The heat just got turned up a notch in the debate over snowmobiling in Yellowstone.
    Seven former National Park Service directors, those spanning every administration from Lyndon Johnson to Bill Clinton, have endorsed a letter to Interior Secretary Dirk Kempthorne urging him to ban snowmobiles in the park.
    "Your strong declaration of support for the longstanding Management Policies that have governed the life of the parks reassured the American public and the Congress that you will insist upon the highest protection of park resources and values and will not allow uses and activities that conflict with this founding principle of the national parks," reads the letter, which was released today.
    "Given this, we must express our alarm over a proposal in Yellowstone National Park that would radically contravene both the spirit and the letter of the 2006 Management Policies. The proposal is to escalate snowmobile use as much as three-fold over current average numbers even though scientific studies have demonstrated conclusively that a two-thirds reduction in average snowmobile numbers during the past four winters is principally responsible for significantly improving the health of the park for visitors, employees and wildlife."

    The letter is signed by George B. Hartzog, Jr., who was director from 1964-1972, Ronald H. Walker (1973-1975), Gary Everhardt (1975-1977), Russell E. Dickenson (1980-1985), James M. Ridenour (1989-1993), Roger G. Kennedy (1993-1997), and Robert Stanton (1997-2001.) Fran Mainella, who served as director from 2001-2006, is constrained by ethics rules from lobbying government for one year, and did not sign the letter.
    Yellowstone officials are expected tomorrow to release their preferred alternative for winter use in Yellowstone and Grand Teton national parks, and that alternative is expected to support as many as 720 snowmobiles a day in Yellowstone. Never mind that studies performed by park scientists have determined that even the current levels of snowmobiles, roughly 250 a day, create pollution problems in the park.
    The former Park Service directors alluded to those studies and noted that the Park Service has spent roughly $10 million on studying snowmobiles in the parks and that those studies consistently have found that "greater volumes of traffic required by an emphasis upon snowmobiling add dramatically to air and noise pollution and disturbance of Yellowstone's wildlife. ... On at least three occasions, the Environmental Protection Agency has independently corroborated that providing access by modern snowcoach and phasing out the use of snowmobiles will provide Yellowstone's visitors, employees and wildlife with dramatically healthier conditions."
    The former directors also pointed out that a plan to allow more, not fewer, snowmobiles in Yellowstone not only would run contrary to the scientific studies conducted on the machines, but would run counter to public comment that ran greater than 80 percent against snowmobile use in Yellowstone and contrary to the Management Policies that Kempthorne has pledged to uphold.
    Also signing off on the letter was Nathaniel P. Reed, assistant secretary of the Interior from 1917-1976, William J. Briggle, NPS deputy director from 1975-1977, Denis P. Galvin, NPS deputy director from 1985-1989 and again from 1998-2002, and Michael Finley, Yellowstone's superintendent from 1994-2001.