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A Plan for Emerging and Unregulated Compounds in the City’s Drinking Water

Archived News Release: September 30, 2022 - ​The Water Treatment Plant (WTP) Facility Plan is in full swing. For background information on this project, please refer to the city's news release on Aug. 31, 2022, and the project website. In the scope of this project, the city is conducting an evaluation of alternatives to identify the preferred approach to meet the drinking water needs of the community well into the future, as well as constructing a pilot plant to test recommended technologies in the real world.

How​​​ does this affect you, and the rest of Ann Arbor's water customers?

Water quality will not change. The city will continue to provide high-quality drinking water throughout the project and beyond. Each alternative has varying financial, environmental and treatment implications, and a part of this analysis gives you a chance to provide input on what your values are.

A framework t​​o consider futur​e unknowns related to drinking water

Another part of this analysis includes preparing for unforeseen contaminants that may affect the city's water supply. The city — and the project — is taking measures to ensure that upgrades to the treatment plant will prepare the city to manage contaminants they may face in the future. A good example of an unforeseen contaminant is the recent hexavalent chromium spill from Wixom's Tribar Industries over 50 miles upstream of the intake used by the WTP.

The spill sparked an intensive week of strategizing on how this spill would impact the city's water supply. City staff was quickly able to demonstrate that, by using a newly acquired chemical commonly used in water treatment to convert the chromium (VI) into chromium (III), it could remove the chromium in the existing water treatment process. For more information about this spill, refer to the chromium spill update page, or the city's September Water Quality Matters issue. Regarding the WTP Facility Plan Project, the evaluation of alternatives considers the risk of this and other contaminants of concern in terms of their potential occurrence and risk to public health. The evaluation of alternatives will better prepare the city to adequately deal with contaminants like this and others into the future.

Part of the facility plan project is to identify the WTP's preferred long-term approach to prepare for the effects of unforeseen events. This includes:

  • Contaminants that are currently regulated but have not been detected in the city's water supply at levels of concern, such as total chromium.

  • Contaminants that are currently regulated in other jurisdictions, which have not yet been detected in the city's water supply, such as some types of algal toxins or hexavalent chromium.

  • Contaminants that are under review by the EPA to determine future regulatory standards such as some disinfection byproducts.

Supporting decision making for the ​​​future of the WTP

The city is committed to maintaining a safe and affordable water supply into the future, as this project would indicate. As part of the evaluation of alternatives, the city will be using multiple criteria in the decision-making process. These criteria will include:

  • Environmental considerations.

  • Financial considerations.

  • Water quality considerations.

The city is seeking input on how to weigh these criteria in terms of community priorities. Please fill out the survey to help ensure community values and priorities are properly reflected. Members of the project team and WTP staff will be hanging out at the Mayor's Autumnal Green Fair on Oct. 7. Project team members will also be at the Ann Arbor Farmers Market on Oct. 12. The community is invited to chat with the project team to learn more. Finally, please visit the project website to get more information on the city's road map forward.

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Media Contact Information

Lisa Wondrash
Communications Director
[email protected]

Ann Arbor has 123,851 residents, spans 28.97 square miles and is frequently recognized as a foremost place to live, learn, work, thrive and visit. To keep up with City of Ann Arbor information, subscribe for email updates, and follow the city on Twitter and Facebook. The city's mission is to deliver exceptional services that sustain and enhance a vibrant, safe and diverse community.