California's Central Valley, 40-60 miles wide and extending about 450 miles from the town of Redding on the north to Bakersfield on the south, is one of the most productive agricultural regions in the world generating over $6 billion in crop value each year. With California's severe ongoing drought, finding adequate supplies of irrigation water for Central Valley's crops is becoming more and more challenging.
One new source of irrigation water is the recycled oil field water produced by Chevron's Kern River oil field in Kern County surrounding the Bakersfield area. For every barrel of oil produced, 10 barrels of salty wastewater are produced as a by-product, which amounts to about 500,000 barrels (21 million gallons) of wastewater per day.
That wastewater is then sold at a very reasonable price to the Cawelo Water District which delivers the wastewater (sometimes mixed with freshwater) to 90 local farmers who use it to irrigate citrus, nut, and grape crops. Although oil products are supposedly removed from the wastewater, it does not receive standard municipal water treatment. The wastewater accounts for about half of the irrigation water used by those 90 farmers.
California has no state regulations for recycling wastewater for agriculture. Although individual water districts, including the Cawelo Water District, are required to send annual salt and boron wastewater content data to the Central Valley Regional Water Quality Control Board, tests for other chemicals are not required.
There is concern about the levels of trace chemicals in the wastewater - chemicals like arsenic, vanadium, chromium, selenium, methanol, biocides, and surfactants. There is also concern about:
- whether the current monitoring is adequate to test for all of the chemicals used in modern-day oil production
- what effect the chemicals might be having on crops
- the long-term effects on the soil of irrigating with sodium-rich water
- the possible long-term effects of chemical seepage into aquifers below the soil
Over the last two years, Scott Smith, chief scientist for the advocacy group Water Defense collected wastewater samples and had them analyzed by a lab which found traces of acetone, methylene chloride, and oil. The general manager of the Cawelo Water District David Ansolabehere questions the sampling methods used by Scott Smith, but he said that Chevron and the Cawelo Water District would contract with a third party to test for a more broad range of chemicals.
Source:
Schlanger, Zoe. (April 6, 2015). "In California, Farmers Rely on Oil Wastewater to Weather Drought". Newsweek. Retrieved 2015-06-14.
Cart, Julie. (May 2, 2015). "Central Valley's growing concern: Crops raised with oil field water". Los Angeles Times. Retrieved 2015-06-14.
"Central Valley (California)". Wikipedia. Retrieved 2015-06-14.
There are nine water control boards in the state of California (CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARDS).
Oct 14, 2015:
California water regulators closed 33 oil wells, 31 of which are in Kern County, because the wells had injected wastewater into potentially drinkable aquifers. This closure brings the total of closed wells to 56.
State shuts 33 wells injecting oil wastewater into aquifers | San Francisco Chronicle
Jul 1, 2015:
The results of further tests on Chevron's recycled oil field water showed no traces of methylene chloride. Previous lab results on tests conducted by Chevron showed small amounts of potentially harmful chemicals, including acetone and benzene. According to Chevron, the presence of acetone in prior tests may be the result of "natural biological processes".
Recycled oil field wastewater is clean, Chevron test results show | Los Angeles Times
Jun 20, 2015:
Testing of recycled oil field water shows small amounts of oil, benzene, and acetone. In California, there is no standard for benzene in irrigation water. All water samples contained total petroleum hydrocarbons, but at low concentrations and well below the maximum level set in the water recycling program's permit.
Potentially harmful chemicals found in oil field water used for irrigation | Los Angeles Times
Mar 3, 2015:
California state regulators ordered the closing of 12 wells.
State shuts 12 oil company wells that pumped waste into aquifers | San Francisco Chronicle
Feb 3, 2015:
According to a report by the San Francisco Chronicle, California state regulators have been allowing oil companies to inject wastewater contaminated with oil, brine, and other chemicals into protected, drinkable water sources.
State let oil companies taint drinkable water in Central Valley | San Francisco Chronicle
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