The water that fills Ken Henrickson's toilet bowl is pumped directly from the lake he lives on, and when he flushes, it goes back to the lake.
"I'm not sure if it's a good system or not," he said last month.
Henrickson lives along the rocky shore of Rainy Lake, which forms part of Minnesota's border with Canada, in the state's far north.
Henrickson's is one of the half-million Minnesota homes from which wastewater flows into buried septic tanks — systems that are maintained, and often ignored, by homeowners, not professional engineers. The Minnesota Pollution Control Agency estimates one in every five septic systems across the state is failing.
The water off Henrickson's piece of shoreline is laced with sewage — likely his own, and that of about 200 neighbors. There are at least that many failing septic systems in a 15-mile stretch from Henrickson's neighborhood east to Voyageurs National Park.
"Nobody says too much about it," Henrickson said, "but yeah, we know it's there."
In Henrickson's neighborhood, the impact and cost of failing septic systems is front and center. But across the rest of the state, both cost and impact are less clear.
By all accounts, the problem on Rainy Lake reaches back to the glacial era: Henrickson's basement floor isn't concrete, but clean, smooth bedrock. Rock is never more than a few feet below the soil in that area. It's a tough place to make a septic system work.
"Wastewater comes out, hits the bedrock and doesn't get completely treated before it flows on to wherever it goes," said Koochiching County Environmental Director Dale Olson.
After working its way through the enzymes of a home's septic tank, it moves through the drain field, an underground network of perforated pipe. Drain fields are supposed to be at least three feet above groundwater level.
Those three feet of dry dirt are meant to filter nutrients from sewage, turning it back to clean water. But thanks to that shallow layer of bedrock around the south shoreline of Rainy Lake, dirt is scarce and wastewater can't be fully treated.
"Generally, eventually it ends up in the lake," Olson said. "All water does."
And that's when it becomes a problem.
"Anywhere where you have wastewater going into a lake, you're going to get extra weed growth," he said. "You're gonna get extra algae. And that can kill off certain species or make them move to different areas."
Twenty years and $17 million for a 6-inch pipe
For the last 20 years, Olson has been working to extend a sewer line from the International Falls water treatment plant to those failing systems in Henrickson's neighborhood. Now, thanks to a handful of state and federal grants, and a county loan, he has the $17 million it will take to bore a 6-inch pipe channel through more than 15 miles of solid granite.
In a little more than a year, he hopes, hundreds of faulty Rainy Lake septic systems will be capped and dormant.
But the Rainy Lake project solves just a tiny piece of Minnesota's septic problem.
The MPCA estimates more than 100,000 septic systems across the state are too old or so close to the water table that they're putting groundwater at risk. A quarter of those are believed to be so degraded that they pose an immediate threat to human health. But MPCA septic supervisor Aaron Jensen said most people never think about their septic systems.
"It's not visual. It's not like the roof of your house that you can see," he said. "A septic system that's in the back yard is kind of out of sight out of mind. It's something that might be leaking on the bottom, but I can still flush the toilet."
The mystery of failing systems
The septic problems are obvious on Rainy Lake. But across most of Minnesota, faulty systems are spread out — and hard to identify.
Phil Votruba knows that challenge firsthand. He tests hundreds of lakes and rivers across north-central Minnesota for contaminants and water quality in his work as a state watershed researcher for the MPCA. Sussing out a septic problem isn't straightforward.
Leaking septic systems can cloud lakes with phosphorous and nitrate. But so can agricultural runoff. Even rotting leaves will leach phosphorous into a lake. It takes a significant amount of sewage in a waterway to raise a red flag.
In his most recent round of testing, Votruba didn't find a single lake with clear signs of septic contamination. Even so, he said, leaking sewage is almost certainly degrading Minnesota waters. Even one failing septic system can have an impact.
"It all contributes," he said. "Each lake and each stream has kind of a pollution diet, so to speak, A lake has so much capacity to assimilate nutrients, but every little bit is a chink in the armor."
No one knows exactly how extensive the damage is, Votruba said. It's up to counties to keep an eye on older systems, and some counties are more vigilant than others. His agency has had a history of conflict with counties over the extent of regulation.
Beltrami County, for instance, is one of several counties that don't report the results of septic inspections to the state.
Others, like Ottertail County, have conducted thousands of inspections over the last few years. Officials there say about one out of every four septic systems within its borders is failing. That's likely close to accurate, but statewide data is less reliable.
All told, about two percent of septic systems in the state are inspected each year. When the MPCA claims that 100,000 systems are failing, that's a guess, based on a narrow slice of data from all 87 counties.
Proof that's 20 years old
Even on Rainy Lake, where enough sewage has leaked down the shore to attract millions in federal funding for the sewer project, solid facts are in short supply.
Hundreds of inspections have confirmed that roughly two-thirds of septic systems in the Voyageurs National Park area are failing, but the only proof of untreated sewage actually having an impact on Rainy Lake is in a dusty old folder in the Koochiching County courthouse.
That proof exists thanks to Dale Olson. Early in his career as the county's environmental services director, he hired a pilot to fly over the south shore of Rainy Lake to gather infrared photos. It was the mid- 1990's and at the time he suspected the septic systems in that area weren't working properly, but he didn't know the extent of the damage.
Those infrared photo slides show blooms of algae feasting on enough sewage to generate visible heat signatures. The images set Olson to work on the sewer line project that has taken most of his career to launch. But that photographic proof — the most tangible proof that exists — of sewage on Rainy Lake is 20 years old. Olson can't even find a place to develop the old slides.
The project he started so long ago is now funded. He expects ground will be broken next summer.
Soon, for the first time, Ken Henrickson will be able to flush his toilet and know he's not polluting his beloved lake. He and his neighbors are funding roughly a quarter of the sewer line project through their monthly utility bills. Henrickson said it's worth whatever he has to pay to keep his lake clean.
"I don't want my kids swimming in stuff that shouldn't be there," he said. "It's a beautiful area. We have to take care of it. That's all."