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It’s been almost four years since the city of Pleasanton began its search for a new groundwater supply after finding PFAS chemicals, also known as forever chemicals, in several of its groundwater wells.
Now, following the April 21 City Council meeting, the city is one step closer to restoring its long-term local water supply thanks to the council’s unanimous vote to move forward with a joint groundwater supply project with the Zone 7 Water Agency.
“I do believe a diversified water supply and portfolio helps all of us in this valley,” Pleasanton Mayor Jack Balch said during last month’s meeting. “From my perspective, we gain a partner with Zone 7’s groundwater knowledge and expertise to help us provide the 3,500 acre-feet, unlocking that lower rate for potential future water rate conversations with our community and that will go a long way to improve the stability of the supply for the whole valley.”
This decision comes after months of analysis on whether the two agencies should work together on this project or not.
“At Zone 7 we’d be looking forward to partnering with Pleasanton on this,” Zone 7 General Manager Valerie Pryor said. “We really think that a joint project is a win-win for Pleasanton and the entire community.”
For decades, the city’s local groundwater supplied roughly 20% to 30% of Pleasanton’s annual water demand. This translated to about 3,500 acre-feet of water per year, according to the city.
However, Pleasanton was forced to shut down three of its local groundwater wells between 2019 and 2022 after staff discovered the synthetic forever chemicals in the groundwater. Since then, the city has had to purchase 100% of its wholesale water from Zone 7.
“This shift increased water supply and distribution costs, contributed to higher water rates, and raised concerns about long-term reliability and drought resilience,” the city stated in an April 23 press release.
In response to the PFAS detection, the council originally approved the start of a PFAS treatment and wells rehabilitation project in 2020 but later suspended the project in 2022 due to escalating costs. That same year, the council approved the start of a Water Supply Alternatives Study, which analyzed multiple options for the city, including the development of new groundwater wells.
The study ultimately identified the development of the new groundwater wells in Pleasanton as the most “economical and reliable long-term path forward,” according to the city. Zone 7 also expressed interest in new groundwater wells in the basin to help expand its groundwater sources for drought conditions.
Eventually, in June 2024, the water agency entered into an agreement with the city to conduct a joint feasibility study to evaluate the new groundwater wells in the subbasin. That study, which was completed in December 2025, found the project is viable and identified Tennis Park and Hansen Park as feasible locations for new wells.
As the city began developing the draft terms for a joint project with Zone 7, the city also performed a cost-benefit analysis of the joint project versus a project solely led by the city. The results of that analysis showed the joint project with Zone 7 is the “most cost-effective and advantageous path forward.”
“The analysis found that annualized costs for the joint project were lower than those of the alternatives and that capital costs were consistent with the assumptions in the City’s 2025 Water Rate Study,” an April 23 press release states.
“At approximately $27 million, the joint project is significantly less than the estimated $65 million it would cost, in today’s dollars, to rehabilitate the City’s existing wells and construct PFAS treatment facilities,” the press release further states. “In addition, the project builds on the City’s longstanding partnership with Zone 7 and reflects both agencies’ shared commitment to delivering reliable, high-quality water service across the region.”
The next step is for staff to work with Zone 7 on drafting the agreement that will oversee how the project will be designed, constructed and operated. Last month’s vote also solidified the city’s position that it will solely pursue the groundwater wells project and not any of the other alternatives.
However, there were still some issues that the council wanted to address during last month’s meeting.
Councilmember Julie Testa addressed concerns the city has heard about potentially pulling the PFAS plume and asked staff for reassurance that will not happen.
Utilities planning manager Todd Yamello said as part of the feasibility study, Zone 7 and the city drilled wells and did water quality and yielding testing. He said Zone 7 then took that information and utilized its groundwater model for evaluation.
“They felt that it did not impact the groundwater sustainability and their results of their model did not show — over I think it was a 20 year span of operations — of the plume moving into the vicinity of these wells,” Yamello said.
Councilmember Craig Eicher also noted how, based on past conversations, even if PFAS is detected, treatment is still an option. He confirmed the cost and implementation of that treatment would also be shared between the city and Zone 7.
Testa also raised the concern of letting go of the city’s control over its water supply because, as outlined in the key draft terms of the joint project, Zone 7 would be the lead agency overseeing the design, construction and operation of the new well facilities.
“The joint project is very appealing. It is, I think, really reassuring to have the expertise of Zone 7 working with us on this,” Testa said. “But to not have as much control over our water, that is something that’s hard to let go of. It’s something that I always heard from our predecessors; how important it was to retain the independence in that 20% to 30% of our water.”
Yamello said that regarding the city’s share of responsibilities city staff will have some oversight but added that Zone 7 will be the main owner and operator of these facilities.
“Where we come into play with that is more of a financial obligation,” Yamello said. “So if improvements do need to be made, we will have to pay our fair share of that.”
One positive note that Balch pointed out was how the new water source in the city gives Pleasanton the opportunity to have different conversations about future water rates.
“That fundamentally may allow us to have a different conversation with water rates, when we get to that again in a certain number of years,” Balch said.
Vice Mayor Matt Gaidos said he also supported moving forward on the project alongside Zone 7 but noted that he wants to see and discuss the details of the agreement between the two before any final action is taken. Gaidos elaborated how he just doesn’t want to end up in a situation where PFAS chemicals are discovered in those new wells and the onus to address that falls to the city.
“I will not support in the future an agreement that would put us in that position,” Gaidos said. “Because Zone 7 has very many places to get their water from … and if they wanted to simply say we don’t need the water from these wells, it would be very, very easy for them to do that, but it would not be easy for us to do that after committing the capital and going all in on these things.”
The forthcoming draft agreement to be developed by city staff and Zone 7 officials regarding design, construction and operation of the new facility will go before the Zone 7 Board of Directors and the Pleasanton City Council for approval at a later date.
