Chapter 3: the Affected Environment
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Chapter 3: The Affected Environment 3.0 THE AFFECTED ENVIRONMENT 3.0.1 Introduction Chapter 3 – The Affected Environment describes the physical and biological environment (e.g., water resources, wildlife, etc.) as well as the human environment (e.g., social and economic factors, recreation, etc.), which may be affected by the range of alternatives, as described in Chapter 2 - Alternatives. Much of the information on the affected environment is compiled from detailed technical reports and other analyses prepared by the USFS and consultants. Some of these reports are attached to this FEIS as appendices. All reports are available for review as part of the Analysis File maintained for this project at the MBSNF Supervisor’s Office. References cited in this FEIS are provided in Chapter 5 - References. 3.0.2 Analysis Area The “analysis area” (referred to as the “Study Area” throughout this document) varies by resource area. The Study Area includes all public (USFS) lands as well as private land owned by Ski Lifts, Inc. and other land holders. When discussing individual projects within the Study Area, the following terms are used to distinguish the different locations within the SUP: Summit East, Summit Central, and Summit West, are collectively referred to as “The Summit.” Alpental, when discussed individually, is referred to as “Alpental.” All four ski areas are collectively referred to as “The Summit-at-Snoqualmie.” Figure 3.0-1, Study Area illustrates the boundaries of the Study Area, including The Summit and Alpental. Figure 3.0-2, 5th Field Watersheds illustrates the boundaries of the two 5th field watersheds used in this FEIS analysis: the South Fork Snoqualmie River Watershed (S.F. Snoqualmie Watershed) and the Upper Yakima River Watershed (U. Yakima Watershed). The Summit-at-Snoqualmie Master Development Plan Proposal Final Environmental Impact Statement 3-1 Chapter 3: The Affected Environment 3.1 - Climate and Snow 3.1 CLIMATE AND SNOW 3.1.1 Regional Climate The Summit-at-Snoqualmie is located within the Pacific Coastal Ecoregion, which has a climate that is characterized by moist, cool winters and warm, dry summers. The mild climate in this region is moderated by the close proximity to the Pacific Ocean. The variation in summer and winter precipitation patterns in this region is due to the seasonal changes in the location of semi-permanent high and low pressure systems and the path of prevailing westerly winds (i.e., the jet stream). In the summer, the Pacific High Pressure system moves northward to a location off the California and Oregon coast, which protects the Pacific Northwest from storms and keeps the summer dry and warm (Ahrens 1993). Occasional thunderstorms develop along the crest of the Cascade Mountain Range as a result of moist marine air from the Pacific Ocean converging with dry unstable air from east of the crest. During the winter, weather patterns in this region are dominated by the combined influences of the Aleutian low pressure system that is located in the Gulf of Alaska and changes in the path of the jet stream that moves these storm systems from their genesis point to the Pacific Northwest (Ahrens 1993). Once these storm systems reach the mainland, they are uplifted by the Cascade Mountain Range, causing significant precipitation. Cold interior air masses from Canada commonly move into Western Washington during the winter. Moist air masses that are carried by the westerlies from the Gulf of Alaska converge with these cold air masses along the crest of the Cascade Mountain range, resulting in considerable snowfall. The Pacific Northwest has a greater average annual snowfall than any other region within the continental United States due in large part to the climate phenomenon described above (RRC Associates 2002). Year-to-year climate variations correlate with two large-scale climate oscillations: El Niño/Southern Oscillation and Pacific Decadal Oscillation, both of which are associated with warm years tending to be dry, and cool years tending to be wet (National Assessment Synthesis Team 2000). 3.1.1.1 Global Warming The global warming hypothesis has been generally accepted by the scientific community and is a concern of ski area operators throughout the United States (NSAA 2000, 2002, and 2005). According to recently published research, projections for climate change scenarios for the Pacific Northwest indicate that average annual temperature would increase by 2.5 to 3.7°F by 2020 and by 3.1 to 5.3°F by 2040 (Mote et al. 2005). Precipitation would increase by 2 to 9 percent by the year 2040 (Mote et al. 2003). In a more recent report, the Climate Impacts Group (2006) examined climate change scenarios for the Pacific Northwest generated by ten different climate models. All models projected temperature increases throughout the year, and most predicted the largest temperature changes would occur during the summer (June-August). The majority of models projected small decreases in precipitation during the summer, and slight increases in winter (December-February), but little change is projected in the annual mean through mid-century. However, precipitation predictions were more variable and less certain than temperature The Summit-at-Snoqualmie MDP Final Environmental Impact Statement 3-2 Chapter 3: The Affected Environment 3.1 - Climate and Snow forecasts, and the precipitation change projections fell within the range of year-to-year variability observed during the 20th century (Climate Impacts Group 2006). Research indicates that the projected increase in temperature would have a much greater effect on winter snowpack and streamflow than the increase in precipitation, especially at middle elevations in the transient snow zone (Mote et al. 2003; Miles et al. 2000; and Snover et al. 2003). The predicted effects of the temperature increase for the middle of the 21st century include: more precipitation falling as rain in the winter, an increase in the typical snow level by as much as 1,000 feet, a decrease in the winter and spring snowpack extent and water content, and earlier spring snow melt and subsequent peak streamflows (Mote et al. 2003; and Miles et al. 2000). According to the Pacific Northwest National Laboratory climate change model, snow cover in Washington State will be lost within the existing snowline, resulting in a projected rise of the average Cascade snowline from its current 3,000 feet to approximately 4,100 feet in the next 50-80 years (Pacific Northwest National Laboratory 2004). Snowpack in the Cascades has been declining since 1945 due predominantly to increases in temperature over the last 80 years (Mote et al. 2005a; Hamlet et al. 2005, 2005a). Model simulations conducted by the Climate Impacts Group showed that temperature changes of 3.6°F, projected to occur around the 2020s, could reduce the season length by 28% at The Summit-at-Snoqualmie, and the percentage of rainy days during the ski season may increase to above 50 percent (Casola 2005). A temperature change of 4.5°F, projected to occur around the 2040s, could reduce the probability of opening by December 1 to less than 25 percent (Casola 2005). However, the study notes that warmer temperatures and less snow on the highways during the ski season could improve customer access to ski areas (Casola 2005). The ability of global climate models to accurately predict localized effects of global warming are still being debated (Climate Impacts Group 2006; Fagre et al. 2003; Watson et al. 2001; Miles et al. 2000; and USEPA 1997). Climate predictions are frequently based on averages of many climate models, which are often based on single runs using the same emissions scenario, resulting in varied climate projections. The National Assessment Synthesis Team of the U.S. Global Change Research Program notes that: “a more reliable regional assessment would require controlled regional-level comparison of several state-of-the-art models, each with a statistical ensemble of multiple similar runs under each of several emissions scenarios” (National Assessment Synthesis Team 2000). While this research represents the best available science regarding climate change impacts in the Pacific Northwest, the prediction models still have many limitations and unknown factors, including insufficient resolution to include regional topographic features (e.g., mountain ranges, large estuaries), high confidence with temperature predictions but low confidence with localized changes in precipitation and weather patterns, and reliance on multiple assumptions for increases in greenhouse gasses and carbon cycling. As a result of the uncertainty that remains with regional climate models and the long timeframes The Summit-at-Snoqualmie MDP Final Environmental Impact Statement 3-3 Chapter 3: The Affected Environment 3.1 - Climate and Snow for the climate change models relative to the timescale of the MDP (i.e., 10 to 15 years), global warming is not an integral part of the climate and snow analysis in this FEIS, but was considered as part of the planning process for the MDP. 3.1.2 Local Climate Conditions The average annual precipitation in the Study Area is approximately 105 inches based on the 40-year period of record for the Snoqualmie Pass weather station (Western Regional Climate Center 2003). Precipitation in mountainous environments such as Snoqualmie Pass is highly variable over time and geographic area. Annual precipitation ranged from approximately 77 to 145 inches in the Study Area for the period of time from 1931 to 1972 (Western Regional Climate Center 2003). In general, December and January are the months with the most precipitation in the Study Area and July is the month with the least amount of precipitation. Temperatures in the Study Area range from an average minimum monthly temperature of 21°F during the month of January to an average maximum monthly temperature of 70°F during the months of July and August (Western Regional Climate Center 2003).