Almost no PFAS are in Eden Prairie’s drinking water. So, what keeps city officials up at night?

Harmful per- and polyfluoroalkyl substances (PFAS) in drinking water are attracting attention, with the first-ever PFAS national drinking water standards taking effect April 10, and east-metro communities working to contain an industry-generated, underground plume of toxic PFAS chemicals that threatens water supplies.

But, in Eden Prairie’s drinking water, only one of numerous PFAS chemicals that are monitored has been detected. The one detected, perfluorobutanoic acid or PFBA, registered at 12.7 nanograms per liter, whereas the level at which the Minnesota Department of Health (MDH) calls it a concern is 7,000 nanograms per liter, or 7 parts per billion.

(Think of 12 marbles in your hand compared to 7,000 marbles piled nearby – that’s the difference between the PFBA level measured in Eden Prairie drinking water and the MDH’s “health value” or “guidance value.” A person drinking water containing PFBA at or below that 7,000 level, or 7 ppb, would be at little or no risk for harmful health effects.)

PFBA is less common than other PFAS, which are chemicals commonly used in non-stick and stain-resistant consumer products, food packaging, and carpets. The MDH says the trace measurement recorded in Eden Prairie poses no health risk.

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“We were not concerned prior to testing, and the results have made us feel quite happy that our residents don’t have to worry about PFAS in their drinking water causing health problems,” noted Rick Wahlen, manager of utility operations for the City of Eden Prairie. “One thing all water utilities are keenly aware of is that PFAS is pervasive all over Minnesota, and it’s quite uncommon to find groundwater that does not have any trace of it. We are very glad that all we have that is detectable is the minuscule quantity of PFBA far, far below the health risk level.”

Not all communities are as fortunate. MDH said in April that 22 Minnesota water systems have PFAS above new federal limits. Some of those are located in the east metro area and are getting financial help in addressing the chemicals under the provisions of a state agreement with 3M, which produced the chemicals for decades.

Wahlen says the absence of PFAS in two 2023 tests of local drinking water is mostly owed to the type of manufacturing industries “upstream” – or north of Eden Prairie, such as in Minnetonka, Plymouth, and Wayzata – from EP’s water supply: the Prairie du Chien-Jordan aquifer.

“We have a lack of PFAS-producing industry upstream of us in our aquifer,” he explained. “Maybe one day we’ll find out that somebody did something we didn’t know about.”

EP water: Safe and soft

Wahlen says there really isn’t anything drinking water-related that keeps him up at night – including state and national headlines about PFAS. But, he says he is “happily contemplating how we’re going to take care of our system and keep it up. 

“Because we’ve got a really good system,” he explained. “We’ve got really good people. We’re very intentional about who we hire. And our community is very good about allowing us the resources to maintain our system.”

The 2024 city budget for utilities is roughly $27.5 million, and about 48% of that is for water-related services. (Wastewater service is about 36% of the utilities budget and stormwater service is 16%.) Fees for water use, which support the utilities budget, were increased 3% at the beginning of 2024 to keep up with increasing costs.

“Safe” and “soft” might be two words to best describe Eden Prairie’s drinking water. In addition to PFAS and other industrial contaminants, Eden Prairie and the labs analyzing water samples regularly check for pesticides, heavy metals like lead and arsenic, radionuclides, bacteria, and more.

There’s no ratings or grades for water-treatment plants across Minnesota, but Amy Barrett, information officer with the MDH, pointed out that community water systems like Eden Prairie’s are required to meet federal Safe Drinking Water Act standards, which protect Minnesotans from substances that may be harmful to their health. The Eden Prairie system meets and is in compliance with all standards, she added.

To keep residents informed, the city publishes a detailed Drinking Water Report on its website.

Eden Prairie stands out from most cities by having a centralized water treatment facility that also softens the water, so no home or office water-softening systems are needed.

 “What’s unique about Eden Prairie’s water treatment plant, especially for the metropolitan area, is that back in the ‘70s, the – I call them ‘the wise city fathers’ – had the foresight to understand that a good quality source of water would bring industry to this town and probably make the community a bit more desirable for people looking to establish businesses and industry and that sort of thing,” said Wahlen. “They spent a little bit of money up front to have a lime softening plant.”

That approach not only adds convenience to Eden Prairie home and business ownership, but the centralized water softening is also better for the environment. The city’s water treatment plant captures the softening byproduct – a lime slurry – that is trucked away and added to farm fields to adjust the soil’s pH – the amount of nutrients available to plants. With home water-softening systems, a leftover brine laden with chlorides often goes down the drain and to the wastewater treatment plant, which is not designed to remove chloride. The chloride passes through the wastewater plant to rivers and streams.

Staying ahead of needs is a challenge

Keeping up with a growing need for drinking-water infrastructure – water treatment plants, replacement of aging water lines, and more – is a growing problem in the U.S. The federal Environmental Protection Agency last fall estimated that Minnesota’s drinking-water infrastructure needs over the next 20 years approach $10.2 billion.

“Where’s that money coming from?” wonders Wahlen.

Eden Prairie is trying to keep pace with the needs of an aging system of water lines, wells, reservoirs, and centralized plant by using a complex financial model that tries to predict the timeline for needed investments.

“We built basically a model to help us understand: How is our relatively new system going to degrade over time? How is it likely going to need to be replaced and repaired? How much is it going to cost in today’s dollars? And, when it comes due for replacement, how much is it going to cost then?” Wahlen said. “We put all that stuff into our predictive model, and we determine that we need to set aside money every year in order to have enough to take care of us in the future. And in order to set aside that money, we have to charge an appropriate amount for the water that we’re selling, in order to generate that revenue. 

“I just pray that we have enough interest in maintaining that idea,” he added. “Because realistically you do have to create quite a kitty, quite a bank account, in order to do that, to maintain that. If people change their priorities away from water to something else, they may not want to continue to do that. 

“I realize that in life you do have to adjust your priorities,” said Wahlen. “But so far our community has been really good about providing the resources to sustain our community into the future, for our kids. I think we’re doing the right things to make sure this is all still functional for our kids.”

Of course, any predictive model can be upended if advancing technology eventually uncovers drinking-water dangers that aren’t even known today.

“Contaminants of emerging concern – that’s CECs – is something that all of us in the water industry worry about,” Wahlen said. “And those are things that are in our water that we currently aren’t aware of that potentially are harmful to us. 

“We’re very careful and prideful about the product we produce, and we’re very competitive about making sure that it meets the highest standards,” he added. “And so we don’t want to find something in our water that would be harmful to the public. But as technology gets greater and greater and more and more accurate, it just seems inevitable that we’re going to find some of that stuff.

“Right now, I’d say we’ve exhausted all forms of treatment that are affordable. Anything else we find is going to be incredibly expensive to take out, because it’s going to be in such small quantities – like that one marble out of a billion marbles. How do you find it, and then take it out? 

“So, if I have a nightmare at night, that’s probably what it is.”