Six environmental groups told the U.S. Environmental Protection Agency Wednesday they plan to sue the agency over its handling of federal regulations that require states to cut air pollution that obscures visibility of national parks and wilderness areas.

In a "notice of intent to sue" sent to EPA Administrator Lisa Jackson, the Sierra Club, Earthjustice, Environmental Defense Fund and other groups accused the EPA of failing to meet a Jan. 15 deadline for establishing federal plans to cut haze caused by pollution in western states that failed to established their own pollution-reduction plans. The groups said they plan to file the lawsuit within 60 days.

In 1999, the EPA established the Regional Haze Rule to improve air quality in national parks and wilderness areas. The rule requires state and federal agencies to collaborate on plans to improve visibility in the Grand Canyon, Yosemite, the Great Smoky Mountains and 153 other national parks and wilderness areas where air pollution from power plants, factories and other sources often reduces visibility.

In January 2009, the EPA found that 32 states, the District of Columbia and the U.S. Virgin Islands had failed to submit regional haze plans by a December 2007 deadline set by the Clean Air Act. The agency notified the states that they had two years in which to submit completed regional haze plans to cut pollution in their states. The EPA told the states that it would establish regional haze plans for them if they didn't do so by January 2011.

The environmental groups argued the EPA was required by federal law to establish regional haze reduction plans for the states by Jan. 15, and that the agency violated the Clean Air Act by not having done so.

"Every year, millions of visitors to our national parks and wilderness areas are unable to see the postcard views because they have been obscured by haze pollution," Stephanie Kodish of the National Parks Conservation Association said in a statement.

The EPA said in a statement that it "remains committed to helping states meet their Clean Air Act goals" although the agency conceded that "there is more work to do."

Several western states, including Colorado, Oregon and California, are in the process of finalizing their regional haze plans, while the EPA has established regional haze plans for land controlled by Indian tribes. In many cases those plans involve requirements for coal-fired power plant operators to shut power plant units or install pollution-control equipment. Among power companies affected by the rules are Xcel Energy's (XEL) Colorado utility, PNM Resources Inc. (PNM) in New Mexico and Pinnacle West Capital Corp.'s (PNW) Arizona Public Service Co. unit.

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