Boulder’s San Lazaro mobile home park has undrinkable water. Fixing it has stalled for years.

For more than 20 years, the water at San Lazaro mobile home park has been considered undrinkable, sometimes smelling like a murky pond, other times like bleach. Though the water meets all enforceable state and federal health standards, it fails odor tests by more than 15 times the recommended limit. Recent tests have detected PFAS, “forever chemicals” linked to cancer, at levels above EPA limits set to take effect in 2029.

Home to more than 800 people, San Lazaro sits on the edge of Boulder, bordered by the city on three sides but outside its limits. For decades, city leaders have talked about annexing the park and connecting it to municipal water. The plan was written into the city’s East Boulder Subcommunity Plan and widely supported by elected officials and staff. 

But in 2022, after briefly making progress, negotiations with the park’s owners collapsed when the city publicized the deal before it was finalized. Formal talks haven’t resumed.

The impasse has left residents in a regulatory gap. State and county agencies can’t force the park to meet higher water quality standards because the water doesn’t violate primary drinking water standards. The city can’t connect the park to city water without the owner’s consent. And many residents, wary of higher costs or displacement, oppose annexation.

‘Like a swimming pool’

San Lazaro’s water comes from nearby Cline Pond, which is also connected to a trout farm. In past years, algae blooms, potentially fueled by the hatchery, gave the water a swampy taste. Now, chemicals added by the owners to curb the algae growth have often left it smelling, residents say, “like a swimming pool” or “like Clorox.”

“When we’ve had a spell of a number of hot days in a row, you can definitely smell the chemicals,” said Julie Heins, who has lived in San Lazaro for 26 years and sits on the resident-led Water Action Council.

A 2024 Boulder Watershed Collective analysis ranked the pond in the top 2% statewide for wastewater discharge from industrial activity. In June 2025, state testing also detected PFAS above EPA maximum contaminant limits. 

PFAS — short for per- and polyfluoroalkyl substances — are a class of thousands of synthetic chemicals used in products from nonstick cookware to firefighting foam. They exist nearly everywhere, often at very low levels, said Chris Higgins, a PFAS expert and distinguished chair of civil and environmental engineering at the Colorado School of Mines. They persist in the environment for decades, accumulate in the human body and have been linked in studies to cancer, liver damage, immune system suppression and developmental issues in children. In some places, Higgins said, groundwater contains PFAS at levels thousands or even millions of times higher than those detected at San Lazaro. 

Higgins said San Lazaro’s PFAS results were worth paying attention to, but not panicking over. “These levels are slightly above the [maximum contaminant limit], but not crazy high,” he said. “The concern is long-term drinking of that water.”

The owners told residents in a written statement obtained by Boulder Reporting Lab that they hope to reduce PFAS levels below the EPA’s maximum contaminant level within a year, but said “an exact timeline for resolving this problem cannot be predicted or even estimated at this time.”

Even before testing revealed PFAS contamination, many residents avoided the tap. In a 2023 survey of 47 residents led by Boulder Watershed Collective in collaboration with local environmental groups and the Water Action Council, 91% said they buy bottled water, and 85% spend more than $50 a month on it. Some use bottled or filtered water for cooking, laundry and bathing. Susana Rodriguez, a longtime resident and member of the Water Action Council, said the calcified water irritates some residents’ skin and tangles their hair. She recalled a period when the water ran yellow with visible particulates and made her laundry smell “so bad.”

The annexation collapse

San Lazaro was established in 1966, and its current owners — San Lazaro Park Properties LLP — have held it for more than 40 years. In 2021, Boulder officials entered months of talks with the owners to annex the park, making city water and other services available to residents.

Under typical annexation agreements, the landowner pays to connect the property to city water and services, and must upgrade infrastructure to meet city standards. But in this case, the draft proposal submitted by the owners’ attorney, David Eisenstein, asked the city to waive all standard annexation fees — including water tap and wastewater permit charges — and not require the park to pay to upgrade its existing infrastructure to receive city water. The proposal also included only a 10-year rent stabilization clause, shorter than the city wanted.

“If this was a regular subdivision we’d probably say flat out ‘no’ to these terms,” Chris Douville, Boulder’s deputy director of utilities, wrote in an internal March 2022 email obtained by Boulder Reporting Lab. “But as you may know this is a Manufactured Home Park and somewhat political as several past and current City Council members would like to see this move forward.”

The deal collapsed shortly afterward, when the city posted the terms to a public website and San Lazaro residents found them. Eisenstein called the terms draft-only and said they had been published without permission, according to emails obtained by Boulder Reporting Lab. He demanded they be taken down, saying the leak had caused “unnecessary and unwanted concerns among the residents.” No revised proposal was ever submitted.

Annexation proposals have to come from a property owner. Without the owners’ cooperation, San Lazaro will remain outside the city. Eisenstein did not respond to requests for comment for this story, nor did San Lazaro Park Properties LLP. 

Mayor Aaron Brockett said, “There have been some potential new discussions between staff and owners of the park, but it’s in early stages.” So while there’s still interest, there’s “not a lot to report so far.”

Residents wary of costs

Many residents oppose annexation because they’re worried about higher costs and lack of clarity over how expensive the process could get. Heins said many fear higher property taxes and sales taxes on large purchases, like cars. While residents don’t own the land their homes sit on, most own their homes and pay property taxes on them, and annexation would add a city tax to their total property tax. 

Rodriguez said people are also concerned about potential lot rent increases, and paying for water, trash and recycling services, which are currently included in their rent. Lot rent is already $950 a month. It rose by $65 in 2025, $75 in 2024 and about $25 each year before that. Many residents are low-income, or elderly and living on fixed incomes. “Where are those people going to go if they keep increasing the rent?” Rodriguez asked.

She added that some also worry annexation could pave the way for redevelopment or a land sale that forces them out. “Every resident that’s in the [water action] council does not want to be annexed into the city,” Heins said.

Brad Mueller, director of planning and development services for the city, told Boulder Reporting Lab that “any annexation discussion would very likely be with the understanding of continued residential use.” And the 2022 draft annexation terms placed limits on how much rent could rise each year. But this and other details were never communicated to residents, who say communication from the park owners about annexation has been virtually nonexistent, according to Heins and Rodriguez.

“There’s been no conversation at all between San Lazaro management and the residents here about the possibility of annexation,” Heins said. “They don’t ask our permission for anything, and they don’t ask our opinion about anything. There’s no reason that they have to. That’s not how mobile home parks work.”

The quality of the park’s drinking water remains the central concern. “Everyone wants good water,” said Marda Kirn, founding director of EcoArts Connections, who helped run the water survey project at the park. “No one that I know of wants annexation if it means that their rent will go up.”

Trying a natural fix

With annexation stalled, two local environmental justice groups, Once and Future Green and FLOWS, are trying a different approach. This month, they’re installing solar-powered aeration systems, a treatment of beneficial bacteria and biochar — a charcoal-like substance made by heating organic material in low oxygen, used to filter contaminants — in Cline Pond to reduce algae growth and improve taste and smell. The biochar also has the potential to reduce PFAS levels, according to Higgins, although he said not all biochar is equally effective and activated carbon is more reliable. 

Residents hope the project, funded by the county and carried out in partnership with the resident Water Action Council and the owners, will make their water drinkable. But the EPA recently cut a grant that would have extended the work into next year. 

Michelle Gabrieloff-Parish, who leads both Once and Future Green and FLOWS, believes the natural methods will be more effective over time than the chemicals the owners use now. “It’s not like turning on a light switch. It’s going to take a minute,” she said. “But I do think that even by the end of the season, we’re going to see a significant reduction in the algae.”

Gabrieloff-Parish is calling for the City of Boulder to support the work with natural solutions while it pursues annexation.

“If annexation was really the answer, we’re talking about probably a multimillion-dollar and multiyear process,” she said. “I feel like it is in everybody’s best interest to try to solve for the root causes of the problem as much as possible, even if long-term they end up saying annexation is a good idea.” 

Waiting on the state

Carl Job, Boulder County’s water quality specialist, is calling on the state to use new authority under Colorado’s 2023 Mobile Home Park Water Quality Act to enforce secondary standards for odor and taste. Under current state and federal law, it is difficult for local governments to force park owners to address those issues, because most water regulations focus on primary standards, those linked to direct health risks. However, the state law allows regulators to consider risks to “welfare,” and Job argues the water’s taste and smell affects quality of life. 

And while PFAS are linked to health risks, EPA regulations don’t kick in until 2029 federally and 2027 in Colorado.

“There’s a regulatory gap,” Job said, noting that a sizable number of mobile home parks have exceeded secondary maximum levels. “If the water looks and smells to a point where it’s not even palatable, people aren’t going to use it,” he said.