A study conducted by researchers at Duke University and RTI International found that reusing oil field produced water that has been mixed with surface water to irrigate crops in Kern County’s Cawelo Water District does not pose any major health risks. To cope with droughts and water shortages, some farmers in the Cawelo district have used diluted produced water to irrigate their crops for over two decades. Though the diluted produced water does contain slightly elevated levels of salts and boron as compared to the local groundwater, those levels are below applicable state standards for drinking and irrigation water. Avner Vengosh, professor of water quality and geochemistry at Duke’s Nicholas School of the Environment, stated that the study “did not find any major water quality issues, nor metals and radioactivity accumulation in soil and crops that might cause health concerns.”

California’s own groundwater regulatory agency is on the brink of coming to the same conclusion. For nearly five years, the Central Valley Regional Water Quality Control Board (“Regional Board”) has been conducting its own investigation into the safety of using produced water to irrigate crops. As part of this effort, the Regional Board assembled a Food Safety Expert Panel, which commissioned various, wide-ranging studies. Regional Board Chair Karl Longley stated that the findings from these studies showed no red flags in crops grown with the recycled produced water. Regional Board staff is currently preparing a white paper summarizing the Food Safety Expert Panel’s findings and recommendations. We are monitoring the Regional Board’s work and will report on its conclusions in future posts.