Six New England states and New York last week asked the Environmental Protection Agency (EPA) to require Midwestern and Mid-Atlantic coal plants to clean up their smokestack mercury emissions.

The seven states—Rhode Island, Connecticut, Maine, Massachusetts, New Hampshire, New York, and Vermont—have claimed that mercury pollution from Pennsylvania, New Jersey, Ohio, West Virginia, Maryland, Michigan, and elsewhere, is contaminating the Northeast’s fish and waterways and directly threatening public health and the environment.

“It is our belief that eliminating our fish-consumption advisories deserves to be a national priority,” the New England Interstate Water Pollution Control Commission (NEIWPCC), a nonprofit group that is helping to collaborate the effort, wrote in a cover letter for the 237-page petition (PDF) filed with the EPA on Tuesday.

The filing was made under an obscure provision, 319 (g), of the federal Clean Water Act. That section requires that the EPA initiate a management conference of polluting Midwest states to develop a cleanup plan that will take specific steps to reduce mercury pollution flowing into the Northeast.

The petition cited a March 2008 Northeast States for Coordinated Air Use Management (NESCAUM) study (p. 163 of the petition), funded by the NEIWPCC and its member agencies. Basing its conclusions on data from 2002, the study said that U.S. sources contribute about 30% of the atmospheric deposition in the Northeast region. In-region sources contribute about half of the deposition from within New England and New York, while about 48% of the region’s deposition originates from states outside the region.

Pennsylvania led the list of out-of-region states with significant contributions (21.7%). It was followed by New Jersey (5.6%), Ohio (5.5%), West Virginia (3.9%), Maryland (3.7%), Michigan (2%), Virginia (1.5%), Indiana (1.3%), and Kentucky (1.2%).

The petition is not the first time the seven states have collaborated in a major move to address mercury contamination. In June 2006, they were among the 16 states that sued the federal government over the legality of the EPA’s Clean Air Mercury Rule (CAMR), which would have limited mercury reductions to 70% and delayed them until 2018.

Earlier this year, the states prevailed when the EPA’s Clean Air Mercury Rule was vacated by the U.S. Court of Appeals for the District of Columbia. CAMR, scheduled to go into effect in 2010, regulated mercury by a cap-and-trade scheme. The court found that mercury is a hazardous air pollutant under the Clean Air Act and that the EPA is obligated to develop maximum achievable control technology (MACT) rules. The EPA has yet to decide whether it will appeal this ruling.

In October last year, the states filed the Northeast Regional Mercury Total Maximum Daily Load (TMDL) with the EPA. A TMDL stipulates the precise amount by which mercury arriving in the region from out-of-region sources must be reduced if fish are to be safe to eat.

Sources: NEIWPCC, Rhode Island Department of Environmental Management