California Farmers Are Watering Their Crops With Oil Wastewater, And No One Knows What’s In It

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As California farmers face a fourth year of the state’s historic drought, they’re finding water in unexpected places — like Chevron’s Kern River oil field, which has been selling recycled wastewater from oil production to farmers in California’s Kern County. Each day, Chevron recycles and sells 21 million gallons of wastewater to farmers, which is then applied on about 10 percent of Kern County’s farmland. And while some praise the program as a model for dealing with water shortages, environmental groups are raising concerns about the water’s safety, according to a recent story in the Los Angeles Times.


Tests conducted by Water Defense, an environmental group founded by actor Mark Ruffalo in 2010, have found high levels of acetone and methylene chloride — compounds that can be toxic to humans — in wastewater from Chevron used for irrigation purposes. The tests also found the presence of oil, which is supposed to be removed from the wastewater during recycling.

“All these chemicals of concern are flowing in the irrigation canal,” Scott Smith, chief scientist for Water Defense, told ThinkProgress. “If you were a gas station and were spilling these kinds of chemicals into the water, you would be shut down and fined.”

Chevron, which produces around 70,000 barrels of oil and 760,000 barrels of water each day at the Kern River oil field, has been selling water to farmers in the surrounding area for two decades. But government authorities have never required that water to be tested for chemicals used in oil production — only naturally occurring toxins like salts and arsenic. And even those standards are “decades-old,” according to the Los Angeles Times.

Before getting to the Central Valley fields, wastewater from the Kern River oil field is mixed with walnut shells, which helps remove residual oil. The water then passes through a series of treatment ponds before flowing down an eight-mile canal to the Cawelo Water District. While in the canal, the wastewater is sometimes diluted with freshwater — and sometimes not. The water from the Kern River oil field is applied to some 45,000 acres of crops, irrigating everything from nut trees to citrus fruits.

Last year, the California state legislature passed a law requiring oil companies to disclose the chemicals that they use in oil extraction, and in April, California water authorities declared that oil companies would need to start checking to make sure that those same chemicals aren’t making it into recycled water bound for agricultural use. Oil companies have until June 15 to disclose the results of these new tests.

“We need to make sure we fully understand what goes into the wastewater,” Clay Rodgers, assistant executive officer of the Central Valley Water Quality Control Board, told the Los Angeles Times.

To test the recycled wastewater for contaminants, Water Defense’s Smith — who has consulted with the EPA and other government offices on more than 50 oil spills — took samples from 10 different points of varying depth along the Cawelo canal’s eight-mile stretch. Smith compares his testing method to a video, and says the state’s method is more like an instant picture — it looks at the wastewater for a split second, and can miss contaminants. His method, he contends, gives a better holistic picture of the water’s composition. One sample Smith took had levels of methylene chloride — an industrial solvent used to soften crude oil — as high as 56 parts per billion, four times the amount of methylene chloride Smith found in 2013 when he tested parts of an Arkansas river fouled by the 2013 ExxonMobil tar sands pipeline spill.

Chevron is pushing back against claims that the wastewater contains dangerous chemicals, saying in a statement emailed to the Los Angeles Times that “protection of people and the environment is a core value for Chevron, and we take all necessary steps to ensure the protection of our water resources.” Out of an “abundance of caution,” however, both Chevron and the Cawelo Water District will contract with an outside group to test the wastewater. Still, Chevron would not disclose publicly the fluids it uses for drilling or well maintenance.

Blake Sanden, an agriculture extension agent and irrigation water expert with UC Davis, told the Los Angeles Times that farmers can smell the petrochemicals in the water, but most assume that the soil is filtering out any harmful toxins before they can be absorbed by the crops. While soil does filter out some impurities, Sanden says it’s impossible to know for sure whether waste from oil production is making its way from irrigation water into the roots and leaves of crops.

To Smith, that’s just another missing piece of information that needs to be understood before wastewater from oil production is deemed safe for agriculture.

“The state appears to not even be testing for oil in the water,” Smith said. “You’re not going to find chemicals of concern if you don’t look for them.”

According to the Los Angeles Times, monitoring the oil fields has been a “low priority” for California’s Water State Resources Control Board, the state body that regulates wastewater. The burden for testing wastewater falls largely on the oil companies, which in the past have sought to reduce testing and disclosure requirements due to concerns over time and expense.

With the drought placing more attention on water resources, Smith says that it’s important for testing of wastewater to continue.

“We want to work with Chevron, we want to work with the regulators. We want to use multiple methods of testing,” he said. “That’s the best way to figure out what’s in that water and what can be done to solve it.”




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