MILWAUKEE — A utility company wants to increase the amount of mercury it's permitted to release into Lake Michigan from a coal-burning power plant in suburban Milwaukee.
The Wisconsin Department of Natural Resources recently held a public hearing about We Energies' request over its Oak Creek plant, which was met by opposition from more than 100 people.
The Milwaukee-based utility's proposal would allow We Energies to dispose up to 4.1 parts per trillion of mercury into Lake Michigan on any day. It's about three times more than the 1.3 parts per trillion threshold that's considered safe for wildlife, Wisconsin Public Radio reported.
Brendan Conway, the utility's spokesman, said new limits wouldn't pose a health risk to humans or wildlife.
"We are not asking to be asked to be treated differently than anyone else along the lake," Conway said. "Other permitees along Lake Michigan have received similar or higher mercury variances. People should also understand this variance we are talking about is allowed by the EPA and the DNR so this is not an imminent public health risk."
The utility has seen its average amount of mercury emitted into the lake creep up, averaging 1.26 parts per trillion over the last five years.
Both the department and We Energies said they don't believe the utility will dispose of the 4.1 parts per trillion of mercury more than once or twice a year.
"Mercury is a difficult pollutant, there is no way to sugar coat it," said Jason Knutson, a wastewater section chief with the department. "Based on our experience, we are not aware of any treatment technology that is able to achieve the 1.3 parts per trillion water quality standards. Faced with that, we ask ourselves what is the best way to realize reductions to improve wastewater quality."
The department has granted variances for other wastewater plants along Lake Michigan, including plants in Kenosha and Racine for variances of 3.0 and 5.8 parts per trillion per day, according to Knutson.
The state requires plants that are granted variances to develop a pollutant minimization plant.
Knutson said the department will continue gathering information and public input before making a determination about whether to change the utility's permits.