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3.1-1 3.1 Introduction 3.0 AFFECTED ENVIRONMENT How to Read 3.1 Introduction 3.0 AFFECTED ENVIRONMENT How to Read Chapter 3.0 Chapter 3.0 provides background information on the various resources, resource uses, and programs managed by the Ely Field Office, and describes their existing conditions, trends, and current management. These subsections contain the following information: • Existing Conditions – description of each resource, resource use, or program. • Trends – description of the changes that are occurring in the existing conditions. • Current Management – description of how the Ely Field Office is currently managing the resource, resource use, or program. This format does not lend itself equally well to every resource, resource use, or program. Where a subsection is not applicable (e.g., trends for special designations), this is noted in the text. NEPA regulations require that an EIS contain a description of the environmental conditions that would be affected by the Proposed Action and alternatives. Thus rather than being encyclopedic, the Affected Environment chapter must focus on those resources and uses that would be impacted by the management direction presented in Chapter 2.0 for Alternatives A through E. The amount of quantitative information that is available to describe existing conditions and particularly trends varies from resource to resource. In general, resources that have formal administrative requirements, such as livestock grazing, have more quantitative information available than resources that are used casually, such as recreation. Where quantitative information is available, it is reflected in the existing conditions and trends descriptions. Where it is not available, the descriptions rely on the observational knowledge of the District developed by the Ely Field Office staff. All maps referenced in Chapter 3.0 are bound at the end of the chapter. 3.1 Introduction Given its size, topographic and geologic diversity, and the isolated nature of habitats within the basin and range landscape, it is not surprising that the Great Basin ecological region ranks second in diversity of imperiled species (Nichols et al. 1998; Rosenzweig 1995; Stein et al. 2000). The vast, visually monotonous areas of sagebrush and salt desert shrublands have a tendency to cloak the great diversity that exists in these ecological systems. Some biologists also have erroneously concluded that the area has relatively low biological diversity (Ehrlich et al. 1988). The Ely District lies in the middle of the Great Basin and exemplifies much of this biological diversity. The large variety of plant species has resulted in an abundance of habitats which are also reflected in the soils 3.1-1 3.0 AFFECTED ENVIRONMENT and their distribution on the District. Soils can indicate the natural mosaic in a landscape or watershed as the complex geology, climate, topography, vegetation, and time work together as factors of soil formation. Soil surveys are inventories of soils that indicate their spatial distribution. As an The restoration and maintenance of healthy ecological example, Map 3.1-1 shows the systems within watersheds is a primary focus for the future management of the Ely District. Healthy ecological systems are distribution of soil mapping units in Egan geographically diverse and change over time. They are Basin, a small watershed on the Ely compatible with soil potential and are resilient to disturbance. District. The soil map unit descriptions indicate where soils occur within map Resources and resource uses would be managed to restore or unit polygons and in what percentages maintain ecological health. Certain resource management they occur. Soil map unit descriptions changes and active treatments may need to be implemented, in also explain the relationship of soil types portions of watersheds, to accomplish this objective. Adaptive to their correlating plant communities. management would be pursued to avoid deteriorating conditions favoring invasive plants and catastrophic fires. Any projects would be implemented so as to result in a mosaic of By designing landscape projects within vegetation within a watershed. the capabilities of the soils, we are able to: In the long term, natural disturbance (such as drought or fire) would occur and fewer treatments would be needed to • Initiate watershed restoration using maintain ecological health. The result would be a variety of the adaptive management model vegetation phases within a watershed, which would provide and best available science. diverse, healthy conditions for future generations. • Develop strategies and implement actions to restore landscapes to an ecologically functioning condition. • Address all vegetation communities within the landscape with respect to vegetation state and transition pathways. • Have negligible adverse effects on soils. • Develop local watershed assessments based on ecological site potential. • Identify where current roads and trails may not be suited to the soil potentials and suggest a better alignment or configuration. 3.1-2 3.2 Air Quality and Climate 3.2 Air Quality and Climate 3.2.1 Existing Conditions Air Quality The current condition of air quality in the Ely District is good, relative to other areas of the nation. The air resource is primarily affected by particulate matter produced by land management activities or natural events on federally administered lands, including wildfire, prescribed burning, road or wind-blown dust, construction, mining, and vehicle use. Of these emission sources, most of the particulate matter of concern is produced from wildfires. Smoke emissions consist mostly of particulate matter with an aerodynamic diameter of 10 microns or less (PM10), as well as fine particulates with an aerodynamic diameter of 2.5 microns or less (PM2.5). According to Sisler et al. (1996), on a national level, the lowest concentrations of fine particulates occur in the Great Basin in Nevada. In other parts of the nation, the largest mass fractions of the fine aerosol are sulfate and organics; however, organic carbon (presumably from wildland burning) is the largest single component in the Great Basin (Sisler et al. 1996). Climatology and Meteorology Most of the District is internally drained and surface runoff is confined to the basins. A few drainages in the southern part of the District in Lincoln County drain into the Virgin River. Those drainages are, from west to east, Coyote Spring Valley, Meadow Valley Wash, and Toquop Wash. The White River Valley, which is located on the eastern edge of Nye County and extends into White Pine County, drains into the Coyote Spring drainage. The Virgin River drains into the Colorado River at Lake Mead, south of the Ely Districts southern boundary. The Ely District is located in the center of the Great Basin. Terrain is internally and externally drained. External drainage is south to the Colorado River. Otherwise, valley drainage is typical of the Great Basin and is covered with a variety of desert shrubs and grasses. The terrain consists of alternating mountain ranges and valleys primarily situated in the Basin and Range physiographic province. The southern portions of the District are more arid and consist of mixed aggraded desert plains situated between elevated terrain in north-south oriented mountain ranges. Elevations in the southern part of the District range from approximately 2,000 to more than 7,400 feet above mean sea level. Baseline meteorology, air quality, and dispersion conditions for the Ely District were characterized by data collected at the Ely airport starting in 1948 and continuing through the present. Data from Caliente were used to characterize the climate in the aggraded desert plains in the southern portions of the District. The climate in the northern portion of the Ely District is classified as a cool semi-arid steppe, and the southern portion of the Ely District is classified as a hot arid desert. The climate is characterized by low rainfall, low humidity, clear skies, and relatively large annual and diurnal temperature ranges (Brown 1974). Because of the typically dry atmosphere, bright sunny days and clear nights frequently occur. This in turn allows rapid heating of the ground surface during daylight hours and rapid cooling at night. The average 3.2-1 3.0 AFFECTED ENVIRONMENT range between the highest and the lowest daily temperatures is about 30 to 35 degrees Fahrenheit. Daily ranges are larger in summer than the winter. Since heated air rises and cooled air sinks, winds tend to blow upslope during the day and downslope at night. This up-slope and down-slope cycle generally occurs in all the geographical features, including mountain range slopes and river courses. The larger the horizontal extent of the feature, the greater the volume of air that moves in the cycle. Terrain diversity causes complex movements in the cyclic air patterns, with thin layers of moving air embedded within the larger scale motions. The low-level, thermally driven winds also are embedded within larger scale upper wind systems (synoptic winds). Synoptic winds in the region are predominantly west to east, are characterized by daily weather variations that enhance or diminish the boundary layer winds, and are substantially channeled by regional and local topography. Atmospheric Dispersion The most important meteorological factors that influence the dispersion of pollutants in the atmosphere are mixing height, wind speed, wind direction, and stability. Mixing height is the thickness of the layer of air above ground within which rising warm air from the surface
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