City of Pomona Triumphs in 13-Year Legal Battle Over Perchlorate Contamination


In the late 2000s, the City of Pomona, California discovered perchlorate contamination exceeding the state’s 6 ppb (parts per billion) regulatory limit in 14 of its drinking water wells. Exposure to perchlorate above recommended levels can result in serious health effects that are especially dangerous for fetuses and infants.

To ensure the safety of the community it serves, the City of Pomona responded to the contamination by shutting down non-compliant wells, making expensive modifications to its existing treatment processes, and ultimately spending millions of dollars to design and build a plant specifically for removing perchlorate from its water sources—which was predicted to cost tens of millions of dollars more to operate and maintain into the future as the contamination was expected to persist. This left Pomona officials searching for a way to cover the increased cost of providing clean, safe drinking water for their community.


To protect its ratepayers from the high cost of perchlorate removal, the City of Pomona sought to hold the polluters accountable for water contamination. However, identifying the source of the perchlorate found in the City’s water supply was no simple task. The potential local sources identified were not found to match the specific type of perchlorate found in the water. Undeterred, the City turned to a team of experts who, through extensive research and investigation, uncovered evidence showing that 90% of the area’s perchlorate contamination came from fertilizer products imported from Chile and used on citrus groves throughout Pomona from the 1930s through the 1950s. This fertilizer, mined from the Atacama Desert in Chile, was sold to Pomona-area citrus growers throughout this period by SQM North America Corporation (SQMNA), a subsidiary of multinational mining company Sociedad Química y Minera de Chile.

With the responsible party successfully identified, the City of Pomona and SL Environmental Law Group began litigation against SQMNA in 2010. SL attorneys argued that SQMNA should take responsibility for the cost of the contamination cleanup caused by its defective products, as manufacturing methods that existed beginning in the 1920s could have removed most of the perchlorate from the fertilizer. The City sought to recover past and future costs associated with investigating and remediating the perchlorate contamination, which it estimated would exceed $30 million.


SQMNA deflected responsibility for its defective product, challenging the City of Pomona through a long legal battle including multiple trials and appeals. Despite SQMNA’s efforts, the City of Pomona and SL Environmental Law Group refused to give up the fight. Finally, after 13 years of hard-fought litigation, the Ninth Circuit Court of Appeals ruled in April 2023 that the evidence supported the city’s claim that the fertilizer had been defectively designed to contain excess levels of perchlorate, and that the suit was not barred by the statute of limitations.

Proceedings in the case officially culminated with SQMNA’s payment to the City in the sum of more than $30 million in the fall of 2023. This payment represents the City’s full costs, both those already incurred and those expected to be over the next 30 years, for treating perchlorate in its drinking water supplies, together with certain costs awarded by the court, plus interest.

For the City of Pomona, persistence paid off. By refusing to back down, even through multiple trials and appeals, the City secured much-needed funding to continue providing safe drinking water to its residents.

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“We are gratified that the Ninth Circuit upheld the jury’s decision holding SQM responsible for tens of millions of dollars in cleanup costs from its defective fertilizer. The City of Pomona has not given up and is to be commended for its resilience in fighting this battle for over a decade. We continue to stand side-by-side with the city in its commitment to ensuring that the polluters, not the taxpayers of Pomona, pay to clean up its drinking water.”


Ken Sansone, Partner, SL Environmental Law Group