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Analyzing Snowmobile Impacts to
Other Winter Recreation Users in the
Sierra Nevada and Southern Cascades

Snowmobiles and other OSVs substantially impact the recreation experience of non-motorized users. These impacts are discussed below. Not discussed in these comments, but also important, are OSV impacts on wildlife, regional air quality, water quality, climate change, and ecosystems. Also important but not discussed in these comments, is creating more trailheads where nonmotorized users can access existing nonmotorized terrain and ensuring continued access to public lands.

OSV impacts on other recreational users include noise, toxic exhaust, consumption of powder snow and rutting of trails and routes. Because nonmotorized users wish to avoid such impacts, nonmotorized use becomes concentrated at the areas where motorized use is prohibited. Where snowmobile use is heavy, non-motorized users are displaced to the extent that the area becomes effectively motorized-use-only. By analyzing and understanding each of the impacts, the Forest Service can enhance opportunities for nonmotorized winter recreation while maintaining a fair balance of motorized recreation opportunity…thereby augmenting the winter tourism dollars brought into local communities.

Two general factors cause the impact of motorized recreation on nonmotorized users to be substantially greater in winter than in summer. First, in summer, nonmotorized users desiring to escape the noise and emissions of vehicles can readily access many large areas of federally-designated Wilderness. In contrast, many roads and trailheads that access Wilderness are inaccessible in winter. Second, wheeled motor vehicle use is generally restricted to designated routes and trails, while OSVs are generally allowed to travel cross-country and into all areas where one might otherwise seek to distance oneself from motorized impacts.

Below, we first discuss the three most significant impacts. Then, we discuss a framework for analyzing motorized and nonmotorized activity that will facilitate a better understanding of impacts and needs and how to manage winter travel so as to maximize recreation opportunity. Lastly, we discuss two particular areas in which current Forest Service management has failed the backcountry nonmotorized user.

1. Impacts


For many nonmotorized users, the ability to enjoy natural soundscapes is a highly important aspect of their recreation experience. For some, the appreciation of natural soundscapes is at least as important as the appreciation of visual landscapes. Although many motorized users also enjoy natural soundscapes, OSV use itself is incompatible with such experience. Indeed, some motorized users seem to be completely unconcerned about their noise impacts on other users.

The intrusion of snowmobile noise is significant and unique. Snowmobiles are extremely loud and on a still winter day (when most users like to recreate), such noise can travel across open landscape (where most use occurs) ten or more miles, completely filling mountain valleys. (By comparison, most automobile noise travels a fraction of such distance.) On most of the accessible national forest lands that are snow-covered, there are natural soundscapes in winter, but for the noise of snowmobiles. Noise is one of the principal reasons that heavy snowmobile activity can completely displace skiers and snowshoers from an area.

Quantification of snowmobile noise levels – as has been done by the National Park Service in Yellowstone – can help analyze and manage noise impacts, but we believe that the primary impact of noise is qualitative. It is the interruption of the natural soundscape, rather than the magnitude of the noise, that creates the disturbance. The fact that the noise is present, rather than just its intensity, is a problem to some users.

Just as sound bounces off ridgelines and noise can fill a valley, ridgelines can confine snowmobile noise, protecting natural soundscapes on the other side. Deep forest also can significantly buffer snowmobile noise. In some areas, such as within sight of highways with significant truck traffic, natural soundscapes are elusive in any event. Each of these factors should be looked at and taken into account in the winter travel management process.

Snowmobiles employing “best available technology” (BAT) emit substantially lower levels of noise, and thus the imposition of BAT restrictions can facilitate shared joint use in some areas.

Emissions and Ambient Air

Snowmobiles are the most polluting recreational vehicle in common use. Snowmobile emissions contain heavy concentrations of toxic compounds, including carbon monoxide. Studies in Yellowstone National Park found snowmobile emissions can cause unhealthy levels of ambient air pollution in congested areas.

Even small amounts of carbon monoxide substantially adversely impact other users. Levels of air pollution that might be acceptable in urban environments, or at snowmobile competitions, are not appropriate for trails in which users seek fresh air. Snowmobile emissions are another reason nonmotorized users can be completely displaced from areas with heavy snowmobile activity.

Some OSV organizations use misleading comparisons to confuse this issue. Comparing OSV emissions to other vehicle emissions is difficult because the EPA regulates OSV emissions based on vehicle power (kilowatt hour) rather than miles travelled. (EPA, Emissions Standards for New Nonroad Engines, EPA420-F-02-037, September 2002.) (Thus, theoretically, a single OSV with unlimited power is legally able to produce unlimited emissions.) Studies conducted by Yellowstone National Park in 2004 found that older-technology 2-stroke snowmobiles, travelling at 15-20 mph produce, per mile, 221 grams of carbon monoxide, 180 grams of hydrocarbons and 4 grams of PM -2.5. (Yellowstone National Park, 2004-05 Winter Use Plan, Air Quality Analysis of Snowmobile and Snowcoach Emissions.) In comparison, cars employing 2002 year automobile technology emit 14.2 grams of carbon monoxide per mile and 1.2 grams of VOC (comparable to hydrocarbons). (Federal Highway Administration, Transportation Air Quality Facts and Figures, January 2006.) Snowmobiles are very dirty vehicles; breathing their exhaust is unhealthy.

In the travel management process, the Forest Service should measure ambient air impacts from snowmobiles at heavily used trailheads and trails. The Forest Service also should consider the feasibility of creating separate trailheads for motorized and nonmotorized users.

BAT-compliant OSVs emit substantially lower levels of toxic emissions and thus the imposition of BAT restrictions can facilitate shared joint use in some areas.

Tracking of the Landscape and Consumption of Powder Snow

Snowmobiles track up the landscape at a rate twenty or more times faster than skiers, snowboarders or snowshoers. Many skiers complain about the severe rutting that snowmobiles can impart, especially when descending or turning at speed. With increased demand for backcountry alpine skiing and snowboarding, powder snow has become a precious resource that merits Forest Service management.

As is apparent at any ski resort on “powder days”, the experience of descending steep slopes blanketed with smooth powder is highly sought by many skiers and snowboarders. In the backcountry, the experience of skiing or riding powder snow often is the primary reward for the strenuous effort of climbing up without a chairlift. Accessible backcountry powder snow on steeper slopes is a limited resource, and a significant impact of OSVs is their disproportionate consumption of this resource. Due to its power, size and speed, one snowmobile can in a matter of hours completely consume (shred, in colloquial terms) all the powder snow on a slope that could otherwise provide recreational opportunity for twenty or more skiers and snowboarders. Acknowledging and addressing this disparate impact is critical to managing the forest lands in a sustainable manner for the future.

In the Sierra Nevada and southern Cascades, demand for nonmotorized winter backcountry recreation well exceeds demand for motorized backcountry recreation. This is reflected in many studies, including Forest Service National Visitor Use Monitoring (NVUM) surveys.

2. A Framework for Effective Management

In analyzing and addressing OSV impacts, it is helpful to distinguish between three types of activity. These same three types of activity are engaged in by both nonmotorized and motorized users. Indeed, one should not lose sight of the fact that both OSV riders and skiers/snowboarders/snowshoers share many of the same interests. For convenience, in the remainder of this discussion references to “skiers” are intended to include snowboarders and, in many cases, snowshoers as well.

In both skiing and snowmobiling, there is a Trail Touring activity, there is a Backcountry Exploring activity, and there is an Alpine Adventure activity. There is also a distinct group of users who use OSVs or skis to access homeowner cabins and other sites, but for management purposes such group has purposes and needs that generally correspond to users engaged in the Trail Touring activity. There are also hybrid users who use OSVs to access slopes they then ski; when riding their OSVs, such group has the same general impacts and concerns as other OSV riders.

When engaging in the Trail Touring activity, users use designated trails, preferably groomed, with moderate climbs and descents. (Grooming is important to Nordic skate skiers, but not as important to Nordic striding skiers, who create their own trails by following each other’s tracks.) Travelling fast and perfecting technique are often important aspects of the experience. When engaging in the Backcountry Exploring activity, users travel cross-country or on marked trails across a variety of terrain; the focus is on travelling and exploring, including away from marked or groomed trails. When engaging in the Alpine Adventure activity the challenge of riding through powder snow on steeper slopes is a primary focus. (Skiers focus on the down, while the challenge of the up may be more important for OSV riders, but all users in this activity seek steep powder-covered slopes.) Certainly there are overlaps and combinations and crossovers of activities, but understanding these shared aspects of each sport facilitates effective winter travel management.

In areas where the primary activity is Trail Touring (and in particular where there is not a high intensity of use), some effective shared use is possible with the imposition of BAT standards and other restrictions. Users are often more concerned about the quality of the trails than obtaining a Wilderness-like experience. Safety issues are important, as beginning skiers (in particular) are not able to change their direction or sidestep rapidly and snowmobiles can travel at highway speeds. Skiers have been hit and, in at least one case, seriously injured due to shared use of trails. (E.g. Bridger-Teton National Forest, December 29, 2011; Acadia National Park, February 8, 2005.) Also, many skiers seek a groomed surface specifically managed for their type of skiing; snowmobile tracks, as well as snowshoe or boot tracks, significantly disturb such surface. The creation of separate trails and/or clear designation of trail protocols, together with BAT restrictions, can substantially reduce user conflict, allowing effective shared use of some areas.

In areas where the Backcountry Exploring activity predominates and OSV activity would otherwise be frequent, there needs to be complete separation of uses because the nonmotorized skier generally seeks to do his exploring in a Wilderness-like environment where he is assured of natural soundscapes and clean air. Frequent encounters with OSVs on such excursions adversely impacts the recreation experience, just as the experience of encountering OHVs would adversely impact a hiker in Wilderness. (In comparison, there is little impact to the OSV user from sharing such space with skiers, who generally cover far less territory and are essentially unobtrusive.) The winter travel management process needs to acknowledge that Wilderness areas are generally inaccessible to day users in winter. Skiers and snowshoers seeking a Wilderness-like experience in winter should be able to do so from available winter trailheads. There is plenty of room in the Sierra Nevada and southern Cascades to set aside areas where nonmotorized users can readily obtain a Wilderness-like experience without impacting overall levels of snowmobile recreation or opportunity.

In areas where there is high user demand, and the primary activity is Alpine Adventure, the conflicts effectively preclude shared use. This is due to safety issues, noise issues, clean air issues and, perhaps most significantly, the substantially disproportionate consumption of powder snow. In chasing powder, skiers cannot compete with snowmobiles. In managing for this activity, primary factors are relative demographics, e.g. the demand for each type of activity, and issues of sustainability. It is fact that far more skiers and snowshoers than snowmobiles can be accommodated on one slope. In areas of high demand, the public as a whole is better served by restricting types of use so as to allow the greatest number of individuals to enjoy their sport. Such management will have obvious benefits to communities dependent on a tourist economy. There are limited areas in the Sierra and the southern Cascades where user demand, easy accessibility and natural terrain features warrant this restrictive management, but in those areas the Forest Service needs to recognize that the importance of maximizing recreation opportunity for the greatest number of users.

3. Two Shortcomings in Past Forest Service Management

The ROS System

Forest Service land management has relied on a system of mapping recreational opportunity called the Recreation Opportunity System. Through this system, current land conditions are mapped so as to understand what areas have a high degree of developed presence and what areas are primitive without development. Thus, the ROS system maps what areas can be managed to provide users a primitive, backcountry experience. This mapping system has considered lands in summer, where access is far easier than winter. Thus, the ROS system has not reflected winter conditions. Areas that are crisscrossed by roads in summer may be relatively inaccessible in winter and thus in winter present a very primitive environment. Some of these lands should be protected for primitive backcountry experiences in winter, because the lands that provide a primitive backcountry experience in summer are largely inaccessible.

Whereas the ROS system has succeeded in preserving opportunities for primitive recreation in summer, it has had the opposite effect in winter. Rather than protecting areas where a primitive experience can be obtained in winter, the ROS system has resulted in mapping these areas as developed or semi-developed and thus opened the door for widespread OSV recreation. This has become a self-fulfilling mapping effort that has failed the nonmotorized winter user. This shortcoming needs to be acknowledged and addressed in the winter travel management process. The Forest Service should acknowledge that some lands mapped as developed or semi-developed under the ROS system are highly-suitable for primitive backcountry recreation in winter but for the presence of OSVs, and should manage some of these lands for that purpose.

Unplowed Forest Roads and Impact of the State OSV Grooming Program

In large part due to the availability of funds under the State of California’s OSV grooming program, many (if not most) of the accessible and scenic unplowed forest roads in California, that are closed to wheeled vehicles in winter, have become dominated by OSV recreation. This has largely displaced skiers and snowshoers from these areas and created an imbalance in recreation opportunity.

The OSV community often claims that skiers and snowshoers like to recreate on their groomed trails. Though there are some skiers and snowshoers who do like to do this, the more important fact is that skiers and snowshoers like to recreate on the unplowed roads. Regardless of whether these roads are groomed, they provide some of the best alternatives for skiers and snowshoers desiring long distance touring on well-marked routes (in our activity analysis above, either a trail touring or backcountry exploring activity, depending on one’s primary focus.) They are wide, easy to follow, with consistent and moderate gradients. They are often very scenic. And, due to the State’s OSV program, they are heavily used by snowmobiles. In many cases, where snowmobile use is heavy, skiers have been largely displaced from such roads. In other areas, growth of ski tourism has been discouraged because of the OSV presence. This is not a fair balance, and it is not economically-sound policy for gateway communities.

This imbalance may be illustrated at the Gold Lakes trailhead in Plumas National Forest. Here a separate ski trail is provided for skiers and snowshoers who do not want to breathe snowmobile exhaust or compete with snowmobile traffic and want to try and distance themselves a bit from snowmobile noise. The ski trail is in the forested valley bottom below the road, while the road travels up the ridge with scenic vistas. The road is wide and open with even snowfall accumulation. The ski trail is in heavy forest where there are no views and uneven snow accumulation that creates constant bumps and bottoms. It is beyond dispute that the recreational experience provided by the ski trail is far inferior – not even comparable – to the recreation experience that otherwise would be available on the unplowed road, regardless of whether or not it is groomed. Perhaps this situation is justifiable at this one trailhead, but it is not justifiable for this situation to exist across the Sierra Nevada and southern Cascades. In the winter travel management process, more of the unplowed scenic forest roads that are closed to wheeled vehicle traffic should be protected for nonmotorized use, even if this results in a discontinuance of grooming on such roads.

Where OSV use is infrequent, shared use can be fostered by designation of trailheads and trails as limited to BAT-compliant OSVs. It needs to be emphasized that such restriction is not intended to give skiers grooming paid for with funds earmarked for snowmobile grooming. The restriction is warranted because it protects a fair balance of recreational opportunity on some of the best routes for touring, regardless of whether the routes are groomed. The OSV community may choose to discontinue grooming in areas with such restriction if it so desires.


Snowlands urges the Forest Service in California to set aside more areas specifically designated for nonmotorized winter use. We seek a fair balance of motorized and nonmotorized winter recreation opportunity, taking into account all relevant factors, including levels of user demand, user trends, relative impacts, and economic benefit to local communities.