Can oilfield water safely be reused for irrigation in California?

Numerous farm fields in the Cawelo Drinking water District of California have been irrigated with reused oilfield h2o combined with area h2o for 25 years. A new Duke-led review finds the practice poses no important overall health hazards. Credit: Avner Vengosh, Duke University

A new analyze by researchers at Duke University and RTI Intercontinental finds that reusing oilfield water that’s been mixed with surface area drinking water to irrigate farms in the Cawelo H2o District of California’s Kern County does not pose main well being hazards, as some opponents of the apply have feared.

“We did not obtain any main water good quality difficulties, nor metals and radioactivity accumulation in soil and crops, that may lead to health concerns,” mentioned Avner Vengosh, professor of drinking water excellent and geochemistry at Duke’s Nicholas School of the Ecosystem, whose lab led the new research.

Confronted with raising droughts and drinking water shortages, some farmers in the Cawelo district have made use of diluted oilfield generated drinking water (OPW) for irrigation for their fields for much more than 25 a long time, as permitted under California Water Board coverage.

Although the oilfield-combined drinking water consists of somewhat elevated stages of salts and boron relative to the regional groundwater, those people concentrations are nevertheless down below the criteria set by the condition for safe and sound ingesting h2o and irrigation in the Cawelo district, Vengosh said.

Boron and salts from the OPW have having said that, accrued over time in the irrigated soil. The district’s farmers will require to plant boron-tolerant crops and maintain mixing the OPW with refreshing h2o to avoid boron toxicity and salinity buildup in their fields, and also to keep on being inside of point out suggestions. “But all issues considered, this is fantastic news,” Vengosh mentioned.

The scientists posted their peer-reviewed conclusions Could 18 in the journal Science of the Overall Atmosphere.

The new analyze need to assist allay fears that contaminants in the Cawelo OPW, which is manufactured as a byproduct of oil and fuel extraction at internet sites adjacent to lots of farm fields in the district, could affect h2o and soil quality, damage crop wellness or pose hazards to human health, the researchers reported.

“People issues assumed that the OPW created by oil and gas wells in the Cawelo district includes very similar mixtures of salts, metals and in a natural way occurring radioactivity as OPW created in oil fields in other regions. But our examine shows that’s not the circumstance,” mentioned Andrew Kondash, a study environmental scientist at RTI Intercontinental, who led the research as portion of his 2019 doctoral dissertation at Duke.

“The OPW created in Kern County is significantly a lot more diluted and small-saline than typical OPW from other areas of the place, so it can be utilized for irrigation if it is combined with area drinking water,” Kondash explained.

Figuring out whether it is safe to use OPW for irrigation in other spots would need a comparable suite of h2o and soil testing, Kondash mentioned. “You can not presume that the success in this review could be used to OPW from other oilfields, where by the salinity is ordinarily a great deal bigger.”

To perform the new research, the researchers collected and analyzed soil samples, irrigation h2o samples, OPW samples and groundwater samples from web sites throughout the Cawelo Drinking water District from December 2017 to September 2018 and analyzed them for a extensive array of contaminants such as, salts, metals and radioactive aspects.

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