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Issues Of The Environment: Higher 1,4 Dioxane Levels In Ann Arbor’s West Park Prompt More Testing

Evan Pratt
Washtenaw County

Amid PFAS contamination, controversial oil and gas pipelines, and lead contamination, another water safety issue in Washtenaw County sometimes drops out of the public discourse.  The expanding 1,4 dioxane plume in the Ann Arbor area has again reared its head.  In this week's "Issues of the Environment," WEMU's David Fair talks to Washtenaw County Water Resources Commissioner Evan Pratt about the steps being taken after recent testing revealed much higher levels of the chemical in the waters in Ann Arbor's West Park. 


  • The Michigan Department of Environmental Quality (MDEQ) recently tested water in a branch of Allen Creek that runs underground through Ann Arbor’s West Park.  Tests revealed that the level of dioxane, a harmful chemical contaminant, has increased from 4.4 parts per billion (ppb) in December 2017 to 19 ppb in September 2018.
  • The test results are concerning because they may indicate that dioxane is migrating farther from the original source of the pollution.  Ann Arbor manufacturer Gelman Sciences, now Danaher Corp., discharged dioxane as a manufacturing byproduct from 1966 to 1986.  It is likely that the plume of dioxane laced groundwater and stormwater is now flowing under neighborhoods in western Ann Arbor and Washtenaw County and inching closer to Barton Pond on the Huron River, the city’s main drinking water source.
  • Dioxane can cause respiratory issues and damage the liver and kidneys.  The U.S. Environmental Protection Agency (EPA) classifies dioxane as a likely carcinogen to humans by all routes of exposure. The federal advisory level for dioxane in drinking water is 3.5 ppb.  The Washtenaw County Office of the Water Resources Commissioner is required under a permit from the MDEQ to keep stormwater free of chemical contaminants, including dioxane, unless an exception is obtained.
  • Evan Pratt, Water Resources Commissioner for Washtenaw County, maintains that there is not a danger to the public at this time.  The infected water mostly runs deep, 150-200 feet beneath the ground.  In low lying areas, like West Park and Veterans Park, groundwater is closer to the surface, however, current levels of contamination are 10-100 times less than what is considered a danger to human health.
  • Pratt says that, although contact with water vapor containing dioxane is hazardous, it is unlikely that residents of Ann Arbor living near West Park are being exposed via basement flooding at this time.
  • Currently, Washtenaw County is a party in a lawsuit against Danaher Corp, joined by the city of Ann Arbor, the Huron River Watershed Council, and the state of Michigan. 
  • Per Pratt’s request, the MDEQ will be conducting more frequent testing of water in West Park and other areas of concern throughout the expected boundaries of the dioxane plume.  According the Michigan Daily, the MDEQ plans to proceed with monthly testing. 

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— David Fair is the WEMU News Director and host of Morning Edition on WEMU.  You can contact David at734.487.3363, on twitter @DavidFairWEMU, or email him at dfair@emich.edu

Contact David: dfair@emich.edu
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