Hexavalent Chromium (Updated on April 11, 2023)

The Town of Shrewsbury has completed the pilot testing of two different technologies for the removal of hexavalent chromium. Ion exchange and biological filtration were tested during the piloting program. Ion exchange was determined to be the preferable option, however, neither technology could reduce the low levels of hexavalent chromium to non-detect. The Water and Sewer Division will continue to monitor the levels of hexavalent chromium in the drinking water. Please follow the links below for more information.

  • Director of Public Works, Jeffrey Howland, P.E., and Water and Sewer Superintendent, Dan Rowley developed an abstract of the findings of the pilot study report that can be found by following this link.

  • A draft of the full report has been completed and the executive summary can be found by following this link.

  • A presentation of the hexavalent chromium piloting project was presented at the March 22, 2022, Board of Selectmen's Meeting. Please watch the video below of the meeting.  

More Information About Hexavalent Chromium

As part of required EPA testing for all water systems serving 10,000 or more people in the United States, the Shrewsbury Water Department conducted UCMR-2 (Unregulated Contaminants Monitoring Rule Round 2) testing in 2013-2014.

hex chrome

Hexavalent Chromium Molecule

Detecting Hexavalent Chromium

A wide range of substances were tested, hexavalent chromium also known as Chromium-6 was included on the list. Our system registered results between 3-4 parts per billion (ppb) well under the EPA and MassDEP Departments standard of 100 ppb for total chromium which adds together trivalent chromium (Chromium-3) and hexavalent chromium (Chromium-6). 

A report came out in 2015 by the Environmental Working Group (EWG) an environmental lobbying group out of Washington, DC headed by activist Ken Cook. This report using the EPA and State databases listed Danvers, Shrewsbury, and a third community on Cape Cod as the three highest in the State for hexavalent chromium.

The Town through the Board of Selectmen took a proactive approach, which continues today to track down the source, to see what wells were affected, identify the feasibility of treatment methods and other alternatives. Since no New England laboratories are able to test for hexavalent chromium to the low levels that were required, we contacted the laboratory used by the EPA for the UCMR-2 testing, Eurofins in California to run our samples. We identified three wells, Home Farm 6-1, 6-3 and 6-4 out of eight wells as having low levels in their supplies.

Treating Hexavalent Chromium

The Town plans to closely monitor the levels of hexavalent chromium and PFAS in all wells on a quarterly basis. Based on this information, the eight different wells will be utilized in the best manner possible in an effort to minimize the hexavalent chromium and PFAS levels in the water entering entering the distribution system. The latest reading for finished water for hexavalent chromium was 4.9 ppb on March 16, 2023. 

More Information About Hexavalent Chromium