Yosemite Valley Plan SEIS, Volume IB, Chapter 4: Alternative 2

Potential Cumulative Impacts on Federal Species of Concern and California Species of Special Concern

Merced Canyon shoulderband snail (Helminthoglypta allynsmithi)

Status: Federal species of concern. Regional planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS) and the Merced Wild and Scenic River Comprehensive Management Plan (NPS) could improve the size, integrity, and connectivity of suitable habitat for the Merced Canyon shoulderband snail. These actions could have long-term, minor, beneficial effects on suitable habitat. The Incline Road Construction, Foresta Road Bridge to South Fork (Mariposa Co.) project could have a detrimental effect on snail habitat, but is expected to be minor because it would primarily affect previously impacted areas. Development that would occur in El Portal under this alternative would cause a negligible impact to this snail species because no suitable habitat would be affected.

Overall, the cumulative impact on the Merced Canyon shoulderband snail would be a minor and beneficial, based on the potential protection of suitable habitat from regional plans, whereas actions under this alternative would have a negligible effect.

Mariposa sideband snail (Monadenia hillebrandi)

Status: Federal species of concern. Regional planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS) and the Merced Wild and Scenic River Comprehensive Management Plan (NPS) could improve the size, integrity, and connectivity of suitable habitat for the Mariposa sideband snail. These actions could have long-term, minor, beneficial effects on suitable habitat. Restoration of potential Mariposa sideband snail habitat in Yosemite Valley under this alternative would augment this beneficial effect. Projects with potential adverse effects on this species include the El Portal Road Improvement Project (NPS), the Incline Road Construction, Foresta Road Bridge to South Fork (Mariposa Co.) project, and Yosemite Motels Expansion, El Portal (Mariposa Co.). Impacts from these projects are expected to have a local, minor, adverse effect on the species because these projects either occur in areas of previous disturbance or in areas that do not contain suitable habitat.

Overall, there would be a minor, beneficial, cumulative impact on the Mariposa sideband snail, based on the potential protection of suitable habitat resulting from regional plans and restoration of habitats in Yosemite Valley.

Sierra pygmy grasshopper (Tetrix sierrana)

Status: Federal species of concern. Regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS), U.S. Forest Service plans for adjacent wilderness, and the Merced Wild and Scenic River Comprehensive Management Plan (NPS) could improve the size, integrity, and connectivity of suitable habitat for the Sierra pygmy grasshopper. These actions could to have long-term, minor, beneficial effects on suitable habitat. Projects with potential adverse effects include the Incline Road Construction, Foresta Road Bridge to South Fork (Mariposa Co.) project and the Yosemite Motels Expansion, El Portal (Mariposa Co.). The effects of these projects would be minor and adverse because they would occur in areas that do not contain suitable habitat or in areas of previous disturbance. Under this alternative, restoration of riparian habitats in Yosemite Valley would beneficially affect this species, while developments in El Portal and South Entrance could have a localized adverse effect on suitable habitat.

The overall cumulative impact on the Sierra pygmy grasshopper is expected to be minor and beneficial, based upon the potential protection of large areas of suitable habitat resulting from implementation of regional plans, in combination with mixed effects from this alternative.

Wawona riffle beetle (Atractelmis wawona)

Status: Federal species of concern. Cumulative effects that could have large-scale benefits to riffle beetle habitat include regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS) and the Merced Wild and Scenic River Comprehensive Management Plan (NPS). These beneficial effects would be augmented by restoration of large areas of riparian and meadow habitat in Yosemite Valley that would occur under this alternative. The Yosemite View Parcel Land Exchange (NPS) could affect aquatic habitat for the Wawona riffle beetle in the adjacent reach of the Merced River. Overall, there would be a minor, beneficial cumulative effect on the riffle beetle. This is largely due to regional and parkwide planning that would protect wide areas of habitat for the Wawona riffle beetle, coupled with habitat restoration that would occur under this alternative.

Bohart’s blue butterfly (Philotiella speciosa bohartorum)

Status: Federal species of concern. The documented occurrence of this species nearest to the Yosemite National Park is near Briceburg, west of El Portal. Regional planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS) could improve the size, integrity, and connectivity of suitable habitat for the Bohart’s blue butterfly over a wide area of foothill habitat. This action could have long-term, minor, beneficial effects on suitable habitat. Further surveys for this species found this butterfly in other areas, such as Merced, Fresno, and Tulare Counties. Projects in those areas, such as the Rio Mesa Area Plan (Madera Co.) and University of California, Merced Campus (Merced Co.) could have a minor, local effect on Bohart’s blue butterfly. These effects would be limited in scale, compared to the beneficial effects of the Sierra Nevada Framework for Conservation and Collaboration (USFS), which would help protect wide areas of foothill woodland habitat that is declining rapidly. Development of parking, housing, and administrative facilities that would occur under this alternative could adversely affect suitable habitat, although the occurrence of the Bohart’s blue butterfly in El Portal is questionable.

The overall cumulative impact on the Bohart’s blue butterfly would be minor and beneficial, based on the potential protection of wide areas of suitable habitat from the Sierra Nevada Framework, as opposed to localized potential impacts in El Portal that would occur under this alternative.

Mount Lyell salamander (Hydromantes platycephalus)

Status: Federal species of concern; California species of special concern. Regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS), U.S. Forest Service plans for adjacent wilderness, the Fire Management Plan Update (NPS), and the Merced Wild and Scenic River Comprehensive Management Plan (NPS) could improve the size, integrity, and connectivity of suitable habitat for the Mount Lyell salamander over a wide area. These actions, augmented by habitat restoration in Yosemite Valley under this alternative, have the potential for long-term, minor, beneficial cumulative effects on suitable habitat, depending upon the alternatives chosen and the extent of their implementation over time. No reasonably foreseeable future projects are expected to have an adverse effect on Mount Lyell salamanders.

Northwestern pond turtle (Clemmys marmorata marmorata) and
Southwestern pond turtle (Clemmys marmorata pallida)

Status: Federal species of concern; California species of special concern. Cumulative effects that could have large-scale benefits to western pond turtle habitat include regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS) and the Merced Wild and Scenic River Comprehensive Management Plan (NPS). These beneficial effects would be augmented by restoration of large areas of riparian and wetland habitats in Yosemite Valley under this alternative. The Yosemite View Parcel Land Exchange (NPS) would directly affect a small area of habitat suitable for the western pond turtle. Overall, there would be a minor, beneficial cumulative effect on the western pond turtle. This benefit would largely derive from implementation of regional and parkwide planning that would protect habitat for western pond turtles and restoration of suitable habitat in Yosemite Valley under this alternative.

Harlequin duck (Histrionicus histrionicus)

Status: Federal species of concern; California species of special concern. Regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS), U.S. Forest Service plans for adjacent wilderness, the Fire Management Plan Update (NPS), and the Merced Wild and Scenic River Comprehensive Management Plan (NPS) could improve the size, integrity, and connectivity of suitable habitat for the harlequin duck. This alternative would restore or protect about 100 acres of suitable riparian and aquatic habitat. These actions have the potential to have long-term, moderate to major, beneficial effects on suitable habitat for the harlequin duck, depending on the alternatives chosen and the extent of their implementation over time.

Current and reasonably foreseeable future projects that could have adverse effects on suitable habitat for the harlequin duck include the Yosemite View Parcel Land Exchange (NPS) and the Incline Road Construction, Foresta Road Bridge to South Fork (Mariposa Co.) project. There are no known populations of harlequin duck in these areas.

Overall, there would be a moderate, beneficial, cumulative impact on the harlequin duck, based on the potential protection of suitable habitat offered by regional plans, combined with restoration of suitable habitat provided under this alternative. The projects resulting in a possible adverse impact on harlequin duck habitat would affect a relatively small area of habitat compared to projects with potential beneficial impacts.

Cooper’s hawk (Accipiter cooperi)

Status: California species of special concern. Regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS), U.S. Forest Service plans for adjacent wilderness, the Fire Management Plan Update (NPS), and the Merced Wild and Scenic River Comprehensive Management Plan (NPS) would improve the size, integrity, and connectivity of suitable habitat for the Cooper’s hawk. These regional plans would have a long-term, moderate to major, beneficial effect on the Cooper’s hawk, depending upon the alternatives chosen and the extent of their implementation over time. These beneficial effects would be augmented by restoration of habitats in Yosemite Valley as provided under this alternative. Current and reasonably foreseeable future projects that could have adverse effects on suitable habitat for the Cooper’s hawk include the Hazel Green Ranch (Mariposa Co.) project, Yosemite View Parcel Land Exchange (NPS), Yosemite Motels Expansion, El Portal (Mariposa Co.), El Portal Road Improvement Project (NPS), Evergreen Lodge Expansion (Tuolumne Co.), and Yosemite West Rezone for 55 Acres (Mariposa Co.). In addition, development of parking at Hazel Green would adversely affect an area of potential Cooper’s hawk habitat, as would development at Wawona and El Portal.

The overall cumulative impact on Cooper’s hawks would be moderate and beneficial, based primarily on implementation of wide-ranging plans that would protect large areas of the Sierra Nevada together with restoration of habitats in Yosemite Valley under this alternative, compared to localized, adverse impacts on relatively small areas from individual projects.

Northern goshawk (Accipiter gentilis)

Status: Federal species of concern; California species of special concern. Projects likely to have a beneficial effect on northern goshawk habitat include the Fire Management Plan Update (NPS), the Sierra Nevada Framework for Conservation and Collaboration (USFS), Wilderness Management Plan Update (NPS), and U.S. Forest Service plans for adjacent wilderness. Implementation of these plans would have a moderate to major, beneficial effect on northern goshawks, depending upon the alternatives chosen and the extent of their implementation over time.

Projects that could have an adverse effect on northern goshawk habitat include the Hazel Green Ranch (Mariposa Co.) project, Evergreen Lodge Expansion (Tuolumne Co.), and the Yosemite West Rezone for 55 Acres (Mariposa Co.). Development of parking at Hazel Green under this alternative would adversely affect an area of forest habitat. These projects, however, would affect relatively small areas of habitat.

Overall, there would be a long-term, moderate, beneficial cumulative impact on the northern goshawk, based primarily on the potential protection of wide areas of habitat through implementation of regional land management plans, compared to localized adverse effects on small areas of habitat from individual projects, including effects from this alternative.

Sharp-shinned hawk (Accipiter striatus)

Status: California species of special concern. Regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS), U.S. Forest Service plans for adjacent wilderness, the Fire Management Plan Update (NPS), and the Merced Wild and Scenic River Comprehensive Management Plan (NPS) could improve the size, integrity, and connectivity of wide areas of suitable habitat for the sharp-shinned hawk. A mix of habitats favorable to sharp-shinned hawks would be restored in Yosemite Valley under this alternative. These regional plans, in combination with this alternative, would have a long-term, minor to moderate, beneficial effect on the sharp-shinned hawk, depending upon the alternatives chosen and the extent of their implementation over time. This effect would be of lower intensity than for other Accipiter species because sharp-shinned hawks do not commonly nest in the Sierra Nevada.

Current and reasonably foreseeable future projects that could have adverse effects on suitable habitat for the sharp-shinned hawks include the Hazel Green Ranch (Mariposa Co.) project, Yosemite View Parcel Land Exchange (NPS), Yosemite Motels Expansion, El Portal (Mariposa Co.), El Portal Road Improvement (NPS), Evergreen Lodge Expansion (Tuolumne Co.), and Yosemite West Rezone for 55 Acres (Mariposa Co.). Under this alternative, some habitat would be adversely affected, including in Wawona, El Portal, and Hazel Green.

The overall cumulative impact on sharp-shinned hawks would be moderate and beneficial, based primarily on implementation of plans that would protect large areas of the Sierra Nevada and restoration of diverse habitats in Yosemite Valley under this alternative, compared to localized, adverse effects on relatively small areas from individual projects.

Golden eagle (Aquila chrysaetos)

Current and reasonably foreseeable future projects that could have an adverse effect on golden eagles include the Rio Mesa Area Plan (Madera Co.); University of California, Merced Campus (Merced Co.); Buildout of City of Merced, General Plan; and the Tioga Inn; Lee Vining (Mono Co.). Development of parking in Foresta could occur under this alternative, which would affect a small area of potential golden eagle habitat. These projects, in total, would have a minor, adverse effect on golden eagles because of the limited area they would affect.

Overall cumulative effects on golden eagles would be minor and beneficial, based primarily on the protection of habitat provided by implementation of land management plans that would cover large areas of the Sierra Nevada in combination with restoration of habitats in Yosemite Valley under to this alternative. There would be a limited area of effect caused by projects that have an adverse impact on golden eagles, including development in some habitat under this alternative.

Merlin (Falco columbarius)

Current and reasonably foreseeable future projects that could have an adverse effect on merlins include the Yosemite View Parcel Land Exchange (NPS); Rio Mesa Area Plan (Madera Co.); Yosemite Motels Expansion, El Portal (Mariposa Co.); University of California, Merced Campus (Merced Co.); and Buildout of City of Merced, General Plan. These projects would have a minor, adverse effect on merlins, depending upon the alternatives chosen and the extent of their implementation over time. Under this alternative, habitat could be adversely affected by development in Foresta and El Portal, but the areas affected would be less suitable habitat.

The overall cumulative effects would be moderate and beneficial, based primarily upon the implementation of land management plans that could affect large areas of the Sierra Nevada, coupled with restoration of habitats in Yosemite Valley that would occur under this alternative.

Prairie falcon (Falco mexicanus)

Current and reasonably foreseeable future projects that could have an adverse effect on prairie falcons include the Rio Mesa Area Plan (Madera Co.); University of California, Merced Campus (Merced Co.); Buildout of City of Merced, General Plan; and Tioga Inn, Lee Vining (Mono Co.). The possible development of parking in Foresta under this alternative could affect prairie falcons, but the affected area is marginal habitat. These projects, in total, would have a minor, adverse effect on prairie falcons because of the limited area they would affect.

Overall cumulative effects on prairie falcons would be moderate and beneficial, based primarily on the protection of habitat provided by implementation of land management plans that would cover large areas of the Sierra Nevada combined with restoration of Yosemite Valley habitats under this alternative. This is compared to the limited area of effect caused by projects that would adversely affect prairie falcons.

Long-eared owl (Asio otus)

Current and reasonably foreseeable future projects that could have adverse effects on suitable habitat for long-eared owls include the Yosemite View Parcel Land Exchange (NPS); Yosemite Motels Expansion, El Portal (Mariposa Co.); El Portal Road Improvement Project (NPS); and Evergreen Lodge Expansion (Tuolumne Co.). Development of parking, housing, and administrative facilities in El Portal under this alternative could affect some areas of potential habitat.

The overall cumulative effects on long-eared owls would be minor and beneficial, based primarily on the protection of habitat provided by implementation of wide-ranging land management plans that would cover large areas of the Sierra Nevada and restoration of large areas of riparian habitat in Yosemite Valley from implementation of this alternative. Projects that could have adverse impacts on long-eared owls would affect a limited area.

Yellow warbler (Dendroica petechia)

Current and reasonably foreseeable future projects with the potential to adversely affect yellow warblers include the Hazel Green Ranch (Mariposa Co.) project, Yosemite View Parcel Land Exchange (NPS), and the Yosemite West Rezone of 55 Acres (Mariposa Co.). Development in El Portal, Wawona, and Foresta that would occur under this alternative would affect habitat. These projects would have a minor, adverse impact because the affected area is limited in size and is generally lower-quality habitat for yellow warblers, and large areas of suitable, unaffected habitat would remain in surrounding areas.

The overall cumulative effects on yellow warblers would be moderate and beneficial, based primarily on the protection of large areas of high-quality habitat provided by implementation of regional land management plans that would cover large areas of the Sierra Nevada and restoration of large areas of high-quality riparian habitat in Yosemite Valley from this alternative. Projects that would have an adverse impact on yellow warblers would affect a limited area of impact on lower-quality habitat.

Mount Lyell shrew (Sorex lyelli)

Status: Federal species of concern. Regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS), U.S. Forest Service plans for adjacent wilderness, the Fire Management Plan Update (NPS), the Wilderness Management Plan Update (NPS), and the Merced Wild and Scenic River Comprehensive Management Plan (NPS) could improve the size, integrity, and connectivity of suitable habitat for the Mount Lyell shrew. These regional plans would have a long-term, minor, beneficial effect on suitable habitat for the Mount Lyell shrew. Possible development at Tioga Pass, the only area of potential effect, would have a negligible impact on Mount Lyell shrews. No reasonably foreseeable future projects are expected to have an adverse effect on this species; therefore, the overall impact from this alternative, and present and reasonably foreseeable future projects, would be minor and beneficial.

Pallid bat (Antrozous pallidus)

Status: California species of special concern. Regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration, U.S. Forest Service (USFS) plans for adjacent wilderness, the Fire Management Plan Update (NPS), and the Merced Wild and Scenic River Comprehensive Management Plan (NPS) could improve the size, integrity, and connectivity of suitable habitat for the pallid bat. These regional plans could have a long-term, minor to moderate, beneficial effect on the pallid bat, depending upon the alternatives chosen and the extent of their implementation over time. Restoration of large areas of riparian, meadow, and California black oak habitats that would occur under this alternative would further benefit pallid bats by providing important foraging habitat.

Current and reasonably foreseeable future projects that could adversely affect suitable habitat for the pallid bat include the Hazel Green Ranch (Mariposa Co.) project; Yosemite View Parcel Land Exchange (NPS); Yosemite Motels Expansion, El Portal (Mariposa Co.); El Portal Road Improvement Project (NPS); Yosemite West Rezone for 55 Acres (Mariposa Co.); and Evergreen Lodge Expansion (Tuolumne Co.). New development that would occur at Foresta, El Portal, Wawona, and Hazel Green under this alternative could affect pallid bats.

Overall, there would be a minor, beneficial cumulative impact on the pallid bat. This is based on the potential protection of suitable habitat from regional plans and restoration of diverse habitats in Yosemite Valley under this alternative. The projects with a possible adverse impact on the pallid bat, including new development under this alternative, would affect a relatively small area of habitat compared to projects with potential beneficial impacts.

Townsend’s big-eared bat (Corynorhinus townsendii townsendii)

Current and reasonably foreseeable future projects that could adversely affect suitable habitat for Townsend’s big-eared bats include the Hazel Green Ranch (Mariposa Co.) project; Yosemite View Parcel Land Exchange (NPS); Yosemite Motels Expansion; El Portal (Mariposa Co.); El Portal Road Improvement Project (NPS); Evergreen Lodge Expansion (Tuolumne Co.); and Yosemite West Rezone for 55 Acres (Mariposa Co.). New development at Wawona, Hazel Green, El Portal, and possibly Foresta, could affect small areas of suitable habitat.

Overall, there would be a minor, beneficial cumulative impact on Townsend’s big-eared bat, based on the potential protection of suitable habitat provided through implementation of regional plans and restoration of Yosemite Valley habitats under this alternative. The projects with a possible adverse impact on the Townsend’s big-eared bat would affect a relatively small area of marginal habitat compared to projects with potential beneficial impacts.

Spotted bat (Euderma maculatum)

Status: Federal species of concern; California species of special concern. Regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS), U.S. Forest Service plans for adjacent wilderness, the Fire Management Plan Update (NPS), and the Merced Wild and Scenic River Comprehensive Management Plan (NPS) could improve the size, integrity, and connectivity of suitable habitat for the spotted bat. These actions could have long-term, moderate to major, beneficial effects on suitable habitat, depending upon the alternatives chosen for implementation and the extent of their implementation over time. Such benefits would be augmented by restoration of large areas of riparian and meadow habitats that would occur under this alternative. These habitats are important foraging areas for spotted bats.

Projects that could adversely affect suitable habitat for the spotted bat include the Yosemite View Parcel Land Exchange (NPS); El Portal Road Improvement Project (NPS); Yosemite Motels Expansion, El Portal (Mariposa Co.); Evergreen Lodge Expansion (Tuolumne Co.); Hazel Green Ranch (Mariposa Co.) project; and Yosemite West Rezone for 55 Acres (Mariposa Co.). New development at Wawona, Hazel Green, and El Portal would affect potential habitat. Adverse cumulative impacts on spotted bats would be minor, based on their relatively limited area of effect and the type of habitat affected.

Overall, there would be a moderate, beneficial impact on the spotted bat, based primarily on the potential protection of large areas of suitable habitat from regional plans in combination with restoration of important habitats in Yosemite Valley that would occur under this alternative. The projects with possible adverse impacts on the spotted bat would affect a relatively small area of less suitable habitat compared to projects with potential beneficial impacts.

Small-footed myotis bat (Myotis ciliolabrum)

Status: Federal species of concern. Regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS), U.S. Forest Service plans for adjacent wilderness, the Fire Management Plan Update (NPS), and the Merced Wild and Scenic River Comprehensive Management Plan (NPS) could improve the size, integrity, and connectivity of suitable habitat for the small-footed myotis bat. These actions could have long-term, moderate to major, beneficial effects on suitable habitat depending upon the alternatives chosen for implementation and the extent of their implementation over time. Further benefits would occur under this alternative from restoration of large areas of riparian and meadow habitats in Yosemite Valley, which are important foraging habitat for the small-footed myotis bat.

Projects that could have adverse effects on suitable habitat for the small-footed myotis bat include the Yosemite View Parcel Land Exchange (NPS); Yosemite Motels Expansion, El Portal (Mariposa Co.); El Portal Road Improvement Project (NPS); Yosemite West Rezone for 55 Acres (Mariposa Co.); and Evergreen Lodge Expansion (Tuolumne Co.). Under this alternative, additional adverse impacts would occur from new development in El Portal, Wawona, Hazel Green, or possibly Foresta.

In total, the cumulative impact on the small-footed myotis bat would be moderate and beneficial, based primarily on implementation of large-scale regional land plans that could protect wide areas of habitat, and restoration of important habitats in Yosemite Valley under this alternative. In comparison, projects with potential adverse impacts would affect relatively small areas of habitat.

Long-eared myotis bat (Myotis evotis)

Status: Federal species of concern. Regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS), U.S. Forest Service plans for adjacent wilderness, the Fire Management Plan Update (NPS), and the Merced Wild and Scenic River Comprehensive Management Plan (NPS) could improve the size, integrity, and connectivity of suitable habitat for the long-eared myotis bat. These actions could have long-term, moderate to major, beneficial effects on suitable habitat, depending upon the alternatives chosen for implementation and the extent of their implementation over time. Further benefit would occur under this alternative from restoration of large areas of riparian and meadow habitats in Yosemite Valley, which are important foraging areas for long-eared myotis bats.

Current and reasonably foreseeable future projects that could have adverse effects on suitable habitat for the long-eared myotis bat include the Yosemite View Parcel Land Exchange (NPS); Yosemite Motels Expansion, El Portal (Mariposa Co.); El Portal Road Improvement Project (NPS); Hazel Green Ranch (Mariposa Co.) project; Yosemite West Rezone for 55 Acres (Mariposa Co.); and Evergreen Lodge Expansion (Tuolumne Co.). Additional adverse impacts would occur from new development in El Portal, Wawona, Hazel Green, or possibly Foresta under this alternative.

Overall, there would be a moderate, beneficial cumulative impact on long-eared myotis bats, based on the potential protection of suitable habitat resulting from implementation of regional plans in combination with restoration of important habitats in Yosemite Valley. The projects with possible adverse impacts on the long-eared myotis bat would affect a relatively small area of habitat compared to projects with potential beneficial impacts.

Fringed myotis bat (Myotis thysanodes)

Status: Federal species of concern. Regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS), U.S. Forest Service plans for adjacent wilderness, the Fire Management Plan Update (NPS), and the Merced Wild and Scenic River Comprehensive Management Plan (NPS) could improve the size, integrity, and connectivity of suitable habitat for the fringed myotis bat. These actions could have long-term, moderate to major, beneficial effects on suitable habitat, depending on the alternatives chosen for implementation and the extent of their implementation over time. Further beneficial effects would be provided by restoration of large areas of riparian and meadow habitats in Yosemite Valley that would occur under this alternative. Such areas are important foraging habitat for fringed myotis bats.

Current and reasonably foreseeable future projects that could adversely affect suitable habitat for fringed myotis bats include the Yosemite View Parcel Land Exchange (NPS); Yosemite Motels Expansion; El Portal (Mariposa Co.); El Portal Road Improvement Project (NPS); Hazel Green Ranch (Mariposa Co.) project; Yosemite West Rezone for 55 Acres (Mariposa Co.); and Evergreen Lodge Expansion (Tuolumne Co.). Additional adverse impacts would occur from new development in El Portal, Wawona, Hazel Green or possibly Foresta under this alternative.

Overall, there would be a moderate, beneficial cumulative impact on the fringed myotis bat, based on the potential protection of suitable habitat resulting from wide-reaching regional plans coupled with actions under this alternative that would restore important habitats in Yosemite Valley. The projects with possible adverse impacts on the fringed myotis bat would affect a relatively small area of habitat compared to projects with potential beneficial impacts.

Long-legged myotis bat (Myotis volans)

Status: Federal species of concern. Regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS), U.S. Forest Service plans for adjacent wilderness, the Fire Management Plan Update (NPS), and the Merced Wild and Scenic River Comprehensive Management Plan (NPS) could improve the size, integrity, and connectivity of suitable habitat for the long-legged myotis bat. These actions could have long-term, moderate to major, beneficial effects on suitable habitat, depending upon the alternatives chosen for implementation and the extent of their implementation over time. Further beneficial effects would result from restoration of large areas of riparian and meadow habitats in Yosemite Valley that would occur under this alternative. Such areas are important foraging habitat for long-legged myotis bats.

Current and reasonably foreseeable future projects that could have adversely affect suitable habitat for the long-legged myotis bat include the Yosemite View Parcel Land Exchange (NPS); Yosemite Motels Expansion, El Portal (Mariposa Co.); El Portal Road Improvement Project (NPS); Hazel Green Ranch (Mariposa Co.) project; Yosemite West Rezone for 55 Acres (Mariposa Co.); and Evergreen Lodge Expansion (Tuolumne Co.). Additional adverse impacts would occur from new development in El Portal, Wawona, Hazel Green, or possibly Foresta under this alternative.

Overall, there would be a moderate, beneficial cumulative impact on the long-legged myotis bat, based on the potential protection of suitable habitat through implementation of regional plans in combination with restoration of important habitats in Yosemite Valley under this alternative. The projects with possible adverse impacts on the spotted bat would affect a relatively small area of habitat compared to projects with potential beneficial impacts.

Yuma myotis bat (Myotis yumanensis)

Status: Federal species of concern; California species of concern. Regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS), U.S. Forest Service plans for adjacent wilderness, the Fire Management Plan Update (NPS), and the Merced Wild and Scenic River Comprehensive Management Plan (NPS) could improve the size, integrity, and connectivity of suitable habitat for the Yuma myotis bat. These actions could have long-term, moderate to major, beneficial effects on suitable habitat, depending upon the alternatives chosen for implementation and the extent of their implementation over time. Actions under this alternative would provide additional benefit to Yuma myotis bats by restoring large areas of meadow and riparian habitats in Yosemite Valley, which are important foraging areas for this species.

Current and reasonably foreseeable future projects that could have adversely affect suitable habitat for the Yuma myotis bat include the Yosemite View Parcel Land Exchange (NPS); Yosemite Motels Expansion, El Portal (Mariposa Co.); El Portal Road Improvement Project (NPS); Hazel Green Ranch (Mariposa Co.) project; Yosemite West Rezone for 55 Acres (Mariposa Co.); and Evergreen Lodge Expansion (Tuolumne Co.). Additional adverse impacts would occur from new development in El Portal, Wawona, Hazel Green, or possibly Foresta under this alternative.

Overall, there would be a moderate, beneficial, cumulative impact on the Yuma myotis bat, based on the potential protection of suitable habitat resulting from implementation of regional plans augmented by restoration of important habitats in Yosemite Valley under this alternative. The projects with possible adverse impacts on Yuma myotis bats would affect a relatively small area of habitat compared to projects with potential beneficial impacts.

Greater western mastiff bat (Eumops perotis californicus)

Status: Federal species of concern; California species of concern. Regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS), U.S. Forest Service plans for adjacent wilderness, the Fire Management Plan Update (NPS), and the Merced Wild and Scenic River Comprehensive Management Plan (NPS) could improve the size, integrity, and connectivity of large areas of suitable habitat for the greater western mastiff bat. These actions could have long-term, moderate to major, beneficial effects on suitable habitat depending upon the alternatives chosen for implementation and the extent of their implementation over time. This alternative would further benefit greater western mastiff bats through the restoration of large areas of meadow and riparian habitats that are important foraging areas for this bat species.

Current and reasonably foreseeable future projects that could have adversely affect suitable habitat for the greater western mastiff bat include the Yosemite View Parcel Land Exchange (NPS); Yosemite Motels Expansion, El Portal (Mariposa Co.); El Portal Road Improvement Project (NPS); Hazel Green Ranch (Mariposa Co.) project; Yosemite West Rezone for 55 Acres (Mariposa Co.); and Evergreen Lodge Expansion (Tuolumne Co.). Additional adverse impacts would occur from new development in El Portal, Wawona, Hazel Green, or possibly Foresta under this alternative, although no suitable mastiff bat roosting habitat (cliffs) is nearby.

Overall, there would be a moderate, beneficial cumulative impact on the greater western mastiff bat based on the potential protection of suitable habitat from implementation of regional plans in combination with restoration of important habitats in Yosemite Valley that would occur under this alternative. The projects with possible adverse impacts on the greater western mastiff bat would affect a relatively small area of habitat compared to projects with potential beneficial impacts.

Sierra Nevada snowshoe hare (Lepus americanus tahoensis)

Current and reasonably foreseeable future projects that could adversely affects suitable habitat for snowshoe hares include the Evergreen Lodge Expansion (Tuolumne Co), Hazel Green Ranch (Mariposa Co.) project, and Yosemite West Rezone for 55 Acres (Mariposa Co.). This project would primarily affect forest habitat. New development of parking at Hazel Green, as would occur under this alternative, could affect snowshoe hare habitat, although the apparent scarcity of this species makes this impact unlikely.

Overall, there would be a minor and beneficial impact on snowshoe hares under Alternative 2, based on the potential protection of suitable habitat resulting from implementation of regional plans. The projects with possible adverse impacts on snowshoe hares would affect a relatively small area of habitat compared to projects with potential beneficial impacts.

White-tailed hare (Lepus townsendii)

Sierra Nevada mountain beaver (Aplodontia rufa californica)

Status: Federal species of concern; California species of special concern. Regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS), U.S. Forest Service plans for adjacent wilderness, the Fire Management Plan Update (NPS), and the Merced Wild and Scenic River Comprehensive Management Plan (NPS) could improve the size, integrity, and connectivity of suitable habitat for the mountain beaver. These regional plans would have a long-term, moderate, beneficial effect on suitable habitat for the mountain beaver. No reasonably foreseeable future projects are expected to have an adverse effect on Sierra Nevada mountain beaver, including increased visitor use at Badger Pass that would occur under this alternative.

Cumulative Impacts Conclusion

Many of the cumulative impact principles given in the conclusion for general wildlife earlier in this alternative also apply to special-status species.

Overall, current and reasonably foreseeable future projects within the cumulative impact assessment area considered in conjunction with the actions under Alternative 2 would have a moderate, beneficial effect on special-status species and their habitats. This is primarily due to the potential effects that would come from implementation of large-scale planning documents that could protect and restore wildlife habitats over much of the Sierra Nevada. These plans would compliment actions under this alternative, which would restore large areas of meadow, riparian, and California black oak habitats that are important to many special-status species.

Under Alternative 2, adverse impacts would affect some special-status species such as valley elderberry longhorn beetle, Sierra Nevada mountain beaver, marten, and Pacific fisher from new development outside of Yosemite Valley. Such impacts would add to the adverse effects of some current and reasonably foreseeable future projects. However, these impacts would be of limited severity, because of the size and type of habitat affected, and would have little effect on the overall cumulative impacts on special-status species under this alternative, which would be moderate beneficial.

VEGETATION

Fifty-one special-status plant species within Yosemite Valley and other out-of-Valley areas could potentially be affected by Alternative 2 as presented in this Final Yosemite Valley Plan/SEIS. Refer to table 3-7 (see Vol. Ia, Chapter 3) for a list of these species; their federal, state, and local status; and their general habitat requirements and locations. The impacts that have been identified in this section are generally long term except where noted.

Yosemite Valley

No federal- or state-listed (threatened or endangered) plant species are known to occur in Yosemite Valley. Twelve park rare plant species currently exist in the Valley: sugar stick, round-leaved sundew, stream orchid, fawn-lily, northern bedstraw, Sierra laurel, false pimpernel, azure penstemon, phacelia, wood saxifrage, giant sequoia, and ladies’ tresses. Restoration of large portions of potentially wet meadows and riparian habitat (at Yosemite Lodge, former Upper and Lower River and Lower Pines Campgrounds, and Housekeeping Camp) under Alternative 2 would have a moderate, beneficial impact on round-leaved sundew, northern bedstraw, false pimpernel, phacelia, ladies’ tresses, and Sierra laurel. Removal of food services at Happy Isles could slightly increase natural habitat for the stream orchid, with minor, beneficial effects.

Removal of the Ahwahnee tennis courts would have a major, adverse impact (long term) on the individual planted giant sequoia trees in this area, because these trees would be removed and the site restored to California black oak woodland. Redesign of the Ahwahnee parking lot could have adverse impacts to the planted giant sequoia trees depending on final alignment of parking lots and driveways. Relocation of Superintendent’s House (Residence 1) to the Yosemite Village Historic District could result in removal of one giant sequoia along the access road. Individual trees would be removed in these areas; however, because none of these actions would affect overall sustainability of giant sequoias within the park’s three naturally occurring groves, there would be a negligible impact on the overall sustainability of giant sequoias in the park.

The fawn-lily is currently affected by trampling and picking of its showy flowers. This species would not be further impacted under Alternative 2. The wood saxifrage typically grows on moist cliffs and also would not be affected by the actions of this alternative.

Out-of-Valley

This alternative would have no impacts on rare plant species at South Landing or Henness Ridge, given that no development actions are proposed in these areas.

El Portal

Currently one federal plant species of concern (Congdon’s lomatium), four state-listed rare species (Yosemite onion, Tompkin’s sedge, Congdon’s woolly-sunflower, and Congdon’s lewisia), and six park rare species (Indian paintbrush, collinsia, pitcher sage, Congdon’s monkeyflower, Palmer’s monkeyflower, and phacelia) occur within the general El Portal area.

Adverse impacts from trampling would continue to occur to all of these species except for Yosemite onion and Congdon’s lomatium, which occur on inaccessible steep slopes in association with poison oak. Impacts on the remaining species from trampling would increase as a result of a substantially increased human population in El Portal. Impacts from habitat loss and competition for resources (i.e., light, water, and nutrients) would continue to adversely affect most species because of the continued high degree of non-native species encroachment expected in this area, as well as the increased potential for new introductions as a result of increased areas of disturbance and landscaping. Potential impacts (including habitat loss and direct loss of plants) would occur to Tompkin’s sedge, Indian paintbrush, collinsia, pitcher sage, Congdon’s monkeyflower, Palmer’s monkeyflower, and phacelia from development of out-of-Valley parking and employee housing. These impacts would be mitigated through avoidance (site selection), salvage and replanting of perennial species (Tompkin’s sedge in particular), and topsoil salvage and re-application after construction, which would protect the seed source of annuals. Impacts to these species in conjunction with mitigation measures would be minor and adverse.

The restoration of habitat at the old sewage treatment plant at Rancheria Flat and sand pit would have moderate beneficial impacts on Congdon’s woolly-sunflower.

Foresta

No federal- or state-listed plant species occur in Foresta; however, five park rare plant species occur in the area (inconspicuous monkeyflower, pansy monkeyflower, goldenaster, snapdragon, and Small’s southern clarkia). These species would experience slightly greater adverse impacts from radiating use because of increased residential and operational activities with the reconstruction of 14 houses and potential relocation of stables to Foresta. However, direct loss of individual plants or populations from construction is not expected because these species are not known to occur in the development area. There would be a potential increase in impacts to rare plant habitat by encroachment of non-native species associated with landscaping activities as well as increased numbers of residential and horse trailer vehicles, with overall minor, adverse effects.

If parking were constructed in Foresta, overall impacts would be moderate and adverse due to loss of habitat for goldenaster and both monkeyflower species. Radiating impacts from visitors in areas adjacent to the parking area would be minimized by the installation of fences, signs, and other measures to direct visitors away from sensitive habitats.

Hazel Green

One federal species of concern (slender-stemmed monkeyflower) and one park rare plant species (Small’s southern clarkia) occur at Hazel Green. These species, which occur in open areas and meadows, could be directly impacted by development of a transit and parking area at Hazel Green. Plants could also be impacted by picnicking, trampling, and random use of sites adjacent to the parking area. These activities would result in minor, adverse impacts on these species.

Badger Pass

No federal- or state-listed plant species occur at Badger Pass. The surrounding montane meadow areas are inhabited by one federal species of concern (Bolander’s clover) and two park rare species (dwarf sandwort and Yosemite ivesia). These species would experience adverse impacts from radiating visitor use at the new day-visitor parking area at Badger Pass. Any impacts would be mitigated through design of the Badger Pass parking facility and installation of signs or fencing to direct people away from sensitive areas. Therefore, the long-term impact would be minor and adverse.

Wawona

No federal-listed plants, one state-listed plant species (Yosemite onion), and eight park rare species occur within the Wawona basin (snapdragon, Child’s blue-eyed Mary, round-leaved sundew, Sierra sweet-bay, Bolander’s skullcap, giant sequoia, trillium, and Hall’s wyethia). New housing development would result in loss of a portion of the trillium population in this area, which would be a moderate, adverse impact. Increased human use in this area during the spring and summer would have potential radiating impacts such as trampling on all of the rare species in the Wawona area. However, these impacts would be minor with the implementation of mitigation measures (such as fencing) to direct visitors away from sensitive plant habitat.

Big Oak Flat Entrance

No special-status species are known to exist in the general vicinity of the Big Oak Flat Entrance area, thus no impacts to federal-, state-, or park-listed species would occur at this site under Alternative 2.

South Entrance

No known federal- or state-listed species occur in the South Entrance area. One park rare species (Sierra sweet-bay) is located within the riparian area adjacent to the Wawona road. Expanded parking and visitor center structures in this vicinity would be designed to avoid riparian areas and, therefore, would minimize the potential impact on the Sierra sweet-bay. The impacts of Alternative 2 on this species would be minor and adverse as a result of increased visitor activity in the South Entrance area and the potential loss of a small area of habitat.

Tioga Pass Entrance

One federal species of concern (Tiehm’s rock-cress) and thirteen park rare species occur within hiking distance of Tioga Pass.

One species, the common juniper, could be directly impacted by construction of a new or expanded entrance/contact station at Tioga Pass. Construction may result in loss of habitat or direct loss of individual plants. There could be indirect effects on Tiehm’s rock-cress and all 13 park rare species from increased foot traffic and associated trampling and soil compaction in the area. There could be increased hiking on Mt. Dana, which is within a day’s hike from the Tioga Pass Entrance Station. The popular hike to the top of Mt. Dana is a cross-country path, without a formal route. Increased use on Mt. Dana could have a long-term, moderate, adverse impact on these rare plant species on Mt. Dana.

Conclusion

Fifty-one species would potentially be impacted in Alternative 2. The proposed actions of this alternative would include mitigation measures to minimize radiating adverse impacts to these species. Radiating impacts from development actions such as trampling, picking, and increases in non-native plant species establishment from increased visitor uses in and out of the Valley would be limited to negligible to minor by managing uses within these sensitive areas and increasing management to control non-native species.

Adverse impacts as a result of habitat loss would occur to trillium in Wawona, to Small’s southern clarkia and slender-stemmed monkeyflower in Hazel Green, to Tompkin’s sedge and six park rare species in El Portal, to Tiehn’s rock-cress at Tioga Pass and to one park rare species in the Valley. These impacts would be mitigated by reasonable designs to avoid these species, as identified in site-specific surveys. For some species, salvaged topsoil at the site would be retained and reused to encourage re-establishment. Consequently, minor to moderate local impacts to individual plants or populations would occur in these areas.

Beneficial impacts would occur to rare species in the Valley (such as northern bedstraw, false pimpernel, and ladies’ tresses), because of the extensive restoration of riparian and meadow habitat, with moderate, beneficial effects. Alternative 2 would have no measurable impacts on the fawn-lily or wood saxifrage. Moderate, beneficial effects would occur in El Portal to Congdon’s woolly-sunflower with restoration of a small area of habitat at the old treatment plant at Rancheria Flat and the sand pit.

The overall impact to special-status plant species would be minor adverse, primarily as a result of habitat loss in Hazel Green, El Portal, and Wawona.

Cumulative Impacts

Many of Yosemite’s special-status plant species are fairly widespread (for the most part, they extend well beyond park boundaries) but are limited to specific substrates or other limited habitats. Analysis of the cumulative impacts on these species focuses on identified projects that are or will be occurring on the western slope of the central Sierra Nevada in the foreseeable future (see Vol. II, Appendix H).

Although substantial habitat fragmentation currently exists in vegetation communities as a whole from human development, the relatively discrete populations of rare plants in Yosemite Valley and surrounding areas are little affected by this phenomenon. Rather, the primary effects on rare plants are short-term impacts to habitat, long-term habitat loss through development or shifts in species composition to non-native cover, and loss of both the occurrence and natural frequency of natural processes that many of these species depend upon.

Many of the lower-elevation wet meadows throughout the Sierra Nevada have been altered through channelization of drainages, grazing, encroachment by non-native species, and even permanent flooding through the construction of water storage and hydroelectric dams. Rare species dependent on these areas have undergone declines due to permanent loss of habitat (as a result of projects such as Hetch Hetchy Reservoir and O’Shaughnessy Dam).

Development of roads through lower-elevation riparian corridors throughout the Sierra Nevada have also led to temporary population declines of some species and permanent loss of habitat for others, depending on the magnitude of the project and extent of actual ground disturbance within the critical habitat zone.

Alterations in fire frequency and intensity have also led to short-term losses of some species dependent on frequent low-intensity fires. Some of these species may be more resilient than previously recognized, with the ability to lie dormant (in seed form) until conditions are favorable for germination, including many species of monkeyflowers in Yosemite National Park.

According to the Sierra Nevada Ecosystem Project (UC Davis 1996b), of the five habitat types in the Sierra Nevada (Jeffrey and ponderosa pine forests, foothill woodlands, subalpine forests, meadows, and chaparral) that contain the most rare and endemic taxa, foothill woodlands and chaparral are receiving the greatest increase in impacts and fragmentation by urbanization along the western slope of the Sierra Nevada. In chaparral vegetation types, the frequency of fire has been altered to protect other resource values such as timber and homes. Taxa that are dependent on fire as a part of their life history and ecology may be adversely impacted by long-term changes in the management of chaparral vegetation. The changes may include a shift from fall to spring burning, mechanical treatments, or alteration of the fire frequency or intensity of burns.

Short-Term Impacts to Habitat

Impacts from past road construction projects (El Portal Road Improvement and Hetch Hetchy Road Reconstruction projects) on some species confined to riparian, lower montane, and foothill areas within Yosemite have occurred. Mitigation efforts have included protection of rare species within these project sites by salvaging individual plants and replanting them after construction is completed; timing construction activities to periods when annuals have gone to seed; or specifying salvage, treatment, and replacement of soils and materials within known population areas. Future construction projects at and in the vicinity of O’Shaughnessy Dam and at Evergreen Road may temporarily affect both annual and perennial park and state rare plant species. Specifically, these actions would result in minor, adverse, short-term impacts to pansy and slender-stemmed monkeyflowers, assuming implementation of the mitigation measures listed above.

Additional short-term impacts would occur to riparian areas outside the park – specifically, actions planned on the main stem of the Merced River. These direct construction actions (the Briceburg Bridge Reconstruction and the Merced River Canyon Trail Acquisition) would cause minor adverse impacts to rare plant habitat.

Long-Term Habitat Loss

Installation of riprap and permanent loss of riparian vegetation as a result of the Yosemite Motels Expansion, El Portal (Mariposa Co.) and the Yosemite View Parcel Land Exchange would lead to loss of habitat in the Merced River corridor, with resulting loss of rare plants growing at those sites. This would be a minor to moderate adverse impact, depending on the site and the species affected by each potential project. Impacts to the special-status species would be partially mitigated by restoration of the sand pit and old treatment plant at Rancheria Flat in El Portal, providing additional rare plant habitat. Projects such as the development of new and additional infrastructure at Evergreen Lodge, Silvertip Resort Village, and Hazel Green Ranch; rehabilitation of Tuolumne Grove trailhead parking, and fuel treatment projects (including logging in Stanislaus National Forest) would lead to long-term loss of habitat for a variety of rare plant species, thereby resulting in minor to moderate adverse impacts.

Change in Frequency of Natural Processes

The addition of lodging units with the Yosemite Motel Expansion, El Portal (Mariposa Co.); Yosemite View Parcel Land Exchange; Silvertip Resort Village; Hazel Green Ranch; and other sites could further limit the management of these areas with natural fire, thereby causing reductions in fire-dependent species at these sites (including state rare Tompkin’s sedge, federal species of concern slender-stemmed monkeyflower, and many lower-elevation chaparral species). These projects would also have the potential for localized minor to moderate and adverse effects on rare species habitat; however, with the implementation of site-specific surveys and state- and federal-required mitigation measures, these localized adverse impacts would be minor. Construction actions to eliminate the threat of flood damage to infrastructure along the South Fork and main stem of the Merced River outside of Yosemite would also lead to a loss of flood frequency. Floods scour out riparian zones and create new available habitat for species such as park rare Sierra sweet-bay.

A number of large-scale planning projects would potentially benefit rare plant species through more comprehensive land use management goals, objectives, and strategies. Some of these planning projects and resulting documents include the Yosemite Fire Management Plan Update, Sierra Nevada Framework for Conservation and Collaboration (USFS), Fire Management Action Plan for Wilderness (USFS, Stanislaus), Merced Wild and Scenic River Comprehensive Management Plan, and other wilderness management plans. These reasonably foreseeable future management and planning projects within the cumulative impact assessment area would have regional minor to moderate and beneficial impacts to rare species and their habitats because of their similar management objectives.

As summarized in the conclusions for Alternative 2, this alternative would have potential adverse impacts to two federal species of concern, one state-listed species, and minor, adverse effects on local populations of park rare species due to loss of individuals or habitat in the Valley, as well as in out-of-Valley areas and/or increased visitor use adjacent to newly impacted areas. When looking at impacts of Alternative 2 in conjunction with impacts of other past, present, and foreseeable regional planning and development activities, the cumulative effect on these special-status plant species would be minor and adverse. The beneficial impacts expected for some species from regional planning efforts would be outweighed by the permanent loss of habitat from regional development projects and developments within the park at out-of-Valley areas.

Air Quality

VEHICLE-GENERATED EMISSIONS

A summary of the traffic air emissions in Yosemite Valley under Alternative 2 is provided in table 4-31. The emissions data noted in table 4-31 show emissions from the following major vehicle fleet categories:

Visitor vehicles
Commercial tour buses (assumed to be conventional diesel propulsion)
In-Valley and out-of-Valley shuttle buses (four propulsion/fuel technology options including diesel, propane, compressed natural gas, and fuel cell were analyzed)
National Park Service and concessioner employee vehicles
National Park Service and concessioner maintenance and administration road vehicles

National Park Service and concessioner maintenance and administration non-road vehicles

Compared to Alternative 1 in the year 2015, volatile organic compound emissions would decrease by 10%, carbon monoxide would decrease by 45%, nitrogen oxides would increase by 32%, and particulate matter would decrease by about 45% assuming conventional diesel technology is used for shuttle buses. There would be a moderate increase in nitrogen oxides emissions, which would be attributable to the operation of shuttle buses from three out-of-Valley parking areas and in expanded in-Valley shuttle service. Nitrogen oxide emissions would also increase with the use of compressed natural gas in buses, but these emissions would decrease with the use of propane or fuel cell technology in the shuttle bus fleet. A major decrease in particulate matter would occur because of the sharp reductions in vehicle miles traveled and associated reductions in road dust.

AMBIENT AIR QUALITY

Traffic flow was modeled (see Vol. II, Appendix I for additional air modeling information) to perform carbon monoxide and PM₁₀ hot-spot analyses for Northside Drive from Yosemite Lodge to park headquarters. This road segment was chosen because it is the most congested roadway in Yosemite Valley under Alternative 1. During the inbound peak travel hour, the EMFAC model predicted a maximum 1-hour average carbon monoxide concentration of 0.5 parts per million, and a carbon monoxide concentration of 0.6 parts per million during the outbound peak travel hour. When added to a background carbon monoxide concentration of 3.0 parts per million, the estimated carbon monoxide concentrations of 3.5 and 3.6 parts per million for inbound and outbound traffic scenarios, respectively, would not exceed the federal or California 1-hour carbon monoxide standards of 35 parts per million and 20 parts per million, respectively. Based on traffic during the inbound peak travel hour, the calculated maximum 8-hour average carbon monoxide concentration was 2.45 parts per million, and the analogous maximum 8-hour carbon monoxide concentration was 2.52 parts per million for traffic during the outbound peak travel hour. The carbon monoxide concentrations for

Table 4-31 Summary of Annual Air Emissions from Vehicles in Yosemite Valley (Tons/Yr)
Alter- native	2000				2005				2010				2015
	Shuttle Bus Fuel Type				Shuttle Bus Fuel Type				Shuttle Bus Fuel Type				Shuttle Bus Fuel Type
	Diesel	CNG	Propane	FC	Diesel¹	CNG	Propane	FC	Diesel¹	CNG	Propane	FC	Diesel¹	CNG	Propane	FC
VOC Emissions
12	50.9	No alternative fuels			28.0	No alternative fuels			14.0	No alternative fuels			8.6	No alternative fuels
2	NA	No alternative fuels			17.0	16.3	19.8	NA³	10.3	9.6	13.0	7.1	7.7	7.0	10.5	4.5
CO Emissions
1²	568.2	No alternative fuels			364.1	No alternative fuels			249.2	No alternative fuels			189.8	No alternative fuels
2	NA	No alternative fuels			184.7	208.6	177.0	NA³	131.2	164.8	131.6	115.5	103.5	145.4	111.0	87.8
NO_X Emissions
1²	84.2	No alternative fuels			59.3	No alternative fuels			44.9	No alternative fuels			38.8	No alternative fuels
2	NA	No alternative fuels			61.2	54.2	47.5	NA³	54.3	47.7	40.6	23.5	51.4	45.1	37.8	20.7
SO₂ Emissions
1²	6.3	No alternative fuels			5.8	No alternative fuels			5.6	No alternative fuels			5.4	No alternative fuels
2	NA	No alternative fuels			4.4	3.3	3.3	NA³	4.2	3.2	3.2	3.2	4.1	3.1	3.1	3.1
PM₁₀ Emissions
1²	2.5	No alternative fuels			2.3	No alternative fuels			2.2	No alternative fuels			2.2	No alternative fuels
2	NA	No alternative fuels			1.3	1.3	1.2	NA³	1.2	1.2	1.2	1.1	1.2	1.2	1.1	1.1
PM₁₀ Road Dust
1²	165				165				165				165
2	80				80				80				80

1. Assumes that in-Valley shuttle buses are conventional diesel buses that would meet emissions standards in effect in 2000. Shuttle buses in this alternative could employ advanced technologies to lower emissions.2. No Action3. NA = Not applicable; fuel cell scenarios were assumed not be available until 2010.Note: Values expressed in tons per year.CNG = compressed natural gasFC = Fuel Cell

Alternative 2 would not exceed the federal or California 8-hour carbon monoxide standard of 9 parts per million. As noted in table 4-32, these carbon monoxide concentrations would represent major reductions in ambient carbon monoxide levels for the inbound and outbound peak hours when compared to Alternative 1.

Table 4-32 Predicted Maximum Carbon Monoxide Concentrations
Alternative	Standard		Inbound Peak Hour		Outbound Peak Hour
	CA	Fed	Maximum (ppm)	Reduction¹ (%)	Maximum (ppm)	Reduction¹ (%)
	(ppm)
1-Hour Concentration
1	20	35	5.10	NA	6.50	NA
2			3.50	76.2	3.60	82.9
8-Hour Concentration
1	9	9	3.57	NA	4.55	NA
2			2.45	76.2	2.52	82.9

1. Based on results without background concentrations and relative to Alternative 1

Based on traffic in the inbound peak travel hour, the maximum 24-hour PM₁₀ concentration would be 27.4 micrograms per cubic meter (m g/m³), and the analogous PM₁₀ concentration would be 28.2 m g/m³ based on traffic in the outbound peak travel hour. The estimated PM₁₀ concentrations for the inbound and the outbound peak hours would not exceed the federal standard of 150 m g/m³ or the California standard of 50 m g/m³. As noted in table 4-33, these PM₁₀ concentrations would represent major reductions in ambient PM₁₀ levels for the inbound and outbound peak hours when compared to Alternative 1.

Table 4-33
Pred