I had a story yesterday about environmental groups urging Maryland to act to reduce mercury emissions from a cement plant in Carroll County (pictured at right) and from a paper mill in western Maryland.

Those aren't the only sources of the toxic metal getting into the air, water and food chain. Nor are they the only ones over which there are disputes about the adequacy of government protections. 

The Bush administration has asked the Supreme Court to review an appellate court ruling overturning its proposed rule governing mercury emissions from power plants.  According to a New York Times report, the Environmental Protection Agency had proposed reducing emissions 70 percent by 2018 using a "cap-and-trade" approach that environmental groups and several states successfully challenged, arguing that it could lead to increased exposure to the toxic metal in some areas while not reducing the overall exposure quickly enough.  But the appellate court rejected that, saying it was out of line with the Clean Air Act.

With federal action on that front tied up in court, Maryland lawmakers approved state action to curb a variety of emissions from power plants in 2006.

EPA also has been sued over its approach to regulating mercury emissions from cement kilns. The agency adopted a rule in 2006 limiting emissions from new plants, but not existing plants.  EarthJustice and the Environmental Integrity Project produced a study earlier this year contending that cement kilns release roughly twice as much mercury into the air as EPA had originally estimated in sparing existing plants tougher limits.

Under threat of more legal pressure, EPA now is committed to proposing a rule by March of next year that would limit mercury from existing cement operations. But Eric Schaeffer, head of the Environmental Integrity Project, says  the agency earlier had promised to propose new rules by this fall, only to push that back.

Assuming EPA meets its latest self-enforced deadline, Schaeffer said it still could be "a year or so before the proposal becomes final, and another three years to comply (which is standard for these rules)." 

All told, he says, "any federal requirements might not take effect for another five years. So we’ll keep pushing Maryland."