After decades of living with undrinkable water, the San Lazaro mobile home park is making its first attempt at improving the park’s water quality with nature-based fixes.
Residents have long avoided drinking from the tap because of the water’s foul taste and smell. In June, they also learned it contained PFAS, “forever chemicals” linked to cancer, at levels above new federal limits. Now, local environmental groups Once and Future Green and FLOWS, working with residents, park owners and Boulder County, are installing natural solutions at Cline Pond, the park’s water source. They hope the project can improve water quality where past efforts have failed.
“We’re about to change the nature of this lake forever,” said Michelle Gabrieloff-Parish, who leads both environmental groups.
Cline Pond is fed by water coming from a trout fishery. Algae blooms, potentially fueled by the fishery, once gave the water a swampy taste. More recently, chemical treatments left it smelling, residents said, “like a swimming pool” or “like Clorox.”
On Sept. 6, the groups and residents installed eight solar-powered aerator diffusers, released beneficial bacteria and added biochar — a charcoal-like material that can absorb contaminants. The treatments are meant to curb algae growth and improve taste and smell. The biochar could also help reduce PFAS levels.
“It’s merging traditional knowledge with scientifically proven techniques,” said Michael Alcazar, an ecosystem services contractor working on the project.
Read: Boulder’s San Lazaro mobile home park has undrinkable water. Fixing it has stalled for years.
Residents gathered at 8 a.m. to assemble aerators, sharing tools and working through instructions as they installed a solar panel for the first time. Spiritual and community leader Atekpatzin led a ceremony to bless the project. Two interpreters helped bridge English- and Spanish-speaking neighbors. Once the panels were set, residents carried long, weighted aeration tubes by boat into the lake. Fueled by breakfast burritos and snacks, the project turned into a full-day community event.
Behind the community’s efforts lies a broader struggle. Taste and odor issues are not regulated under state and federal law. PFAS limits also won’t be enforceable until 2029. The City of Boulder has long tried, unsuccessfully, to annex the park and connect it to city water. Boulder County Public Health is also weighing whether to provide residents with in-home water filters that remove PFAS. For now, natural solutions are one of the few immediate options left.
“My hope is that it improves the quality of our water so much that they will stop having to use quite so many chemicals in our water,” said Julie Heins, a longtime resident and member of the residents’ Water Action Council.
Gabrieloff-Parish expects to see less algae by the end of fall but said the long-term impact is uncertain.
“Everyone acknowledges that it’ll help, but we don’t know by how much and what timeframe,” she said. “It’s not like turning on a light switch.”
PFAS concerns grow
Chris Higgins, a PFAS expert at the Colorado School of Mines, said San Lazaro’s results are troubling, but not extreme. “These levels are slightly above the [EPA maximum contaminant limit], but not crazy high,” he said. The bigger risk, he added, is long-term exposure.
Gabrieloff-Parish said the findings made the project more urgent. She quadrupled the amount of biochar being deployed and provided the park owners with more to use in six months to a year.
“I’m really excited and surprised that the solution that we already had planned is going to really help with this pollutant that so many people don’t know what to do with,” Gabrieloff-Parish said. She’s also asking local and state agencies to continue testing San Lazaro’s water to track whether PFAS levels are declining.
San Lazaro is one of several water systems in Boulder County with PFAS above EPA maximum contaminant limits, including the City of Lafayette, Blue Leaf School on Baseline and Glacier View Ranch, state data show.
Carl Job, a county water quality specialist, called the project a “meaningful community-led initiative” and said it fits into Boulder County Public Health’s broader strategy, “alongside our continued collaboration with state regulators to address water quality concerns.”
Job has urged state regulators to use new authority under Colorado’s 2023 Mobile Home Park Water Quality Act to enforce secondary standards, like odor and taste, in addition to those linked to direct health risks. The 2023 state law allows regulators to consider risks to “welfare.” He argues the foul-tasting water diminishes quality of life.
Additional PFAS testing will continue through December 2025 under the state’s Mobile Home Park Water Quality Program. “Once the state has gathered more data, BCPH will be in a stronger position to assess the situation and advocate for any specific actions,” Job said.
Por Jaijongkit contributed to this story.
Correction, September 11, 2025 10:18 am: An earlier version of this story misstated the relationship between Cline Pond and a nearby facility. Cline Pond is fed by water coming from the fishery; it does not feed the fishery. The facility is a fishery, not a trout hatchery.
Thanks for this interesting article, Brooke. Would you please clarify how water from this pond is currently treated before consumption by the San Lazaro residents? Surely they don’t drink directly from the pond without treatment! Or do they use well water that is affected by the pond?
It is great to provide this article in Spanish. Is it beyond BRL’s resources to have both English and Spanish pages for the entire website? You could have a toggle button on the banner that allow selection of language. I doubt there are many options for Spanish speakers in Boulder to get new content within Boulder, so this could be a great community service, as well as a potential source of expanded readership and income for BRL.