Is Recycled Oilfield Water Safe for Crop Irrigation?

irrigating grapes

by | Jan 19, 2016

irrigating grapesSome 50,000 acre feet of recycled oilfield wastewater is used to irrigate about 90,000 acres of crops in California’s Central Valley, one of the world’s most productive agricultural regions.

But is this produced water safe for use on food crops? A newly formed panel aims to answer this question.

“There appears to be a data gap here,” the Central Valley Water Board’s Clay Rodgers, project supervisor of the Food Safety/Oil Field Produced Water project team, told Environmental Leader. “There’s not much research we can find anywhere on using produced water for crop irrigation and that’s the reason we brought in food safety experts.”

As farmers in drought-stricken California look for alternative water sources for their crops, a $54 billion industry, recycled oilfield wastewater has become an attractive source. In 2013, about 150 million barrels of oil were produced in the state, along with nearly 2 billion barrels of water. While the bulk of this water (878 million barrels) is recycled for use in the oil fields, a portion of the produced water is recycled to irrigate crops for human consumption.

At least five oil fields in the state provide recycled water to irrigate crops including almonds, grapes, pistachios and citrus.

Chevron and the California offshoot of Occidental Petroleum, called California Resources Corporation, are the primary oil companies supplying oilfield wastewater to farmers.

There’s a desire to increase use of produced water for irrigation — and also concern about oilfield wastewater, and whether it contains chemicals and other harmful substances.

Assuming it’s safe, recycled water is a boon for agriculture.

“For the Central Valley, what we need to look for is how can we diversify our water supply and that often means looking at more local and recycled water in all forms. Oilfield water is just one potential source of water that could be used for irrigation,” the Almond Board of California’s Dr. Gabriele Ludwig told Environmental Leader. Ludwig sits on the new food safety panel.

Ludwig says there are two concerns with using alternative sources of water for irrigation. “One, from the safety perspective, is making sure there is nothing harmful that can get into the food supply, and that’s an issue that has been controversial in terms of using urban recycled water. The other concern is the plant itself. There are only certain compounds the plants can handle. So those are examples that need to be addressed.”

In December, the Pacific Institute, a nonprofit that studies water issues, published a study, Oil, Food, and Water: Challenges and Opportunities for California Agriculture, that, among other things, looked at the reuse of oilfield water for crop irrigation.

“There is an opportunity to expand the recycling of oil-field wastewater for ‘beneficial uses,’ such as for crop irrigation or livestock watering,” the study said. “However, the health and food safety impacts of this practice are poorly understood…Scientists should conduct a study to determine what level, if any, of chemicals in oil-field wastes is safe for farmworkers, animals, and consumers. Such a study should be performed by an independent science panel, and would help to reduce the uncertainties around the safety of this practice.”

The Central Valley Water Board’s first Food Safety/Oil Field Produced Water panel met last week. Panel members include experts from the California Department of Food and Agriculture, California Department of Fish and Wildlife, California Department of Public Health and Lawrence Berkeley National Laboratory.

Pacific Institute researcher Matthew Heberger presented the nonprofit’s study at the meeting.

“We are concerned about the health and safety of the people who live and work near oil and gas production,” Heberger told Environmental Leader. “We are especially concerned about farmworkers. Oilfield wastewater can contain volatile chemicals such as benzene and toluene that are known to have health impacts, and Central Valley residents that we spoke to cited this as a concern.

“We are obviously also concerned about the safety of our food supply. We need to take a more careful look at projects where oilfield wastewater is treated and sent to irrigators to make sure that the practice is safe. The bigger concern for me is pollution due to spills, leaks, or unsafe disposal of oil-field wastes that can contaminate the soil and water resources used by agriculture.”

The panel aims to produce a white paper, or a series of white papers, that addresses the safety of using recycled oilfield water for crop irrigation. Rogers says he hopes the white paper will be ready by the end of summer but acknowledges, “obviously this is an issue of critical importance to us. We want to get through it as quickly as we can but we also want to makes sure we do the things we need to do. If it takes longer to do it right, we’ll take more time.”

Photo Credit: irrigating grapes via Shutterstock

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