Continued testing over the weekend has not detected further contamination in the Huron River.
Testing conducted by the Michigan Department of Environment, Great Lakes, and Energy (EGLE) did not detect the presence of hexavalent chromium downstream of a chemical release that occurred the weekend of July 30 from one of Tribar Manufacturing’s facilities in Wixom.
On Saturday, EGLE says its crews tested 55 locations throughout the river system from Barton Pond – where the city of Ann Arbor has a drinking water intake – upstream to Wixom. None of the 75 samples tested from those locations had detectable level of either hexavalent chromium or total chromium.
Hexavalent chromium is a known carcinogen that can cause a number of adverse health effects through ingestion, skin contact or inhalation.
Of 144 water samples collected throughout 42 river miles since the release, only three have come back with detections of hexavalent chromium – two detections in Milford’s Hubbell Pond and one in the middle of Kent Lake. The Kent Lake detection, completed by lab analysis late Friday – was 5 parts per billion (ppb) – just at the detectable limit of 5 ppb. The two Hubbell Pond detections were 11 and 9 parts per billion. All three were at or below values to protect aquatic life.
Investigators are evaluating test results from wastewater solids that were sequestered at the Wixom Wastewater treatment plant that appear to have trapped chromium, including hexavalent chromium, and of a carbon filtration system at Tribar that may have trapped the hexavalent chromium before it was discharged to the wastewater plant.
Despite the results, the Michigan Department of Health and Human Services (MDHHS) continues to recommend that people and pets avoid contact with the Huron River water between North Wixom Road in Oakland County and Kensington Road in Livingston County. This includes Norton Creek downstream of the Wixom Wastewater Treatment Plant (Oakland County), Hubbell Pond (also known as Mill Pond in Oakland County) and Kent Lake (Oakland and Livingston counties).
As additional test results are received, MDHHS will update this recommendation.
EGLE staff continues the investigation to determine why the release occurred, the exact volume and product that was released, and the timeline of events.