Sunny Slope Water Company Shifts TCP Cleanup Costs to Polluters


Sunny Slope Water Company is a mutual water company in Pasadena, California that provides water to a population of more than 25,000 in parts of Arcadia, San Gabriel, San Marino, Temple City, and unincorporated Los Angeles County. The water company discovered TCP contaminants at dangerous levels in two of its drinking water wells, which left the wells inoperable and forced Sunny Slope to rely on other wells to offset reduced production.  

Sunny Slope faced two signification challenges: finding water sources to meet the demands of the growing population in the mostly residential service area, and finding the funds to treat the contaminated wells. They first explored upgrading a pipe, and then looked into installing a filtration system to remove the contaminants. The filtration system was deemed the best path forward, but had a $2 million dollar price tag. The water company secured a grant that covered less than half the cost of installing the system, but that left the second half of installation and the millions more required to maintain and operate it over the decades the TCP was expected to remain in the wells.


The water company initially hired an out-of-state law firm who could not find evidence of who was responsible for the contamination. So Sunny Slope turned to SL, who used careful research and related experience in the field to identify the source of the contamination: the use of Shell and Dow products at nearby plant nurseries.


SL pushed forward with Sunny Slope’s lawsuit against Dow Chemical and Shell Oil, accusing the oil producers of knowingly polluting its groundwater by manufacturing and selling pesticides contaminated with TCP. In 2021 Sunny Slope reached a settlement with the companies that were responsible for the contamination, allowing the water company to fully recover the cleanup costs.

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“When SL Environmental took on the case, we started to see real progress. We are such a small company, so it was very helpful to have SL’s environmental knowledge and leadership. They moved on the case quickly, worked with us, and guided us through the process.”

Ken Tcheng

GM, Sunny Slope Water Company