Yosemite Valley Plan SEIS, Volume IB Part 2, Unavoidable Adverse Impacts

UNAVOIDABLE ADVERSE IMPACTS

The following discussion identifies impacts to resources associated with the implementation of each alternative. These impacts have been identified as being unavoidable, moderate to major, and adverse.

Alternative 1

Generally, Alternative 1 would result in continued degradation of natural resources due to continued use and existing development. Existing structures would remain within highly valued resource areas such as wetlands, meadows, riparian areas, and California black oak woodlands. Existing bridges would also continue to impede flood flows and channel movement. Visitation levels would also continue to grow, resulting in more crowding, congestion, and delays for visitors. The potential risk for unavoidable adverse impacts to structures and human life would continue within the floodplain and rockfall zones.

CULTURAL RESOURCES

The Superintendent’s House (Residence 1) would be allowed to deteriorate, leading to its eventual loss.

Alternative 2

No appreciable, unavoidable, adverse impacts on scenic, geologic hazards, or energy consumption would take place under this alternative.

WATER RESOURCES

The Camp 6 parking area would be situated within a portion of the floodplain that could experience high-velocity, deep flows during a flood event such as were observed during the January 1997 flood. This parking facility could impede the river’s ability to naturally migrate and change course during extreme flood events and reduce the area available to the river for sediment deposition. In addition, impacts to riverbank stability (soils compaction, accelerated erosion, and vegetation loss) could occur due to the radiating effects associated with the increased concentration of visitors. Overall, development of a parking facility in the Camp 6 area could result in localized adverse impacts on hydrology and floodplain values.

FLOODPLAINS

The construction of 657 employee beds in the 100-year floodplain at Hennessey’s Ranch would have long-term, adverse impact due to the presence of people in the floodplain at night; however, risk to property and human safety would be mitigated through the extension and elevation of the existing levee. (see also Water Resources above)

WETLANDS

In Yosemite Valley up to 141 acres of wetland would be restored, however, Alternative 2 would adversely impact up to approximately 23 acres of potential wetland areas, resulting in direct wetland loss and indirect impacts on wetland hydrology. These impacts would occur from proposed new development (12 acres) and redevelopment of facilities (11 acres). Impacts to these potential wetland areas would be minimized to the extent feasible during facility design and site layout once the potential wetland areas have been fully delineated. There would be no net-loss of wetlands.

SOILS

Alternative 2 would develop and therefore adversely affect 69 acres of soil within the Valley and up to 80 acres of soil in out-of-Valley areas, the majority of which would occur within non-highly valued resource soil types. These adverse impacts would include soil removal, profile mixing, compaction, and erosion as a result of new development activities. Impacts to highly valued resource soils would be minimized to the extent feasible during facility design and site layout.

VEGETATION

Alternative 2 would impact 75 acres of vegetation within the Valley, 54 acres of which would occur within non-highly valued resource vegetation types. Up to 80 acres of vegetation would be impacted in out-of-Valley areas. These adverse impacts would include loss of vegetation and degradation of vegetation communities from new development and changes in visitor use. In Yosemite Valley and out-of-Valley areas, impacts to highly valued resource vegetation types would be minimized to the extent feasible, and special consideration would be given to retaining natural topography, native soils, and large trees during facility design and site layout.

WILDLIFE

Unavoidable adverse effects on wildlife would be caused by loss or degradation of 75 acres of habitat in Yosemite Valley, 54 acres of which would occur in non-highly valued resource habitat types. Up to 80 acres of habitat would be affected in out-of-Valley areas. Wildlife would be affected by habitat fragmentation, local reductions in food, cover, and reproductive sites at project locations, and by the disturbance from increased human use of these areas. To the extent feasible, impact to wildlife would be minimized through site design to avoid highly valued resource habitats, by the preservation of features important to wildlife (e.g., snags), and control of human access to sensitive habitats.

SPECIAL-STATUS WILDLIFE SPECIES

Alternative 2 would potentially have adverse effects on three special-status wildlife species. These effects would occur through removal or degradation of habitat (thus affecting the availability of food, cover, and reproductive sites), habitat fragmentation, and through an increase in human disturbance in the vicinity of developments. To the extent feasible, these impacts would be minimized through site-specific surveys for special-status species, and site designs limiting the effects on species found in the areas of potential development.

SPECIAL-STATUS PLANT SPECIES

Alternative 2 would result in the potential loss or degradation of habitat with moderate to major, adverse effects for three park rare species. These impacts would occur as a result of new development, including parking facilities. These impacts would be mitigated to the extent practicable through site-specific surveys and design to avoid impacts to individuals found in development areas.

AIR QUALITY

Under this alternative there would be short-term adverse impact to air quality due to the increased emissions of nitrogen oxide which is attributed to the operation of shuttle buses from the three out-of-Valley parking areas and the expanded in-Valley shuttle fleet. Nitrogen oxide would also increase with the use of compressed natural gas fueled buses.

CULTURAL RESOURCES

Alternative 2 would result in the potential destruction of the majority of one archeological site with high data potential, and one historic village site in El Portal. Development in Yosemite Valley and El Portal would result in the potential loss of many traditional gathering areas. It would also result in the loss of historic structures such as the individually significant Stoneman and Sugar Pine Bridges, the concessioner’s stable, and many other contributing elements of the cultural landscape. As with Alternative 1, the Superintendent’s House (Residence 1) would be lost. The Camp Curry Historic District also would be changed substantially, resulting in the loss of a majority of the character-defining tent cabins. Actions in the Merced River gorge would result in the removal of six of the remaining seven elements of the Yosemite Hydroelectric Power Plant historic property. However, the National Park Service would pursue a data recovery program, including an inventory and evaluation of impact areas, continue consultation with culturally associated American Indian tribes, and examine alternative uses for historic structures in an effort to avoid, minimize, and mitigate impacts. In keeping with the Programmatic Agreement, the National Park Service would continue to consult with the State Historic Preservation Office during continued studies, the creation of site-specific designs, and project implementation.

MERCED WILD AND SCENIC RIVER

Reconstruction of the El Portal Road between the Cascades Diversion Dam and Pohono Bridge could, depending on design, have a long-term, adverse impact on the hydrologic processes Outstandingly Remarkable Value due to the continued presence of bank stabilization materials in the river channel. The reconstruction of the El Portal Road and the removal of the Cascades Diversion Dam would have a short-term, adverse impact on the scenic Outstandingly Remarkable Value. The removal of historic bridges (i.e., Sugar Pine and Stoneman) would have long-term, moderate, adverse impacts on the cultural Outstandingly Remarkable Value because river-related historic structures would be lost and could have short-term, adverse impacts to the scenic and hydrologic processes Outstandingly Remarkable Value, due to the presence of construction equipment in and near the river. The relocation of the former Superintendent’s House (Residence 1) would have a long-term, moderate, adverse impact on the cultural Outstandingly Remarkable Value because the structure would be moved away from the river, an important consideration in the original placement of the historic structure. The construction of a new parking facility in Yosemite Village (Camp 6) could have a long-term, adverse impact on the scenic Outstandingly Remarkable Value depending on design. The possible construction of a traffic check station would have a long-term, adverse impact on the cultural Outstandingly Remarkable Value due to the possible disturbance of ethnographic gathering areas and a river-related archeological site.

VISITOR EXPERIENCE

This alternative would have impacts on visitor experience, including an increase in the amount of time required for day visitors to travel to the Valley, some loss of private vehicle access to east Valley destinations, and the inconvenience of having to carry personal possessions instead of relying on private vehicles as transport and storage devices. This would result from many day visitors having to park in out-of-Valley areas and enter the Valley by shuttle during peak season. Lodging units would decrease to 961, but campsites would increase to 500. The net effect would be a reduction of the overnight visitor capacity of Yosemite Valley. The impacts related to discontinuation of commercial stock rides would be long-term and adverse. Difficult access for raft and kayak users could lead to their displacement; this impact would be long-term and adverse. The potential development of a traffic check station at Taft Toe could result in a long-term, adverse impact on the night sky.

TRANSPORTATION

Alternative 2 would result in an increase in the average travel time necessary for day visitors to access the Valley from the entrance stations (an additional 21 minutes on average). This increase would be caused by having to wait at transit facilities and shuttle stops, and by the longer travel times on buses.

NOISE

This alternative would result in an increased number of sound events as a result of an increased number of bus trips west of El Capitan crossover, along Southside Drive west of Sentinel Bridge, on Sentinel Drive, Yosemite Village and in the out-of-Valley parking locations.

SOCIAL AND ECONOMIC ENVIRONMENTS

Alternative 2 would cause increases in population growth in the local communities of El Portal and Wawona, and would have an adverse impact on the local social environment, including law enforcement and court services, medical services to park employees, the elementary school system, and child care operations. In Foresta, the social environment would experience adverse impacts associated with visitor parking facilities if they are to be developed. Limited housing for Yosemite Association employees would have an adverse impact.

PARK OPERATIONS

Under this alternative, the profit level of the primary concessioner would be reduced to the point that an additional $3 million annually would need to be mitigated. If the concessioner is unable to make a fair and reasonable profit from its operations, the concessioner would presumably choose to discontinue operations in the absence of measures to mitigate this economic impact. Some of these measures, if selected, could adversely affect park operations. Two such mitigation measures would include (1) changing the distribution of park entrance fee revenues and (2) providing relief from building repair and maintenance costs. If either or both of these measures were to be used to offset impacts to the primary concessioner, National Park Service operating costs would increase. For example, the National Park Service would be responsible for funding the building repair and maintenance costs no longer allocated to the primary concessioner. If entrance fees were allocated to the concessioner and diverted from other projects, either those projects would not go forward or the National Park Service would have to secure additional park operating funds.

Alternative 3

No appreciable, unavoidable, adverse impacts on water resources, air quality, geologic hazards, transportation, park operations, or energy consumption would take place under this alternative.

FLOODPLAINS

The construction of 656 employee beds in the 100-year floodplain at Hennessey’s Ranch would have a long-term, adverse impact, due to the presence of people in the floodplain at night; however, risk to property and human safety would be mitigated through the extension and elevation of the existing levee.

WETLANDS

In Yosemite Valley there would be 156 acres of wetland restored; however, alternative 3 would adversely affect up to approximately 17 acres of potential wetland areas, resulting in direct wetland loss and indirect impacts on wetland hydrology. These impacts would occur from proposed new development (7 acres) and redevelopment of facilities (10 acres). In addition, impacts to wetland areas in the vicinity of Taft Toe would be expected as a result of the radiating effects of increased visitor presence. Impacts to these potential wetland areas would be minimized to the extent feasible during facility design and site layout once the potential wetland areas have been fully delineated. There would be no net-loss of wetlands.

SOILS

Alternative 3 would impact 98 acres of soil within the Valley and less than 40 acres of soil in the out-of-Valley areas, the majority of which would occur within non-highly valued resource soil types. These adverse impacts would include soil removal, profile mixing, compaction, and erosion as a result of new development activities. Impacts to highly valued resource soils would be minimized to the extent feasible during facility design and site layout.

VEGETATION

Alternative 3 would affect 99 acres of vegetation within the Valley, the majority of which (85 acres) would occur within non-highly valued resource vegetation types. Up to 37 acres of vegetation in out-of-Valley areas would also be impacted. These adverse impacts would include loss of vegetation and degradation of vegetation communities from new development and changes in visitor use. Impacts to highly valued resource vegetation types would be minimized to the extent feasible, and special consideration would be given to retaining natural topography, native soils, and large trees during facility design and site layout.

WILDLIFE

Unavoidable adverse impacts on wildlife would be caused by loss or degradation of 99 acres of habitat in Yosemite Valley, 85 acres of which would occur in non-highly valued resource habitat types. Up to 37 acres of habitat would be affected in out-of-Valley areas. Wildlife would be affected by habitat fragmentation, local reductions in food, cover, and reproductive sites at project locations, and by the disturbance from increased human use of these areas. To the extent feasible, impact to wildlife would be minimized through site design to avoid highly valued resource habitats, by the preservation of features important to wildlife (e.g., snags), and control of human access to sensitive habitats.

SPECIAL-STATUS WILDLIFE SPECIES

Alternative 3 would potentially have adverse effects on one special-status wildlife species. These effects would occur through removal or degradation of habitat (thus affecting the availability of food, cover, and reproductive sites), habitat fragmentation, and through an increase in human disturbance in the vicinity of developments. To the extent feasible, these impacts would be minimized through site-specific surveys for special-status species, and site designs limiting the effects on species found in the areas of potential development.

SPECIAL-STATUS PLANT SPECIES

Alternative 3 would result in the potential loss or degradation of habitat for two park rare species. These impacts would occur as a result of new development including parking facilities. However, these impacts would be mitigated to the extent practicable through site-specific surveys and designs to avoid impacts to individuals found within areas of potential development.

SCENIC RESOURCES

Alternative 3 would affect 99 acres of scenic resources due to vegetation loss. However, these impacts would occur in areas adjacent to existing development, limiting the amount of new development that would be noticeable, with the exception of the new parking/transit facility and visitor center at Taft Toe which would be adverse, major, and long-term.

NOISE

This alternative would result in an increased amount of nonvehicle noise events in the new housing areas proposed in El Portal. The number of sound events as a result of an increased number of bus trips east of El Capitan crossover, along Southside Drive, and Yosemite Village.

CULTURAL RESOURCES

Alternative 3 would result in the potential destruction of the majority of one archeological site, and one historic village with high data potential in El Portal. Development in El Portal and Yosemite Valley would also damage or destroy gathering areas and historic villages. Individually significant historic structures, Stoneman Bridge, and Sugar Pine Bridge would be lost. Many contributing elements of the cultural landscape would be lost such as the Ahwahnee Row Houses, NPS maintenance facilities, and the concessioner stables, among others. The Camp Curry Historic District would be substantially changed, resulting in the loss of a majority of the character-defining tent cabins and other contributing structures. The historic land use and spatial organization of the Valley would be substantially altered with the addition of day-visitor parking and transit and orientation facilities at Taft Toe. Removal of the Cascades Diversion Dam, screenhouse, and residences would result in the loss of six of the remaining seven elements of the Yosemite Hydroelectric Power Plant historic property. However, the National Park Service would pursue a data recovery program, including an inventory and evaluation of impact areas, continue consultation with culturally associated American Indian tribes, and examine alternative uses for historic structures in an effort to avoid, minimize, and mitigate impacts. In keeping with the Programmatic Agreement, the National Park Service would continue to consult with the State Historic Preservation Office (SHPO) during continued studies, the creation of site-specific designs, and project implementation.

MERCED WILD AND SCENIC RIVER

The reconstruction of the El Portal Road between the Cascades Diversion Dam and Pohono Bridge could, depending on design, have a long-term, adverse impact on the hydrologic processes Outstandingly Remarkable Value due to the continued presence of bank stabilization materials in the river channel. The reconstruction of the El Portal Road and the removal of the Cascades Diversion Dam would have short-term, adverse impacts on the scenic Outstandingly Remarkable Value. The removal of historic bridges (i.e., Sugar Pine, Stoneman, Superintendent’s, and Housekeeping) would have long-term, adverse impacts on the cultural Outstandingly Remarkable Value because river-related historic structures would be lost and could have short-term, adverse impacts to the scenic and hydrologic processes Outstandingly Remarkable Value, due to the presence of construction equipment in and near the river. The removal of the former Superintendent’s House (Residence 1) and Lamon Orchard would have long-term, adverse impacts on the cultural Outstandingly Remarkable Value because river-related historic resources would be lost. The possible construction of a traffic check station would have a long-term, adverse impact on the cultural Outstandingly Remarkable Value due to possible disturbance to ethnographic gathering areas and a river-related archeological site. The discontinuation of private stock use would have a long-term, adverse impact on the recreation Outstandingly Remarkable Value because the diversity of river-related recreational opportunities would be diminished.

VISITOR EXPERIENCE

This alternative would have impacts on visitor experience including the need for most visitors to travel by means other than their private vehicles to destinations within the Valley. This would also result in some loss of private vehicle access to east Valley destinations and the inconvenience of having to carry personal possessions instead of relying on private vehicles as transport and storage devices. The number of campsites would decrease to 449 and lodging units would decrease to 982, resulting in fewer units and sites available for overnight users. The impacts related to discontinuation of commercial stock rides would be long-term and adverse. Difficult access for raft and kayak users as well as anglers could lead to their displacement; this would be long-term and adverse. The development of a parking and transit facility at Taft Toe would result in a long-term, adverse impact on the night sky.

SOCIAL AND ECONOMIC ENVIRONMENTS

Alternative 3 would cause increases in population growth in El Portal that would have an adverse impact on the local social environment, including law enforcement and court services, medical services to park employees, the elementary school system, and child care operations.

Alternative 4

No appreciable, unavoidable, adverse impacts on geologic hazards, water resources, park operations, or energy consumption would take place under this alternative.

FLOODPLAINS

The construction of 656 employee beds in the 100-year floodplain at Hennessey’s Ranch would have a moderate, adverse impact, due to the presence of people in the floodplain at night; however, risk to property and human safety would be mitigated through the extension and elevation of the existing levee.

WETLANDS

In Yosemite Valley there would be 149 acres of wetland restored; however, Alternative 4 would adversely affect up to approximately 18 acres of potential wetland areas resulting in direct wetland loss and indirect impacts on wetland hydrology. These impacts would occur from proposed new development (7 acres) and redevelopment of facilities (11 acres). In addition, impacts to wetland areas in the vicinity of Taft Toe would be expected as a result of the radiating effects of increased visitor presence in this area. Impacts to these potential wetland areas would be minimized to the extent feasible during facility design and site layout once the potential wetland areas have been fully delineated. There would be no net loss of wetlands.

SOILS

Alternative 4 would affect 98 acres of soil within the Valley and up to 70 acres of soil in out-of-Valley areas, the majority of which would occur within non-highly valued resource soil types. These adverse impacts would include soil removal, profile mixing, compaction, and erosion as a result of new development activities. Impacts to highly valued resource soils would be minimized to the extent feasible during facility design and site layout.

VEGETATION

Alternative 4 would impact 102 acres of vegetation within the Valley, of which 88 acres would occur within non-highly valued resource vegetation types. Up to 70 acres of vegetation in out-of-Valley areas would also be impacted. These adverse impacts would include loss of vegetation and degradation of vegetation communities from new development and changes in visitor use. In Yosemite Valley, impacts to highly valued resource vegetation types would be minimized to the extent feasible and special consideration would be given to retaining natural topography, native soils and large trees during facility design and site layout.

WILDLIFE

Unavoidable, adverse impacts on wildlife would be caused by loss or degradation of 102 acres of habitat in Yosemite Valley, 88 acres of which would occur on non-highly valued resource habitat types. Up to 70 acres of habitat would be affected in out-of-Valley areas. Wildlife would be affected by habitat fragmentation, local reductions in food, cover, and reproductive sites at project locations, and by the disturbance from increased human use of these areas. To the extent feasible, impact to wildlife could be minimized through site design to avoid highly valued resource habitats, by the preservation of features important to wildlife (e.g., snags), and control of human access to sensitive habitats.

SPECIAL-STATUS WILDLIFE SPECIES

Alternative 4 would potentially have adverse effects on 2 special-status wildlife species. These effects would occur through removal or degradation of habitat (thus affecting the availability of food, cover, and reproductive sites), habitat fragmentation, and through an increase in human disturbance in the vicinity of developments. To the extent feasible, these impacts would be minimized through site-specific surveys for special-status species, and site designs limiting the effects on species found in the areas of potential development.

SPECIAL-STATUS PLANT SPECIES

Alternative 4 would result in the potential loss or degradation of habitat for three park rare species. These impacts would occur as a result of new development including parking facilities. However, these impacts would be mitigated to the extent practicable through site-specific surveys and designs to avoid impacts to species occurring in these development areas.

AIR QUALITY

SCENIC RESOURCES

Alternative 4 would affect 99 acres of scenic resources due to vegetation loss. However, these impacts would occur in areas adjacent to existing development, limiting the amount of new development that would be noticeable, with the exception of the new parking/transit center and visitor center at Taft Toe which would be adverse, major, and long-term.

CULTURAL RESOURCES

Alternative 4 would result in the potential destruction of the majority of one archeological site, and one historic village with high data potential in El Portal. Development in El Portal and Yosemite Valley would also damage or destroy gathering areas and historic villages. It would also result in the loss of individually significant historic structures such as the Stoneman and Sugar Pine Bridges. In addition, many contributing elements of the cultural landscape would be lost (such as the Ahwahnee Row Houses, National Park Service maintenance facilities, and the concessioner stables). The Camp Curry Historic District would be substantially altered, resulting in the loss of a majority of the character-defining tent cabins and other contributing structures. The historic spatial organization and land-use patterns in the cultural landscape would be altered substantially with the addition of day-visitor parking, transit, and orientation facilities at Taft Toe. Removal of the Cascades Diversion Dam and residences would result in the loss of six of the remaining seven elements of the Yosemite Hydroelectric Power Plant historic property. However, the National Park Service would pursue a data recovery program, including an inventory and evaluation of impact areas, continue consultation with culturally associated American Indian tribes, and examine alternative uses for historic structures in an effort to avoid, minimize, and mitigate impacts. In keeping with the Programmatic Agreement, the National Park Service would continue to consult with the State Historic Preservation Office (SHPO) during continued studies, the creation of site-specific designs, and project implementation.

MERCED WILD AND SCENIC RIVER

The reconstruction of the El Portal Road between the Cascades Diversion Dam and Pohono Bridge could, depending on design, have a long-term, adverse impact on the hydrologic processes Outstandingly Remarkable Value due to the continued presence of bank stabilization materials in the river channel. The reconstruction of the El Portal Road and the removal of the Cascades Diversion Dam would have a short-term, adverse impact on the scenic Outstandingly Remarkable Value. The removal of historic bridges (i.e., Sugar Pine, Stoneman, Superintendent’s, and Housekeeping) would have long-term, adverse impacts on the cultural Outstandingly Remarkable Value because river-related historic structures would be lost and could have short-term, adverse impacts to the scenic and hydrologic processes Outstandingly Remarkable Values due to the presence of construction equipment in and near the river. The removal of the former Superintendent’s House (Residence 1) would have a long-term, adverse impact on the cultural Outstandingly Remarkable Value because a river-related historic structure would be lost. The possible construction of a traffic check station would have a long-term, adverse impact on the cultural Outstandingly Remarkable Value due to possible disturbance to ethnographic gathering areas and a river-related archeological site.

VISITOR EXPERIENCE

This alternative would have impacts on visitor experience, including an increase in the amount of time necessary to travel to the Valley caused by the need to park at Taft Toe or out-of-Valley areas and access the Valley by shuttle. This would also result in some loss of private vehicle access to east Valley destinations and the inconvenience of having to carry personal possessions instead of relying on private vehicles as transport and storage devices. The number of campsites would decrease to 441 and lodging units would decrease to 982, resulting in fewer units and sites available for overnight users. The impacts related to discontinuation of commercial stock rides would be long-term and adverse. Difficult access for raft and kayak users as well as anglers could lead to their displacement; this would be long-term and adverse. The development of a parking and transit facility at Taft Toe would result in a long-term, adverse impact on the night sky.

TRANSPORTATION

Alternative 4 would result in an increase in travel time needed to access the Valley from the entrance stations (additional 29 minutes on average). This increase would be caused by having to wait at transit facilities and shuttle stops for buses.

NOISE

SOCIAL AND ECONOMIC ENVIRONMENTS

Alternative 4 would cause increases in population growth in El Portal that would have an adverse effect on the local social environment, including law enforcement and court services, medical services to park employees, the elementary school system, and child care operations.

Alternative 5

No appreciable, unavoidable, adverse impacts on geologic hazards, scenic, transportation, park operations, or energy consumption would take place under this alternative.

WATER RESOURCES

The Camp 6 parking area would be situated within a portion of the floodplain that could experience high-velocity, deep flows during a flood event such as were observed during the January 1997 flood. This parking facility could impede the river’s ability to naturally migrate and change course during extreme flood events and reduce the area available to the river for sediment deposition. In addition, impacts to riverbank stability (soils compaction, accelerated erosion, and vegetation loss) could occur due to the radiating effects associated with the increased concentration of visitors. Overall, development of a parking facility in the Camp 6 area could result in localized, long-term, adverse impacts on hydrology and floodplain values.

FLOODPLAINS

The construction of 656 employee beds in the 100-year floodplain at Hennessey’s Ranch would be a long-term moderate, adverse impact, due to the presence of people in the floodplain at night; however, risk to property and human safety would be mitigated through the extension and elevation of the existing levee.

WETLANDS

In Yosemite Valley there would be 131 acres of wetland restored; however, Alternative 5 would adversely affect up to approximately 27 acres of potential wetland areas resulting in direct wetland loss and indirect impacts on wetland hydrology. These impacts would occur from proposed new development (12 acres) and redevelopment of facilities (15 acres). Impacts on these potential wetland areas would be minimized to the extent feasible during facility design and site layout once the potential wetland areas have been fully delineated. There would be no net loss of wetlands.

SOILS

Alternative 5 would have impacts to 67 acres of soil within the Valley and up to 80 acres of soil in the out of Valley areas, the majority of which would occur within non-highly valued resource soil types. These adverse impacts would include soil removal, profile mixing, compaction, and erosion as a result of new development activities. Impacts on highly valued resource soils would be minimized to the extent feasible during facility design and site layout.

VEGETATION

Alternative 5 would impact 69 acres of vegetation within the Valley, of which 53 acres would occur within non-highly valued resource vegetation types. Up to 78 acres of vegetation in the out-of-Valley areas, would also be impacted. These adverse impacts would include loss of vegetation and degradation of vegetation communities from new development and changes in visitor use. In Yosemite Valley, impacts to highly valued resource vegetation types would be minimized to the extent feasible, and special consideration would be given to retaining natural topography, native soils, and large trees during facility design and site layout.

WILDLIFE

Unavoidable, adverse impacts on wildlife would be caused by loss or degradation of 69 acres of habitat in Yosemite Valley, 53 acres of which would occur in non-highly valued resource habitat types. Up to 78 acres of habitat would be affected in out-of-Valley areas. Wildlife would be affected by habitat fragmentation, local reductions in food, cover, and reproductive sites at project locations, and by the disturbance from increased human use of these areas. To the extent feasible, impact to wildlife could be minimized through site design to avoid highly valued resource habitats, by the preservation of features important to wildlife (e.g., snags), and control of human access to sensitive habitats.

SPECIAL-STATUS WILDLIFE SPECIES

Alternative 5 would potentially have adverse effects on 3 special-status wildlife species. These effects would occur through removal or degradation of habitat (thus affecting the availability of food, cover, and reproductive sites), habitat fragmentation, and through an increase in human disturbance in the vicinity of developments. To the extent feasible, these impacts would be minimized through site-specific surveys for special-status species, and site designs limiting the effects on species found in the areas of potential development.

SPECIAL-STATUS PLANT SPECIES

Alternative 5 would result in the potential loss or degradation of habitat for three park rare species. These impacts would occur as a result of new development including parking facilities. However, these impacts would be mitigated to the extent practicable through site-specific surveys and design to avoid impacts to individual plants occurring in these development areas.

AIR QUALITY

CULTURAL RESOURCES

Alternative 5 would result in the potential destruction of the majority of one archeological site, and one historic village with high data potential in El Portal. Development in El Portal and Yosemite Valley would also damage or destroy gathering areas and historic villages. It would also result in loss of individually significant historic structures such as the Sugar Pine and Ahwahnee Bridges. Many contributing elements of the cultural landscape would be lost, including the Ahwahnee Row Houses, NPS maintenance facilities, and the concessioner stables. The Camp Curry Historic District would be substantially changed, resulting in the loss of a majority of the character-defining tent cabins and other contributing structures. Removal of the Cascades Diversion Dam and residences would result in the loss of six of the remaining seven elements of the Yosemite Hydroelectric Power Plant historic property. However, the National Park Service would pursue a data recovery program, including an inventory and evaluation of impact areas, continue consultation with culturally associated American Indian tribes, and examine alternative uses for historic structures in an effort to avoid, minimize, and mitigate impacts. In keeping with the Programmatic Agreement, the National Park Service would continue to consult with the State Historic Preservation Office (SHPO) during continued studies, the creation of site-specific designs, and project implementation.

MERCED WILD AND SCENIC RIVER

The reconstruction of the El Portal Road between the Cascades Diversion Dam and Pohono Bridge could, depending on design, have a long-term, adverse impact on the hydrologic processes Outstandingly Remarkable Value due to the continued presence of bank stabilization materials in the river channel. The reconstruction of the El Portal Road and the removal of the Cascades Diversion Dam would have short-term, adverse impacts on the scenic Outstandingly Remarkable Value. The construction of new campsites would have long-term, adverse impacts on the hydrologic processes and biological Outstandingly Remarkable Values due to occupation of the 100-year floodplain, loss of river-related vegetation, and radiating impacts to the river from the concentration of visitors. The removal of historic bridges (i.e., Sugar Pine and Ahwahnee) would have long-term, moderate, adverse impacts on the cultural Outstandingly Remarkable Value because river-related historic structures would be lost and could have short-term, adverse impacts to the scenic and hydrologic processes Outstandingly Remarkable Value due to the presence of construction equipment in and near the river. The removal of the former Superintendent’s House (Residence 1) would have a long-term, adverse impact on the cultural Outstandingly Remarkable Value because a river-related historic structure would be lost. The possible construction of a traffic check station would have a long-term, adverse impact on the cultural Outstandingly Remarkable Value due to possible disturbance to ethnographic gathering areas and a river-related archeological site.

NOISE

VISITOR EXPERIENCE

This alternative would have impacts on visitor experience, including an increase in the amount of time necessary to travel to the Valley caused by the need for many day visitors to park in out-of-Valley areas and access the Valley by shuttle. This would also result in some loss of private vehicle access to east Valley destinations and the inconvenience of having to carry personal possessions instead of relying on private vehicles as transport and storage devices. Difficult access for raft and kayak users as well as anglers could lead to their displacement; this would be long-term and adverse. Impacts due to the loss of lodging would be long-term and adverse. The potential development of a traffic check station at Taft Toe could result in a long-term, adverse impact on the night sky.

SOCIAL AND ECONOMIC ENVIRONMENTS

Alternative 5 would cause increases in population growth in the local communities of El Portal and Wawona and would have an adverse impact on the local social environments, including law enforcement and court services, medical services to park employees, the elementary school system, and child care operations. In Foresta, the social environment would experience adverse impacts associated with parking facilities.

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