Most water that comes up with oil is pretty nasty stuff, full of heavy metals and loaded with salts, says Clay Rodgers, executive officer for the Central California Regional Water Quality Control Board.
In fact, most oilfield produced water is very close to seawater with 20,000 to 30,000 parts per million of total dissolved solids (TDS) — mostly salts.
But, in Kern County’s east side oilfields, such as the Kern River and Kern Front fields, the produced water has only 500 to 700 TDS, and can be as low as 300 TDS, Rodgers said.
“Almost always, if water is less than 1,000 TDS it meets drinking water standards for salinity,” he said.
Monterey Shale Uplift
Why is oilfield water quality so much better on the east side of Kern than the west?
Rodgers explained that as the Sierra Nevada range grew, sediments in the deepest parts of the middle of the Valley where oil had formed in what’s known as the Monterey Shale tilted up toward the east.
“Oil is light and wants to be on top of water. It migrated up the slope along the east side over millions of years,” Rodgers said.
As the oil was migrating up, fresh mountain runoff was coming down the slope and percolating into the ground. And that’s what’s coming up with the oil today.
“So, there’s no seawater, that’s typically associated with oil,” Rodgers said.
Click here to read all the Food Safety Advisory Panel reports on the use of oilfield produced water for agricultural irrigation.
About the Author
Lois Henry is the CEO and editor of SJV Water. She has 30 years’ experience covering water and other issues in the San Joaquin Valley. Henry lives with her husband, five dogs, one orange cat, and a cranky rescue mustang horse in Bakersfield.