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Draft Sylvan Pass Avalanche Hazard Assessment

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Date: February 26, 2007
Contact: Nash, (307) 344-2010
Contact: Vallie, (307) 344-2012

Snowplows plow through deep snow.
Operators using heavy equipment to clear snow from Sylvan Pass - April 11, 2006.
NPS Photo

No changes are planned to shorten the season in which wheeled vehicles travel the East Entrance Road over Sylvan Pass into Yellowstone National Park.

Questions about spring opening and fall closing dates of the East Entrance Road have been raised since a draft avalanche hazard assessment and mitigation report regarding Sylvan Pass was released for technical review late last week to the ten cooperating agencies involved in Yellowstone’s winter use planning.

The draft avalanche report was commissioned in conjunction with the current winter use planning process. More information on winter use planning and a copy of the draft avalanche report are available online at www.nps.gov/yell/parkmgmt/winterusetechnicaldocuments.htm.

The avalanche report will be used in preparation of a Draft Winter Use Environmental Impact Statement (EIS) released for public review and comment in late March. It will include some alternatives that propose closing Sylvan Pass to motorized over snow vehicles, due to safety concerns surrounding winter avalanche control operations.  

Yellowstone National Park currently conducts avalanche control missions on the East Entrance Road before spring plowing begins. The road typically opens to wheeled vehicle access in early May. Every effort is taken to keep the road open through the first weekend in November.  

The Draft Winter Use EIS will not address or change spring opening or fall road closures over Sylvan Pass. There are no proposals to change the East Entrance Road clearing procedures or alter spring and fall opening and closing dates. The road opening and closing schedule would not change if a winter use alternative was chosen which would eliminate winter avalanche control operations and grooming of Sylvan Pass for motorized over snow travel.

Since the late 1950s, Yellowstone National Park has worked to open most park roads - including the East Entrance Road - to wheeled vehicle access by early May. This road clearing was successfully done long before the park began winter avalanche control missions in Sylvan Pass in the early 1970s.


Producers/Editors note:   A reproduction quality copy of the digital image used in this news release is available on request.

Bottom Bar Graphic With NPS Arrowhead

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