CHAPTER 3 AFFECTED ENVIRONMENT CHAPTER 3: AFFECTED ENVIRONMENT INTRODUCTION This chapter provides a description of the existing biological, physical, and socioeconomic characteristics, including human uses that could be affected by implementing the action alternatives as described in Chapter 2, for this resource management plan (RMP). Information from broad-scale assessments were used to help set the context for the planning area. The information and direction for the Bureau of Land Management (BLM) resources has been further broken into fine-scale assessments and information where possible. The public and agency scoping process raised specific aspects of each resource discussed in this section (e.g., weeds, fire, and off-highway vehicle [OHV] use). The level of information presented in this chapter is used to help assess potential effects of the action alternatives in Chapter 4. Because acre figures and other numbers used are approximate projections, readers should not infer that they reflect exact measurements or precise calculations. Acreages were calculated using geographic information systems (GIS) technology and there may be slight variations in total acres between resources. HOW TO READ THIS CHAPTER This chapter is organized into four sections, including Resources, Resource Uses, Special Designations, and Social and Economic Conditions. These sections are further divided into resources or programs, which are also presented in Chapter 3. For a description of the affected environment, see below or, for electronic drafts, click on the following link to take you to a specific section: RESOURCES: Air Resources and Climate, Cultural Resources, Fish and Wildlife, (Aquatics, Terrestrial, and Special Status Species) Geology, Invasive Species (Vegetation), Lands with Wilderness Characteristics, Paleontological Resources, Riparian and Wetland Areas, Soils, Special Status Species-Plants, Vegetation, Visual Resources, Water Resources, Wildland Fire Management and Ecology RESOURCE USES: Coal, Forestry and Woodland Products, Geothermal, Lands and Realty, Livestock Grazing, Locatable Minerals, Minerals, Mineral Materials, Oil and Gas, Recreation, Renewable Energy, Travel Management and OHV SPECIAL DESIGNATIONS: Areas of Critical Environmental Concern, Back Country Byways, National Trails, Special Designation Areas, Wild and Scenic Rivers, Wilderness, Wilderness Study Areas SOCIAL AND ECONOMIC CONDITIONS: Environmental Justice, Hazardous Materials and Waste, Social and Economic, Tribal Interests 3-1 CHAPTER 3 AFFECTED ENVIRONMENT RESOURCES AIR RESOURCES AND CLIMATE The air quality of any region is controlled primarily by the magnitude and distribution of pollutant emissions and the regional climate. Pollutant transport from specific source areas is affected by local topography and meteorology. In the mountainous western United States, topography is particularly important in channeling pollutants along valleys, creating upslope and downslope circulations that may entrain airborne pollutants and block the flow of pollutants toward certain areas. In general, local effects are super-imposed on the general synoptic weather regime and are most important when the large-scale wind flow is weak. This section begins with a description of current climate and currently identified climate change trends. Following this discussion, air resources will be described in terms of air quality, air quality related values (AQRV), specifically acid deposition and visibility, current emissions in the planning area, and smoke management. CLIMATE Climate is the combination of temperature, humidity, atmospheric pressure, wind, rainfall, sunshine, cloudiness, and other meteorological characteristics in a given region over a long period of time. Climate differs from weather, which is the present condition of these characteristics and their variations over shorter periods. Climate change involves long-term trends indicating a noticeable shift in climate. Primary climate indicators that can be monitored include ambient air temperature, atmospheric pressure, wind, relative humidity, precipitation amounts and timing, annual snowpack levels, streamflow volume and timing, and solar radiation. Current Conditions The planning area is within the Great Plains-Palouse Dry Steppe Province (Eco-region 331) of the Temperate Steppe Division (Division 330) in the Dry Domain (Bailey 1995). The planning area is in the rain shadow of the Rocky Mountains and is characterized as a semi-arid continental regime of the Great Plains grasslands. Average annual temperature is about 45 degrees Fahrenheit (°F). Winters are cold and dry while the summers are warm to hot. The frost-free season ranges from 90 days per year in the north to up to 140 days in the central and southern portions of the planning area. Maximum rainfall occurs in summer, with about 10 inches of precipitation per year. Because evaporation exceeds precipitation, the total supply of moisture is low. Specific climate data from seven Cooperative Observer Program weather stations (Baker, Broadus, Glendive, Jordan, Lame Deer, Miles City, and Sidney) within the planning area are shown in Tables 1 through 7 in the Air Resources and Climate Appendix. Data for each site spans 50 or more years. The average annual temperature is approximately 45 °F at most of the sites. Winters are cold and dry, with the lowest average minimum monthly temperature occurring in January and varying from 1°F in Sidney to 9.4°F in Baker. Summers are warm to hot with average maximum monthly temperatures occurring in July and varying from 84.9°F in Sidney to 90.7°F in Baker. The frost-free season ranges from 100 days per year in the north to more than 200 days further east. Mean annual precipitation at locations throughout the planning area varies from 11.7 to approximately 15.0 inches (Tables 1 through 7 in the Air Resources and Climate Appendix and Figure 3-1 here). Maximum rainfall occurs in summer. Because evaporation exceeds precipitation, the total supply of moisture is low. Average total annual snowfall varies from 27.4 to 46.3 inches (Tables 1 through 7 in the Air Resources and Climate Appendix). Based on hourly wind data from airport locations in Baker, Glendive, Jordan, Miles City, and Sidney (Table 8 in the Air Resources and Climate Appendix), average annual wind speeds varied over the region from 8.6 to 11.1 miles per hour (mph), while the average monthly wind speeds varied from approximately 7.7 to 12.7 mph. 3-2 FIGURE 3-1. AVERAGE ANNUAL PRECIPITATION IN MONTANA (1971 TO 2000) 3 - 3 AFFECTED ENVIRONMENT CHAPTER 3 CHAPTER Source: MNRIS 2004 CHAPTER 3 AFFECTED ENVIRONMENT March, April, and May are typically the windiest months of the year. Wind roses shown in Figures 1 through 5 of the Air Resources and Climate Appendix illustrate wind direction and wind speed at five locations within the planning area. Each wind rose consists of 16 arms whose radial positions indicate the frequency of wind blowing from the indicated direction. Longer arms indicate that the wind more frequently originates from the illustrated direction. Colored bands within each arm indicate the proportion of time that the wind blows with a given speed. Trends Climate trends are discussed in the Climate Change section. CLIMATE CHANGE Climate change includes two separate issues: cause and effect. Climate change is caused by physical and chemical changes in the environment, such as increased atmospheric concentrations of greenhouse gases (GHGs) and changes in albedo (surface reflectivity). The effects of climate change are widespread and include changes in climate indicators, such as temperature and precipitation, as well as effects on many natural resources, including air quality, water quality, flora, fauna, and many other resources on local, regional, national, and global scales. Climate change also affects human health and economic resources. Primary climate change indicators that can be monitored are similar to those for climate, with some additions. Atmospheric concentrations of GHGs, surface albedo, and ocean temperatures are also important climate change indicators, although these additional indicators are not monitored in the planning area. Current Conditions The Intergovernmental Panel on Climate Change (IPCC) concluded that “warming of the climate system is unequivocal” (IPCC 2007b, p. 5) and “most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations” (IPCC 2007b, p. 10). Chapter 9 of Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change addressed the causes of climate change. Some of the conclusions included: human-induced warming of the climate system is widespread, “it is likely” that there has been a substantial anthropogenic contribution to surface temperature increases since the mid-20th century, and surface temperature extremes have “likely” been affected by anthropogenic forcing. As with any field of scientific study, there are uncertainties associated with the science of climate change. This does not imply that scientists do not have confidence in many aspects of climate change science. Some aspects of the science are known with virtual certainty because they are based on well-known physical laws and documented trends. The temperature of the planet’s atmosphere is determined by the amount of solar radiation absorbed by the earth