Illegal trails disturb deer at a time when they need to conserve energy to survive the winter. photo by Jim Yskavitch
Illegal trails disturb deer at a time when they need to conserve energy to survive the winter.

photo by Jim Yskavitch

Beginning in July, the U.S. Forest Service will begin decommissioning an extensive, illegal trail system in the Stevens Canyon area northeast of Sisters. Located within the Metolius Deer Winter Range, the trail system was begun about two decades ago by some off-road motorcycle enthusiasts who took it upon themselves to build a trail through public and private lands.

Over the years, this clandestine trail system has grown to about 20 miles as more off-road-vehicle users created additional trail segments. Since the Forest Service implemented its rule in 2009 limiting off-road vehicles to designated roads and trails, illegal OHV use of the Stevens Canyon trails has declined. However, mountain bikers have since discovered the system and are riding it extensively.

All that activity in the Stevens Canyon portion of the Metolius Deer Winter Range - which stretches from the Metolius River east to the Deschutes River and includes National Forest, Bureau of Land Management and private lands - has Sisters Ranger District wildlife biologist Monty Gregg concerned.

"People think that because there is lots of forest then there is room for a trail," said Gregg. "But it's mule deer winter range that is significant and critical habitat, and the trail goes through areas that are also important to other species of wildlife."

A mule deer population of about 5,700 animals uses the winter range. They migrate down from higher elevations in November and December, then back up again in April and May, traveling through Stevens Canyon during the early part of the fall migration and later parts of the spring migration.

Sara Gregory, wildlife habitat biologist for the Oregon Department of Fish and Wildlife, studied the Metolius deer herd from 2005 to 2012, putting radio and GPS collars on about 100 animals and tracking where they went to determine such things as habitat preferences, migration routes and causes of mortality. One of her findings was an unequivocal correlation between human activity - especially roads - and disturbing deer, causing them to expend energy they need to survive the winter.

"It's not just one activity," said Gregory. "It's OHVs, mountain bikes, and hikers that all add up. When you have a lot of people out there recreating, it's going to affect the critters."

Illegal trails are often poorly constructed, causing environmental damage; and may be unsafe or conflict with hunters, birders and other forest users, according to District recreation team leader Amy Iracki.

The illegal trail system's effect on cultural resources is also a concern, particularly from erosion that may wash away valuable artifacts. Because deer congregate in the area during the winter, prehistoric people and later Native Americans came here to hunt them, leaving behind projectile points and remains of "processing stations" where they cleaned their game.

"There are sections of the trail where OHV use has impacted these cultural resources," said Matt Mawhirter, Sisters Ranger District archaeologist.

Officer Fred Perl, the District's law-enforcement officer, is seeing signs of increasing use of the trails by mountain bikers.

"The trails are becoming more visible, and what that means to me is that they are becoming more popular and more people are using them," said Perl.

Since there are residences in Stevens Canyon there have also been occasional complaints of trespassing from the trails onto private property adjacent to the National Forest, and a large segment of the trail was actually built on privately owned forestlands.

Forest Service staff have placed signs at trail entry points informing trail users that the system was illegally built and is being closed. Students from the Sisters High School Interdisciplinary Environmental Expedition Class helped identify trail access points and marked their locations with GPS coordinates. The Forest Service will obliterate these trail entry points with berms, logs and boulders. Work will be completed by September.

The Stevens Canyon trail system decommissioning is part of a larger project, called the Garrison Project, to improve wildlife habitat in the National Forest portion of the winter range that will include forest thinning and other vegetation management work.

The Forest Service is supportive of mountain bike trails on the Sisters Ranger District, but wants future trail systems to be sustainable in that they take into consideration other forest values and minimize their impacts on important resources like wildlife and archeological sites.

"I think that can work," said Gregg. "We just need to identify the impacts, and then we can bring it all together."

For more information contact District Wildlife Biologist Monty Gregg at the Sisters Ranger District, 541-549-7724.