Xcel Energy's Riverside Power Plant in northeast Minneapolis has been producing electricity on the edge of the Mississippi since 1911.
After burning coal for almost a century, in 2009 it switched to natural gas. Instead of the 121 pounds of mercury released into the atmosphere each year by the Riverside plant, it now emits zero.
Riverside is one of three plants in the metro area that Xcel improved as part of its Metro Emissions Reductions Project.
"We at Xcel Energy recognize and really appreciate the partnerships among regulators, utilities, customers, environmental advocates and other stakeholders that made possible the significant reductions in mercury in the state of Minnesota," said Xcel Energy Regional Vice President Laura McCarten.
Minnesota Power in northeastern Minnesota is targeting several of its plants and has already reduced its mercury emissions by 70 percent.
Minnesota Pollution Control Agency commissioner John Linc Stine called the state's progress on mercury a "remarkable achievement." In 2006, state lawmakers, energy companies and environmentalists worked to pass the Mercury Reduction Act, which set targets to lower mercury emissions.
Emissions from power companies are less than half what they were a decade ago, and will drop even more sharply by 2016, Stine said.
"We saw the data come together in such an impressive fashion that we felt like this is a good news story for the state," Stine said. "We want to get people focused on the future as well."
The MPCA is also working to reduce mercury emissions in the taconite industry and various other sources. Mercury is found in dental fillings, old thermostats, car parts, school chemistry labs, even cremation.
The MPCA said mercury levels in fish have been dropping, though not enough to lift fish consumption advisories. That's because the MPCA estimates 90 percent of mercury that falls into Minnesota lakes comes from out of state. Some of that occurs naturally around the world — mercury is spewed out by volcanoes. But much of it comes from growing economies in China and India that burn more coal.
Minnesota's progress on mercury may do more than simply reduce the fraction of mercury the state puts out, said Bill Grant, Department of Commerce deputy commissioner.
"By showing leadership on this issue, Minnesota has demonstrated that such reductions are possible, leading other states and now the federal government to follow," Grant said.
State leaders say Minnesota is ahead of new EPA requirements and could point the way to global reductions down the road.