California is facing “massive” groundwater contamination due to the practice of dumping wastewater into "percolation pits," being the last state in the US that allows dumping into these unlined ponds.  The amount of water being disposed of this way is increasing rapidly: in 2019, there was nearly 3 billion barrels of produced water generated by the oil/gas sector, or roughly 18 barrels per barrel of oil produced, having more than doubled from the 8bbls per barrel of oil registered 20 years ago.  There are 1,850 produced water ponds in California’s Tulare Basin alone, and to date regulators and corporates have generally concluded that the cost of the clean-up of legacy contamination is excessive - even while the dumping of 16bbls/year into the percolation ponds continues.  These percolation ponds and “spray-fields” allow toxins to either seep into underground aquifers or flow into rivers and aqueducts when it rains.  In one case, the carcinogen benzene was found at 45x the safety limit for drinking water.

Articles:

https://www.newsbreak.com/news/2414440322358/study-toxic-fracking-waste-is-leaking-into-california-groundwater

https://insideclimatenews.org/news/24102021/california-oil-wastewater-produced-water-drought-groundwater-contamination/

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