is designed to check for various pollutants as well as ozone levels and weather. A 2005 study of the water of Jackson, Jenny, and Taggart Lakes indicated that all three of these lakes had virtually pristine water quality. Of the three lakes, only on Taggart Lake are motorized boats prohibited, yet little difference in water quality was detected in the three lakes. In a study published in 2002, the Snake River was found to have better overall water quality than other river systems in Wyoming, and low levels of pollution from anthropogenic sources. Climate According to the Köppen climate classification system, Grand Teton National Park has a humid continental climate (Dfb). Recreation Mountaineering Grand Teton National Park is a popular destination for mountain and rock climbers partly because the mountains are easily accessible by road. Trails are well marked and routes to the summits of most peaks are long established, and for the experienced and fit, most peaks can be climbed in one day. The highest maintained trails climb from the floor of Jackson Hole over to mountain passes that are sometimes called saddles or divides. From these passes, the climbs follow routes that require varying skill levels. Climbers do not need a permit but are encouraged to voluntarily register their climbing plans with the National Park Service and inform associates of their itinerary. Any climb requiring an overnight stay in the backcountry does require a permit. Climbers are essentially on their own to determine their own skill levels and are encouraged to not take unnecessary risks. The Exum Mountain Guides, which is considered one of the finest mountaineering guide services in the U.S., as well as the Jackson Hole Mountain Guides, offer instruction and climbing escorts for those who are less experienced or unfamiliar with various routes. An average of 4,000 climbers per year make an attempt to summit Grand Teton and most ascend up Garnet Canyon to a mountain pass called the Lower Saddle, which is between Grand Teton and Middle Teton. From the Lower Saddle, climbers often follow the Owen-Spalding or Exum Ridge routes to the top of Grand Teton though there are 38 distinct routes to the summit. The north face route to the summit of Grand Teton is a world-renowned climb involving a dozen distinct pitches and is rated at grade 5.8 in difficulty for the vertical ascent. On a connecting ridge and just north