8 Dec 2016

Oily water does not make for good salads!

BB sent me this report ("Hazard Assessment of Chemical Additives Used in Oil Fields that Reuse Produced Water for Agricultural Irrigation, Livestock Watering, and Groundwater Recharge in The San Joaquin Valley of California: Preliminary Results" [pdf]), to whose authors I sent the following questions:
Do I read your report correctly, that you are merely enumerating the chemicals but NOT measuring their concentrations?  And am I right to assume that produced water use/discharge is occurring WITHOUT any purification treatment? Or is there some treatment that’s not detailed?
Seth B.C. Shonkoff, PhD, MPH replied with:
You are correct that we did not evaluate concentrations of these chemical additives in the produced water. The first step that we undertook in this hazard analysis was to compare the recently reported chemical constituents to toxicity, priority pollutant, and other databases to identify what should be monitored for and then how. To date the only chemical constituents monitored for were naturally occurring constituents (e.g., boron, arsenic, heavy metals) as well as some others less frequently (annually or every 5 years). This is the first assessment of chemical ADDITIVES used during oil and gas production in fields that are reusing their water for these purposes.

There is very limited treatment prior to irrigation, groundwater recharge and livestock watering. The produced water undergoes oil-water separation and then is run through walnut shells prior to application. Depending upon water availability from other sources it is mixed with between 20% to 50% other water sources prior to application.
In other words (my summary), scientists are merely identifying which chemical additives and related byproducts may be present in the Central-Valley-oil-field wastewater now used for irrigation. The concentrations and impacts of those chemicals are yet to be understood.

Bottom Line Higher water scarcity results in greater use of sources that are farther, dirtier and potentially more harmful to public health and the environment. Policies dating from an age of abundance may not consider the costs of those sources to health or the environment. They need to be updated.

H/T to BB