| Table of Contents | Alternative 3 | Alternative 4 | Alternative 5 | Commitments of Resources | Uses/Productivity |
| Short-Long Term | Chapter 5 | Chapter 6 | Bibliography | Glossary | Acronyms/Abbreviations | Index |
| Part 1 | Part 2 | Part 3 | Part 4 |

The analysis of potential impacts from actions implemented under Alternative 5, Yosemite Village and out-of-Valley parking (El Portal, Henness Ridge, and Foresta), are presented in this section.

This section analyzes impacts on water resources: hydrology, including floodplain values, and water quality. Impacts to water resources are described by area (i.e., Yosemite Valley, El Portal, Wawona, and out-of-Valley parking locations) and are characterized as long-term alterations or restoration of hydrologic processes (e.g., water flow and flood regime) or water quality (e.g., turbidity, and non-point source pollution from vehicles or recreational use).

YOSEMITE VALLEY HYDROLOGY

Actions to implement the River Protection Overlay include the removal of development within 150 feet of the river. These actions would restore the river to more natural geomorphologic conditions through restoration of stream banks (i.e., stream bank stability) and the 100-year floodplain. The River Protection Overlay would allow natural processes to prevail in the river and floodplain and minimize the alterations of the floodplain due to existing and future facilities. Further, removal of development from the River Protection Overlay would potentially reduce visitor degradation of stream banks and the river channel by concentrating visitor use away from the river. Examples of these areas include Housekeeping Camp, certain meadow roads and turnouts, and campsites immediately adjacent to the river. Removal of facilities from the River Protection Overlay would allow natural floodplain alterations and lateral movement of the river channel (i.e., meandering), and increase opportunities for restoration of riparian vegetation, which would reduce unnatural erosion and deposition. Ultimately, the implementation of the River Protection Overlay would result in a regional, long-term, major, beneficial impact on hydrology and floodplain values.

At Camp 6, the River Protection Overlay would be restored, including oxbows and cut-off channels that once existed in the area. Changes to the existing river dynamics through restoration of oxbows and braided streams could, over time, become more locally pronounced and eventually contribute to restoration of natural stream flow conditions downstream of the Camp 6 area. Restoration actions at Camp 6 would result in localized, long-term, moderate, beneficial impacts on hydrology and the floodplain values.

The Camp 6 parking facility would be situated within a portion of the floodplain that could experience floodwater velocities up to 3 feet per second and floodwater depths exceeding 5 feet in places, as was observed during the January 1997 flood. These facilities, although in an area of low relief and not likely to divert flood flow due to obstructions, could impede the river’s ability to naturally migrate and change course during the extreme flood events. For example, an asphalt pavement surface could hinder the formation of natural flow channels or accelerate surface soil erosion once the asphalt surface and underlying base material is scoured and removed by high-velocity flood waters. A flat-surface parking facility could also reduce the area available to the river for sediment deposition and new bank slope formation. In addition, riverbank stability (soils compaction and vegetation loss) could be reduced due to the radiating impacts associated with the increased concentration of visitors. Overall, development of a parking facility and picnic area in the Camp 6 area could result in localized, long-term, moderate, adverse impacts on hydrology and floodplain values.

The construction of a picnic area at the location of the former Lower River Campground would have a long-term, minor, adverse impact on hydrology due to radiating impacts of increased visitor use to a sensitive stretch of riverbank.

The transit center at Yosemite Village would be constructed outside of the 100-year floodplain, but the concentration of visitors would have radiating impacts to the river and its hydrologic processes. This would be a long-term, minor, adverse impact.

At Yosemite Lodge, Northside Drive would be rerouted to the edge of the 100-year floodplain, and parking would be reconfigured, but would remain in the 100-year floodplain. This would result in a long-term, minor, adverse impact on hydrology because flood flow would be altered.

The removal of three structures at Ahwahnee Row that are located in the 100-year floodplain would have a long-term, localized, minor, beneficial impact on floodplain values by removing impediments on flood flow (particularly pooling in this area).

Restoration areas include the portions of Yosemite Lodge (including motel units that impede flood flow and the former cabins area), Upper and Lower River Campgrounds, and roads from Stoneman and Ahwahnee Meadows that are in the 100-year floodplains. Removal of these facilities and restoration would restore the hydrologic process of flooding, and would be a long-term, moderate, beneficial impact on hydrology.

The presence of a bridge as a fixed structure within a river course can cause alterations in river flow and result in localized morphologic changes to the beds and banks of the river. Morphologic changes attributable to bridge placement, and that are most readily observable, would include scour holes on the downstream side of the abutment, formation of deposition bars downstream of the scour holes, bank instability, unnatural erosion and deposition, changes in flow velocity, and localized channel widening. Removal of these fixed structures would provide for restoration of natural erosion and deposition processes; allow the river to meander and naturally alter course; and reduce flooding potential by removing flow impediments. The impacts of bridge removal would be noticeable as scour holes and downstream deposition bars caused by their in-river abutments diminish and the riverbank is reestablished by natural flow patterns. Bridge removal would continue to improve natural river flow dynamics along extended reaches of the river, and the impacts would be observable for years to come.

Sugar Pine Bridge constricts the river severely, largely because this bend of the river immediately downstream of the Tenaya Creek confluence has always been dynamic. The approach road that connects Ahwahnee Bridge to Sugar Pine Bridge eliminated the numerous small cutoff channels that existed prior to construction in 1929. The loss of the numerous small cutoff channels, combined with the constriction of the river by Sugar Pine Bridge, has forced the creation of a single large cutoff channel immediately adjacent and parallel to the approach road. Removal of Sugar Pine Bridge and the approach road and restoration of the riverbank (vegetation, bank slope, channel width) would be a localized, long-term, major, beneficial impact on the Merced River’s hydrology, by reducing unnatural erosion and scouring, reducing unnatural deposition downstream of the bridge, and allowing the river to meander.

Ahwahnee Bridge moderately constricts flood flow, and has two center piers in the river channel that trap logs at high flows. The trapped logs threaten the structure, but are also important components of the hydrologic and biologic processes of the Merced River. Removal of Ahwahnee Bridge and restoration of the riverbank (vegetation, bank slope, and channel width) would be a localized, long-term, moderate, beneficial impact on the Merced River’s hydrology by reducing scouring and unnatural erosion, and by allowing large, woody debris to remain in the river.

Removal of these two bridges would also be a localized, long-term, major, beneficial impact on floodplain values by removing impediments to flood flow, particularly large flood events such as the January 1997 flood event. Local, short-term, minor, adverse impacts to hydrology may occur during bridge removal due to construction activities in the main river channel.

The possible reconstruction of Swinging Bridge would have long-term, localized, minor, beneficial impacts to the Merced River’s hydrology, because the bridge abutments would be removed from the river channel (although some piers would remain in the river). Local, short-term, minor, adverse impacts to hydrology may occur during reconstruction due to construction activities in the main channel.

At Yosemite Creek, the human built rock rubble pile blocking the western channel would be removed, as would the pedestrian bridge and its abutments immediately upstream of the Yosemite Creek Bridge (vehicle). Removal of these impediments would restore hydrologic processes such as annual spring runoff, particularly restoration of flow to the western channel of the braided stream network, and would be a long-term, minor, beneficial impact on hydrology. Local, short-term, negligible, adverse impacts to hydrology may occur during removal due to construction activities in the western channel during low water.

A new vehicle bridge would be constructed downstream of the existing Yosemite Creek Bridge. The abutments of the new bridge would be outside of normal high water and would minimally impact hydrologic processes. This would result in a long-term, minor, adverse impact on hydrology. Local, short-term, minor, adverse impacts to hydrology may occur during bridge construction due to construction activities in the main channel.

Cascades Diversion Dam was constructed in 1917 to impound water for the intake structure that diverted river flows to a downstream powerhouse. Use of the powerhouse to generate hydroelectric power was discontinued in 1985, as was the diversion of river flows. The dam is located at a natural breakpoint in the channel gradients: upstream of the dam the gradient is .01 feet/feet; downstream of the dam the gradient is .06 feet/feet. The pool and backwater created by the dam extend upstream from the dam about 550 feet. The dam is in danger of failure: outside of spring snowmelt runoff and rain-on-snow winter floods, water flows under the dam instead of through the spillway or over the dam. Failure of the dam would result in unmitigated release of the sediment trapped behind the dam, and materials that comprise the dam. Removal of the dam would have a localized, long-term, major, beneficial impact on the Merced River’s hydrology by preventing the adverse impacts of dam failure and by restoring the free-flowing condition of the river: sediment transport would be unimpeded; natural low-water and flood flow would be restored; and riparian vegetation currently displaced by the pool and backwater would be restored on the riverbanks.

Removal of Cascades Diversion Dam would also be a localized, long-term, major, beneficial impact on floodplain values by removing a substantial impediment to flood flow: both annual spring runoff, and large flood events such as the January 1997 flood event.

Reconstruction of the El Portal Road between the Cascades Diversion Dam and Pohono Bridge could have a beneficial impact on hydrology if the footprint of the existing bank stabilization in the river is reduced, or could have an adverse impact on hydrology if the footprint of the existing bank stabilization in the river is increased. Additional environmental compliance, including a Wild and Scenic River Act Section 7 determination, would be necessary before this segment of road can be reconstructed.

YOSEMITE VALLEY WATER QUALITY

Actions to implement the River Protection Overlay would remove sources of pollutants and reduce erosion and sedimentation by removing facilities and limiting activities associated with facility use and maintenance. These activities include construction and maintenance of visitor use facilities. Additionally, the possible realignment or relocation of roads, trails, and visitor facilities could reduce the introduction of refuse and bacteria by visitors. The removal of the concessioner stable and Swinging Bridge Picnic Area and restoration to natural conditions would reduce a source of nutrients, coliform, turbidity, and other water pollutants to the Merced River. Overall, actions to implement the River Protection Overlay would result in a regional, long-term, moderate, beneficial impact on water quality by removing development immediately adjacent to the Merced River.

The removal of parking spaces from Curry Orchard, Yosemite Falls, the concessioner stable, Stoneman Meadow, and roadside areas throughout the Yosemite Valley would substantially reduce the potential sources of non-point source pollution that are inherent in areas with heavy, concentrated vehicular use. Vehicles can release pollutants onto pavement, including asbestos, heavy metals, petroleum-based products, and other chemicals such as ethylene glycol. Some fraction of these chemicals can be carried by surface-water runoff to streams, and eventually the Merced River. A formalized parking facility would be established at Camp 6, and a transit facility at Yosemite Village; stormwater pollution controls would be incorporated into the facilities’ design (possible treatment methods include sand filters, underground water collection and treatment tanks, or oil/water separators). Replacing the existing parking areas listed above with a formalized parking facility at the Camp 6 area would reduce non-point source pollution from stormwater runoff from large paved surfaces, resulting in a regional, long-term, moderate, beneficial impact on water quality.

The construction of a gas station in Yosemite Village would be a new source of non-point source pollution. Impacts on water quality would be mitigated through stormwater pollution controls at the facility, and have a localized, long-term, minor, adverse impact on water quality.

The increased use of shuttle buses would reduce the number of vehicle miles traveled in the Valley, and allow the removal of some roads (e.g., roads through Stoneman and Ahwahnee Meadows). This would have a long-term, minor, beneficial impact on water quality by reducing non-point source pollution.

EL PORTAL HYDROLOGY

As a result of a U.S. Army Corps of Engineers study (1998), the flood protection levee (hereafter, "levee") in the Hennessey’s Ranch area would need to be raised and extended in order to protect employee housing, the impacts of which would be two-fold.

First, the levee would limit and possibly redirect natural river flow through a localized reach of the river during a 100-year flood event, reducing channel width and increasing flows or eddies depending on floodwater velocity and height. The levee is above the normal high water line and would not affect the river flow during normal spring runoff periods. Increasing the length and height of the levee would be a localized, long-term, minor, adverse impact on the river’s hydrology because this reach of river has low susceptibility to bank scour, erosion, and slope instability.

Secondly, any structure intended to prevent flooding has the potential to limit the natural formation and function of that river’s floodplain. Most of the Merced River in El Portal confined within a bedrock gorge channel, and the floodplain is narrow due to the river gradient and resistant bedrock. Consequently, the majority of the floodplain is more resilient and less susceptible to adverse impacts of altered river flow. The area at Hennessey’s Ranch is one of the few flat, alluvial floodplain sections adjacent to the Merced River at El Portal. The alluviated area was formed through years of river sediment deposition. After construction of the existing flood protection levee, this area was isolated from further sediment deposition because the levee height prevented inundation by large flood flow such as the January 1997 flood event, which was the largest flood event in the 80+ years of stream gauge data at the Pohono gauging station. When compared to the impact of the existing flood protection levee in the No Action Alternative, increasing the length and height of the levee would be a localized, long-term, minor, adverse impact on floodplain values because only flood flow greater than the January 1997 flood event would be affected.

Removal of housing from the River Protection Overlay at Hennessey’s Ranch and restoration of the area would have long-term, minor, beneficial impacts on hydrology by restoring river-related communities and hydrologic processes.

Construction of new housing in the 100-year floodplain but outside of the River Protection Overlay would require the modification of the levee (discussed above), and would result in radiating impacts to the riverbank due to increased employees living in the area. These radiating impacts would have a long-term, minor, adverse impact.

Two pedestrian bridges would be constructed in the vicinity of Hennessey’s Ranch. The bridges and their abutments would be designed to not interfere with the free-flowing condition of the river, and the banks of this river reach are relatively stable and resilient. The two pedestrian bridges would have localized, long-term, minor, adverse impacts on the river’s hydrology and floodplain values. Local, short-term, minor, adverse impacts on hydrology may occur during construction due to construction activities in the main channel.

EL PORTAL WATER QUALITY

Actions to implement the River Protection Overlay would reduce discharge of non-point source pollutants into the river by providing a buffer area where development is removed (e.g., at Hennessey’s Ranch) and future development is constrained (e.g., at Village Center and Railroad Flat). Water quality could be adversely impacted by runoff associated with increased parking spaces for both visitors and employees, although this impact would be mitigated by non-point source pollution controls at large paved areas. The increase in employees living in El Portal would likely result in increased recreational use of the river and subsequent increase in fecal coliform and bacteria levels, resulting in a regional, long-term, minor, adverse impact on water quality. Wastewater from all new buildings (e.g., housing, park headquarters, etc.) would be connected to the existing sanitary sewage system and would meet all applicable water treatment requirements. The impacts of Alternative 5 on water quality in El Portal would be localized, long-term, minor, and adverse, due to increased non-point source pollution resulting from increased development.

WAWONA HYDROLOGY

Construction of employee housing in Wawona would be outside of the 100-year floodplain, approximately 1,000 feet away from the South Fork Merced River. Radiating impacts to the river due to increased numbers of employees accessing the river would reduce bank stability and result in localized, long-term, negligible, adverse impacts on hydrology and floodplain values.

WAWONA WATER QUALITY

Actions to implement the River Protection Overlay would reduce discharge of non-point source pollutants into the river by providing a buffer area where future development is constrained. Water quality could be adversely impacted at the new employee housing by runoff associated with increased parking spaces, although this impact would be mitigated by non-point source pollution controls at large paved areas. Wastewater from all new buildings would be connected to the existing sanitary sewage system and would meet all applicable water treatment requirements. The impacts of Alternative 5 on water quality in Wawona would be localized, long-term, minor, and adverse.

FORESTA HYDROLOGY AND WATER QUALITY

The project site at Foresta is approximately three-quarters of a mile from Crane Creek, but has no rivers, streams, or other hydrologic features, and surface runoff is the only pertinent hydrologic process. A parking facility, Volunteers-in-Parks campground, 14 houses, and a new National Park Service stable at McCauley Ranch (depending on the outcome of the Wilderness Feasibility Study) would be constructed in the Foresta area. These actions would have a localized, long-term, negligible, adverse impact on hydrology resulting from reduced ground cover and potentially increased runoff. These actions would result in increased non-point source pollution, which would be mitigated through stormwater pollution controls at the parking facility, and have a localized, long-term, minor, adverse impact on water quality.

HENNESS RIDGE HYDROLOGY AND WATER QUALITY

Henness Ridge has no significant hydrologic features, and surface-water runoff is the only pertinent hydrologic process. The construction of a parking facility would have localized, long-term, minor, adverse impacts on hydrology resulting from reduced ground cover and potentially increased runoff. Construction of a parking facility would increase non-point source pollution, which would be mitigated through stormwater pollution controls, and would have a localized, long-term, minor, and adverse impact on water quality.

BIG OAK FLAT, TIOGA PASS, AND SOUTH ENTRANCE
HYDROLOGY AND WATER QUALITY

The locations of these entrance stations have no major rivers, streams, or other hydrologic features. Surface-water runoff is the only pertinent hydrologic process. A visitor center and associated visitor service facilities would be constructed, resulting in reduced ground cover and potentially increased runoff. These actions would have a localized, long-term, negligible, adverse impact on surface water hydrology. These actions would have a localized, long-term, negligible, adverse impact on water quality resulting from increased non-point source pollution associated with development.

CONCLUSION

The collective actions of this alternative have regional, long-term, moderate, beneficial impacts on hydrology and water quality, largely due to the removal of facilities in Yosemite Valley from the River Protection Overlay and the 100-year floodplain and removal of the bulk fuel storage facility in El Portal. The beneficial impacts of removing two bridges, Cascades Diversion Dam, campsites, Housekeeping Camp units, etc., have been weighed against the adverse impacts on hydrology and water quality in El Portal due to increased development near the river.

CUMULATIVE IMPACTS

This section assesses the impacts of past, present, and reasonably foreseeable future actions to water resources. The actions identified below have generally occurred within the watershed of the Merced River–both main stem and South Fork.

Past Actions

The water resources of the Merced River have been historically affected by a variety of actions within the floodplain since Euro-American settlement. In Yosemite Valley, the transportation network interferes with flooding and surface-water flow, and lodging, campgrounds, and other structures have been constructed in and immediately adjacent to the river channel. In El Portal, a large portion of the riverbank has been artificially stabilized to protect primary roads and buildings immediately adjacent to the river. Because artificial stabilization of the riverbank began in the 1800s, the Merced River has been separated for decades from substantial portions of its floodplain. During spring runoff floods, this riprap serves to keep the channel from moving, and quickly conveys the water downstream. During winter floods, artificial bank stabilization prevents damage to dwellings and roads in the best-protected sections, but increases bank destruction where there is little or no artificial bank stabilization.

Present Actions

The El Portal Road Improvement Project (NPS) is currently under way from the park boundary to the Cascades Diversion Dam, and affects river-related communities of the Merced River immediately adjacent to the roadway. Natural resources are protected during construction by implementation of a compliance-monitoring program, erosion and sediment controls, hazardous materials controls, revegetation and reclamation, and excluding construction from sensitive habitats. Between El Portal and Yosemite Valley, riprap has been placed in some locations along the north bank of the Merced River to protect the reconstructed El Portal Road, altering the overall flow regime of the river.

Reasonably Foreseeable Future Actions

Reasonably foreseeable future actions proposed in the region are separated below into four general categories: (1) projects expected to have a net beneficial impact; (2) projects expected to have both beneficial and adverse impacts; (3) projects expected to have a net adverse impact; and (4) projects that have no impact relative to the actions of this alternative.

Reasonably foreseeable future projects that could have a net beneficial impact on water resources of the Merced River include:

• The Merced River at Eagle Creek Ecological Restoration Project (NPS)

• Merced Wild and Scenic River Comprehensive Management Plan (NPS)

• Yosemite Wilderness Management Plan Update (NPS), which will address land management issues within the wilderness

• Fire Management Plan Update (NPS)

• Potential Land Use and Management on Lands Adjacent to Yosemite National Park (Sierra Nevada Framework for Conservation and Collaboration).

• Several transportation-related projects (e.g., Yosemite Area Regional Transportation System [YARTS]), which have the general goals of increasing transportation options and reducing reliance on automobiles in the area

• Replacement/Rehabilitation of Yosemite Valley Sewer Line (NPS)

• South Fork Merced River Bridges Replacement (NPS)

• Bridalveil Horse Camp Rehabilitation (NPS)

• Yosemite Creek Campground Restoration (NPS)

• Wawona Campground Rehabilitation (NPS)

• Merced River Canyon Trail Acquisition (BLM)

These projects would have net beneficial impacts on water resources through improved coordination of resource management activities and restoration, although there might be site-specific or short-term, adverse impacts.

Reasonably foreseeable future projects that could have both beneficial and adverse impacts on water resources include:

• Mariposa Grove Roadway Improvement and Giant Sequoia Restoration (NPS), which would remove parking from the Lower Mariposa Grove of Giant Sequoias, restore the area, and realign the intersection at the South Entrance Station.

• Rogge — Ackerson Fire Reforestation (Tuolumne Co.), which would improve slope stability and reduce sedimentation by reforesting 5,000 acres; however, activities could also adversely impact water quality by burning, tilling, and herbicide application.

• A-Rock Reforestation (USFS, Stanislaus), which would improve slope stability and reduce sedimentation by reforesting 4,500 acres; however, activities could also adversely impact water quality by burning, tilling, and herbicide application.

These projects would have beneficial impacts on water resources by removal of facilities, restoration, and slope stabilization, and adverse impacts on water resources through increased non point source water pollution.

Reasonably foreseeable projects that could have a net adverse impact on water resources include:

• The Yosemite View Parcel Land Exchange, El Portal (NPS)

• Merced River Canyon Trail Acquisition (BLM)

• Yosemite Motels Expansion, El Portal (Mariposa Co.)

These projects would have adverse impacts on water resources through increased use and facility development, which could result in stream bank instability and increased non-point source water pollution.

Beneficial impacts on water resources of past, present, and reasonably foreseeable future projects on the Merced River watershed would be related to removal of facilities from the riverbanks and floodplain, restoration of previously developed areas and areas significantly impacted or altered by visitor use, removal of channel obstructions, and reduced human-related impacts. Adverse impacts of these projects on the Merced River watershed would be related to increased use and facility development, which could result in stream bank erosion, soil compaction, loss of vegetation, refuse accumulation, non-point source pollution generation, and degradation of stream characteristics and water quality in the Merced River. Overall, the past, present, and reasonably foreseeable future projects would have a long-term, minor, beneficial impact on water resources. The actions of this alternative would have a long-term, moderate, beneficial impact on water resources. The actions of this alternative, in combination with past, current, and reasonably foreseeable future projects would have a long-term, moderate, beneficial impact on water resources.

This evaluation identifies non-exempted actions within the floodplain that could increase or decrease risk to human life and property by adding or removing housing and facilities from floodplains. The proposed removal and addition of non-exempted facilities from the floodplain are listed below by area and summarized in table 4-117; all impacts would be long-term unless otherwise noted (see plate E for Yosemite Valley flood extent). For related effects on floodplain values and hydrology, see the Water Resources section in this chapter.

1 Development may be in or surrounded by the floodplain2 Impact intensity listed is after implementation of mitigation. All impacts would be long-term unless otherwise noted.

YOSEMITE VALLEY

Cascades Diversion Dam

Dam safety engineers have classified the Cascades Diversion Dam as a "high hazard potential structure" and assigned a Safety of Dams condition of "unsatisfactory." This classification requires immediate corrective action. The removal of the dam would be a long-term, localized, major, and beneficial impact to human health and safety.

Concessioner Stable Area

A moderate, beneficial impact would result from the removal of houses and tent cabins (49 employee beds) and the concessioner stable from the floodplain. This beneficial impact would be related to reduced risk to both human life and property during a flood event. Although the area would be redeveloped as campgrounds, this type of facility is exempt from National Park Service Floodplain Management Guideline. Campgrounds would be located outside the River Protection Overlay and designed to minimize flood flow.

Housekeeping Camp

The removal of 164 housekeeping units and retention of 84 units in the 100-year floodplain would result in a moderate, beneficial impact because overnight lodging within the 100-year floodplain would be reduced, decreasing flood-related risk to both human life and property. Compared to the No Action Alternative, the beneficial effect related to human life is limited, however, because the units are not in use during the winter flood season.

Yosemite Village

Removal of the Concession Headquarters, Indian Creek employee housing (14 employee beds), and removal of three Ahwahnee Row houses (three employee beds) from the floodplain would result in an overall moderate, beneficial impact because fewer people would be living and working within the floodplain and flood hazard related to human safety would be reduced. Redevelopment of this area would minimize placement of structures in the floodplain and include mitigation measures to protect people during flood events. With mitigation, in accordance with National Park Service Floodplain Management Guideline, risk to both human safety and property would be a minor, adverse impact.

Yosemite Lodge Area

Removal of the Superintendent’s House (Residence 1) and five motel units from the floodplain would result in a moderate, beneficial impact because overnight lodging within the floodplain and the associated risk to human safety and property would be reduced. Relocation of the Wellness Center and nearby custodial cabins outside the floodplain would also result in a minor, beneficial impact because the number of facilities and people working within the floodplain would be reduced, resulting in a reduction in the flood hazard related to human safety and property. New overnight parking would be developed that incorporates design standards to minimize the effect on flood flow and allow for runoff, resulting in a negligible, adverse impact. Adverse effects in the Yosemite Lodge area would be further reduced by designs that minimize impacts on natural flood processes and flood damage to structures, and by preparation of evacuation plans and routes (evacuation routes would be located outside the floodplain).

EL PORTAL

Village Center

Moderate, beneficial impacts at the Village Center would result from the adaptive reuse of El Portal Hotel (removal of 12 employee beds and relocation of Yosemite Institute Office), and the removal of the Motor Inn cabins (24 employee beds) because overnight occupation of the floodplain would be reduced. Removal of the bulk fuel storage facility would result in a moderate, beneficial impact on human safety because the number of people working within the floodplain would be reduced. Adaptive reuse of these facilities would include mitigation consistent with National Park Service Floodplain Management Guideline to reduce the risk of property damage due to flooding.

Parts of the Village Center area that would be redesigned to support commercial services and parking would be placed out of the floodplain where possible. For new structures constructed in the floodplain an evacuation and safety plan would be developed. With these mitigation measures in place, there would be a minor adverse impact.

Hennessey’s Ranch

The construction of 656 new employee beds at Hennessey’s Ranch would be a major, adverse impact on human safety because employee beds would be constructed within the 100-year floodplain. However, because mitigation would be incorporated into the design to protect employees and structures during flood events (e.g., raising and extending the levee, evacuation planning), the overall impact would be reduced to moderate and adverse.

WAWONA

There would be no impact to the South Fork Merced River floodplain because the employee housing considered for Wawona would be outside the floodplain.

CONCLUSION

Beneficial impacts in Yosemite Valley would include removal from the floodplain of 164 housekeeping lodge units, the kennel, concessioner stables and associated housing (49 employee beds), the Superintendent’s House (Residence 1), five Yosemite Lodge motel units, the Wellness Center and nearby custodial cabins, and 14 employee beds at Indian Creek. The Concession Headquarters and Indian Creek employee housing would be redeveloped as parking/visitor services, and new overnight parking would be developed at Yosemite Lodge which would have a minor, adverse impact on the floodplain. Overall, the aggregate impact of these actions in combination with mitigation in Yosemite Valley would be moderate and beneficial, because the flood-related risk to human safety and property would be reduced.

Actions in El Portal would include removal from the floodplain of 36 employee beds (moderate, beneficial) and the bulk fuel facility (moderate, beneficial), removal or adaptive reuse of El Portal Hotel (employee housing and Yosemite Institute Office; moderate, beneficial), 656 employee beds at Hennessey Ranch (moderate, adverse) and redevelopment of Village Center (minor, adverse). Beneficial impacts would be related to reduction in the flood-related hazard to human safety. Adverse effects to both human safety and property associated with new development or redevelopment/adaptive reuse within the floodplain would be minimized by mitigation (e.g., design and siting specifications, extending and raising existing levees, and a mandatory evacuation plan) resulting in a net minor, adverse impact.

The total net effect of Alternative 5 would be moderate and beneficial, because the number of people working and overnight lodging/housing within the floodplain would be reduced (reducing flood-related risks to human safety), and mitigation would be implemented to reduce adverse effects on human safety and property associated with development/redevelopment within the floodplain.

CUMULATIVE IMPACTS

The impacts of past, present, and reasonably foreseeable future actions to floodplain values discussed herein are based on analysis of past, present, and reasonably foreseeable future actions in the Merced River watershed from its source near the crest of the Sierra Nevada to Briceburg Bridge. The actions identified below include those projects that have the potential to affect the floodplain of the Merced River.

Past Actions

The Merced River has been historically affected by a variety of actions within the floodplain since Euro-American settlement. In El Portal, from the park boundary to Briceburg Bridge, a large portion of the riverbank has been artificially manipulated. Much of this manipulation is riprap used to stabilize the riverbanks by the California Department of Transportation to protect Highway 140. The National Park Service and Yosemite Motels also placed riprap in the Merced River channel to rebuild roads (e.g., Foresta Road) and protect buildings immediately adjacent to the river. Because stabilization of the riverbank began in the 1800s, the Merced River has been separated for decades from substantial portions of the floodplain in the Merced River Canyon. During spring runoff floods, this riprap serves to keep the channel from moving, and quickly conveys the water down to Lake McClure. During winter floods, bank stabilization prevents damage to dwellings and roads in the best-protected sections, but increases bank destruction where there is little or no bank stabilization.

Present Actions

No current actions are increasing or decreasing flood-related risk to human life. Between El Portal and Yosemite Valley, riprap has been placed in some locations along the north bank of the Merced River to protect the reconstructed El Portal Road. This riprap would have essentially no flood-related risk to life or property.

Reasonably Foreseeable Future Actions

Reasonably foreseeable future actions that could have a potential cumulative beneficial or adverse effect on risk to human life and property during flood events are:

• El Portal, Trailer Village Closure (NPS)

• Yosemite Motels Expansion, El Portal (Mariposa County), (approximately 148 new hotel units)

• Yosemite View Parcel Land Exchange (NPS)

Cumulative effects of past, present, and reasonably foreseeable future actions would have both beneficial (e.g., implementation of the Trailer Village Closure Plan) and adverse (i.e., increased development of overnight lodging units and offices within the floodplain at El Portal) impacts on human life and property during flood events. In El Portal, approximately 59 employee trailers with 68 employee beds at Hennessey’s Ranch (currently Trailer Village) would continue to be scheduled for removal from the 100-year floodplain. This action which occurs outside the scope of actions considered in the Final Yosemite Valley Plan/SEIS, is in accordance with the current provisions of the Trailer Village Closure Plan (NPS 1993b). Cumulative adverse impacts of these potential future projects on the floodplain hazard of the Merced River would be related to increased overnight use and facility development. In El Portal, potential overnight residents and hotel visitors would slowly increase from approximately 1,300 to about 1,600 beds because of the Yosemite Motel’s expansion and the Yosemite View parcel land exchange. This represents an increase of approximately 25% in the number of people potentially affected during a flood.

Overall, the past, present, and reasonably foreseeable future actions listed above would have a long-term, moderate, and adverse effect on risk to human life and property due to the amount and type of new development planned within the floodplain. The total net effect of Alternative 5 would be moderate and beneficial, because overnight lodging/housing within the floodplain would be reduced (reducing flood-related risk to human safety), and mitigation would be implemented to reduce adverse effects on human safety and property associated with development/redevelopment within the floodplain. Effects associated with this alternative, in conjunction with other past, present, and reasonably foreseeable future cumulative actions, would be long-term, minor, and adverse, because potential flood-related impacts to human safety and property from cumulative actions outside the scope of the Final Yosemite Valley Plan/SEIS (e.g., increased overnight lodging within the floodplain in El Portal would increase flood-related risk to human safety and property) would outweigh the beneficial impacts of this alternative.

In this section, wetlands were evaluated in the following locations: Yosemite Valley, El Portal, Tioga Pass Entrance, South Entrance, and Foresta. The Henness Ridge, Wawona, and Big Oak Flat Entrance locations have no wetlands and are not discussed below. There are no actions proposed at Badger Pass, South Landing, or Hazel Green in this alternative.

SIZE

Yosemite Valley

Wetland impacts would take place in the wetland types in Yosemite Valley shown in table 4-118. Acres of impacts are estimated based on geographic information system analysis of meadow and riparian vegetation types from the Yosemite Valley vegetation map (NPS 1994e).

There would be a net gain of 104 acres of wetlands in the Valley. In Yosemite Valley, about 131 acres of wetlands would be restored, 12 acres of new development in wetlands would take place, and 15 acres of redevelopment in potential wetlands would take place under Alternative 5. Overall, this would be a moderate, long-term, beneficial impact on the size of wetlands in Yosemite Valley.

Restoration would take place primarily at the cabin area at Yosemite Lodge, parts of Upper and Lower River Campgrounds, North Pines Campground, Lower Pines Campground, Backpackers and Group Campgrounds, the River Protection Overlay portion of Housekeeping Camp, Camp 6, and Swinging Bridge Picnic Area.

New development in wetlands could take place on 12 acres. Wetland delineation would be completed prior to the planning and design phase for Curry Village, where potential wetlands have been identified, to maximize the opportunity for wetland avoidance and minimization of adverse impacts. If wetlands are present in the area, adverse impacts would be avoided during site design and minimized through design modifications to the greatest extent practicable. If potential adverse impacts on wetlands are disclosed in subsequent planning efforts, additional compliance documentation would be completed as appropriate.

Potential impacts to wetlands would require a Wetland Statement of Findings to be prepared in accordance with Director’s Order #77-1. Wetlands proposed for restoration by this Final Yosemite Valley Plan/SEIS would be counted toward the compensation of wetlands if needed for future compliance. A wetland delineation and a functional analyses would be included in each Statement of Findings. A U.S. Army Corps of Engineers 404 permit would be prepared as required.

Redevelopment in potential wetlands under Alternative 5 would occur on about 15 acres (see table 4-118). The larger areas of redeveloped wetland would occur at Sentinel Beach Picnic Area and Upper Pines Campground. Wetland delineation would be completed prior to the design phase for the proposed Sentinel Beach Picnic Area. Wetland delineation has been completed for Upper Pines Campground (Kleinfelder 1998). Redevelopment within wetland boundaries would be avoided in the Upper Pines Campground area. Redevelopment in areas adjacent to wetlands would occur primarily at Yosemite Lodge, Yosemite Village, and Ahwahnee parking. Redevelopment could have a minor, beneficial effect on neighboring wetlands if water flows that sustain wetlands are improved in the site design.

Redeveloped wetlands may be considered an adverse impact if the sites still qualify as wetlands. Procedural Manual #77-1, Section 5.4 states that "development activities proposed for wetland sites that have been modified or degraded as a result of human activities" (but still meet the wetland definition) are considered "new actions" subject to Director’s Order #77-1 and other statutes. Consequently, degraded wetlands should not be treated as preferred development sites simply because they are already in an impacted condition.

Out-of-Valley Areas

No impacts on the size of wetlands would occur at Henness Ridge, El Portal, South Entrance,Tioga Pass Entrance, or Foresta.

INTEGRITY

Yosemite Valley

The integrity of wetlands would be improved by actions proposed in Alternative 5 in terms of the benefits of the River Protection Overlay such as the re-establishment of riverine and palustrine forest wetlands along the Merced River. The restoration of campgrounds to natural conditions would also decrease foot traffic along the Merced River and allow these wetlands to become reestablished.

Under Alternative 5, no transportation-related activities would directly benefit wetlands. Transportation-related activities that could have indirect adverse impacts on wetlands include the realignment of Northside Drive south of Yosemite Lodge and construction of a new bridge across Yosemite Creek. These indirect impacts would include increased runoff and potential changes to wetland hydrology. These impacts would be mitigated through treatment ponds and road design. Direct impacts to riverine and palustrine forest would occur with the new bridge construction across Yosemite Creek; however, this would be a minor, adverse impact because of the existing level of impact that has occurred to these wetlands.

Out-of-Valley Areas

In El Portal, implementation of the River Protection Overlay and protection of existing wetlands at Hennessey’s Ranch would minimize wetland impacts. Rebuilding the levee could adversely affect wetlands within the levee alignment. These impacts would be minimized by restoration of the riverine and palustrine forest wetlands between the levee and the river’s edge. Should parking be constructed near the El Portal Community Hall, site designs would protect the historic river channel. Impacts on wetlands in El Portal are expected to be long term and minor and would not affect the overall viability of wetlands in the area.

In Foresta, a one and one-half acre artificial palustrine scrub shrub wetland (in an old borrow pit) is directly adjacent to the proposed parking site and is expected to be impacted by heavy foot traffic. This would be a long-term, minor, adverse impact on wetlands in Foresta, with implementation of appropriate mitigation measures (see Vol. IA, Chapter 3). Wetlands adjacent to McCauley Ranch would be avoided through site design with relocation of stable operations to Foresta. Radiating impacts from increased nutrients and potential non-native plant species introductions from the stables would be minimized by aggressive management of stock waste and feed.

CONNECTIVITY

Yosemite Valley

The entire riparian corridor in Yosemite Valley along the Merced River would be restored, reconnected, and protected from future degradation by implementation of the River Protection Overlay and removal of campgrounds at Upper and Lower Rivers Campground and other areas. This would be a long-term, major, beneficial impact on palustrine forest wetland connectivity in Yosemite Valley, though benefits to palustrine emergent wetlands would be minor.

Out-of-Valley Areas

No additional adverse impacts on wetland connectivity would take place in El Portal, Foresta, Henness Ridge, or Tioga Pass Entrance beyond those presented in Alternative 1.

CONCLUSION

Under Alternative 5 there would be a 104-acre net gain in the size of wetlands. The implementation of the River Protection Overlay would enhance the integrity of existing wetlands along the Merced River. Wetlands would remain fragmented by campgrounds and roads in Stoneman and Ahwahnee Meadow, parking at Camp 6, and other infrastructure. The actions that are proposed in Alternative 5 would have a long-term, moderate, beneficial impact on the size, integrity, and connectivity of wetlands in Yosemite Valley.

Under Alternative 5 there would be a long-term, minor, adverse impact on wetland integrity in Foresta and El Portal. Henness Ridge would have no wetland impacts. Heavy foot traffic would have minor impacts to wetland integrity at the Tioga Pass Entrance.

CUMULATIVE IMPACTS

Past, present, and reasonably foreseeable future actions that could have a cumulative impact on wetlands are all considered to be long term.

Regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS); U.S. Forest Service management plans for adjacent wilderness; the Wilderness Management Plan Update (NPS); and the Fire Management Plan Update (NPS) could provide benefits to the size, integrity, and connectivity of wetlands. Cooperation among land management agencies would increase the opportunity to share common objectives and improve resource protection. These plans could also increase knowledge of resources and recreational use; they have the potential to have long-term, moderate, beneficial impacts on wetlands, though the proposed management direction has not been finalized. The Merced Wild and Scenic River Comprehensive Management Plan would affect wetlands through zoning and management designed to protect the river system and adjacent wetlands with long-term, major, and beneficial impacts.

The Tuolumne Meadows Water and Wastewater Improvements (NPS) project and the Mariposa Creek Pedestrian/Bike Path (Mariposa Co.) project are in the early stages of planning. Until the scope and design of these projects is determined, it is not possible to determine the extent of impacts on wetlands in these areas.

Other projects approved or planned for construction that could have beneficial effects on wetlands include erosion mitigation projects in Tamarack, Yosemite Creek, Bridalveil, and Hodgdon Meadows, and the Merced River at Eagle Creek Ecological Restoration Project (Yosemite Valley). Erosion control could enhance and strengthen palustrine forest and palustrine scrub shrub wetlands. The Eagle Creek project would revegetate riverbanks of palustrine forest and palustrine scrub shrub wetland. The erosion control and restoration projects would have long-term, localized, and therefore minor, beneficial impacts on wetlands.

Projects approved or planned for construction that could have adverse effects on wetlands include the Yosemite View Parcel Land Exchange (NPS), University of California, Merced campus (Merced Co.), and the Hazel Green Ranch (Mariposa Co.) project. The Yosemite View Parcel Land Exchange could directly affect existing palustrine forest and palustrine emergent wetlands. A wetland traverses the Hazel Green Ranch site, though proposed new development would not take place within the wetland corridor. The long-term direct impacts on wetlands would be moderate and adverse due to the relative rarity of undeveloped wetlands between the elevations of 1,000 and 3,000 feet and the relative importance of remaining habitat in the Sierra Nevada. Foothill areas below about 3,300 feet appear to have the greatest loss of wetlands of any region in the Sierra Nevada (UC Davis 1996a) and are particularly important in terms of their productivity and diversity.

Large-scale benefits to wetlands could take place as a result of regional and parkwide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS) and the Merced River Plan. Should substantial or full implementation of the actions included in these plans occur over time, long-term cumulative impacts on wetlands may, on balance, be moderate and beneficial. These regional plans are tempered by adverse impacts that include existing infrastructure to divert water away from wetlands in Yosemite Valley, and projects impacting wetlands outside the park with the potential direct loss of wetland habitat, including at the Yosemite View Parcel Land Exchange (NPS), and University of California Merced campus (Merced Co.) projects.

When the impact of the past, present, and future actions are combined with the actions proposed in Alternative 5, there would be a minor, beneficial impact on wetland size.

The following discussion identifies and characterizes the soils impacts expected from implementation of Alternative 5. Impact intensities are based on the size, type, and disturbance history of the soil resources impacted. Soil resources are identified as highly valued resources (HVR), resilient (R) or other (O). The primary activities that would affect soil resources are discussed for each of the project areas. Generally, adverse impacts to soils would include a combination of soil removal, profile mixing, compaction, erosion, and contamination. Beneficial impacts would occur as a result of soil restoration. Construction-related impacts (such as compaction from equipment and erosion) would be expected to be short term and temporary, because they would be minimized through the use of Best Management Practices and would occur for a limited time. All other impacts are expected to be long term unless otherwise noted.

YOSEMITE VALLEY

Approximately 228 acres would be affected by actions proposed under Alternative 5 (table 4-119). Highly valued resource soils comprise 122 acres, resilient soil resources comprise 83 acres, and other soils comprise 23 acres. Of the total area affected, 161 acres would be restored, while 67 acres would be associated with new development. Construction-related impacts (short-term) would be negligible to minor because Best Management Practices would be used to minimize erosion and to contain construction activities to the immediate area. Some minor discrepancies between acreages in the text and tables may occur due to rounding, differences in mapping sources, and because impacts less than 1 acre were not mentioned in the text. A summary of affected Valley soils is found in table 4-119.

1. HVR = Highly valued resource soil, R = Resilient soil, O = Other soil (non-HVR and non-Resilient)2. F=Flooding, SBE=Stream Bank Erosion, SE=Slope Erosion, HWT=High Water Table, D=Doughty (low water holding capacity), LOS=Loss of Organic Surface, C=Compaction, AC=Active Colluvium, B=Bedrock Out-of-ValleySource: Soil Survey of Yosemite National Park, Yosemite Valley, California (SCS 1991)

Curry Village

Approximately 22 acres would be affected by actions proposed under Alternative 5: 15 of these acres would be restored (HVR=9, R=3, O=3); and 7 acres would be developed (R=5, O=2). The proposed development activities would have a negligible, adverse effect on soil resources because of their small size (7 acres) and focus on resilient soil resources. Overall, Alternative 5 would have a minor, beneficial effect on the soil resources in Curry Village.

Yosemite Lodge

Approximately 49 acres would be affected by actions proposed under Alternative 5: 42 of these acres would be restored (HVR=18, R=23, O=1); and 7 acres would be developed (R=6, O=1). Restoration of the floodplain area between Yosemite Lodge and the Merced River would result in major, beneficial impacts to soil resources. Construction activities, such as those required for additional housing units and the new bridge south of the Yosemite Creek Bridge, would have negligible, adverse impacts since these activities are concentrated on resilient soils and the size of the impact would be relatively small. The overall impact to soil resources at Yosemite Lodge would be major and beneficial.

Yosemite Village

Approximately 20 acres would be affected by actions proposed under Alternative 5: 6 of these acres would be restored (HVR=5, O=1), and 14 acres would be developed (R=6, HVR=8). The adverse impacts would be due to construction activities related to the visitor center, and day-visitor parking. The net effect of the actions proposed at Yosemite Village would be a negligible, adverse effect on soil resources.

West Valley

Approximately 11 acres would be developed by actions proposed under Alternative 5 (R=7, O=4). Adverse effects are related primarily to the construction of the North American Wall Picnic Area and the El Capitan crossover. Both activities would occur on previously undisturbed resilient or other soil resources. The overall impact of activities planned for the west Valley would be minor and adverse because of the relatively small impact area and resource type.

Campgrounds

A total of 126 acres would be affected by actions proposed under Alternative 5: 97 of these acres would be restored (HVR=86, R=11); and 29 acres would be developed (R=27, O=2). Fewer campground areas would be restored under Alternative 5, with a resulting lesser beneficial impact. Campground restoration activities would result in moderate, beneficial effects. Adverse effects would be related to the development of new campground areas. Nearly all of the proposed area for new campgrounds would affect resilient soil resources. Generally, the impacts of campground development would be less disturbing to soil resources than other construction activities. Thus, although the area of impact would be relatively large (29 acres), the actual area of soil disturbance would be much less extensive. Adverse effects due to campground development are expected to be moderate. The overall impact within the campground area would be moderate and beneficial due to the amount of restoration proposed.

Roads and Trails

Transportation corridors such as multi-use paved trails and roadways have the potential to affect several soil resource types. Generally, trail construction would occur adjacent to existing linear corridors such as roads or utilities, or would be upgrades of existing informal trails. The impact of new trail construction would be adverse; however, the impact would be minor since the impacts would primarily be in linear segments of previously disturbed soils. New trails would be constructed to accommodate surface and subsurface water flow. Additionally, upgrades to existing trails would decrease erosion in high-use areas. Overall, the construction of new roads and trails would have minor, adverse effects.

OUT-OF-VALLEY

Soils information is limited for many of the out-of-Valley locations. The following discussion is based on the available general soils information or extrapolated from other local soil surveys. It is assumed that out-of-Valley impacts would likely occur on resilient soil resources, because the geographic features outside of the Valley tend to be less constricting than those in the Valley. Disturbance to highly valued resource soils would be avoided as practicable, to reduce the likelihood of impacts on highly valued resource soils. General Best Management Practices and design requirements would reduce potential impacts to other soils. Thus, the following discussion is based on the premise that the majority of adverse impacts would occur on resilient soil resources, where feasible.

El Portal

All of the impacts at El Portal would be long-term and adverse. Impacts are related to the construction of parking facilities and employee housing. Soils within the El Portal area tend to be susceptible to mass movement and erosion and have substantial development limitations. Therefore, Best Management Practices and other mitigation measures described in Vol. IA, Chapter 2, Soil Mitigation would be implemented to minimize erosion and soil movement. Due to the size of the proposed activities and the limited space available for construction, this alternative would have a moderate, adverse impact on soil resources in the El Portal area.

Henness Ridge

Under Alternative 5, construction of a parking facility at Henness Ridge would require a relatively small area of development. Generally, the soils at Henness Ridge are suitable for the proposed activity. Impacts are expected to be moderate and adverse.

Foresta

Impacts to soils in Foresta would occur if the National Park Service and concessioner stables are relocated to McCauley Ranch, and as a result of the reconstruction of employee beds destroyed in the 1990 A-Rock fire. However, impacts would be minor and adverse, because soils in these areas tend to be resilient and the area of impact would be relatively small. A day-visitor parking facility would also be constructed in Foresta, and would result in moderate, adverse impacts to soils.

Wawona

The soils within the Wawona area have mostly minor limitations for structures. Construction of housing facilities would occur on mostly resilient soils that are suitable for this use and would be expected to cause minor and adverse soil impacts.

Entrance Stations

Development or redevelopment of visitor centers near the existing entrance stations would result in adverse impacts to soil resources. The centers would be developed adjacent to existing stations, and generally would be located in areas suitable to the proposed use. The size of impact for each facility would be relatively small in relation to the surrounding soil resources. The impact due to construction of visitor centers would be negligible and adverse.

CONCLUSION

Four out of the five Valley locations would have overall beneficial impacts under this alternative, which proposes restoration of 161 acres and new development of 67 acres. West Valley would have the largest adverse impact. This adverse impact would be offset to a large extent by the restoration of 114 acres of highly valued resource soils, 33 acres of resilient soils, and 14 acres of other soil resources. The proposed developments would be focused on resilient soils (51 acres). Thus, the overall impact of Alternative 5 in the Valley would be minor and beneficial.

The actions under Alternative 5 would affect approximately 80 acres outside of the Valley. Most of this impact would be focused on resilient soil resources. Proper use of engineering controls and mitigation measures would result in an overall moderate, adverse impact on out-of-Valley soils.

Overall, Alternative 5 would have beneficial impacts on 161 acres and adverse impacts on approximately 67 acres. Out-of-Valley development would affect approximately 80 acres of non-highly valued resource soils. Generally, the facilities that would be relocated outside of the park would affect less sensitive resources than are currently being affected in the Valley. Furthermore, facility design and construction would use current technologies and Best Management Practices to minimize impacts. Out-of-Valley impacts would be locally moderate and adverse, but would occur on resilient soil resources at all locations except for El Portal. The overall impact for Alternative 5 would be negligible and beneficial because of the smaller scale restoration and adverse impacts at El Portal, Henness Ridge, and Foresta.

CUMULATIVE IMPACTS

The impacts of past, present, and reasonably foreseeable future areawide projects would be the same as described under Alternative 2, minor and adverse. In relation to the expected impacts resulting from areawide projects, the beneficial impacts related to restoration under this alternative would be substantial because they would be the primary beneficial impacts on soil resources that would occur in the region. Thus, the actions of this alternative would serve to offset some of the adverse cumulative effects of other projects in the vicinity of the park. Therefore, the cumulative impact of Alternative 5, in conjunction with other areawide projects, would be negligible and beneficial.

All impacts on vegetation are considered long term unless otherwise noted. Short-term impacts would occur during construction or implementation of actions. Based on the mitigation measures to be taken (see Vol. Ia, Chapter 2), all short-term impacts are expected to be negligible.

The composition of plant communities found in Yosemite Valley and those in out-of-Valley locations varies considerably. For example, the dominant plant species within a riparian vegetation type in El Portal would not be the same as those found within a riparian vegetation type in the Valley. Therefore, vegetation types in each of the distinct out-of-Valley locations analyzed for this section are described separately from the vegetation types described for the Valley.

YOSEMITE VALLEY

The actions proposed under Alternative 5 would result in a net gain in all plant community types, except upland and other. Table 4-120 summarizes the total areas of each vegetation type that would be adversely and beneficially impacted by this alternative. Minor discrepancies in totals between table and text are due to rounding impacts to the nearest acre. It should be noted that the size of the area affected was only one of the factors used to evaluate impact magnitude. The continuity, productivity, natural structure, and diversity of the vegetation type were also factors considered in this impact analysis.

Approximately 93 acres of existing developed or disturbed areas within the Valley would be restored to natural vegetation through the restoration actions described below. These actions would have a long-term, major, beneficial impact to the continuity of Yosemite Valley’s plant communities.

Due to their linear nature, transportation corridors (such as multi-use paved trails and roadways), would have the potential to affect multiple vegetation types. Therefore, rather than repeating this discussion under each vegetation type below, road and trail impacts are generally described here. Under Alternative 5, new multi-use paved trail segments would be constructed. Generally, these trails would either parallel existing linear corridors such as roads or utilities, or would be located within areas that have been previously disturbed by past actions or informal trails. The purpose of these new trail segments would be to provide connections to existing trails, thus improving the overall paved trail network for alternative modes of transportation through the Valley and minimizing the need for cars. The impact of the new trail construction would be adverse to vegetation; however, the impact would be minor given the small amount of vegetation impacted (3 acres). The impacts would occur primarily in previously disturbed uplands (non-highly valued resource), and the trails would be designed to avoid mature trees as much as possible and accommodate surface and subsurface water flow. New paths would increase habitat fragmentation. Similarly, the one segment of realigned roadway and the one widened roadway would also have minor, adverse impacts on vegetation (0.7 acre). The new bridge over Yosemite Creek would have a moderate, adverse impact on a small area of California black oak vegetation (0.5 acre) adjacent to the existing bridge.

Restoration of meadow (0.5 acre) and California black oak (0.5 acre) vegetation would occur as a result of road removal within the turnout lanes at Northside Drive through El Capitan Meadow and Southside Drive through Sentinel Meadow. The impact on these vegetation types would be minor and beneficial since they are both highly valued resource types.

Overall, the road and trail impacts would have a negligible adverse effect on vegetation because any adverse effects would occur on previously disturbed, non-highly valued resource types and the beneficial effects to highly valued resources would be small.

Upland Communities

Uplands comprise the largest vegetation type within Yosemite Valley. Alternative 5 actions would result in the restoration of approximately 15 acres of currently undeveloped upland vegetation in the east Valley, and new development would impact roughly 48 acres of upland. The overall impact of this alternative on uplands would be minor and beneficial due to improved conditions of upland vegetation through the re-introduction of fire (prescribed burning) and decreased community fragmentation.

Beneficial Impacts

The main areas of restoration within upland communities would include the Group and Backpackers Campgrounds (3 acres), the talus slope at Curry Village (6 acres), the Yosemite Lodge area (5 acres), and the Church Bowl Picnic Area.

The beneficial effects of Alternative 5 on the size and continuity of upland vegetation would include the following:

• At the Group and existing Backpackers Campgrounds area, restoration would include small areas of upland mixed in with other high-value vegetation types. This restoration would have a minor impact.

• In the area between the Yosemite Lodge and the Merced River, areas of restoration would provide a continuous California black oak and upland vegetation corridor, linking the upland areas to restored riparian and meadow areas. This impact would be moderate.

• The Church Bowl Picnic Area restoration would have minor impacts on overall upland vegetation continuity.

• In the Ahwahnee utility area (3 acres), the current utility area would be removed and restored to upland vegetation, thus restoring habitat continuity. This impact would be minor.

• In the talus slope zone of Curry Village (6 acres), the continuity of upland stands of canyon live oak would be improved by the removal of housing and restoration of the talus slopes, resulting in a moderate impact.

The beneficial impacts to natural structure, diversity, and productivity of the upland vegetation would include the following:

• The canyon live oak community at Yosemite Village would be made more continuous through the removal of outbuildings and the National Park Service stables in the vicinity of the NPS Operations Building (Fort Yosemite), with restoration of these areas to natural vegetation cover resulting in improved habitat and decreased fragmentation. This impact would be moderate.

• The ability to manage many of the continuous, unnaturally dense stands of incense-cedar and ponderosa pine with fire would be increased. This would help slow or stop the spread of annosus root rot through many of the currently developed areas of the east Valley (such as the Upper and Lower River Campgrounds area) and would improve overall forest health. This impact would be major.

• The need to manage hazard trees within and around developed areas would be reduced because many current upland vegetation areas would be restored. Older individual trees and snags would be retained that provide important wildlife habitat. This impact would be minor.

• The productivity of smaller, more disjunct stands of upland coniferous vegetation would increase as a direct result of prescribed fire, a reduction of stand densities, a reduction in spread of annosus root rot (due to reduction in stand densities), and establishment of understory herbaceous and shrub vegetation. This impact would be major.

• The understory integrity, diversity, and overall productivity of upland vegetation would continue to improve due to the re-establishment of native understory resulting from the reduction of trampling in developed zones in the east Valley. This impact would be moderate.

• The encroachment of upland vegetation into meadows and oak communities would be reversed through fire management. The upland community would be reduced in size under Alternative 5 due to the removal of various developments in the east Valley, which would facilitate the ability of National Park Service staff to manage these areas with prescribed fire and other management tools. This would have a moderate effect on upland communities.

Adverse Impacts

The new development in upland areas would occur within both the east and west Valley and would generally be concentrated in areas that have been previously disturbed. Most of the adverse impacts in the east Valley would be in the area of the new walk-to campground north of Tenaya Creek, walk-in and drive-in campgrounds east of Upper Pines Campground (21 acres), South Camp and Backpackers Campground, the new campground check-in station at the east end of Curry Village, Yosemite Lodge (6 acres) and Curry Village (5 acres). The adverse west Valley impacts would occur mainly at the potential El Capitan crossover checkpoint (10 acres) and the North American Wall Picnic Area (2 acres).

The adverse impacts on upland community size, continuity, natural structure, diversity, and productivity would occur within the following areas:

• At Yosemite Lodge, the addition of lodging into the area north of existing Northside Drive and parking within the area would cause adverse, minor impacts to upland coniferous forest and canyon live oak communities due to establishment of new buildings, paved trails, and the need to trench underground to provide utilities for these structures. This area has been previously disturbed.

• At the Upper and Lower River Campgrounds area, upland communities would also be converted from existing upland back to a mosaic of California black oak, riparian, and meadow communities through the removal of fill material. This would have only a minor impact on upland communities because this area does not have an intact understory and was not originally upland vegetation.

• The new walk-in campgrounds in the Valley would have a moderate impact on upland communities due to trampling of the understory layer.

• The addition of South Camp and the relocated Backpackers Campground would result in moderate upland impacts due to trampling and loss of understory vegetation.

• New lodging at Curry Village would be constructed outside of the talus slope zone near the existing lodging. This impact would be minor because the area is currently impacted by trampling.

• Potential development of a traffic check station (if required) at El Capitan crossover would have a major impact on up to 10 acres of relatively undisturbed upland vegetation because of the additional pavement, utilities, and infrastructure.

• A number of the restoration actions proposed would convert existing upland vegetation types to highly valued resource types (meadow, riparian, California black oak). This would have a minor impact on upland vegetation communities because many areas to be converted were originally highly valued resource vegetation types that have since been modified due to human influences.

California Black Oak Communities

The California black oak vegetation type is considered a highly valued resource because of its transitional character between wet meadows and drier uplands, as well as its links to wildlife and ethnographic resources. Under Alternative 5, the actions proposed would result in approximately 4 acres of adverse impact and about 16 acres of beneficial impacts to this community. The overall impact of this alternative on California black oak would be major and beneficial.

Beneficial Impacts

The restored California black oak areas would primarily be in portions of the Upper and Lower River Campgrounds area, Lower Pines and Backpackers Campgrounds (12 acres), the Yosemite Lodge area (1 acre), the Ahwahnee tennis courts (1 acre), and the Superintendent’s House (Residence 1) (1 acre).

The beneficial effects of Alternative 5 on the size and continuity of California black oak vegetation types would include the following:

• The reduction in size of North Pines Campground and its change from a drive-in to a walk-in area would facilitate an improved ecotonal transition from the riparian communities near Tenaya Creek and the Merced River to more California black oak stands to the south and east, thus slightly increasing the size of both vegetation communities as well as reducing some of the habitat fragmentation in this area. This impact would be minor.

• The relocation of the concessioner stable from its current location to one east of Curry Village would facilitate a continuous ecotonal transition from the riparian communities near Tenaya Creek and the Merced River to more California black oak stands to the south and east. This would increase the size of both communities and result in minor, long-term benefits.

• At Yosemite Lodge, adjacent areas of California black oak would be restored, thus creating a larger, more continuous area of potential California black oak woodland. Due to the presence of a large annosus root rot population in the area, landscaping would focus on California black oaks (which are resistant to annosus root rot) rather than conifers, leading to a greater proportion of oaks in this area. Long-term, moderate impacts would result.

• Removal of the Ahwahnee tennis courts and associated non-native vegetation would remove the gap in this otherwise intact oak woodland that surrounds the courts, thus improving the continuity of the oak woodland through the entire area between the Upper and Lower River Campgrounds and Ahwahnee Meadow to The Ahwahnee. This action would result in a moderate impact to the oak woodland community.

• Removal of some fill material at restoration sites (such as the Upper and Lower River Campground area) would remove habitat for upland communities and restore original lower (topographic) layers to California black oak woodland, which would result in long-term, major benefits.

• Restoration at the Superintendent’s House (Residence 1) and the Church Bowl Picnic Area would result in minor, beneficial impacts (primarily due to their small size).

• California black oak stands in the east Valley would be minimally fragmented by development, roads, and encroaching conifers due to the enhanced ability of the National Park Service to manage areas with fire, removal of facilities, and restoration of areas such as the Ahwahnee tennis courts and portions of the Upper and Lower River Campgrounds areas, into a mosaic of oak woodlands, meadows, and riparian areas. Moderate impacts would result.

• The natural structure of California black oak stands in the west Valley would improve due to prescribed burning, with the subsequent reduction in conifer encroachment resulting in a moderate impact. Other components of California black oak communities, such as deer grass (an important ethnographic resource), would significantly increase due to the reintroduction of natural and simulated natural processes (such as fire and corrections in drainages), resulting in a moderate impact.

• The correction of drainage problems associated with roads (potentially on Northside Drive at El Capitan Meadow and Southside Drive in the Bridalveil Fall area) and the removal of roads through Ahwahnee and Stoneman Meadows would improve the condition of California black oak stands in these locations by re-establishing natural drainages. These actions would correct problems associated with the impoundment of water upslope of roads, which keeps soils wetter for longer periods during the summer and encourages armillaria rot to become fully established. These drainage corrections would result in major impacts to vegetation communities.

• The restoration of historic landscaping characteristics at the Yosemite Village Historic District housing area would improve the condition of existing mature California black oaks and facilitate the establishment of younger generations of these trees within the district, thus improving stand structure and increasing the continuity of stands in this portion of the Valley. Moderate impacts would be expected.

Adverse Impacts

The adverse impacts on California black oaks under Alternative 5 would primarily be a result of new lodging at Curry Village (5 acres) and South Camp (2 acres) and construction of a parking lot east of Curry Village for backpackers (3 acres). The adverse effects of Alternative 5 on the size, continuity, natural structure, diversity, and productivity of California black oaks would include the following:

• The development of additional lodging units adjacent to Stoneman House would result in a direct loss of some mature oak trees and a loss of regenerating saplings, and understory structure and function. In addition, radiating human activities and a lack of prescribed burning would continue encroachment by conifers, thus leading to a gradual shift from a California black oak-dominated community to a mixed conifer, California black oak community that is more common in the Valley. The shift in the dominant vegetation community’s composition would result in long-term, moderate impacts.

• The addition of the new South Camp walk-in sites would result in moderate impacts to California black oak due to trampling and loss of understory vegetation.

• Mature California black oak trees would potentially be removed during site grading and development, and additional trees could be lost with root impacts during construction, changes in drainage, and hazard tree removal, thereby resulting in loss of stand structure and continuity in all areas of proposed development and redevelopment of the east Valley. This impact would be moderate and long term.

Meadow Communities

The meadow vegetation communities within Yosemite Valley are similar in size to the California black oak vegetation communities. The overall impact on meadow vegetation would be moderate and beneficial, with 42 acres of beneficial impacts and 5 acres of adverse impacts.

Beneficial Impacts

The proposed actions under Alternative 5 would have a beneficial impact to 42 acres through restoration. This would include 21 acres in the campgrounds, 20 acres at Yosemite Lodge, 1 acre at Superintendent’s House (Residence 1), areas within the River Protection Overlay throughout the Valley, and benefits through improved water flow and a decrease in radiating impacts such as trampling.

The beneficial effects of Alternative 5 on the size and continuity of meadow vegetation types would include:

• The ecological restoration of the entire area south of the proposed new road alignment at Yosemite Lodge (aside from utilities and access near the confluence of the Merced River and Yosemite Creek) would have major, beneficial effects to the ecological function of this section of the Valley, with the potential for increased meadow acreage, enhanced wetlands, and minimal habitat fragmentation of a large low-lying area.

• An area of North Pines Campground within the River Protection Overlay would be restored to meadow; this would be a minor, beneficial impact due to the small area and radiating campground impacts.

• Meadow size (of Ahwahnee and Stoneman Meadows by the removal of the bisecting roads) would increase substantially, with improved natural drainage patterns and continuous meadow cover over large areas of the east Valley. This would result in a major impact.

• Areas of former meadow at the Upper and Lower River Campgrounds area; Ahwahnee Meadow where it is bisected by Northside Drive; former sections of Lower Pines Campground, Southside Drive near Bridalveil Fall, and Cook’s Meadow would be restored by unburying meadow soils where fill was added. Hydrology would be restored over time through the restoration of original topographic variations and re-establishment of native herbaceous species due to improved soil and hydrologic conditions. This impact would be major.

• Connectedness of meadows to riparian and wetland areas would be created by removing roads and reconstructing portions of roads to facilitate natural drainage patterns, which would result in a major impact.

• Implementing the River Protection Overlay, with access direct to appropriate sites along the river, would minimize impacts to this critical ecotone and result in a major impact.

• The modification of roads at Bridalveil, El Capitan, and Cook’s Meadows to allow drainage would allow for the re-establishment of functioning oxbow and cutoff channels through meadows. These modifications would create a critical link between meadow, riparian, and wetland systems, with increases in native plant establishment (due to wetter conditions), greater native biodiversity, and greater overall productivity due to changes in species, food for wildlife, cover, etc. This action would result in a major impact.

Adverse Impact

The actions proposed under Alternative 5 would result in negligible adverse impacts to the size, continuity, natural structure, diversity, or productivity of meadow vegetation types in Yosemite Valley, with consolidation of day-visitor parking at Yosemite Village/Camp 6 (1 acre) and management of Lamon Orchard for retention of this cultural resource. Impacts to underlying and adjacent meadow vegetation would be increased by these actions.

Adverse impacts to the size and continuity of meadow communities are listed below:

• Construction of new parking in the area of Camp 6 would result in negligible impact to the remaining meadow fragments (the existing meadow is less than an acre in size and severely fragmented by roads, trails, and utility lines).

• Development of a multi-use paved trail between Curry Village and Yosemite Village through Upper and Lower River Campgrounds area, as well as a picnic area in the Lower River Campground area, would not allow for the complete elimination of habitat fragmentation and impacts to existing and potential meadow and riparian zones. Aligning the multi-use paved trail along the utility corridor through the Upper and Lower River Campgrounds area, and construction of the picnic area near Housekeeping Bridge and the paved trail would minimize fragmentation somewhat (by overlapping uses), resulting in a minor impact.

• Development of a vehicle management station (if required) at El Capitan crossover could result in undesired and unplanned parking along road shoulders at El Capitan Meadow, resulting in additional impacts from vehicles, trampling, the continued need to remove hazard trees, and introduction of non-native plant species into the meadow. However, these radiating impacts would be mitigated through restricting parking along the roadway and restricting human use of the meadow, resulting in a minor impact.

Riparian Communities

Alternative 5 actions would result in an adverse impact on an estimated 7 acres of riparian vegetation but would create beneficial impacts on over 89 acres of riparian vegetation. The overall impact of this alternative on riparian vegetation would be major and beneficial.

Beneficial Impacts

Restoration actions would be concentrated in the floodplain areas near Yosemite Lodge (17 acres); the Upper and Lower River, Lower Pines, Group and Backpackers Campgrounds and the dump station (58 acres); Housekeeping Camp (9 acres); and the Swinging Bridge Picnic Area (2 acres) as well as the talus slope zone at Curry Village (3 acres).

The beneficial effects of Alternative 5 on the size and continuity of riparian vegetation types would include the following:

• The removal of Sugar Pine and Ahwahnee Bridges would eliminate the hydrologic alterations that are causing loss of riparian vegetation both upstream and downstream of these bridges. This would allow restoration to create continuous riparian bands along a portion of the Merced River and Tenaya Creek through the east Valley, which currently is almost entirely denuded. This action would result in a major impact.

• The removal of Swinging Bridge Picnic Area would improve habitat condition of the riparian communities in this area, thus promoting the establishment of understory and herbaceous vegetation layers that are currently nonexistent. This action would result in a minor impact.

• Restoration of portions of the Upper and Lower River Campgrounds area, the Upper Pines Campground dump station, a portion of Lower Pines Campground, a portion of Housekeeping Campground within the 150-foot River Protection Overlay, and Group and Backpackers Campgrounds would facilitate re-establishment of riparian corridors (oxbows and cutoff channels) through these sites as well as along the Merced River and Tenaya Creek. This impact would be major.

• Restoration of the riparian corridor within the River Protection Overlay at Camp 6 would improve the continuity of riparian habitat along the Merced River corridor through the East Valley, and would provide a connection between the wetland and meadow communities to the northeast and northwest of the proposed Yosemite Village parking area. The improvements would result in a minor impact.

• Removal of the human-built rock-rubble pile from the western channel of Yosemite Creek would allow this channel to flow for a longer period of time, thus enabling riparian vegetation to become established in this currently barren channel. The action would result in a moderate impact.

• Rehabilitation of bridges over Yosemite Creek in the braided stream channel area would remove impacts associated with these undersized bridges, which have resulted in scouring of the channel banks and loss of riparian vegetation. This would provide a moderate improvement and reduce impacts to riparian vegetation in this area in conjunction with removal of the western channel human-built rock-rubble pile.

• The redesign of portions of Southside Drive in the Bridalveil Fall area would facilitate water flow under the road and enhance the continuity of the riparian community upslope and downslope of the existing road. This impact would be moderate.

• Converting the trail south of the Happy Isles Loop Road between Curry Village and Happy Isles to a multi-use paved trail would result in continued and increased negative impacts to the fen (an alkaline wetland fed from groundwater sources located near Happy Isles) and adjacent riparian vegetation. These impacts would be due to the widening of the current trail to accommodate heavier bicycle traffic, with a long-term loss of more fen habitat. This fen is the only one of its kind in Yosemite National Park, and any impacts would be considered major due to the rarity of this type of vegetation community.

• Repair and construction of the road between the Cascades Diversion Dam and Pohono Bridge would eliminate road-edge parking and the resultant human impacts on riparian vegetation along this section of the Merced River corridor. This impact would be minor.

Adverse Impacts

Adverse impacts on riparian vegetation would occur at the new walk-in campgrounds east of Upper Pines Campground (7 acres) and at the new lodging at Curry Village (4 acres). Additional impacts would occur as a result of radiating use from new and redeveloped sites.

The adverse impacts to the size, continuity, productivity, diversity, and structure of riparian vegetation are listed below:

• At Curry Village, a small area of riparian vegetation would be impacted so that existing lodging can be relocated outside of the talus slope zone. This new lodging development would be designed to minimize impacts to riparian vegetation. This would result in moderate local impacts. In relationship to the overall impacts to riparian vegetation these impacts would be minor.

• Walk-in camp sites would have minor impacts on riparian vegetation due to trampling and localized fill for tent pads.

• Development of a picnic area with restrooms, barbecue grills, and picnic table pads at the Lower River Campground near Housekeeping Bridge could result in moderate, adverse impacts due to trampling and increased radiating human impacts. These impacts would result in a loss of structure and integrity of riparian vegetation, but mitigation would include fencing, signage, and other measures to keep trampling confined to the picnic area. This would result in a minor overall impact.

• Paving or hardening the eastern channel trail at Yosemite Creek for accessibility would directly impact some riparian vegetation because this action would involve widening or relocating the current trail. However, the area of impact would be small, and this site has already had an almost complete loss of herbaceous cover due to undirected foot traffic adjacent to the current access trail to Lower Yosemite Fall Bridge. The resulting impact would be minor.

• Development of a 550-vehicle parking lot in Yosemite Village would have a minor impact on riparian vegetation, from radiating uses to the Merced River. These would be mitigated by directing visitors to resilient areas of the riverbank.

Other Communities

The Alternative 5 actions would result in adverse impacts to about 5 acres of other types of vegetation ground cover. Twenty-five acres of bare ground, orchards, watered lawns, bare areas, and developed open areas would be restored to either upland or highly valued resource vegetation types. The beneficial impacts have been discussed in the upland, California black oak, meadow, and riparian discussions above. They include restoration of much of the Curry Orchard to a mix of meadow, riparian, and California black oak woodlands and restoration of the River Protection Overlay at North Pines Campground to riparian, meadow, and California black oak woodlands. Adverse impacts would occur in areas where sparsely vegetated lands would be developed, such as the addition of parking at Camp 6 and new housing and lodging at Curry Village. Overall, there would be negligible beneficial impacts on these other vegetation types under Alternative 5.

Out-of-Valley Areas

The proposed out-of-Valley day-visitor parking locations would be at Henness Ridge, El Portal, and Foresta. Housing would be developed in Wawona and Foresta and improvements would be made at the South, Big Oak Flat, and Tioga Pass Entrance Station areas. The overall impact of Alternative 5 on out-of-Valley areas would be moderate and adverse.

El Portal

Vegetation in the El Portal area of impact include canyon live oak (a type of upland) and riparian types; however, the plant composition of these types varies from those in the Valley. Meadow and California black oak types are not represented here. The overall impact of this alternative on El Portal area vegetation would be moderate and adverse.

Oak and Upland Communities

• Existing oak stands would experience moderate, long-term impacts from the development of housing throughout El Portal. A direct loss of trees would occur with the development of housing within areas that are already somewhat impacted by low-density housing, as well as development of new housing sites at Hillside East and Hillside West. These developments would prevent retained trees from reproducing (due to pavement, yard activities, landscaping, trampling, and the presence of structures), resulting in a decrease in the size and continuity of these oak woodlands.

• The natural structure, diversity, and productivity of oak and upland communities would be moderately impacted because of the increased likelihood of non-native plant species and lack of natural fire and fire frequencies.

• Prescribed burning and mechanical treatment of vegetation surrounding El Portal would continue to maintain semi-natural stands of oaks around developed areas. These actions would promote oak regeneration by reducing competing vegetation. Many areas currently managed this way would be developed into housing, parking, and infrastructure, leaving fewer acres of oaks to regenerate, provide habitat, and add to the diversity of this area, which would result in a minor impact.

• The development of a parking area could require the removal of large individual oaks adjacent to the Merced River at Middle Road. The development of housing upslope of this site would eliminate the connectedness of the oak stands on the slopes above El Portal with riparian and flat terrain oak communities. The action would result in a minor impact.

Riparian Communities

• Riparian areas would receive minor impacts from the development of high-density housing at Hennessey’s Ranch (due to their currently impacted condition). Associated increases in human use would cause a decline in the continuity of this vegetation community as social trails develop.

• The size of riparian areas would continue to be impacted by existing developments and new development (at Hennessey’s Ranch and Village Center). A continued decline in riparian community size would also occur both in length along the river and width from the water’s edge up to the bank edge, resulting in a minor impact.

• An increased human population and an associated increase in landscaping, numbers of vehicles, and foot traffic (and means for seed dispersion), would result in more non-native plant species problems throughout the riparian and oak woodland areas. Increases in non-native species would result in a moderate impact.

• The isolated nature of riparian areas in the El Portal core area (Crane Creek to Foresta Bridge), because of structures and Highway 140 riprap, would continue to inhibit natural exchange of other biological components (mammals, amphibians, and reptiles) as well as wind-dispersed seeds. This would result in lower overall productivity of these areas and a minor impact.

• The removal and restoration of the old treatment plant at Rancheria Flat adjacent to the river would enhance the continuity of riparian vegetation along this bend of the Merced River, with potential increased habitat for rare plant species growing adjacent to the site. This action would result in a major impact to vegetation communities in the area.

• Implementation of the River Protection Overlay and management zoning, prescribed in the Merced Wild and Scenic River Comprehensive Management Plan, would help protect the riparian corridor throughout the El Portal Administrative Site.

• Restoration of the sand pit area, with removal of the remaining concrete wing wall and re-establishment of riparian vegetation, would enhance the river corridor and increase potential habitat for Congdon’s woolly-sunflower, a state-listed rare plant, resulting in a minor impact.

Foresta

Alternative 5 would not replace Yellow Pine Campground; therefore, no impacts would occur in that area. As under the other alternatives, 14 employee houses would be added, as well as a stable for National Park Service and concessioner administrative use, and a parking facility for 660 vehicles (18 acres). This alternative would therefore have moderate, adverse impacts on vegetation in the Foresta area.

• Use of the Foresta area, and specifically Big Meadow, would likely increase substantially due to the development of a parking facility above the meadow. This would reduce the size and continuity of vegetation (by paving) and would increase radiating use levels to the riparian and meadow communities in and around Foresta. Impacts would be moderate and adverse.

• Isolated but extreme impacts from the establishment and spread of non-native plant species (including spotted knapweed, yellow star-thistle, and oxe-eye daisy) would occur at a much more rapid rate from the substantially increased vehicle use of this area with the development of a parking area. Management efforts would continue to attempt to contain and control (and eventually eradicate) existing and new non-native species. This would be a major and adverse impact.

• Development of the National Park Service and concessioner administrative stables at McCauley Ranch in Foresta, with access road widening and rebuilding of a bridge along the access road, would further break up the continuity of the upland and riparian communities that exist along this road corridor. These adverse impacts would be minor since a road and bridge are already present.

• Development in Foresta, would also increase the possibility for the establishment and spread of non-native plant species. Foresta remains fairly susceptible to non-native plant species establishment because of the severe impacts that occurred during the 1990 fires. Stable operations (with constant ground disturbance, the need to maintain road corridor, and the importation of potentially contaminated feed) could increase the chance of additional non-native species becoming established in the vicinity of the road and corral. This would result in moderate impacts.

Henness Ridge

Development of a 370-vehicle parking area at Henness Ridge would necessitate removal of a large number of overstory trees as well as the intact shrub and herbaceous layers. This development would result in long-term, moderate, adverse impacts to this somewhat intact mixed coniferous forest (roads and social trails currently exist).

Adverse Impacts

• Installation of utilities and facilities associated with the parking area would require trenching and the expansion of existing infrastructure. Impacts would occur to root systems and riparian zones (due to trenching and the potential need to create an expanded wastewater leach field). Additional radiating impacts would occur on conifers, with the potential for higher stress levels on large sugar pines in the area, thus increasing their susceptibility to white pine blister rust.

• Higher levels of vehicle use and more open areas (disturbed ground) could increase the potential for introduction and establishment of non-native plant species.

Wawona

Construction of housing with associated infrastructure improvements, would have a long-term, moderate, and adverse overall impact on vegetation in Wawona.

Adverse Impacts

• The addition of housing on approximately 8 acres of land would adversely impact the lower mixed conifer forest and stands of California black oak, resulting in a moderate impact. The size of the stand and continuity of the canopy would be broken by the addition of housing units and associated infrastructure.

• Continuity of the surrounding area would be further impacted by the need to manage for hazard trees that could potentially impact the new housing development. The impacts would be minor.

• The overstory, understory, and herbaceous vegetation structure would be adversely impacted by the addition of housing, access roads, and trails, and installation of infrastructure. Some vegetation structure could be maintained through site planning to avoid large trees and concentrate housing to allow for larger blocks of intact vegetation between units. The impacts would be moderate.

• The diversity of native vegetation would decline due to the loss of some layers of the forest (primarily understory and herbaceous) from the developments under the overstory canopy. The diversity decline would result in long-term, moderate impacts.

• The potential for introduction and establishment of non-native plant species would increase due to landscaping and groundskeeping activities in and around the housing area. This could be minimized by aggressive adherence to the landscaping guidelines outlined in the Vegetation Management Plan.

• Productivity of the site would decline due to the need to remove hazard trees, resulting in a loss of structure and diversity. These dying and dead trees and snags currently provide habitat for a wide range of wildlife, which would be impacted by their loss at this site. This impact would be long-term, moderate, and adverse.

• Increased ground disturbance during construction and through higher levels of human use would increase the potential for non-native plant species to be established through inadvertent introductions. Since the site is currently not impacted by many non-natives, this would be a short- to long-term, moderate, adverse impact.

• Radiating impacts to surrounding areas (the river to the north and designated Wilderness to the south and east) would directly effect ground cover, thus changing structure of litter and duff (through trampling) and resulting in reduced effectiveness of prescribed fire activities. This would impact the National Park Service’s ability to continue managing natural stand structure (and thus productivity) throughout Wawona. However, this could be mitigated through fencing, trails, and linking to established trail systems, and signs to keep people out of sensitive areas, resulting in a minor impact.

Big Oak Flat Entrance

Additional parking and construction of a new visitor contact station (visitor center) would increase the footprint of the existing site by up to 5 acres. Impacts at the Big Oak Flat Entrance would be long-term, minor, and adverse due to the small size of additional impact, the existing level of habitat fragmentation, and the existing high potential for introduction of non-native plant species.

Impacts to upland vegetation (ponderosa pine forest and mixed conifer forest) may occur depending on the actual site design, which is not known at this time. Impacts would include paving, the removal of trees and groundcover, an increased difficulty in managing fuels and vegetation structure with fire (due to the presence of additional structures requiring fire protection), and trenching impacts to root systems (with potential weakening of health of directly affected trees).

Tioga Pass Entrance

Tioga Pass vegetation is characterized by a mosaic of both wet and dry subalpine meadows (dominated by native perennial grasses, sedges, rushes and forbs), and lodgepole pine forests. Continued degradation of these vegetation types would occur under Alternative 5. The impact resulting from this alternative would be long-term, moderate, and adverse, as there would be loss of vegetation and further degradation of vegetation community structure and diversity within a currently disturbed area.

Adverse Impacts

• Construction of a new visitor center and associated parking (with potential impacts of up to 5 acres) in the vicinity of Tioga Pass would impact lodgepole pine forests and wet and dry subalpine meadows. Dry meadows and lodgepole forests would be affected by paving and the addition of structures, utility lines, and trails, thus reducing both the size and continuity of these vegetation types and resulting in long-term, moderate, and adverse impacts. Wet meadows would receive long-term, moderate, and adverse impacts from radiating uses as a result of increased human activity in the area. Impacts to wet meadows could be mitigated by more clearly defining trails leading to the Mt. Dana cross-country route, and would most likely remain moderate (despite any mitigation) simply as a result of increased levels of human use in the area.

• Paved areas and structures would result in changes in drainage patterns, with moderate adverse impacts. An increased number of visitors because of the new visitor center would increase the likelihood of additional firewood collection (causing a loss of nutrient recycling), more vehicles in the area would increase the chance of non-native plant establishment as a result of more trampling and denuding of soils.

South Entrance

Vegetation at the South Entrance to Yosemite National Park is characterized by dense montane, mixed conifer forest dominated by a white fir overstory with subordinate sugar pine, Douglas-fir, ponderosa pine, and Jeffrey pine. Riparian vegetation occurs along ephemeral and perennial stream channels. Continued degradation of these vegetation types would occur under Alternative 5. The impact of this alternative would be long-term, minor, and adverse because there would be some increase in vegetation loss and degradation as compared to the existing condition.

Adverse Impacts

• Increased parking and structures would further add to the fragmentation of the South Entrance area, with an increased loss of riparian vegetation from the potential filling in of drainages and increased loss of forest cover. The loss of riparian vegetation could be minimized by using existing old road and railroad corridors rather than creating new developed areas, resulting in minor, adverse impacts (due to the small area affected). Forests would be impacted by the loss of up to 5 acres of trees in a currently forested area. Additional impacts would occur from the expansion of the hazard tree management zone along the corridor and around new parking areas.

• An increase in paved areas, how long vehicles are parked, and levels of human use in the South Entrance area would increase the potential for introduction and establishment of non-native species through higher levels of road-edge maintenance, increased introduction of sand with potential weed seeds, and more people with seeds clinging to clothing and cars. Impacts would be moderate and adverse to riparian vegetation and minor to forested areas.

• The increased human population would make reintroduction of fire into the South Entrance area more problematic due to smoke and the presence of structures. These limitations could be minimized by designing the site to concentrate structures in as small an area as possible. Vegetated "islands" would also be minimized to allow management of adjacent vegetation with fire.

CONCLUSION

In Yosemite Valley, minor, beneficial impacts would occur under Alternative 5 to upland communities due to the removal of some facilities. California black oak and meadow vegetation would experience moderate, beneficial impacts due to the relocation of some facilities out of California black oak and potential meadow areas. Riparian areas would experience major, beneficial impacts under Alternative 5 from the removal of some facilities, the consolidation of others out of the Merced River floodplain, and an increased ability to restore some large portions of the Valley to natural conditions.

In El Portal, long-term, moderate, and adverse impacts would occur to the oak and upland communities as a result of new housing and parking development, with a permanent loss of habitat. Riparian areas would also experience moderate, adverse impacts due to the following: (1) radiating uses from increased human presence, (2) an increased likelihood of establishment of non-native plant species, and (3) loss of fire as a management tool to retain natural structure to forests and meadow areas.

Wawona, Foresta, Tioga Pass, and Henness Ridge would experience moderate, adverse effects. In each of these areas, upland forests and California black oaks would be impacted by new housing; montane forests, lodgepole pine, and riparian areas would be impacted by new parking. Expected radiating impacts would have minor, adverse effects on meadow, riparian, and other adjacent vegetation types due to an increased human presence in the spring and summer.

Long-term, minor, and adverse impacts would occur at Big Oak Flat Entrance and South Entrance due to a slight increase in vegetation habitat fragmentation.

The overall effect of Alternative 5 on vegetation would be minor, long term, and beneficial based on the relatively large areas of highly valued resource vegetation that would be restored in Yosemite Valley, as compared to the majority of adverse impacts outside the Valley that would occur in non-highly valued resource vegetation types (uplands and other) and involve limited amounts of new habitat fragmentation.

CUMULATIVE IMPACTS

The overall cumulative impacts of past, present, and reasonably foreseeable future projects on vegetation would be the same under Alternative 5 as it is described under Alternative 2. The majority of these adverse impacts would occur within non-highly valued resource vegetation types.

Increased human activity and related air quality degradation in the El Portal area and elsewhere could adversely affect ponderosa pine, Jeffrey pine, and other ozone-intolerant species. The National Park Service has operated an ozone monitoring station at Turtleback Dome for more than a decade to identify ozone trends in the Valley. Although cleaner burning vehicles and fuels should reduce the amount of ozone in the atmosphere in the future, cumulative effects to such species are expected to continue.

Other cumulative impacts to vegetation under Alternative 5 would include community fragmentation resulting from increased land development and potential continued introduction of non-native plant species. Cumulative impacts to riparian vegetation would also be expected due to development and other pressures along the narrow Valley floor adjacent to the Merced River.

Adverse impacts to upland vegetation communities under Alternative 5 would occur at Henness Ridge, El Portal, Foresta, Wawona, and at all entrance stations. These impacts, in conjunction with impacts to upland communities in Yosemite Valley from a loss of forests over time to highly valued resource meadow, California black oak, and riparian vegetation types, would constitute minor overall impacts to upland vegetation types. In conjunction with reasonably foreseeable future projects, actions proposed under Alternative 5 would result in a cumulative, minor, adverse impact to upland vegetation due to the abundance of upland vegetation types throughout the Sierra Nevada region.

Some restoration actions are proposed to take place in oak woodlands through the removal of structures, but development of new facilities within oak stands would negate some beneficial impacts. Adverse impacts would also occur to canyon live, blue, black, and valley oaks by the development of housing and parking in El Portal. Site planning would be used to avoid large trees and minimize irrigation impacts, somewhat mitigating these adverse impacts. Talus live oak communities in the Valley would continue to be impacted under this alternative. In conjunction with reasonably foreseeable future projects, there would be cumulative minor, negligible impacts to oaks as a result of this project.

Alternative 5 also calls for the implementation of a River Protection Overlay zone in Yosemite Valley, which would create some long, linear sections of intact riparian vegetation following restoration efforts. The natural links with meadows would be restored by restoring large continuous meadow areas throughout most of the east Valley. This alternative also prescribes some additional multi-use paved trails, which often follow or cross riparian areas. Impacts could also occur to subalpine meadows at Tioga Pass. Thorough site planning could prevent impacts to riparian and meadow vegetation in these newly developed areas by avoidance, resulting in a cumulative minor, beneficial impacts to riparian and meadow vegetation. Therefore, the overall cumulative impacts of Alternative 5, in conjunction with reasonably foreseeable future projects, would be negligible and beneficial.

This analysis describes impacts to wildlife in terms of changes to habitat, such as habitat loss or gain, degradation or enhancement, fragmentation or connectivity, amount of human disturbance, and potential for increased or decreased conditioning of wildlife to human food. The Vegetation section provides detail (including acreage breakdowns) on the vegetation types that are related to the habitat types covered in this section: upland, California black oak woodland, meadow, riparian, and other. All but the upland and other habitat types are considered highly valued resources by the park because of their value to wildlife combined with other factors, such as scarcity on a regional basis and value as critical components in park ecosystems. General wildlife species associated with these habitat types are discussed in Vol. Ia, Chapter 3, Affected Environment, Wildlife; table 3-5 illustrates the connections between vegetation types and wildlife habitats. Special-status wildlife species are discussed in a separate section of this chapter.

Short-term impacts would occur to wildlife during construction or implementation of actions described in this section. Based on the mitigation measures that would be implemented during construction, all expected short-term impacts would be negligible.

Other impacts on wildlife and wildlife habitat generally would be characterized as long term for the actions reviewed under this alternative.

YOSEMITE VALLEY HABITATS

Habitat restoration would result in approximately 162 acres of restored or enhanced wildlife habitat within the Valley, of which 147 acres would be restored to highly valued resource habitat types. New or relocated development within existing wildlife habitat would result in approximately 69 acres of lost or degraded wildlife habitat, of which 53 acres would occur within upland or "other" habitat types within the Valley.

In restored habitat of all types, the resulting benefit to wildlife is highly dependent upon the size of the area restored and its connection or proximity to other natural or restored areas. Such benefit is also related to the proximity of the restored area to continued human activities and development. Larger restored areas of habitat tend to support a higher abundance and diversity of wildlife species and are less affected by human disturbance from adjacent development and uses. Connections within and among habitat types allow more natural wildlife movement, and access to food, cover, and reproduction sites necessary for all stages the life cycles of various species. Management of human use in areas adjacent to natural or restored areas can minimize disturbance that would degrade habitat quality, especially of sensitive habitats such as meadows and riparian. For example, signs and fencing could keep visitors away from sensitive habitats or wildlife species, and control of human food sources in developed areas could reduce conditioning of wildlife and minimize human/wildlife conflicts.

In addition, where development is removed and human presence is reduced, management practices required to enhance public safety (at the cost of natural resources) could also be reduced. For example, dead trees (snags) are important habitat features for many wildlife species, but must be removed when they occur in or near roads, developed areas, or other sites of high human use. With the removal of development and the reduction in human use in an area, snags can be allowed to stand and benefit wildlife.

Upland Habitats

Approximately 47 acres of existing upland habitat would be developed under this alternative, approximately 16 acres would be restored, and an additional 78 acres would be restored to highly valued resource habitat types. The beneficial impacts to upland habitats would primarily be the result of increased connectivity of uplands with other habitats as well as enhancement of habitat structure. Adverse impacts to upland habitat would occur primarily as a result of habitat loss.

Beneficial and adverse impacts are generally the same as described for Alternative 2. The primary differences in actions from those described in Alternative 2 are the numerous restorations not included in Alternative 5, such as Yellow Pine Campground and Curry Orchard parking lot. A summary of actions and impact intensities for Alternative 5 are provided in table 4-121.

• A new picnic area with grills would be established at Curry Orchard, causing moderate, adverse effects through creation of a new area for human/wildlife conflicts. The removal of parking from the orchard under this alternative would reduce the conditioning of bears to food in vehicles, and reduce damage to vehicles. Picnicking in the orchard, however, would likely result in dangerous interactions between wildlife and humans, especially when the apple trees are fruiting, attracting large numbers of black bears, deer, and squirrels. This situation would be prolonged by maintenance of the orchard, which could increase the longevity of the trees.

• Development of the Yellow Pine Campground for volunteers and groups would cause moderate, adverse impacts. A small area of forest habitat would be removed to expand the existing development. Increased radiating impacts into adjacent riparian and wetland areas would affect those highly valued resource habitat types and disturb wildlife. The site would become an increased source of human food to wildlife, leading to further conditioning of wildlife and human/wildlife conflicts. Animal-resistant trash cans and food lockers would help limit this problem, but adverse effects on wildlife behavior would still occur.

• Relocation of the concessioner commercial stable to east of Curry Village and continuation of guided trail rides would support a large population of brown-headed cowbirds, with continued effects of nest parasitism on species such as yellow warbler, solitary vireo, and warbling vireo. However, with the removal of the National Park Service and concessioner administrative stables operations from the Valley under this alternative, minor, beneficial effects would occur to songbird populations.

• The use of Northside Drive for motor vehicle traffic would perpetuate the impacts of noise, light, and roadway mortality on wildlife and continue to fragment habitat in Yosemite Valley. There would be no impact from this action, since it is essentially the existing condition.

1. Reasons for impact intensities are described in the text, along with explanations of mitigation measures incorporated into this evaluation. A complete list of mitigation measures is found in Chapter 2, Alternatives, Mitigation Measures Common to All Action Alternatives, Wildlife.

| Table of Contents | Alternative 3 | Alternative 4 | Alternative 5 | Commitments of Resources | Uses/Productivity |
| Short-Long Term | Chapter 5 | Chapter 6 | Bibliography | Glossary | Acronyms/Abbreviations | Index |
| Part 1 | Part 2 | Part 3 | Part 4 |

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