A foul, persistent smell residents have complained about for years is likely coming from a landfill on State Road 46, and not from Mount Dora’s wastewater treatment plant right around the corner, according to the second odor study commissioned by the city in the last year. Collectively, the two studies cost a total of nearly $520,000.
The first study determined only that the smell was not coming from the city’s wastewater plant on James P. Snell Drive, without identifying another likely source. The latest study, which Lake County helped pay for, specifically sought to nail down where the chemical odor is coming from.
Although residents have reported several different smells in and around Mount Dora in recent years, one chief complaint is the odor of hydrogen sulfide, or H2S: a colorless, flammable gas that becomes rapidly deadly at high concentrations, particularly when found in a confined space.
RELATED: What’s that smell? Study suggests Mount Dora wastewater plant not to blame
The study by V&A Consulting Engineers, shared publicly by the city on Tuesday, analyzed nine potential odor sources, including both of the city’s wastewater treatment plants, two landfills and two marijuana processing facilities.
Ultimately, the study narrowed it down to just three potential odor sources: the wastewater plant on James P. Snell, the Mid-Florida Mount Dora Landfill, and Shelley’s Septic, a septic waste and biosolids processing facility. Public records show over the years, the Florida Department of Environmental Protection has cited all three facilities for various violations.
The study used several different methods to investigate the smelly mystery, including analysis of hydrogen sulfide data captured by the city’s 12 existing odor loggers.
The highest H2S readings were detected at the perimeter of the landfill owned by Mid-Florida Materials, peaking at around 1,300 parts per billion (ppb) on March 14, according to the study. That is a relatively low concentration of hydrogen sulfide, unlikely to trigger any health impacts beyond minor irritation to the eyes and throat, according to the National Academies.
H2S was also found near the wastewater plant at much lower levels, always below 200 ppb, according to the study. No H2S data was available for Shelley’s, although engineers ran models indicating odors from the septic facility have no impact on the area studied.
None of the H2S readings at any of the facilities were concerningly high from a human health perspective. H2S can be fatal at levels of between 500-1,000 parts per million (ppm), which is exponentially higher than any reading recorded and analyzed by the new study.
Still, some area residents have reported headaches from the odor in recent years. Others worry it could be making their asthma worse.
Models, human observation and raw H2S data all indicate “the Mid Florida Mount Dora landfill is the likely source of the pervasive odors experienced in the southeast Mount Dora area,” according to the study. H2S levels were lower in windier conditions, compared to times when the air was calm.
Many residents said they were skeptical of the first study, which was done by a different engineering firm. Now, following the second study, some remain unconvinced.
Linda Bramer lives a few miles south of the wastewater plant and landfill, just over the Orange County line, in Tangerine. She said she’s left with some outstanding questions about how — or whether — engineers conducted the study.
“I have no confidence in the results, because I never, ever, ever saw any of their workers, and everyone I've spoken to has never seen any of their workers,” Bramer said. “We were told they were going to be camped out.”
Bramer and others still have concerns about the city’s wastewater plant. Meanwhile, Caleb Soileau said he never doubted the landfill was likely the odor’s primary source.
“Don't get me wrong, the water treatment plant does smell, and has smelled,” Soileau said. “But I mean, the dump is literally directly behind my house. So it's obviously going to be the number one culprit.”
Soileau said he’s frustrated by what he sees as a lack of action from regulators, including FDEP, and would like to see both facilities held more accountable for their impacts on the surrounding area. But when it comes to debating which of the two sites smells worse, Soileau said, he’s lost interest.
“It doesn't really even matter,” said Caleb Soileau. “Where I'm coming from, I don't care. If it's the dump, great. If it's the [waste]water treatment plant, also great … Let’s just fix it.”
"The Mid Florida Mount Dora landfill is the likely source of the pervasive odors experienced in the southeast Mount Dora area."V&A Consulting Engineers, April 2025 odor study
Responding to a request for comment, a representative for Mid-Florida Materials shared the following written statement on behalf of the company:
“We are aware of a report, and are going to look into it. Our facility has been and remains in full compliance with applicable air quality regulations, and we will address any concerns of the DEP.”
Meanwhile, a city spokeswoman shared the following written statement with news media:
“This final report confirms the origin of the issue. As staff continues to work collaboratively with Lake County, and plans to engage with the identified source moving forward to address the issue, the City will not be issuing a statement at this time.”
