about $30 an acre-foot, about half the going rate, according to the LAT.

It complies with testing regulations, but the list of chemicals state regulators test for is limited, according to the LAT.

There are reports, secondhand through the LAT, that the water smells like petrochemicals.

In response to hearing that Business Insider was writing about this story, Chevron sent a long email detailing its process, which included a report the company had done on the chemical makeup of the water it sells to Kern County farmers. It is uploaded and available here.

Chevron says it's been providing water for decades and it has a "rigorous water monitoring program." From the email sent to BI:

All of this water comes from conventional oil producing wells and Chevron conducts a rigorous water monitoring program to ensure the quality of our produced water prior to discharge, which is covered by a permit issued by the Regional Water Quality Control Board.



Chevron has been supplying water to local farmers for more than 20 years and while we can’t disclose the terms of the sales agreement, it has been essentially provided “at cost” since the contract was signed in 1994.

The Times says scientists have found toxins in the water after testing it for a broader number of chemicals than usual. The one thing to note in its analysis, though, is it doesn't quantify how much of each of these chemicals were found in the water. Those levels matter (see the arsenic-in-wine debate from last March). Chevron also denied to the Times that it uses some of the toxic chemicals found in the test in its oil production process, although it will not release a list of the chemicals it does use.

Further, scientists aren't sure if chemicals from the water affects the plants that grow from the irrigation. "it's not clear whether oil field waste is making its way into the roots or leaves of irrigated plants, and then into the food chain," the Times says.

Here's more:

One environmental group has tested the irrigation water for oil field chemicals. Over the last two years, Scott Smith, chief scientist for the advocacy group Water Defense, 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.

Water Defense, founded by actor Mark Ruffalo in 2010, works to promote access to clean water by testing local supplies and documenting contamination.

Sarah Oktay, a water testing expert and director of the Nantucket field station of the University of Massachusetts Boston, reviewed Smith's methods and the laboratory analysis of the water he sampled.

"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. "My next step would be most likely to look and make sure the crop is healthy."

The bottom line is that this might be bad news, but no one really knows for sure.