Welcome to the “Oilfield Produced Water for Crop Irrigation in California” web site!


A USDA-NIFA funded project

As severe droughts limit irrigation water availability in many U.S. watersheds, demand for irrigation efficiency and alternative water sources increases. Oilfield produced water (OPW), a byproduct of oil extraction, has been used in Central California for years. However, permitted OPW uses may change in the future based on food and water regulations, with growers concerned about crop health and sufficient irrigation water, while consumers are concerned about and food safety. While U.S. OPW production is projected to increase, beneficial irrigation use is hindered by a current lack of publicly available, peer-reviewed scientific evidence on its safety.

Goal – This integrated project aims to provide data-driven and risk-based evidence to evaluate human health risks associated with OPW use for produce irrigation, with a focus on potential chemicals in OPW from California oilfields.

Approach – The study includes four interdisciplinary research modules: (1) Screening of existing OPW quality datasets (metals, salts, radionuclides), (2) Sampling and analyzing water, soil, and crops at farms using OPW, (3) Assessing health risks of foodborne and incidental exposure to OWP-associated metals, (4) Translating risk estimates into watershed-scale policy scenarios. A strong extension component will engage stakeholders in risk/benefit and watershed governance training. Case studies will be incorporated into university curriculum on the energy-water-food nexus.

Significance – Study outcomes seek to advance the evidence base needed for risk-based policy on the safe use of OPW for irrigation, ensuring continued productivity in drought-stricken watersheds.

Products: Our paper “The impact of using low-saline oilfield produced water for irrigation on water and soil quality in California” was published in the journal  Science of the Total Environment.

Here is the abstract of the paper:

The consecutive occurrence of drought and reduction in natural water availability over the past several decades requires searching for alternative water sources for the agriculture sector in California. One alternative source to supplement natural waters is oilfield produced water (OPW) generated from oilfields adjacent to agricultural areas. For over 25 years, OPW has been blended with surface water and used for irrigation in the Cawelo Water District of Kern County, as permitted by California Water Board policy. This study aims to evaluate the potential environmental impact, soil quality, and crop health risks of this policy. We examined a large spectrum of salts, metals, radionuclides (226Ra and 228Ra), and dissolved organic carbon (DOC) in OPW, blended OPW used for irrigation, groundwater, and soils irrigated by the three different water sources. We found that all studied water quality parameters in the blended OPW were below current California irrigation quality guidelines. Yet, soils irrigated by blended OPW showed higher salts and boron relative to soils irrigated by groundwater, implying long-term salts and boron accumulation. We did not, however, find systematic differences in 226Ra and 228Ra activities and DOC in soils irrigated by blended or unblended OPW relative to groundwater-irrigated soils. Based on a comparison of measured parameters, we conclude that the blended low-saline OPW used in the Cawelo Water District of California is of comparable quality to the local groundwater in the region. Nonetheless, the salt and boron soil accumulation can pose long-term risks to soil sodification, groundwater salinization, and plant health; as such, the use of low-saline OPW for irrigation use in California will require continual blending with fresh water and planting of boron-tolerant crops to avoid boron toxicity.

The impact of using low-saline oilfield produced water for irrigation on water and soil quality in California