The city’s wastewater treatment facility is an activated sludge process facility located on the east end of Grand Marais; it was constructed in the late 1980s. Both Hansen and Roth acknowledged that while all wastewater treatment facilities emit some degree of odor, there are periods throughout the year where the smell is notably worse. However, this is not due to the plant being physically overloaded. 

“The plant was built with the capacity for three times the size town of Grand Marais,” Mike Roth said. “The town has stayed about the same size since then, so there’s not a capacity issue. The plant can handle more housing and there’s a capacity to handle more tourists in the summer too.”

But while the facility is not being physically overloaded, the odors point to another issue: an imbalance between microbes and oxygen. A wastewater treatment facility relies on a balance of oxygen, water, and the bacteria that break down solid waste. In July of 2019, Boreal published a press release from the City that explained how this process works. According to the press release, factors such as temperature, humidity, and amounts of incoming waste can disrupt the chemistry of the system’s sludge digestion tanks. When there isn’t enough oxygen being introduced to the system, certain kinds of bacteria start to dominate and emit strong odors.

“It’s inevitable that a wastewater treatment system will have some degree of smell,” Roth said. “I’ve been here about 20 years and in my time here, there have always been a few times a year where the smell gets stronger. The plant is also very close to town–it’s right in the middle of it–which isn’t changeable. So we want to manage the smell but we can’t make it go away completely.”

In a July 2022 meeting of the Grand Marais City Council, former Wastewater Superintendent Tom Nelson explained how occasionally, large “slugs” of waste come through the system and disrupt the microbe-to-oxygen balance. These are particularly troublesome in the summer as warmer water holds less oxygen. Typical household use–such as washing dishes, flushing toilets, or showering–doesn’t produce these kinds of incoming waste, and it’s not clear where they are coming from. 

“If we ever think a specific establishment might be putting something in there that’s causing issues, we can go ahead and sample directly from their waste to check it out,” Roth said. “So far that hasn’t been found to be the case, but it’s something that we’re always considering and looking at.”

Both Roth and Hansen said that while the smells are a nuisance, the plant–like all wastewater treatment facilities in the state–is monitored by the Minnesota Pollution Control Agency (MPCA) to ensure it complies with all regulations. However, the plant is getting older, and Hansen said that continually aging parts and tightening environmental regulations will mean inevitable repairs and upgrades in the years ahead. When asked if the system needs updates to mitigate the smells, such as increasing the oxygenation, Roth said that no major changes can be implemented soon because the city is currently working with the MPCA to address another concern–mercury coming from the plant. 

“We have a mercury limit on what we can send out of the plant which is measured in parts per trillion, which is a really hard number to wrap your mind around,” Roth said. “We don’t have any mercury sources in town, so it’s just coming from the groundwater. But it’s right on the threshold of that limit which is why we’re having this conversation. It makes it more complicated to plan improvements to the plant, and it’s made us pause for a few years in doing some of the improvements to the plant that we would want to do while we figure out what the rule is going to be with the mercury limits.”

The city has been working with an engineering firm to discuss possible updates, and hopes to explore those possibilities once the question of mercury output is answered. Until then, Roth said that those at City Hall are happy to talk with any community members who have concerns or want to know more about how the wastewater treatment center works. The City of Grand Marais is also still looking for an additional employee for the wastewater treatment plant.