A National Park Service script of "Frequently Asked Questions" on the decision to continue snowmobile use in Yellowstone National Park is revealing on several fronts.

For starters, the FAQs point out that part of the plan to allow upwards of 540 snowmobiles a day in Yellowstone is to help the park's gateway communities economically.

WHAT IMPACT WOULD THESE NEW DAILY LIMITS FOR SNOWMOBILES AND SNOW COACHES HAVE ON THE COMMUNITIES NEAR YELLOWSTONE WHICH PROVIDE SERVICES TO WINTER VISITORS?

Last winter, we averaged 290 commercially guided, BAT snowmobiles and 34 commercially guided snow coaches entering the park per day. The ROD will allow 540 commercially guided BAT snowmobiles and 83 commercially guided snow coaches to enter the park each day. We believe this provides the potential for economic growth for the communities serving winter visitors to Yellowstone.

While the Park Service's data show a snow-coach-only alternative would somewhat diminish tourism in the gateway communities when compared to the preferred alternative, the data also show that snow coach use in Yellowstone is growing much more vigorously than snowmobile use. As a result, there might be some "fluidness" in the discussion over which alternative would help the communities the most.

"More recently, snowmobile visitation has begun to increase, and snow coach visitation has been increasing even more, suggesting that some who would otherwise snowmobile may be taking snow coach tours instead," reads the FEIS in Chapter 3. "Snowmobile visitation increased 20% in the winter of 2005-2006 and another 10% last winter. These increases have been due partly to good snowmobiling conditions in those winters as compared to the winter of 2004-2005, when dry and warm conditions meant that the NPS was unable to open the park’s westside roads to snowmobiles until after the normally busy Christmas season had already ended.

"During the same time period (2001-2002 and 2006-2007), the number of visitors touring YNP by snow coach rose 72.0%, averaging 34 coaches per day (with ridership averaging about 8 passengers per coach)," the report says. "For the winter of 2006-2007, 39 percent of OSV passengers in YNP traveled by snowcoach, with about 61 percent traveling by snowmobile (these figures exclude those traveling by wheeled vehicle)."

Elsewhere in the FAQs is the Park Service's acknowledgment that there were resource problems in Yellowstone the past three winters, even as "best available technology" snowmobiles were being integrated into those traveling the park.

WHY DOES THE RECORD OF DECISION REDUCE SNOWMOBILE NUMBERS TO 540 A DAY? WHY NOT STAY WITH 720 A DAY LIKE YOU'VE ALLOWED THE PAST THREE WINTERS, AND WHICH YOU SUPPORTED IN THE DRAFT EIS?

The ROD reduces the maximum number of snowmobiles allowed in the park from 720 to 540 per day as a means to better protect park resources.

There's no question we've seen significant improvements in air quality, fewer wildlife disturbances, and a reduction in sound impacts with the managed, limited use of BAT snowmobiles the past three winters when compared with historic, unregulated use.

We've now had three full winters to collect and analyze data from limited, managed use. This has helped us refine the models used to analyze the impacts of a variety of alternatives involving over-snow vehicles.

Further analysis and modeling have shown that reducing snowmobile numbers from 720 to 540 a day is one of several actions we need to take in order to better address resource protection, especially sound impacts. Even at current levels of use (290 snowmobiles per day, 32 coaches per day), sound levels were higher than expected, and snow coach and snowmobile vehicle sounds could be heard for longer periods of time than expected. Monitoring thresholds are already exceeded.

The FAQs go on to say park officials hope to reduce those impacts by better management, and by requiring that all snowmobiles and snow coaches entering the park beginning with the winter of 2008-09 are "BAT" machines.

HOW CAN YOU SUPPORT ALLOWING 540 SNOWMOBILES A DAY WHEN YOU'RE ALREADY EXCEEDING ADAPTIVE MANAGEMENT THRESHOLDS FOR SOUND AUDIBILITY WITH MUCH LOWER SNOWMOBILE NUMBERS?

First, let's back up a bit. BAT snowmobiles are about ten decibels quieter than 2-stroke machines. At 50 feet, the sound of a 4-stroke snowmobile traveling at 30 miles an hour is about as loud as normal conversation in an office or home.

Requiring the use of BAT snowmobiles, placing limits on the number of snowmobiles, and keeping snowmobiles together in guided groups have all reduced overall audibility in the parks compared to unregulated, historic use.

But the question is valid. As noted above, monitoring data shows that even with these improvements, there are times we've exceeded the sound thresholds at current snowmobile and snow coach use levels, especially in some of the busier travel corridors such as the route from West Yellowstone to Madison and on to Old Faithful.

That same monitoring data shows that the reason sound levels have been higher than expected is mainly due to certain models of older snow coaches. Since they were designed and built many years ago, some of these snow coaches are louder than their modern counterparts. Administrative use of over-snow vehicles like grooming machines and some 2-stroke snowmobiles also added to the few occurrences when the thresholds were exceeded.

Modeling shows that by upgrading the older snow coaches to meet modern sound and emission standards, limiting the total number of over-snow vehicles to 540 BAT snowmobiles and 83 BAT snow coaches a day, and requiring that all administrative snowmobile use utilize BAT snowmobiles will result in lower sound levels than those measured under the level of over-snow vehicle use experienced the past three winters.

Also, the ROD includes an Adaptive Management Program. If monitoring of use levels of snowmobiles and snow coaches allowed under the ROD indicates acceptable conditions, the NPS will increase use levels to the extent acceptable conditions can be maintained. Conversely, if monitoring of use levels of snowmobiles and snow coaches allowed under the ROD indicates unacceptable conditions, the NPS will reduce use levels to the extent acceptable conditions can be maintained.

As for all those public comments urging the Park Service to phase-out snowmobiles in favor of snow coaches? According to the FAQs, the Park Service assumed those comments were directed at 2-stroke snowmobiles, not four-stroke machines.

PUBLIC COMMENTS ON THE DRAFT EIS AGAIN HEAVILY FAVORED SNOW COACH-ONLY ACCESS. WHY DID YOU IGNORE PUBLIC SENTIMENT AGAINST SNOWMOBILE USE A THIRD TIME?

When we first began to seriously examine ways to deal with over-snow vehicle use and impacts more than a decade ago, the alternative of a cleaner, quieter snowmobile did not exist. The only way at that time to protect the park and provide a quality visitor experience was to propose the elimination of snowmobile use in the park.

An agreement to settle a lawsuit halted the implementation of the original decision and plunged us into a new planning effort. It was during this period that manufacturers began to produce 4-stroke snowmobiles, which are much cleaner and quieter than 2-stroke machines.

During the past three winters, we've provided for limited, managed access using only cleaner, quieter, BAT snowmobiles. This has led to significant improvements in air quality and sound levels. It has improved protection of the park and improved the visitor experience.

BAT machines are not in widespread use in other areas where snowmobiles are found. We believe that the vast majority of those favoring snow coach-only access are against returning to the unacceptable conditions that resulted from the historic, unregulated use of 2-stroke snowmobiles, not the significantly improved conditions experienced with limited, regulated use of BAT machines.

We agree with the vast majority of those who have submitted comments on this subject over the years that historic, unregulated use of 2 -stroke snowmobiles resulted in unacceptable impacts.

A large number of those submitting comments on the Draft EIS told us that if we were to continue snowmobile use in the park, we should continue to require the 100% guiding requirement and should reduce the number of snowmobiles allowed per day. In part for this reason, we reduced the maximum number of snowmobiles allowed in Yellowstone under the ROD from 720 to 540 a day.

The National Park Service believes that the limited, managed use of both BAT snowmobiles and snow coaches for over-snow travel provides for a wide range of visitor experiences without impairing the integrity of park resources or values in full compliance with the Organic Act, the NPS Management Polices (2006), and the Clean Air Act.