City releases annual drinking water report

EPA ups ante with new health advisories for PFAS June 15

By Joseph Back

The City of Cottage Grove has released its annual drinking water report, both at its website and in mailings sent to city residents.

Monitoring the water from January through December 2021, the annual required report found that City water “met all federal and state standards.” So what’s in it?

A hardness factor of 298 parts per million or 17 grains, to start out. An alkalinity score of 236 and a pH of 7.6, for the aesthetic qualities. A value of 7 is considered ‘neutral’ on the pH scale, with lower numbers trending in the ‘acidic’ range and higher values (up to 14) classed as being in the ‘base’ range.

So what about PFAS, those per-flourylakyl substances that have caused so much trouble in recent decades?

It turns out there’s a new EPA guideline for that, and while not yet enforceable, it’s not encouraging: the federal agency just reduced by a factor of 10 the amount of ‘safe’ PFAS in drinking water, from parts per trillion (ppt) to parts per quadrillion (ppq), or a level currently below testing ability. The present situation has the City

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Complete with its own system infrastructure, the 3M Chemolite Plant is seen here off Keats Avenue in south Cottage Grove. Picture by Joseph Back. CITY


filtering its water and storing what’s filtered out in other substances to prevent the spread of PFAs even as the City also works to build permanent treatment plants, still some years out. Research is ongoing into how the forever chemicals—so named for stability—might actually be destroyed instead of filtered, with the EPA offering states and territories $1 billion in funds along with new guidelines. So what’s the plan going forward?

“The city will be following the lead of the Minnesota Department of Health regarding these new EPA health advisories, as the MDH will handle reviewing this information for the state of Minnesota,” Cottage Grove Communications Manager Jen Longaecker said. “Health Based Values set by MDH for PFAS still govern drinking water in Minnesota and Cottage Grove continues to meet those values through the use of our existing water treatment plants.”

As to other contaminants, here are some numbers for each per the most recent water report:

• Cis-1, 2-Dichloroethene – 0.27 parts per billion (ppb)

• Combined radium – 1.9 PicoCuries per liter (pCi/L )

• Flouride – 0.73 parts per million (ppm)

• Gross Alpha – 8.6 pCi/L

• Nitrate – 0.66 ppm

• Total Chlorine – 0.42 ppm

• Total Haloacetic Acids 1.2 ppb.

• Nickel – 16.7 ppb

• Sodium – 11.6 ppm

• Sulfate – 35.3 ppm The full report with all listings can be viewed online at

Covered at a joint Cottage Grove-Woodbury meeting earlier this year, a draft timeline shows the path to permanent treatment plants for PFAs. The City currently has three temporary treatment plants to filter city well water for safety of residents. Image from joint meeting PowerPoint.

Scanning the QR code with one’s phone will lead one to a water quality message from Mayor Bailey posted on the City’s YouTube channel.

QR code from City newsletter.

June 29, 2022