Final Environmental Impact Statement for the Nevada Test Site and Off-Site Locations

5.5 Unavoidable Adverse Effects

Unavoidable impacts constitute a substantial adverse change to existing environmental conditions that cannot be fully mitigated by implementing mitigation measures. The potential unavoidable adverse impacts that could arise from implementing the alternatives discussed in Chapter 5 are summarized below. Under Alternatives 1, 2, 3, and 4, the unavoidable adverse impacts of past underground nuclear testing activities would remain.

5.5.1 Alternative 1

The unavoidable adverse effects that would result from implementing Alternative 1 are presented in the following sections.

5.5.1.1 Nevada Test Site

All continuing programs and operations at the NTS would produce some environmental impacts that are not mitigated. The unavoidable adverse effects at the NTS are presented in this section.

UNDERGROUND TESTINGFirst and foremost among the unavoidable adverse effects are the impacts resulting from underground testing, both in terms of the magnitude of the impacts and their duration. As noted in the Final Environmental Impact Statement, Nevada Test Site, Nye County, Nevada (ERDA, 1977), other activities conductedat the NTS "for the most part are registered immediately and those effects are very small in comparison with the effects of underground nuclear testing." Under Alternative 1, the DOE would maintain the readiness and capability to conduct one or more underground nuclear weapons tests, if directed by the President, within the 10-year timeframe.

The major unavoidable effects of underground testing include the release of large quantities of radioactivity into the subsurface, the formation of new subsidence craters, and the generation of ground motion that might be felt outside the boundaries of the NTS.

The underground nuclear tests conducted under Alternative 1 would contaminate the subsurface with a large amount of short- and long-lived radionuclides. As discussed in Section 4.1.2 , approximately 45,000 Ci/kt wouldremain in the subsurface 180 days after a test. The types of radionuclides produced are further discussed inSection 4.1.5.2 , with tritium likely to be the most abundant radionuclide. Many of the other radionuclides would remain bound up in the melt glass in the event cavity. Some groundwater might be unavoidably contaminated if the shot cavity is below or intercepts the water table. The surface areas below which the contaminants are released are strictly controlled for safety and security reasons.

An underground nuclear test would also unavoidably disrupt the integrity of the subsurface geologic environment. Contamination might extend as far as five times the radii of the cavity from the shot point. Following the tests, subsidence craters often form because of the collapse of the geologic units. These impacts preclude the use of the geologic values inherent at the site for the long term. Subsidence craters alter the natural surface drainage and might locally increase soil erosion. Preferential drainage from subsidence craters down the rubble chimney to the shot cavity might occur and might contaminate the groundwater as a result, although little data exist to determine whether this is the case.

Ground motions accompanying underground nuclear explosions and some other tests conductedat the NTS are felt in Las Vegas, Nevada, and elsewhere in the surrounding region. Occasionally, ground motion from a larger test might cause nonstructural off-site damage, such as plaster cracks. A larger underground test could cause perceptible motion at off-site locations, particularly in high-rise structures in Las Vegas.

SUBCRITICAL EXPERIMENTSUnderground subcritical experiments would produce some physical effects on the geologic media. Approximately 2,314 m³ (81,700 ft³) would be disturbed each year in association with the conduct of up to four experiments. Irreversible effects would include the deposition of radiological material within and near the cavity mined in the subsurface. Approximately 20 acres of surface geologic media are currently disturbed in association with the Lyner Complex, where these experiments would be conducted.

LAND USELand uses would continue to be restricted at the underground test areas and at the radioactive waste management sites because of subsurface contamination and the presence of landfilled wastes, respectively. Revegetation of the surfaces as sections of the radioactive waste management sites are closed would create stable soils and better habitat. Decommissioning of some contaminated facilities would result in their demolition. If the facility is of historic significance, as many of them are, the loss of the structure would represent an unavoidable adverse impact. The loss would be partially mitigated by data gathered in accordance with the documentation requirements of the Historical American Buildings Survey/Historical Engineering Records system of the National Park Service.

Airspace restrictions would continue to prohibit commercial and general aviation use. Because the NTS airspace is nearly surrounded by NAFR Complex restricted airspace, the added increment of limitation would be minor.

TRANSPORTATIONVehicular traffic at the NTS would continue at about 1,890 average daily trips, while off-site trips would continue at a rate of about 2,480. The contribution of NTS-related traffic to the Las Vegas area’s already unsatisfactorylevel of service on major roadways would be minimal. Though a small increment in emissions would not cause additional violations, mobile-source emissions would continue to contribute to theLas Vegas Valley’s sometimes poor air quality.

GEOLOGY AND SOILSThe impact to geology and soils is presented in the discussion of the underground testing effects.

HYDROLOGYThe impacts to hydrology are discussed in the underground testing effects section.

BIOLOGICAL RESOURCESSurface disturbance associated with remediation, construction, and testing programs would cause unavoidable impacts on habitat. Surface-disturbing activities may kill or displace wildlife such as small mammals, reptiles, and soil-dwelling invertebrates. If ground clearing for construction occurs during the breeding season, the eggs of birds in nests on the ground within a project area may be destroyed. Despite attempts to find and relocate desert tortoises before events occur that could threaten them, some tortoises, particularly juveniles, might be missed and could be killed by heavy equipment or vehicles. Training exercises that take place in desert tortoise habitat could result in tortoise mortality. Normal road traffic on the NTS has resulted in less than one tortoise mortality per year. This rate would be anticipated to continue. Wildfires in tortoise habitat would also constitute a source of potential tortoise mortality.

Sumps at the underground test area wells and open containers at the proposed Liquid Waste Treatment System Facility might attract some birds, bats, or mammals and cause their deaths through drowning or contamination. Although not studied, it is likely that losses would be very small. Developed areas of the NTS that have buildings, roads, storage lots, sewage lagoons, and other infrastructure would remain unavailable for natural habitat.

AIR QUALITYCertain activities would produce PM₁₀ and mobile-source emissions. Particulate matter less than 10 microns (PM₁₀) would be produced through surface disturbance. Particulates would not threaten Nye County’s attainment, however, and would only contribute 0.03 percent ofthe County’s total. Similarly, the PM₁₀ contribution to Clark County’s total would be very small.

VISUAL RESOURCESDeveloped areas of the NTS that have buildings, roads, storage lots, sewage lagoons, and other infrastructure would continue in many cases to affect the viewshed. Project areas are initially accessed by graded gravel or dirt roads. If the projects become long-term, these roads would require upgrading, which would have increased impacts on habitat and visual resources.

CULTURAL RESOURCESIf cultural resources exist inan area too highly contaminated to survey or to conduct data recovery, then these resources may be lost when remediation disturbs the surface. This is an unavoidable impact. Impacts resulting from the illicit collection of artifacts by NTS workers may be partially mitigated through education, but it is likely that some workers would persist in such activities. This would be an unavoidable impact.

OCCUPATIONAL AND PUBLIC HEALTH AND SAFETYPreparations for activities, such as the Big Explosives Experimental Facility and radioactive waste management sites, would result in new surface disturbances. Similarly, Environmental Restoration Program activities would disturb surface areas during the process of remediating industrial sites, plutonium-contaminated soils, Defense Nuclear Agency sites, and during the preparation of well pads for groundwater characterization. Approximately 1,890 acres on the NTS and 1,169 acres on the NAFR Complex would be affected. It should be noted, however, that the restoration of contaminated areas represents the mitigation of impacts that have resulted from past actions at the NTS. Thus, the unavoidable negative impacts associated with these actions would be counterbalanced by the reduction in the risk to human health caused by the contamination.

NOISEWhile there would be no off-site impacts, temporary high noise levels would prevail in the proximity of operations like the Spill Test Facility, drilling operations, and the Big Explosives Experimental Facility during detonations.

5.5.1.2 Tonopah Test Range

Remediation of the environmental restoration sites and the SoilsMedia Corrective Action Unit areas would result in removal of the vegetation and surface soil layers. This would produce PM₁₀ at about 27 kilograms (kg) (60 pounds [lb]) per acre per year. Particulates and mobile-source emissions represent a minor degradation of the air quality. Vegetation and some animals would be destroyed, but no population's viability would be threatened. Visual resources would be unavoidably altered. Removal of vegetation and disturbed soils that differ from the surroundings in color or tone would become visually evident until revegetation had progressed. In some cases, however, vegetation types might be substantially different from that in surrounding areas if rehabilitation with local native species is unsuccessful. The change in species could produce areas that differ in color, tone, or texture from the surroundings. Since these areas are not located where they can be observed from public viewpoints and are classified as common scenery, the effects to visual resources would be minor.

GEOLOGY AND HYDROLOGYGrading of the surface for restoration of the Soils Media Corrective Action Unit sites would cause some minor alteration of surface-water drainage patterns and some accelerated erosion until stabilization occurred. Minor use of groundwater for dust control and revegetation of the Soils Media Corrective Action Unit sites would be an unavoidable, but minor, impact.

NOISELocal noise from heavy equipment and drill rigs would be an unavoidable, but minor, impact.

CULTURAL RESOURCESIn some cases, contamination levels might pose an unacceptable high risk to archeological surveyors. Any cultural resources in these areas would be lost to surface disturbance during remediations. The necessity of removing cultural resource materials that would otherwise be destroyed by remediation activities would represent a benefit to the present knowledge base. However, data recovered represent a benefit to the present knowledge base. However, materials removed from their context and studied with present technology would be unavailable for subsequent study using improved future technologies.

5.5.1.3 Project Shoal and Central Nevada Test Areas

Monitoring, characterization, and minor remediation would result in very limited surface disturbance, totaling about 54 acres. This would result from well drilling, minor excavation, and backfilling of the Project Shoal area emplacement shaft. Small amounts of PM₁₀ and mobile-source emissions would be produced. Heavy equipment and drill rig operations would produce sporadic local noise.

Remediation activities might require data recoveryfrom some cultural resource sites. Removing cultural resource materials that would otherwise be destroyed by these activities would represent a benefit to the present knowledge base. However, materials removed from their context and studied with present technology would be unavailable for subsequent study using improved future technologies. Impacts resulting from the illicit collection of artifacts by workers may be partially mitigated through education, but it is likely that some workers would persist in such activities. This would be an unavoidable impact.

Geologic media contaminated by the test would remain contaminated and would be unavailable for other uses. Groundwater in the vicinity of the shot cavity at each test area might be contaminated and, if so, would remain unavailable for any use.

5.5.2 Alternative 2

The unavoidable adverse effects resulting from implementation of Alternative 2 are discussed in the following sections.

5.5.2.1 Nevada Test Site

Closure of operations at the NTS would produce some environmental impacts that could not be mitigated, but significantly fewer than those under Alternative 1. Areas developed with buildings, roads, storage lots, sewage lagoons, and other infrastructure, except as slowly modified by deterioration, would remain unavailable for natural habitat and would continue to affect the viewshed in many cases. There would be minor production of PM₁₀ from operations at the radioactive waste management sites as they finish operations and close, and from security patrols on unpaved roads. Monitoring and patrols wouldproduce minor mobile-source emissions. These would be reduced when compared to Alternative 1. The facilities would no longer contribute to research and development, training, and employment levels.

Deterioration of unmaintained facilities and infrastructure would result in a need for major repairs or demolition and reconstruction if the site were to be reactivated at some future time.

Closure of the NTS would result in unavoidable adverse impacts to the regional socioeconomic conditions, including the loss of a substantial number of relatively high-paying jobs, increases in unemployment rates, loss of economic diversification, and out-migration of DOE and contractor employees and their families. These adverse effects would be relatively short term. Unrelated and economic community growth would be expected to overshadow these effects in time.

Preparations for closure activities at the radioactive waste management sites would result in minor new surface disturbances. At those sites where action would be necessary because of hazard or monitoring requirements, the Environmental Restoration Program would disturb some surface areas in the process of stabilizing or remediating industrial sites and Defense Nuclear Agency sites and in the preparation of well pads for groundwater monitoring. The total disturbance would be considerably less than with Alternative 1.

Subsurface contamination from historic underground nuclear tests would continue to restrict access to the underground zone surrounding the expended test for reasons of safety and security. The presence of subsidence craters would result in alteration of surface drainages and increased soil erosion. Most of the radionuclides are thought to be bound up in the melt glass surrounding the shot cavity. However, some groundwater would be unavoidably contaminated if the shot cavity was below, or intercepted, the water table. Preferential drainage from subsidence craters down the rubble chimney might occur and might contaminate the groundwater. The underground effects of this alternative vary little from those in Alternative 1 except that there would be no remediation of theunderground testing areas other than possible long-term institutional controls.

Surface disturbances have caused unavoidable impacts on habitat that would not be restored under Alternative 2. Normal road traffic at the NTS has resulted in less than one tortoise mortality per year. This rate would be anticipated to decline with the decreased road traffic under Alternative 2. Wildfires in tortoise habitat would also constitute a source of potential tortoise mortality.

Shutdown of some wells would result in drying up of associated sumps that are presently perennial water sources. Wildlife that is dependent upon these sources and unable to relocate would be unavoidably lost.

Sumps at Underground Test Area wells would be temporarily wet during sampling activities and might attract some birds, bats, or mammals and cause their deaths through drowning or contamination.

Under Alternative 2, on-site average daily trips at the NTS would decrease by 1,868, while off-site trips would decrease by 760 in 1996, and by 1,440 in 2000 and 2005. The contribution of NTS-related traffic to the Las Vegas area's already unsatisfactory level of service on major roadways would be minimal. Though a small increment that would not cause additional violations, mobile-source emissions would continue to contribute to the Las Vegas Valley's sometimes poor air quality.

The NAFR Complex airspace restrictions would continue to prohibit commercial and general aviation use. Since the NTS airspace is nearly surrounded by NAFR Complex restricted airspace, the added increment of limitation would be minor.

Since the site would be locked up, the NTS would be unavailable for most human-oriented land use. Natural recovery would slowly progress, and ecosystems would begin to approach an equilibrium largely unaffected by humans.

Impacts resulting from the illicit collection of artifacts by workers may be partially mitigated through education, but it is likely that some workers would persist in such activities. This would be an unavoidable impact.

5.5.2.2 Tonopah Test Range

No Environmental Restoration Program projects would occur except at those sites that present an immediately hazardous situation. This would result in no change to present land use. Presently, applicable land-use restrictions would continue to limit the types of access and activities for which these lands could be used.

Affected soils would remain unavoidably contaminated, thereby restricting their use and potentially reducing their productive capacity. Under certain conditions, it would be possible for surface water to transport contamination to other areas and become contaminated itself. Similarly, under certain uncommon conditions, it would be possible for air to suspend and transport contamination to other areas.

5.5.2.3 Project Shoal and Central Nevada Test Areas

Geologic media contaminated by each of the tests would remain so and would be unavailable for other use. Groundwater in the vicinity of each shot cavity might be contaminated and, if so, would remain unavailable for any use. A contaminated mud pit at the Central Nevada Test Area would not be remediated.

5.5.3 Alternative 3

The unavoidable adverse effects resulting from implementation of Alternative 3 are discussed in the following sections.

5.5.3.1 Nevada Test Site

The unavoidable adverse environmental impacts addressed in this alternative would include those discussed for Alternative 1, as well as additional ones. New projects, which would include a facility for handling and storing weapons-usable fissile materials; expansion of the Device Assembly Facility; and a large, heavy-industrial facility, would increase the amount of land committed to other land use. Some additional disposal area would result from increased disposal of low-level waste, mixed waste, and sanitary waste. Since this disposal would occur within the boundaries of the sitesalready designated for waste disposal, it would not represent a significant new commitment of land use.

No specific location has been proposed for some of these projects, so it is not possible to identify impacts precisely. Therefore, a range of potential impacts is discussed in terms of how these differ from the impacts in Alternative 1.

Visual impacts would vary with location, but would generally be negligible because most of the NTS is not visible from public viewpoints, and much of the site has scenery common to the region.

An added increment of air contaminants would result both from construction and operations. The effect of one or more underground nuclear tests would be the same as under Alternative 1.

Most of the additional projects proposed would affect relatively limited surface areas. The notable exception would be the alternative energy proposal. Depending upon the technology or technologies pursued, the solar energy projects could affect up to 2,400 acres. If located in habitats containing plants of limited distribution, the viability of the population could be threatened. Increased road traffic, in addition to habitat destruction and crushing because of construction activity, would result in increased tortoise mortality. The overall doubling of traffic on the NTS would likely produce tortoise mortality of about two per year.

Increased groundwater pumping at the NTS might have the potential to reduce discharge at regional springs such as Devils Hole and Ash Meadows. Devils Hole harbors a population of pupfish, which is very sensitive to falling water levels. Ash Meadows has a great number of sensitive species of fish, invertebrates, and plants dependent upon its springs.

Project areas would initially be accessed by graded gravel or dirt roads. Traffic impacts resulting from the construction of new facilities would peak during the construction phase. If the projects become long term, these roads would require upgrading that would create additional visual, erosional, and habitat impacts.

Average daily trips on the NTS would be about 13,300, an increase of 11,400 over Alternative 1. Additional off-site average daily trips over Alternative 1 would range from 210 in 1996 to a high of 1,520 in 2000. This would not cause any air-quality violations. The increased traffic would add a small increment to the Las Vegas area's freeways and arterials, which are anticipated to be at unacceptable levels of service without any NTS activity. This would also add a small increment of pollution to the sometimes poor air quality of the Las Vegas Valley.

Because of the presence of a doubled workforce, an increase in vandalism to cultural resource sites would occur. Despite efforts to control workers’ impacts on cultural resources by training, site avoidance through relocation of activities, or data recovery, some individuals would persist in vandalizing sites. This is, to some degree, an unavoidable impact.

Decommissioning of some contaminated facilities would result in their demolition. If the facility is of historic significance, as many of them are, the loss of the structure would represent an unavoidable adverse impact. The loss would be partially mitigated by data gathered in accordance with the documentation requirements of the Historical American Buildings Survey/Historical American Engineering Records system of the National Park Service.

5.5.3.2 Tonopah Test Range

Risk to the public would remain the same as that discussed under Alternative 1.

Remediation of the Environmental Restoration Program sites and the Soils Media Corrective Action Unit areas would unavoidably result inremoval of the vegetation and surface soil layers. This would produce PM₁₀ at a rate of 27 kg (60 lb) per acre per year in the case of the Environmental Restoration Program sites. Particulates and mobile-source emissions would represent a degradation of air quality, though minor in this case. Vegetation and some animals would be destroyed, but no population's viability would be threatened. Visual resources would be unavoidably altered. Removal of vegetation and disturbance of soils that differ from the surroundings in color or tone would become visually evident until recovery had progressed. In some cases, however, vegetation types might be substantially different from that in surrounding areas if rehabilitation with local native species is unsuccessful. The change in species could produce areas that differ in color, tone, or texture from the surroundings. Since these areas are not located where they can be observed from public viewpoints and are classified as common scenery, the effects to the visual resource would be minor.

Grading of the surface for restoration of the Soils Media Corrective Action Unit sites would cause some minor alteration of surface-water drainage patterns and some accelerated erosion until stabilization occurred. Minor use of groundwater for dust control and revegetation of the Soils Media Corrective Action Unit sites would be an unavoidable, though minor impact.

Local production of noise from heavy equipment and drill rigs would be a minor impact.

The necessity of removing cultural resource materials that would otherwise be destroyed by remediation activities would represent a benefit to the present knowledge base. However, materials removed from their context and studied with present technology would be unavailable for subsequent study using improved future technologies. In some cases, contamination levels might pose an unacceptably high risk to archeological surveyors. Any cultural resources in these areas would be lost to surface disturbance during remediation.

5.5.3.3 Project Shoal and Central Nevada Test Areas

Monitoring, characterization, and any minor remediation would result in very limited surface disturbance. This would result from well drilling, minor excavation, and backfilling of the ProjectShoal Area emplacement shaft. Small amounts of PM₁₀ and mobile-source emissions would be produced. Heavy equipment and drill rig operation would produce temporary local noise. Drilling sumps would pose a minor threat to some animals. The level of habitat recovery would depend upon the degree to which native plants could be reestablished.

Geologic media contaminated by the test would remain contaminated and would be unavailable for other uses. Groundwater in the vicinity of the shot cavity might be contaminated and, if so, would remain unavailable for any use.

5.5.3.4 Eldorado Valley

Land used for this proposal is designated for renewable energy development and would be committed to a single use. Depending on where in Eldorado Valley the project is sited, existing land use would be affected to a greater or lesser degree. Some of the more intensive present uses of the playa are recreational, including land sailing, model aircraft flying, ultralight operations, off-highway vehicle use, and camping. Areas off the playa are used for bird hunting and off-highway vehicle races. All these uses would be incompatible within the area developed for solar generation; those uses that disturb the surface would probably be considered undesirable in the vicinity of collectors where they cause airborne particulates. The loss of these opportunities would be an unavoidable adverse impact.

Some power and natural gas line construction would be necessary. This construction would create additional access roads in the region. Access roads would cause habitat fragmentation and adverse effects to tortoises and other species. Fragmentation would reduce or prevent movementand consequently would affect gene-pool flow in less mobile species like tortoises. Construction of the projects would cause an increase in traffic in the area with potential to increase tortoise mortality on the highways and roads and on the construction sites themselves. A total of up to 2,400 acres of habitat could be lost to project construction, and approximately 42 acres may be lost to power and pipe line construction. A similar amount of soils would be disturbed.

The site lies within the Class B airspace (Terminal Control Area) for McCarran International Airport. Glare from the collectors could affect aircraft operations. Should this occur, operations at the Solar Enterprise Zone facility would have to be altered to lessen the effect, which would adversely affect its production, or airport operations would have to be modified to avoid this conflict.

Although the scenery is common to the region, the site is viewed by large numbers of the public travelingHighway 95 and engaging in recreational pursuits. There are also three U.S. Bureau of Land Management Wilderness Study Areas within the site’s view shed. Construction of the solar facilities and associated infrastructure would create considerable change in the visual environment of the valley.

Surface disturbance and construction would result in the production of PM₁₀ and mobile-source emissions. Local noise levels would be present during construction. Recovery of cultural resource data would be a short-term benefit, but would reduce the opportunity to gain greater data recovery using enhanced future technologies.

5.5.3.5 Dry Lake Valley

Land used for this proposal would be committed to a single use. Some areas of the valley are used for occasional off-highway vehicle races. This use would be incompatible within the area developed for solar generation, and because it disturbs the surface, it would probably be considered undesirable in the vicinity of collectors because of airborne particulates. The loss of vehicle race opportunities would be an unavoidable adverse impact.

A limited amount of power and natural gas line construction would be necessary. A proposal exists to construct a water line to Coyote Spring Valley to support the facility. This construction would create additional access roads in the region. Access roads would cause habitat fragmentation and adverse effects to tortoises and other species. Fragmentation would reduce or prevent movement and consequently would affect gene-pool flow in less mobile species like tortoises. The water line has the potential to affect a large area of tortoise habitat in the area to the north along the west side of the Arrow Canyon Range. Construction of the projects would cause an increase in traffic in the area with potential to increase tortoise mortality on the highways and roads and on the construction sites. A total of 2,400 acres of habitat could be lost to project construction, and approximately 560 acres may be lost to power and pipe line construction.

Depending on the quantity of water involved and the source of that water, the use of groundwater from Coyote Spring Valley would have the potential to affect discharge at Muddy Spring, which has a population of threatened Moapa dace.

The site lies within the Class B (Terminal Control Area) for McCarran International Airport and Nellis Air Force Base. Glare from the collectors could affect aircraft operations. In that event, either the solar facility would have to alter its operations to lessen the effect, which would adversely affect its production, or the airfields would have to modify their operations to avoid conflict.

Although the scenery is common to the region, the site is viewed by large numbers of the public traveling the highways and engaging in recreational pursuits. Construction of the solar facilities and associated infrastructure would have a large impact on the visual environment.

Surface disturbance and construction would result in the production of PM₁₀ and mobile-source emissions. Local noise levels would be present during construction.

Recovery of cultural resource data would be a short-term benefit, but would reduce the opportunity togain greater data recovery using enhanced future technologies.

5.5.3.6 Coyote Spring Valley

Land used for this proposal would be committed to a single use. Some areas of the valley are lightly used for dispersed recreation. This use would be incompatible within the area developed for solar generation. The loss of the opportunities would be a minor unavoidable adverse impact.

Substantial power and natural gas line construction would be necessary. A water line would have to be constructed to support the facility. This construction would create additional access roads in the region. Access roads would cause habitat fragmentation and adverse effects to tortoises and other species. Fragmentation would reduce or prevent movement and consequently would affect gene-pool flow in less mobile species like tortoises. Construction of the projects would cause an increase in traffic in the area with potential to increase tortoise mortality on the highways and roads, and on the construction sites. A total of 2,400 acres of habitat could be lost to project construction, and approximately 960 acres may be lost to power and pipe line construction. The habitat in Coyote Spring Valley has been designated by the U.S. Bureau of Land Management as critical habitat for the threatened desert tortoise. Specific project locations are necessary before a determination can be made regarding the potential to adversely affect any other sensitive species present in the valley.

Depending on the quantity of water involved, the use of groundwater from Coyote Spring Valley would have the potential to affect discharge at Muddy Spring, which has a population of threatened Moapa dace. The use of groundwater might also have the potential to affect local springs in the valley.

Scenic quality of the site has been designated Class B. The site is viewed by the public traveling U.S. Highway 93 and engaging in recreational pursuits. There are also three U.S. Bureau of Land Management Wilderness Study Areas within the site’s viewshed. Construction activities of the solar facilities and associated infrastructure would greatlychange the landscape character of Coyote Spring Valley and have an adverse impact on the visual environment.

Recovery of cultural resource data would be a short-term benefit, but would reduce the opportunity to gain greater data recovery using enhanced future technologies.

5.5.4 Alternative 4

The unavoidable adverse effects resulting from the implementation of Alternative 4 are discussed in the following sections.

5.5.4.1 Nevada Test Site

Continued operations at the NTS, even without the Defense Program, would produce some environmental effects that remain unmitigated. Areas would remain developed in buildings, roads, storage lots, sewage lagoons, and other infrastructure, as in Alternative 1, and would be unavailable for natural habitat. In addition, development of a Solar Enterprise Zone facility would affect a land base of up to 2,400 acres. This may substantially increase the impact on public viewsheds as the solar site proposed for Area 22 may be visible from U.S. Highway 95. Increased public access for museum visits, road races, special hunts, and other recreation would make substantially more area of the NTS visible to increasing numbers of visitors, thus increasing the impact of existing or new development on visual resources. However, much of the scenery in the region is common. Some operations would produce PM₁₀ and mobile-source emissions.

Underground test areas would unavoidably remain contaminated and result in continued restricted access to the subsurface. Construction sites and subsidence craters would result in altered surface drainage and increased soil erosion. Most of the radionuclides are thought to be bound up in the melt glass surrounding the shot cavity. However, some groundwater would be unavoidably contaminated when the shot cavity was below, or intercepted, the water table. Preferential drainage from craters down the rubble chimney might occur and might contaminate the groundwater as a result. There would not be the small additional increment ofimpact with this alternative as no further underground nuclear tests would occur.

Surface disturbance would cause unavoidable impacts on habitat. While no additional increment would ensue because of the Defense Program, a Solar Enterprise Zone facility would require a substantial acreage. If the Solar Enterprise Zone facility were located in an area that supports sensitive species, a threat to their viability would exist. Reduced habitat and increased risk of crushing during construction and on roads would unavoidably affect tortoises if the sites were located in their habitat. Increased groundwater use for the Solar Enterprise Zone efforts might adversely affect discharge at regional springs. Reductions at Devils Hole and Ash Meadows could have a large impact on the numerous sensitive species depending on the water levels and discharge rates.

Some mortality might occur to birds, bats, and other mammals through drowning or contamination at the Underground Test Area well sumps and open tanks at the Liquid Waste Treatment System Facility.

Particulate and mobile-source emissions would not threaten attainment in Nye County. They would not cause additional violations in Clark County, but would add a small increment to Clark County’s existing air-quality problems.

Average daily trips offsite would fall by 330 relative to Alternative 1. This would cause an additional small increment to the unsatisfactory levels of service on key roadways in the Las Vegas Valley.

Termination of Defense Program activities at the NTS would result in unavoidable adverse impacts to the regional socioeconomic conditions including the loss of 4,625 (1,496 direct and 3,129 secondary) jobs in 1996 and 7,981 (2,748 direct and 5,233 secondary) in 2000 and 2005. These adverse effects would be relatively short-term, and economic and natural growth would be expected to compensate for these effects over time.

Because of the presence of landfill wastes, some land uses would continue to be restricted at the radioactive waste management sites and the solid waste landfills.

If cultural resources exist in an area too highly contaminated to survey or to conduct data recovery, then these resources may be lost when remediation disturbs the surface. This is an unavoidable impact. Impacts resulting from the illicit collection of artifacts by NTS workers may be partially mitigated through education, but it is likely that some workers would persist in such activities. This would be an unavoidable impact. Increased numbers of workers and other staff during portions of the period analyzed in this EIS would result in an unavoidable adverse impact on cultural resources. Decommissioning of some contaminated facilities would result in their demolition. If the facility is of historic significance, as many of them are, the loss would be partially mitigated by data gathered in accordance with the documentation requirements of the Historical American Buildings Survey/Historical American Engineering Record system of the National Park Service.

5.5.4.2 Tonopah Test Range

Remediation of the Environmental Restoration Program sites and the Soils Media Corrective Action Unit areas would unavoidably result in removal of the vegetation and surface-soil layers. This would produce PM₁₀ in the case of the Environmental Restoration Program sites. Particulates and mobile-source emissions would represent a degradation of the air quality, though minor in this case. Vegetation and some animals would be destroyed, but no population's viability would be threatened. Visual resources would be unavoidably altered. Removal of vegetation and disturbance of soils that differ from the surroundings in color or tone would become evident until recovery had progressed. In some cases, however, vegetation types might be substantially different from that in surrounding areas if rehabilitation with local native species were unsuccessful. The change in species could produce areas that differ in color, tone, and/or texture from the surroundings. Since these areas are not located where they can be observed from public viewpoints and are classified as common scenery, the effects to the visual resource would be minor.

Grading of the surface for restoration of the Soils Media Corrective Action Unit sites would cause some minor alteration of surface-water drainage patterns and some accelerated erosion untilstabilization occurred. Minor use of groundwater for dust control and revegetation of the Soils Media Corrective Action Unit sites would be an unavoidable, though minor impact.

Local noise from heavy equipment and drill rigs would be a minor impact.

The necessity of removing cultural resource materials that would otherwise be destroyed by remediation activities would represent a benefit to the present knowledge base. However, materials removed from their context and studied with present technology would be unavailable for subsequent study using improved future technologies. In some cases, contaminated lands might pose an unacceptably high risk to archeological surveyors. Any resources in these areas would be lost to surface disturbance during remediation.

5.5.4.3 Project Shoal and Central Nevada Test Areas

Well drilling and characterization activities might require data recovery from some cultural resource sites. Removing cultural resource materials that would otherwise be destroyed by these activities would represent a benefit to the present knowledge base. However, materials removed from their context and studied with present technology would be unavailable for subsequent study using improved future technologies. Impacts resulting from the illicit collection of artifacts by workers may be partially mitigated through education, but it is likely that some workers would persist in such activities. This would be an unavoidable impact.

Geologic media contaminated by the tests would remain contaminated and would be unavailable for other uses. Groundwater in the vicinity of the shot cavity might be contaminated and, if so, would remain unavailable for any use.

5.5.4.4 Eldorado Valley

Land used for this proposal would be designated for renewable energy development and would be committed to a single use. Depending on where in Eldorado Valley the project is sited, existing land uses would be affected to a greater or lesser degree. Some of the more intensive present uses of the playa are recreational, including land sailing, model aircraft flying, ultralight operations, off-highway vehicle use, and camping. Areas off the playa are used for bird hunting and off-highway vehicle races. All these uses would be incompatible within the area developed for solar generation, and those uses that disturb the surface would probably cause airborne particulates. This would be considered undesirable in the vicinity of solar collectors. The loss of these opportunities would be an unavoidable adverse impact.

Some power and naturalgas line construction would be necessary. This construction would create additional access roads in the region. Access roads would cause habitat fragmentation and adverse effects to tortoises and other species. Fragmentation would reduce or prevent movement and, consequently, would affect gene-pool flow in less mobile species like tortoises. Construction of the projects would cause an increase in traffic in the area with the potential to increase tortoise mortality on the highways and roads and on the construction sites themselves. A total of 2,400 acres of habitat could be lost to project construction, and an unknown additional amount would be lost to power and pipe line construction.

The site lies within the Class B airspace (Terminal Control Area) for McCarran International Airport. Glare from the solar collectors could affect aircraft operations. Should this occur, operations at the Solar facility would have to be altered to lessen the effect, which would adversely affect its production, or airport operations would have to be modified to avoid this conflict.

Although the scenery is common to the region, the site is viewed by large numbers of the public travelingHighway 95 and engaging in recreational pursuits. There are also three U.S. Bureau of Land Management Wilderness Study areas within the site’s viewshed. Construction of the solar facilitiesand associated infrastructure would create considerable change in the visual environment of the valley.

Surface disturbance and construction would result in the production of PM₁₀ and mobile-source emissions. Local noise levels would be present during construction.

Recovery of cultural resource data would be a short-term benefit, but would reduce the opportunity to gain greater data recovery using enhanced future technologies. Construction of roads in areas proposed for solar generating facilities may increase access to archaeologically sensitive areas. This could result in unavoidable impacts such as vandalism and illicit artifact collecting.

5.5.4.5 Dry Lake Valley

Land used for this proposal would be committed to a single use. Some areas of the valley are used for occasional off-highway vehicle races. These races would be incompatible within the area developed for solar generation because the races disturb the surface. The loss of vehicle race opportunities would be an unavoidable adverse impact.

A limited amount of power and natural gas line construction would be necessary. A proposal exists to construct a water line to Coyote Spring Valley to support the facility. This construction would create additional access roads in the region. Access roads would cause habitat fragmentation and adverse effects to tortoises and other species. Fragmentation would reduce or prevent movement and, consequently, would affect gene-pool flow in less mobile species like tortoises. The water line has the potential to affect a large area of tortoise habitat in the area to the north along the west side of the Arrow Canyon Range. Construction of the projects would cause an increase in traffic in the area with potential to increase tortoise mortality on the highways and roads and on the construction sites. A total of 2,400 acres of habitat could be lost to project construction; and 560 acres would be lost to power and pipe line construction. Depending upon the quantity of water involved, the use of groundwater from Coyote Spring Valley would have the potential to affect discharge at Muddy Spring, which has a population of threatened Moapa dace.

The site lies within the Class B airspace (Terminal Control Area) for McCarran International Airport and Nellis Air Force Base. Glare from the collectors could affect aircraft operations. Should this occur, operations at the Solar Enterprise Zone facility would have to be altered to lessen the effect, which would adversely affect its production, or airport operations would have to be modified to avoid this conflict.

The scenery is common to the region, and the site is viewed by the public traveling Highway 93 and Interstate 15 and engaging in recreational pursuits. However, construction of solar facilities and associated infrastructure would have a minor impact on the visual environment because of extensive man-made modifications to the area.

5.5.4.6 Coyote Spring Valley

Land used for this proposal would be committed to a single use. Some areas of the valley are lightly used for dispersed recreation. This use would be incompatible within the area developed for solar generation. The loss of recreation opportunities would be a minor unavoidable adverse impact.

Substantial power and natural gas line construction would be necessary. A water line would have to be constructed to support the facility. This construction would create additional access roads in the region. Access roads would cause habitat fragmentation and adverse effects to tortoises and other species. Fragmentation would reduce or prevent movement and, consequently, would affect gene-pool flow in less mobile species like tortoises. Construction of the projects would cause an increase in traffic in the area with potential to increase tortoise mortality on the highways and roads and on the construction sites themselves. A total of 2,400 acres of habitat could be lost to project construction, and 960 acres would be lost topower and pipe line construction. This habitat in Coyote Spring Valley has been designated by the U.S. Bureau of Land Management as critical habitat for the threatened desert tortoise. Specific project locations are necessary before a determination can be made regarding the potential to adversely affect any sensitive species present in the valley. Depending on the quantity of water involved, the use of groundwater from Coyote Spring Valley would have the potential to affect discharge at Muddy Spring, which has a population of threatened Moapa dace. The use of groundwater might also have the potential to affect local springs in the valley.

Scenic quality of the site has been designated Class B and the site is viewed by the public traveling Highway 93 or engaging in recreational pursuits. There arealso three U.S. Bureau of Land Management Wilderness Areas within the site’s viewshed. Construction activities, and the solar activities and associated infrastructure would greatly change the landscape character of Coyote Spring Valley and have an adverse impact on the visual environment.

Recovery of cultural resource data would be a short-term benefit, but would reduce the opportunity to gain greater data recovery using enhanced future technologies.

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Weapons of Mass Destruction (WMD)