Water Treatment

Chromium Spill in Huron River Update

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Frequently Asked Questio​ns

1. What happe​​​ned?

On August 1, 202​2,​ at 3:21 p.m., Michigan Department of Environment, Great Lakes, and Energy (EGLE) was notified by Tribar Manufacturing in Wixom that it had released several thousand gallons of a liquid containing 5% hexavalent chromium into the sewer system. The company discovered the release Monday, but indicated it started as early as Saturday morning, July 30, 2022, according to Wixom city officials. It is believed that much of the contaminant already made its way through the treatment plant by the time the release was discovered.

2. What about Ann Arbor's drin​​​king water?

​The City’s water is safe for all uses.  Safety is our number one priority.  Although the closest drinking water intake is in Ann Arbor, the time-of-travel modeling indicates it would take the contaminant several weeks or more to make its way to the city's water intakes. The city is increasing its monitoring in the Huron River so we are able to identify when and if the chromium plume reaches our intake. 

City staff have ordered materials that will arrive next week that will help us evaluate our ability to remove chromium from the water supply should it become necessary.  We will have more information available to share by the end of next week.  Concurrently, EGLE continues to sample along the Huron River in an attempt to identify the location and extent of contamination.  We will keep our website updated with new information as it becomes available.

​3. What is ch​​romium?

Hexavalent chromium, or Chromium VI, is a carcinogen if inhaled and can result in an increased risk of lung cancer. Total chromium is regulated by the Safe Drinking Water Act and has a Maximum Contaminant Level in drinking water of 0.1 mg/l.

4. What is being done?

On August 2, 2022, EGLE began taking river water samples from multiple areas downstream from the treatment plant and is working with local and state health officials to assess the extent of the contamination. Testing is also taking place within the Tribar facility and the Wixom wastewater treatment plant. Monitoring will continue in coming days and weeks.

EGLE estimates that the travel time between the time of release and when it may reach the city's drinking water intake is several weeks. The city is increasing its monitoring in the Huron River so we are able to identify when and if the chromium plume reaches our intake. We have ordered materials and are evaluating our ability to remove chromium from the water supply should it become necessary.  Concurrently, EGLE continues to sample along the Huron River.  We keep our website updated EGLE test results as soon as it becomes available.​

5. What agencies ​are involved? 

The Michigan departments of Health and Human Services (MDHHS) and Environment, Great Lakes, and Energy (EGLE), and local health and government officials are working together in Monroe, Oakland, Livingston, Wayne and Washtenaw counties to implement plans to address the situation.  

6. What is the​​ impact?

Currently, there are no recreational limitations in the river for canoe liveries or recreation in Ann Arbor. However, until further notice, MDHHS is recommending that all people and pets avoid contact with the Huron River 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). This means:

  • Don't swim in the Huron River.
  • Don't wade in the Huron River.
  • Don't play in the Huron River.
  • Don't drink water directly from the Huron River.
  • Don't water your plants or lawn with Huron River water.
  • Don't eat fish caught in this section of the Huron River. A do-not-eat advisory for PFOS is already in effect.​​​​​

Residents with questions about hexavalent chromium, potential health effects or exposures can call the MI Toxic Hotline at 800-648-6942, 8 a.m. to 5 p.m. Monday through Friday. Extended hotline hours will be offered on Saturday, Aug. 6 and Sunday, Aug. 7, from 8 a.m. to 5 p.m.​ ​

7. How will the city keep the public ​informed?

In order to keep our community informed, the city will post all information, agency news releases and analytical test data related to this spill on this webpage and promote updates via city communication channels. ​You may also subscribe to water quality email updates from the city​. ​

8. Is it possible to clean up or stop the flow of chromium before it could reach Ann Arbor? 

No. EGLE has not identified a means to stop the flow or migration of the contaminant plume.

9. If chromium is detected in the Ann Arbor water supply, what action will the city take? 

City staff have ordered materials that will arrive the week of August 8 to test whether the treatment process can be modified to remove chromium.

10. Is it possible to remove Chromium with filtration, and if so, are filters installed in the City water treatment facility? 

Filtration is not the process that would remove chromium. Metal precipitation and settling would be the most effective treatment.​

11. Is there an alternative source of water identified that can be used instead of the Huron River? ​

The city has two water sources, the Huron River and wells at Steere Farm. The Steere Farm wells are not impacted by this event and can be used if the Huron River source were to be compromised.​

12. Should residents be stockpiling water?

No. The city's water is safe for all purposes.​  

13. Does the Water Treatment Plant observe a standard of 100 parts per billion (ppb) of overall chromium? 

Hexavalent chromium is not currently regulated at the state or federal level. The drinking water standard for total chromium is 100 ppb.

14. What is your sampling strategy for the Barton intake? 

Staff have been collecting samples daily at our intake in Barton Pond. Our sampling strategy will continue to evolve as the location of the plume is identified.

15. What are the range of possible scenarios from best to worst case regarding this spill in the Huron River? 

The best-case scenario is that the plume never reaches the city's intake in Barton Pond at detectable levels. The detection levels for total chromium and hexavalent chromium are below health-based criteria, so non-detects would be protective of public health. The worst-case scenario is if the plume reaches the city's intake at concentrations above the Safe Drinking Water Act maximum contaminant limit of 100 ppb. This scenario would require treatment. If it is determined that the city is not able to treat the surface water and meet Federal health-based regulatory limits, then we would rely on our well water sources until the plume passes the intake.

​ Upda​ted 8/​​8​/22​