Carcinogenic chemical found in Flathead and Missoula Counties’ drinking water

By Catherine Haug, Sept 24, 2016

This is a critical issue, and I just learned about it from the Environmental Working Group (EWG) (1). See also their interactive map (2):

  • Counties in various shades of yellow, green, blue and black were found to be positive for the toxic chemical Chromium-6.* These include Flathead and Missoula counties.** A total of 1,370 U.S. counties had an average level of chromium-6 exceeding California’s non-binding public health goal of 1 ppb. (see below).
  • Counties in gray have not been tested.

If you saw the 2000 movie “Erin Brockovich” (played by Julia Roberts), then you know about chromium-6, because that is the deadly chemical she fought to expose. And Erin has not given up the fight; see EWG article (1). This carcinogen has been found in tap water of more than 200 million Americans.

If you wish to take action on this, sign the online petition to the EPA (5)

*NOTE: Chromium-6 is not the same as Chromium-3, which is considered by some to be an essential nutrient for humans.

** Flathead Co. testing was only Kalispell Municipal drinking water; Missoula Co. testing was only Mountain Water Company.  (However, our levels are below California’s limit goal of 1 ppb).

The problem

A 2 year study (3) concluded this chemical is carcinogenic to rats and mice. Another study (4) found a higher incidence of stomach cancers in workers (people) routinely exposed to chromium-6. Breathing airborne chromium-6 particles can cause lung cancer, according to studies by government and independent scientists worldwide.

The chemical has also been connected to liver damage, reproductive problems, and developmental issues (1).

Yet the Environmental Protection Agency (EPA) has never set limits for this chemical – it tried but was stalled by the polluters. Only California has set a goal on this chemical:1 part per billion (equivalent to 1 drop of water in Olympic-size swimming pool). NOTE: the EPA does have an exposure limit on total chromium in water (chromium-6 and chromium-3 combined) of 100 ppb (8).

The Environmental Working Group (EWG) tested more than 600,000 water samples between 2013 and 2015. They estimate that the water supplies serving 218 million Americans contain unsafe levels of this chemical.

Sources of chromium-6 

These include (1):

  • steel making,
  • chrome plating,
  • manufacturing dyes and pigments,
  • preserving leather and wood and, as in the Brockovich case,
  • lowering the temperature of water in the cooling towers of electrical power plants.
  • ash from coal-burning power plants (e.g., Colstrip* and Erin Brockovich’s case), which is typically dumped in unlined pits that a 2011 report by the nonprofit Earthjustice said may threaten hundreds or thousands of water supplies and private wells.
  • Recent research has suggested that some methods of treating water supplies to remove other contaminants may actually increase levels of chromium-6.

‘*NOTE: According to a July 21, 2016 report in the Great Falls Tribune (6), Colstrip “will convert two of the four units to a nonliquid disposal system, which environmental groups called a major step toward ending 30 years of groundwater pollution caused by leaking coal-ash ponds” in 2018. The two units to convert are  numbers 3 and 4; the other two units (1 and 2) will close in 2022 to settle another major lawsuit by environmental groups. (7)

What you can do

Filter your drinking water. Reverse osmosis filters are the best, provided the filters are replaced regularly (mine is from Culligan who replace my filters for me on a pre-determined schedule).

Sign the online petition to the EPA (5).


  1. EWG article (9/20/16):
  2. EWG interactive map:
  3. Chromium-6 study on rats and mice:
  4. Chromium-6 and stomach cancer study:
  5. EWG petition to the EPA:
  6. Great Falls Tribune article:
  7. KXLH article:
  8. 9/29/16 email from Prof. Kent Sugden, Department of Chemistry and Biochemistry, University of Montana.

Tags: , ,

Comments are closed.