See the most up to date Grand Teton & Yellowstone national park winter use documents and updates:
http://www.nps.gov/yell/planyourvisit/winteruse.htm

September 2007
Final EIS for Winter Use Plan Released

March 2007
Draft EIS released and available for public review

November 2006
Yellowstone/Grand Teton Draft Winter Use Plan Out for Technical Review

July 2006
Winter Use Newsletter

March 2006
Winter Use Newsletter

Resources
Snowmobiles Meeting Best Available Technology (BAT) Requirements

June 2005
Winter Use Planning for Yellowstone and Grand Teton National Parks

Public Scoping Begins for Winter Use Plan and EIS for Grand Teton and Yellowstone National Parks and the John D. Rockefeller, Jr. Memorial Parkway (press release from Yellowstone National Park, June 24, 2005)

Information regarding the public scoping process can be found on the NPS Planning, Environment and Public Comment (PEPC) System website.

January 2005
The Temporary Winter Use Plans Environment Assessment and Finding of No Significant Impact and final rule can be downloaded at: http://www.nps.gov/yell/planvisit/winteruse/winteruse-ea.htm.

Final Rule, November 10, 2004
http://www.nps.gov/yell/planvisit/winteruse/fedegfinalrule11-10.pdf

Relevant Documents
Grand Teton National Park and John D. Rockefeller, Jr. Memorial Parkway Compendium Amendment, February 11, 2004

Judge Brimmer's Order, February 10, 2004

U.S. District Court's Ruling, December 16, 2003

Final Record of Decision, March 25, 2003

Final Winter Use Environmental Impact Statement (FEIS) 2002