In the next few months, Wisconsin regulators plan to propose a comprehensive rule that calls for a reduction in mercury emissions from coal-fired power plants. The proposal would put Wisconsin ahead of the U.S. EPA’s schedule for controlling mercury from these plants and marks the first state rule of its kind.

In June 2001, the Wisconsin Department of Natural Resources (DNR) released its first proposal to require mercury emission reductions from power plants and other large industrial facilities in three phases, beginning three years after the final rule is put into place: a 30% reduction in five years, 50% in 10 years, and a 90% reduction in 15 years. To meet the standards, utilities could apply control technologies, such as activated carbon injection and new fabric filters, switch from coal to natural gas, or buy credits to cover up to 50% of their plant’s required reduction from other facilities operating in the state. Following public hearings, DNR staff has been analyzing the comments and may revise the June proposal before releasing a new proposal, says Jon Heinrich, rule manager for DNR.

Wisconsin’s actions have a precedent: In 1985, it became the first state to issue rules to control acid rain-causing SO₂ and NO_x emissions from power plants, five years ahead of the federal Clean Air Act. The reasons were the same then as they are now, says Heinrich: greatly impaired natural resources, a concerned citizenry, legislators eager to act, and a utility industry that is willing to discuss regulation.

“All of the major stakeholders agree that mercury emissions reductions should occur in Wisconsin, that we shouldn’t necessarily wait for the federal government to act,” Heinrich says. Wisconsin is also one of many states in the Great Lakes

region and New England that have mercury advisories on most if not all of their water bodies and have voluntary mercury reduction plans in place aimed at reducing mercury use and releases from hospitals, companies, and schools. And in August, the New England Governors and Eastern Canadian Premiers agreed to begin developing strategies to reduce utility mercury emissions.

The rule would apply to any industrial source that emits more than 10 lbs. of mercury annually, including waste incinerators, chlor-alkali plants and other industrial boilers. The DNR would set an emission ceiling for these facilities, and if they exceed that ceiling, they could buy emission credits to make up the difference. The baseline, developed by the source owners, will be the average annual mercury emissions from 1998 to 2000 calculated using procedures outlined in the final rule. Stack emissions testing could be used for the baseline, Heinrich says. Later, facilities would report their emission reduction results to DNR, but the rule won’t require continuous emission monitoring (CEM). “We’ve recognized that CEMs are not there as a technology,” Heinrich says.

Critics of the trading scheme, including environmentalists, say that because mercury is emitted in very small volumes, a trading program would be hard to support. “We may consider phasing that out,” Heinrich says.

Utility executives throughout the country maintain that despite pilot tests of control technologies, many questions remain, including how to deal with the mercury-contaminated fly-ash waste from activated carbon injection. But putting a regulation in place will move the technology discussions forward, Heinrich says. “Within three years, we are convinced we will have answers to the key questions about control technologies.”

Executives from power companies that serve Wisconsin are participating, with environmentalists, citizen groups, and others, in an advisory group on DNR’s proposal, but the utilities are pushing for a multiemissions approach to be included in the rule. Calling for reducing levels of SO₂, NO_x, and mercury in the same rule would allow companies to plan ahead for reductions and cost, they say. Coming down the pike for utilities are federal rules to control NO_x in mid-2004, compliance with a national mercury rule and ozone rules in 2007, and new fine particulate matter (PM_2.5) rules in 2010, utility executives point out.

“The technology decision has to be made after the control level is in place, and it should be made in the context of multi-emissions controls,” says Joseph Shefcheck, managing director and chief environmental officer of Alliant Energy, an international energy company. “That is why we support [President Bush’s] Clear Skies [initiative]” (Environ. Sci. Technol. 2002, 36, 181A–182A.).

Wisconsin’s proposal is more stringent than Clear Skies, which lays out plans to reduce mercury emissions by 69% in 15 years. Wisconsin is considering including a multipollutant emission reduction compliance option in its rule, says Heinrich. But it would be an alternative, rather than the primary path to achieve reductions, he adds.

At the same time that Wisconsin is crafting a proposal, staff at the U.S. EPA are gathering data for a technology-based standard they must propose in December 2003, that will be based on the average emissions reductions achieved by the top 12% of power plants. This approach, known as a Maximum Achievable Control Technology (MACT) rule, is not likely to include phased reductions, and will require facilities to meet the standard by 2007.

EPA is under a court order to move forward with the MACT rule, but policy leaders at the agency say they prefer Bush’s Clear Skies approach. “The Clear Skies initiative will reduce more emissions faster than the program in the Clean Air Act,” says John Bachmann, associate director of science and policy and new programs in EPA’s Office of Air Quality Planning and Standards.

In September Heinirch told DNR’s Natural Resources Board, which will ultimately decide on the final language of the rule, that there is no consensus. Still, many participating in the advisory group say they are “guardedly optimistic” that a proposal will be approved by the board and released in the next few months. By press time in October, DNR’s final proposal was still taking shape. “We all agree to reduce mercury emissions, but we can’t agree on what to move forward on,” Heinrich said. —CATHERINE M. COONEY