PARLIER – With filtration systems now operating at multiple well sites, the city of Parlier is set to bring the amount of 1,2,3-Trichloropropane in its drinking water down to safe levels.
Public works staff, engineering consultants and community members not deterred by a rainy and windy afternoon helped the city celebrate this milestone with a ribbon cutting ceremony on Feb. 17 at Well #9A in Parlier, located off Mendocino Avenue south of Manning Avenue. Parlier has been working to address its levels of the chemical, also referred to as 1,2,3-TCP or TCP, for almost a decade.
“For years the city has worked diligently to address the water quality challenges and ensure compliance with the state standards,” Mayor Alma Beltran said. “Throughout the collaboration, persistence and the support of our partners, … we have achieved a milestone that will serve Parlier for generations to come.”
Removing 1,2,3-TCP in 3,2,1…
The contaminate, 1,2,3-Trichloropropane, is a man-made chemical found at industrial or hazardous waste sites. According to a fact sheet from the State Water Resources Control Board, the chemical has been used as an intermediate in the production of other chemicals and as an industrial solvent and degreasing agent.
TCP can also result from the production of soil fumigants, such as pesticides that were used to prevent parasitic worms from harming crops in the Central Valley, according to a fact sheet from the city of Parlier. This use led to TCP leaching through soils into the groundwater over time. Due to the chemical’s properties, it has become a persistent contaminant in groundwater.
The chemical was identified as an “emergencing contaminant” by the U.S. Environmental Protection Agency in the 2000s. In 2009, the EPA determined it was likely to be carcinogenic to humans, meaning exposure to it can cause cancer. This was based on studies conducted on animals, in which significant TCP exposure caused tumors to grow on multiple organs.
With this in mind, the California State Water Resources Control Board (SWRCB) established a maximum contaminant level (MCL) for the chemical in 2017. Since then, cities have been required to test TCP levels in their drinking water to ensure they are in compliance with the MCL.
Persistence in Parlier
The MCL for 1,2,3-TCP is 5 parts per trillion (ppt). According to notices sent to water customers by the city of Parlier since 2018, tests have ranged from detecting no TCP in some water samples to detecting up to 208 ppt in others.
Test results from April 2025 had ranges of TCP between 1.9 ppt and 120 ppt, according to a notice from the city of Parlier. The range was between 5 ppt and 48 ppt in January 2024 and between 1.7 ppt and 208 ppt in January 2023.
To reduce these levels, the city of Parlier has installed granular activated carbon (GAC) filters at most of its wells to remove the TCP and other contaminants. Javier Andrade, Parlier’s city engineer, said they installed GAC filters at five locations and also revitalized two wells that were not operational.
“We originally only had four working wells throughout the whole city, and now we have up to seven,” Andrade said. “So we have seven working wells, and not only did we increase our water quality but increased our capacity, so now we have redundancy, we have safe, reliable water within the city, so we’re really excited about that.”
Funding for the project came from a grant made available through the Drinking Water State Revolving Fund.
Andrade said the ribbon cutting ceremony marked the completion of the entire project, with one caveat being that the city has now received additional funding to make improvements to a well along Zediker Avenue. He said the Zediker well is used for backup and the city did not initially install a filter there because it was not testing positive for TCP; however, because the composition of groundwater changes, that well is now out of compliance as well.
Parlier will need to replace the granular activated carbon used in the filters yearly or once every two years depending on usage and other factors, Andrade said, but the steel tanks that store the filters will be good for decades.
Beltran said the ribbon cutting ceremony represented a promise kept to the community. She thanked city staff, the engineers, contractors, state planners and community members who stood by the city throughout the lengthy process.
“Most importantly, I want to thank the residents of Parlier,” Beltran said. “Your patience, your trust and resiliency are the reason we push forward and continue building the city stronger. Today we celebrate progress, we celebrate health and we celebrate the future of Parlier.”
