| Table of Contents | Environmental Consequences | Alternative 1 | Alternative 2 |
| Part 1 | Part 2 | Part 3 | Part 4 |

The analysis of potential impacts from actions implemented under Alternative 1, the No Action Alternative is presented in this section.

This analysis assesses impacts to 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 potential 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, non-point source pollution from vehicles or recreational use).

YOSEMITE VALLEY HYDROLOGY

There are currently campsites, rustic lodging units, employee housing, stables, parking areas (e.g., Camp 6) and other facilities immediately adjacent to the Merced River and within its floodplain. This development, as well as roads through Stoneman, Ahwahnee, and Cook’s Meadow, would continue to adversely affect the river’s ability to develop natural meanders, change course, and maintain a natural floodplain because facilities often obstruct and divert natural river flows. Development immediately adjacent to the Merced River and within its floodplain would continue to represent long-term, adverse impacts to hydrology.

Man-made obstructions in the Merced River and its tributaries (e.g., the rock-rubble pile at Yosemite Creek), such as bridge abutments (e.g., Sugar Pine Bridge) and riprap that protect facilities (e.g., El Portal Road), would continue to constrict and alter water flows. All eleven bridges and assorted riprap in Yosemite Valley would continue to have a long-term, adverse impact to the river’s hydrology. See Vol. Ia, Chapter 3, Affected Environment, for a description of the bridges and their interaction with the Merced River.

Cascades Diversion Dam would continue to have a long-term, adverse impact to hydrology by impeding river flows.

Pedestrian use along the banks of the Merced River has resulted in soil compaction, erosion, and riparian vegetation loss or decline, with consequent bank instability. The ultimate effect of bank instability is unnatural erosion, unnatural sediment deposition into the river, and localized river widening. Local, long-term, adverse impacts to riverbank stability would continue to occur due to visitor access to the river in some locations.

The existing three structures at Ahwahnee Row that are located in the 100-year floodplain would continue to have a long-term, localized, adverse impact to floodplain values by impeding flood flow (particularly pooling in this area).

YOSEMITE VALLEY WATER QUALITY

Water quality throughout Yosemite National Park is considered to be good and generally above state and federal standards. An inventory of water quality data performed by the National Park Service indicated excellent conditions in many parts of the park, but some water quality degradation in areas of high visitor use (Williamson et al.1996a). The State of California considers the surface water quality of most park waters beneficial for wildlife habitat, freshwater habitat, non-contact recreation, canoeing, rafting, and water contact recreation.

Surface water draining over granitic bedrock in the park exhibits considerable variability in chemical composition, despite the relative homogeneity of bedrock chemistry. Surface water in most of the Merced River basin is very diluted (lacking in dissolved solids), making the ecosystem sensitive to human disturbances and pollution. Studies have indicated a presence of Giardia lamblia and fecal coliform in various surface waters throughout the park, thereby limiting direct consumption of surface water by humans (Williamson et al. 1996a).

Good water quality is critical for the survival and health of species associated with riparian and aquatic ecosystems. Water quality elements that affect aquatic ecosystems include water temperature, dissolved oxygen, suspended sediment, nutrients, and chemical pollutants. These elements interact in complex ways within aquatic systems to directly and indirectly influence patterns of growth, reproduction, and mobility of aquatic organisms. For example, sediment may not be directly lethal to fish, but sediment deposited on the streambed may disrupt the productivity and life cycles of fish and aquatic insects.

Existing parking areas and turnouts in areas such as Curry Orchard, Yosemite Falls, Stoneman Meadow, Bridalveil Falls area, El Capitan Meadow, and Cook’s Meadow would continue to be sources of non-point source pollution. Nutrients, turbidity and coliform would continue to enter the river from both National Park Service and concessioner stables. Recreational uses such as swimming and rafting would continue to be sources of non-point source pollution. These facilities and uses in and immediately adjacent to the Merced River would continue to have long-term, adverse impacts to water quality.

EL PORTAL HYDROLOGY AND WATER QUALITY

The existing flood control levee (hereafter, levee) in the Hennessey’s Ranch area is above the normal high water line and does not affect annual spring runoff, but would continue to redirect river flows during large flood events. The levee is designed to protect facilities located within the natural floodplain in this area, and was not overtopped by the January 1997 flood. The levee prevents floodwaters from depositing sediment in the area, disrupting the natural processes of the floodplain. The levee would continue to have adverse impacts to the hydrology and floodplain values of the Merced River in the vicinity of Hennessey’s Ranch.

Facilities and recreational use along the banks of the Merced River throughout El Portal have resulted in soil compaction, erosion, and decline or loss of riparian vegetation. The ultimate effect of bank instability by these mechanisms is unnatural sediment deposition into the river, and localized river widening, although riverbank instability is less severe in El Portal than in Yosemite Valley. Artificial bank stabilization mechanisms such as riprap would continue to restrict and divert river flows, especially larger flood flows, and displace riparian vegetation. In El Portal, localized, long-term, adverse impacts to hydrology would continue to occur within the floodplain under the No Action Alternative.

Almost all of the facilities in El Portal are in close proximity to the Merced River, including the gas station and bulk fuel storage facility, employee housing, the market and post office, and operational facilities at Railroad Flat. These facilities, and the concentration of residential and operational activity associated with them, would continue to adversely impact water quality by contributing to non-point source pollution. In particular, the bulk fuel storage facility has a regional, long-term, adverse impact to water quality due to the inherent risk of fuel release during large flood events.

WAWONA HYDROLOGY

At Wawona, there are a few facilities immediately adjacent to the South Fork Merced River and within the river’s floodplain: private homes, portions of the Pioneer Yosemite History Center (including the covered bridge), a small portion of the maintenance complex, and the Wawona Road vehicle bridges. These facilities, and the concentration of visitor and employee activity associated with them, would continue to adversely impact the hydrology of the area, including floodplain values.

WAWONA WATER QUALITY

There is substantial development at Wawona, some of which is immediately adjacent to the South Fork Merced River and Chilnualna Creek: employee housing, private houses, lodging at the Wawona Hotel and at the Redwood Cottages, a National Park Service maintenance yard, the Yosemite Pioneer History Center, etc. This development has a long-term, adverse impact to water quality by contributing to non-point source pollution.

HAZEL GREEN HYDROLOGY AND WATER QUALITY

Hazel Green is located near the headwaters of Bull Creek, which drains into the North Fork of the Merced River, and Hazel Green Creek, which drains into Crane Creek. The hydrology of Hazel Green Creek and surface water runoff are the only pertinent hydrologic processes. The area is undeveloped and there is currently no impact associated with development at the project site.

FORESTA HYDROLOGY AND WATER QUALITY

Foresta is located on the banks of Crane Creek. The hydrology of Crane Creek, a small wetland, and surface water runoff are the only pertinent hydrologic processes. Within this area there are residential houses, a corral, and an access road to the area, all of which contribute non-point source pollution to Crane Creek. Two bridges across Crane Creek alter the creek’s flow. The continuation of non-point source pollution to Crane Creek and the small wetland, and continued alterations of Crane Creek from the bridge would be a continuing, long-term, adverse impact.

SOUTH LANDING HYDROLOGY AND WATER QUALITY

South Landing has no significant hydrologic features, and surface water runoff is the only pertinent hydrologic process. The access road adversely impacts hydrology by diverting and concentrating water at several locations. The area is used to store materials and equipment and has been used as a firing range; these uses contribute to non-point source pollution, and adversely impact 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. There is a small, disturbed area at the site that would have continuing adverse impacts to water quality.

BADGER PASS HYDROLOGY AND WATER QUALITY

Badger Pass has several springs, seeps, and wetlands that form the headwaters of Grouse Creek. The hydrology of these headwaters and surface water runoff are the only pertinent hydrologic processes. The existing parking lot and structures associated with the ski area would continue to adversely impact water quality by contributing non-point source pollution.

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. The existing facilities at these entrance stations would continue to adversely impact water quality by contributing non-point source pollution.

CONCLUSION

Conditions and features that affect Merced River hydrology are characterized in table 4-8. Development within the Merced River floodplain would continue to represent long-term, adverse impacts to hydrology, floodplain values, and water quality. Bridges, including the Sugar Pine, Stoneman, Housekeeping, Ahwahnee, Superintendent’s, and Swinging, would have a long-term adverse impact to river hydrology and the natural formation of floodplains. Local, long-term, adverse impacts to riverbank stability would continue to occur due to visitor access to the river in some locations under the No Action Alternative. Non-point source pollution resulting from development and recreational use of the river would continue to be a long-term, adverse impact in both El Portal and Yosemite Valley. Impacts to hydrology and floodplain values and water quality in El Portal would be long-term, localized, and adverse due to the current configuration of the flood control levee and presence of a bulk fuel storage facility adjacent to the Merced River. In Hazel Green, Henness Ridge, Foresta, and Badger Pass, both localized and regional long-term, adverse impacts would occur relating to water quality and soil stability.

The net impact of the actions of this alternative relative to hydrology, floodplain values, and water quality would be long-term and adverse.

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 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)

• 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)

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:

• Merced River Canyon Trail Acquisition (BLM)

• 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 to water resources through increased non-point source water pollution.

Reasonably foreseeable projects that could have a net adverse impact to 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 to water resources of past, present, and reasonably foreseeable future projects on the Merced River watershed would be related to removal of facilities from the river banks 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 to 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, adverse impact on water resources. The actions of this alternative, in combination with past, current, and reasonably foreseeable future projects would have a long-term, adverse impact on water resources.

This section identifies non-exempted facilities that would remain in the Merced River floodplain in Yosemite Valley, El Portal, and Wawona as a result of implementation of the No Action Alternative (table 4-9). This section also evaluates the current level of risk to human life and property associated with these properties during a flood event. The Water Resources section of this chapter addresses potential impacts to floodplain values and hydrology. All impacts on floodplains would be of long-term duration.

1. Development may be in or surrounded by the floodplain.

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 continued presence of the dam, and its risk of failure, would be a long-term, localized, adverse impact to human health and safety.

Concessioner Stable Area

Houses and tent cabins with a total of 49 employee beds at the concessioner stable, and the kennel would remain within the 100-year floodplain. However, because floods in this area are typically predictable, occupants of these facilities would have advance warning of potential flooding and would be able to safely evacuate. The risk to human life in this area is considered minimal.

Housekeeping Camp

The 248 housekeeping units would remain in the 100-year floodplain of the Merced River. These lodging units are not used during the winter flood season; therefore, the risk to human life is considered minimal. The risk of property damage occurring to these units during a flood event would, however, continue to exist.

Yosemite Village

A total of 17 employee beds, the concession headquarters, and 1 lodging unit at the Ahwahnee are in the 100-year floodplain of the Merced River. However, because floods in this area are typically predictable, occupants of these facilities would have advance warning of potential flooding, and would be able to safely evacuate. The risk to human life in this area would therefore continue to be minimal; however, the risk of damage to these facilities during a flood event would continue to exist.

Yosemite Lodge Area

Five motel buildings, overnight parking, the Wellness Center, and nearby custodial cabins at Yosemite Lodge would remain in the 100-year floodplain. The Superintendent’s House (Residence 1), across from the lodge would also remain within the 100-year floodplain. Flood events in this area are typically predictable. Occupants of these facilities would have advance warning of potential flooding, and would be able to safely evacuate. The risk to human life is thus considered minimal; however, the risk of damage to these facilities during a flood event would continue to exist.

EL PORTAL

Four houses would remain in the 100-year floodplain at Abbieville. A total of 36 employee beds at the El Portal Motor Inn cabins and El Portal Hotel would remain in the 100-year floodplain at the Village Center. Additional facilities at the Village Center that occur within the floodplain and would remain include the El Portal Hotel (Yosemite Institute office and housing), the bulk fuel facility, gas station, El Portal Market, and National Park Service offices and ranger station. At Railroad Flat, portions of the El Portal Warehouse complex would remain in the 100-year floodplain. Based on historic records, it would take at least 48 hours from the start of a rain event for the river to rise to a stage where it would cross Highway 140 in the vicinity of the Village Center, allowing time for safe evacuation. The risk to human life would thus be minimal; however, the risk of damage to the facilities during a flood event would continue to exist.

WAWONA

Portions of the Pioneer Yosemite History Center would remain in the floodplain. The Center is not occupied overnight and could easily be evacuated in the event of a flood. The risk to human life at the Center would thus be minimal; however, the risk of damage to the Center during a flood event would continue to exist.

CONCLUSION

Approximately 106 employee beds and 248 lodging units would remain within the Merced River’s 100-year floodplain (66 employee beds and 248 lodging units in Yosemite Valley and 40 employee beds in El Portal) in structures not designed for flooding. Additional facilities in Yosemite Valley that would remain within the floodplain include the kennel, Concession Headquarters, the Superintendent’s House (Residence 1), five Yosemite Lodge Motel buildings, overnight parking at Yosemite Lodge, and the Wellness Center and nearby custodial cabins. In El Portal, non-lodging facilities that would remain within the floodplain include the Yosemite Institute office, bulk fuel facility, gas station, El Portal Market, the ranger station and offices at the Village Center, and portions of the El Portal warehouse at Railroad Flat. Portions of the Pioneer Yosemite History Center in Wawona would remain within the floodplain. Flood events along the Merced River and South Fork are generally predictable, and occupants of these facilities would have advance warning of potential flooding, and would be able to safely evacuate. Therefore, the risk to human life is considered adverse but minimal. The risk of damage to these facilities during a flood event would continue, resulting in an adverse impact.

CUMULATIVE IMPACTS

The impacts of past, present, and reasonably foreseeable actions to flood hazard 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 effect the watershed 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 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 Co.), (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. 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. There could be risks to life and safety associated with construction of the Resources Management Building at Railroad Flat. A Statement of Findings would be developed as part of the El Portal design concept process to provide an accurate description of flood hazards and identify necessary mitigation. In El Portal, potential overnight residents and hotel visitors would slowly increase from approximately 1,300 to about 1,600 beds because of the proposed 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, 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 1 would be long-term and adverse, because overnight lodging/housing and facilities within the floodplain would remain and continue to pose flood-related risks to human safety and property. Effects associated with this alternative, in conjunction with past, present, and reasonably foreseeable future actions, could be long-term and adverse.

In the middle of the 19th century, Yosemite Valley encompassed vast palustrine emergent wetlands that extended in places from valley wall to valley wall (Heady and Ziuke 1978). Bands of palustrine forest and scrub shrub wetlands along tributaries and the banks of the Merced River meandered between these emergent wetlands. As early settlers arrived in the middle of the century, uses of the Valley changed from subsistence hunting and farming with the addition of agriculture and grazing in support of the early tourist trade. The vast wetlands in Yosemite National Park began to shrink in size as waters were diverted or drained to protect facilities, aid farming, and rid the Valley of mosquitoes.

Today, an extensive network of structures, roads, campgrounds, and utilities is found in the Valley. Modern infrastructure coexists with remnants from past management operations such as ditches in meadows and channeled creeks. Wetlands (as represented by acreage of meadow and riparian areas), have shrunk to less than half of the acreage that was present when C. F. Hoffman mapped Yosemite Valley and calculated meadow acreage in the 1860s (Hoffman 1866; NPS 1994e).

In El Portal, a highway, roads, an historic railroad grade, and structures were constructed in areas that impacted riverside wetlands. Wetlands at Foresta and Hazel Green have remained relatively unimpacted by development. A ski resort was built at Badger Pass, affecting wetlands on the lower slopes and flat areas. There are no wetlands in the areas proposed for development at South Landing, Henness Ridge, Wawona, or Big Oak Flat Entrance, and therefore, they are not discussed below.

SIZE

Yosemite Valley

The size of existing wetlands in Yosemite Valley is directly compromised by development in former wetlands, and indirectly by development that alters hydrologic flows that sustain wetlands. Heavy foot traffic also threatens the size of wetlands, particularly in parts of the east Valley along the Merced River.

The extent of existing development that lies in former wetlands in Yosemite Valley was estimated from historic photos and narratives, historic topographic maps (NPS 1921), and current soils maps (SCS, USDA 1991). Wetlands probably occurred in parts of Upper and Lower River Campgrounds, Yosemite Lodge, Yosemite Village, Housekeeping Camp, North Pines Campground, and Lower Pines Campground, and along Northside and Southside Drives. These developed areas do not currently meet the definition of a wetland because they do not retain characteristic wetland hydrology, soils, or vegetation.

Existing development that alters hydrologic flows connected to wetlands includes roads, channeled creeks and rivers, and ditched meadows. Existing roads bisect Bridalveil, El Capitan, Sentinel, Cook’s, Ahwahnee, Leidig, and Stoneman Meadows. Parts of Ribbon Creek, Yosemite Creek, Indian Creek and many other tributaries of the Merced River are channeled, often for relatively long stretches (Milestone 1978). Ditches were dug in the mid-1900s along roads to prevent visitors from driving on the meadows. Many are still maintained to protect road surfaces.

The Merced River has tripled in width since the early 1900s in parts of the east Valley. This impact on palustrine forest wetlands along the riverbank is a result of heavy foot traffic and subsequent loss of riparian vegetation that protected highly erodable riverbanks, and trapped sediments and organic matter.

The size of palustrine emergent wetlands in Yosemite Valley is diminishing due to encroachment by conifers, resulting in a type conversion to upland habitat. This is most likely due to water tables lowered by redirected hydrological flows, ditching, and roads; and a lack of burning by American Indians, as theorized by recent studies (NPS 1943; Reynolds 1959; Gibbons and Heady 1964; Anderson and Carpenter 1991). Lowered water tables create conditions that foster conifer invasion at a rate that is far beyond the natural range of variability (Wood 1975).

Under the No Action Alternative, palustrine forest and palustrine scrub shrub wetlands along the Merced River would continue to sustain heavy foot traffic through the campground area in the east Valley and the river would continue to widen. Remaining palustrine emergent wetlands in Yosemite Valley would remain at similar sizes due to on-going prescribed fire management actions. Existing development in potential wetlands would remain, including roads, campgrounds, and lodging. Under the No Action Alternative, these adverse impacts on the size of palustrine forest, palustrine scrub shrub, riverine, and palustrine emergent wetlands in Yosemite Valley would continue.

Out-of-Valley Areas

Negligible impacts on the size of wetlands in Foresta and Hazel Green would continue. The size of historic wetlands at Badger Pass would continue to be adversely affected by impacts radiating out from the ski resort. In El Portal, the highway, roads, and structures would remain in areas that adversely affect riverside wetland vegetation. Palustrine forest wetlands at South Entrance would continue to receive negligible impacts from the adjacent road.

INTEGRITY

Yosemite Valley

The wetland integrity in Yosemite Valley is degraded, particularly in terms of the proportion of non-native to native plant species in meadows, and a loss of vegetation along riverbanks in the campground area of the east Valley.

Deep-rooted non-native perennial grasses, which were historically cultivated for agricultural purposes, outcompete native plant species in drier parts of palustrine emergent wetlands. When water tables are sustained at normally high levels, native species are able to outcompete non-native plant species. Analysis of Yosemite Valley vegetation shows that 24% of Valley palustrine emergent wetlands (represented by meadows) are dominated by non-native vegetation and another 23% of these wetlands are in transition from native to non-native vegetation (NPS 1994e).

Palustrine forest, scrub shrub, and riverine wetlands in the Merced River channel are particularly degraded in the campground section of Yosemite Valley. In this area the river has widened considerably and created a warmer, shallower river without the variety of riffles and deep pools needed to sustain natural aquatic life. Riverside vegetation overhanging the main channel is absent in many locations, and does not contribute nutrients, organic matter, or shade to the riverine system.

Yosemite Valley is traversed by a series of roads and multi-use paved trails that can directly affect wetland integrity by:

• Converting productive wetlands to barren road surfaces

• Constraining and diverting surface and subsurface flows

• Dewatering wetlands

• Concentrating and accelerating runoff

• Creating a source of toxic pollution

• Intercepting groundwater flows (USFS 1996)

Roads can also indirectly affect wetland integrity by:

• Increasing or decreasing channel gradients and runoff velocities

• Accelerating soil erosion and the loss of soil nutrients

• Triggering site conversion from wetland plant species to upland species

• Impairing habitat suitability for wildlife

• Degrading water quality (USFS 1996)

Under the No Action Alternative, integrity of palustrine emergent wetlands would continue to degrade from non-native plant species and conifer encroachment. Wetlands along the Merced River and its tributaries would continue to be degraded by heavy recreation-related foot traffic. Roads would continue to bisect palustrine emergent wetlands and divert water traveling from upland habitats to the river and tributaries. Under the No Action Alternative, these adverse impacts on the integrity of wetlands in Yosemite Valley would continue.

Out-of-Valley Areas

Adverse impacts on the integrity of wetlands in El Portal, Foresta, South Entrance, and Hazel Green would continue due to non-native plant species encroachment, and as a result of existing road and paved trail impacts. The integrity of historic wetlands at Badger Pass would continue to be adversely affected by the ski resort.

CONNECTIVITY

Yosemite Valley

Palustrine forest wetlands that line the Merced River would continue to be fragmented by heavy foot traffic that degrades vegetation alongside campgrounds, rafting focal points, parking at Camp 6, roads, and at focal points such as Sentinel Beach Picnic Area. Connections between the Merced River and upland habitats would remain compromised by roads, structures, utilities, and water diversions. Connections along the Merced River corridor and between the river and upland habitats are important for wildlife travel and access to water. Under the No Action Alternative, adverse impacts on the connectivity of wetland habitats in Yosemite Valley would continue.

Out-of-Valley Areas

Adverse impacts on the connectivity of wetlands in Foresta, Tioga Pass Entrance, and Hazel Green would continue due to the existence of roads through these sites. The connectivity of historic wetlands at Badger Pass would continue to be adversely affected by the ski resort.

CONCLUSION

Under the No Action Alternative, the Merced River would continue to widen unnaturally in Yosemite Valley. This would foster a shallower river that would not contain a variety of riffles and pools, would not have a ready source of large woody debris, and would be subject to temperature extremes; factors that otherwise contribute to the health of the aquatic system. Palustrine wetland vegetation would remain severely degraded in the campground area of east Yosemite Valley. Facilities and infrastructure would remain, some of which directly impact former wetlands such as Upper and Lower River Campgrounds. Surface water flows that sustain wetlands would remain obstructed by roads and other development. These conditions would continue to have long-term adverse effects on the size, integrity, and connectivity of wetlands in Yosemite Valley.

Long-term adverse impacts on riverine, palustrine forest, and palustrine scrub shrub wetlands along the river in El Portal would continue due to the presence of roads and structures impeding natural water flows through old river channels and impacting river-edge vegetation. Adverse impacts to palustrine emergent wetlands at Badger Pass would continue as a result of radiating use of the meadow from the ski area and parking lot. Palustrine forest and scrub shrub wetlands in Foresta, Hazel Green, and South Entrance would continue to be adversely impacted by adjacent roads and non-native species encroachment. Wetlands at Tioga Pass would continue to receive negligible, adverse impacts from current levels of human use.

CUMULATIVE IMPACTS

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 also could increase knowledge of resources and recreational use. These plans 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, 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 the 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 campground rehabilitation projects in Tamarack, Yosemite Creek, Bridalveil and Hodgdon Meadows Campgrounds, and the Merced River Eagle Creek Ecological Restoration Project (Yosemite Valley). Erosion control and mitigation as a result of these projects could enhance and strengthen palustrine forest and palustrine scrub shrub wetlands. The Eagle Creek project would revegetate currently denuded riverbanks that were formerly palustrine forest and palustrine scrub shrub wetlands. The erosion control and restoration projects would have long-term, localized, 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 impact existing palustrine forest and palustrine emergent wetlands. A palustrine scrub shrub wetland traverses the Hazel Green Ranch site and a palustrine emergent wetland exists in the center of this area. Proposed new development would not avoid the wetland corridor. The long-term direct impacts on wetlands would be adverse due to the relative rarity of undeveloped wetlands between 1,000 and 3,000 feet in elevation, and the relative importance of remaining wetland habitat throughout 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.

Regional and parkwide plans which could result in long-term, moderate, and beneficial cumulative impacts on wetlands are tempered by adverse impacts that include extensive infrastructure that diverts water away from wetlands in Yosemite Valley, the potential direct loss of wetland habitat at the Yosemite View Parcel Land Exchange, and other projects outside Yosemite National Park, and continued unnatural widening of the Merced River in the east Valley.

These areawide projects (as described in Vol. II, Appendix H), in conjunction with the impacts of the No Action Alternative, would have overall adverse impacts on wetlands in the area. All of these impacts would be long term. The potential for beneficial and adverse impacts to wetlands would be greater from projects occurring within the cumulative impact assessment area of the Sierra Nevada bioregion than from this alternative. Therefore, Alternative 1, in conjunction with other regional planning and development activities, would have a minor to moderate, adverse impact to wetlands due to the relative rarity of undeveloped wetlands in the Sierra Nevada.

The soils impact analysis is based on three integrated parameters: the size of the area affected, degree of previous disturbance, and soil resource type. Three soil resource types are defined in the Methodology section of this chapter: resilient soils (R), highly valued resource soils (HVR), and other soils not identified as resilient or highly valued resource soils (O).

The No Action Alternative is provided as the baseline condition by which all other alternatives are evaluated. Existing conditions and trends in land management are assumed to continue in the future. Further degradation of soil resources may occur as a result of continued human use and existing development in the area. The following discussion is provided to characterize these impacts.

YOSEMITE VALLEY

Approximately 407 acres of soil is currently affected by some level of previous disturbance. Of this acreage, 120 acres are highly valued resource soils and 217 acres are resilient soils. Acreages were calculated with the parameters used in the 1991 Yosemite Valley Soil Survey. Table 4-10 summarizes Yosemite Valley soil types and currently affected acreage. Affected acreage totals were rounded to the nearest acre. Some minor discrepancies between acreage in the text and table may occur due to rounding, differences in mapping sources, or because impacts were not mentioned in the text if they were small (less than 1 acre).

Adverse soil impacts would continue to be associated with existing structures, roads, trails, campgrounds, and parking facilities. Impacts would be primarily related to erosion, compaction, soil profile mixing, and soil removal. Soils associated with riparian areas, such as the Riverwash series, are susceptible to erosion. Generally, these soils are coarse textured and have little organic matter to provide structural integrity. Removal of vegetation in heavily traveled areas further reduces soil stability. Continued uncontrolled access to the river would result in further erosion and decreased bank stability.

Soils that have been excavated and/or covered by impervious surfaces such as roads, parking lots or buildings may lack typical physical, biological, and chemical properties. In Alternative 1, soil removal and profile mixing have occurred in localized areas for building, road, and trail construction activities. For example, the Miwok complex soil type will continue to be impacted by buildings and parking lots at the general maintenance area and Curry Village.

Adverse impacts to soils resulting from current uses have lasted for several decades at existing building and road sites. Most of the impacts are long term. Erosion impacts may be temporary to long term, depending on the location and potential for renewal through sedimentation associated with flooding. For example, adverse impacts to floodplain soils are ameliorated over time by renewal during flood events.

Adverse impacts would continue on a mix of resilient and highly valued resource soil series. For example, the Lower Pines Campground would continue to affect highly valued resource soils (e.g., El Capitan) as a result of compaction and erosion impacts; likewise the Upper and Lower River Campgrounds would continue to affect resilient soils of the Miwok complex. These resilient soil types have physical attributes that generally support current land-use practices. However, hydric and other highly valued resource soils would continue to be disturbed by current land-use practices, including 101 Riverwash along the Merced River above Stoneman Meadow and 104 Aquandic Humaquepts at the Tenaya Creek/Merced River confluence. Although the area of disturbance is fairly localized, these soils cover much less acreage than the resilient soil types.

The current soil impacts within Yosemite Valley would remain unchanged under Alternative 1. The continued impacts associated with Alternative 1 would be adverse and long-term.

Soil impacts for seven areas or activities are characterized below. These conditions would continue under the No Action Alternative.

Curry Village

• Scattered visitor parking continues

• Current use of lodging units, campgrounds, ice rink, and area trails continues

The current affected acreage is approximately 49 acres (HVR = 0, R = 20, O = 29).

Yosemite Lodge

• Yosemite Creek human built rubble pile remains

• Lodge cabins are neither rebuilt nor restored

• Scattered visitor, staff, and employee parking continues

• Use of lodging units, area roads, parking lots, and trails continues

The current affected acreage is approximately 79 acres (HVR = 8, R = 69, O = 2).

Yosemite Village

• Use of current road through Cook’s Meadow

• Camp 6 continues as parking area

• Current use of Church Bowl picnic area continues

• Current concession uses in Yosemite Village center remain

• All housing units remain

The current affected acreage is approximately 105 acres (HVR = 16, R = 60, O = 29).

West Valley

Current land use remains at El Capitan Picnic Area, Cathedral Beach Picnic Area, and Bridalveil Fall. The current affected acreage is approximately 6 acres (HVR = 3, R = 2, O = 1).

Campgrounds

Use of current campgrounds continues at all sites. The current affected acreage is approximately 171 acres (HVR = 94, R = 65, O = 12).

Roads and Trails

Soils that have a seasonally high water table are susceptible to localized compaction. Existing roads and trails on soils such as the El Capitan and Leidig series have altered subsurface flow of groundwater, due to soil removal and compaction.

OUT-OF-VALLEY AREAS

The current development impacts within out-of-Valley areas would continue and remain unchanged under Alternative 1. The impacts would continue to be adverse and long term, because there would be no measurable change to existing baseline conditions.

CONCLUSION

Current visitor services and facilities within Yosemite Valley affect approximately 400 of the 3,555 acres of land area in the Valley. Further degradation of soil resources resulting from visitor use would continue. Impacts currently occur to several highly valued resource soils. Although these impacts may be ameliorated over time through restoration and visitor use access restrictions, the implementation of such restrictions would not be comprehensive. Thus the impacts are likely to remain over an extended period of time. The sum of all impacts resulting from current land use would have a long-term, adverse impact on existing soil resources.

CUMULATIVE IMPACTS

Since soil types vary by geographical location, actions outside Yosemite National Park generally do not impact the same soil types as those found within the Valley. Therefore, other present and reasonably foreseeable future projects considered to possibly have a cumulative impact on soils described in the Final Yosemite Valley Plan/SEIS must occur in the park or in proximity to the park. For purposes of this evaluation, projects within five miles of the park were considered to have a potential effect on soil types consistent with those found in the park. These projects include:

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

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

• Evergreen Lodge Expansion (Tuolumne Co.)

• Evergreen Road Improvements (Multi-agency, see Appendix H)

• Yosemite West Rezone for 55 Acres (Mariposa Co.)

• Tuolumne Meadows Development Concept Plan (NPS)

• Tuolumne Meadows Water and Wastewater Improvements (NPS)

• Hodgdon Meadow Campground Rehabilitation (NPS)

• Hodgdon Meadow Water and Wastewater Treatment Improvements (NPS)

Each of the above projects has the potential to produce further soil disturbances. These disturbances would include erosion and compaction associated with development, such as the expansion of the Evergreen Lodge and Hotels in El Portal. Projects in Tuolumne Meadows may impact highly valued resource soils that are susceptible to erosion. While projects such as the sewer line rehabilitation may have beneficial effects on water resources, their effect on soils would generally be adverse due to soil mixing, compaction, and erosion. Overall, the projects located outside of the park that may have cumulative impacts are small in scope, as compared to the total area of the region. Additionally, the impacts associated with those projects would be minimized through the use of Best Management Practices as required by local, state, and federal regulations.

As described above, impacts to soils under Alternative 1 would consist of a continuation of adverse effects associated with existing development and visitor activities in Yosemite Valley. No specific actions are proposed beyond current land management practices. Consequently, the cumulative impacts that would result from the combination of Alternative 1, as well as the other past, present, and reasonably foreseeable future projects, would continue to be long term and adverse.

YOSEMITE VALLEY

The Valley vegetation can be assembled into five general groups or types: upland, California black oak, meadow, riparian, and other (NPS 1994e). The other type includes miscellaneous non-native vegetation such as apple orchards and lawns, as well as bare ground and river channel. The Valley includes approximately 3,555 acres, of which approximately 70% is classified as upland, 5% as California black oak, 11% as riparian, 8% as meadow, and 6% as other.

Upland Communities

The majority of Valley vegetation falls under the upland vegetation type. Most of this has been disturbed to some extent by humans in the past; approximately 10% of upland acreage is heavily disturbed by past development of roads, facilities or structures, and frequent human activities. This category includes ten different subtypes of mixed conifers and canyon live oaks. Alternative 1 would provide no comprehensive approach to improvements, restoration, or management of these previously disturbed uplands or adjacent communities, resulting in continued and long-term degradation.

Size and Continuity

The size and extent of uplands in the Yosemite Lodge, Yosemite Village, and campground areas are unnaturally large due to lack of fire and modified hydrology, which has resulted in the encroachment of conifers into former meadows, riparian areas, and oak woodlands. This would continue under Alternative 1 due to the National Park Service’s inability to manage trees by prescribed fire within and around developed areas. Impacts would also continue where fill material was used to raise the level of the ground surface to provide drier sites for development (Camp 6 and the former Upper and Lower River Campgrounds). These upland communities would continue to expand and become more continuous through the Valley as existing and newly established conifers dry out soils, and woody debris and duff accumulate, gradually raising and drying the underlying substrate over time.

The unnaturally dense stands of incense-cedar and ponderosa pine would continue to contribute to the spread of annosus root rot through many of the developed areas in the east Valley (such as at Camp 4 [Sunnyside Campground], Yosemite Lodge, and Upper and Lower River Campgrounds area). Additionally, annosus root rot would continue to spread through the more open areas in the west Valley (such as Taft Toe and the vicinity of the old El Capitan picnic area), leading to continued high levels of management effort to remove hazard trees (dead or dying trees) from developed sites and road corridors.

Canyon live oak communities would continue to be impacted by housing and development at the Curry and Yosemite Village areas, while communities in the west Valley would continue to function naturally (albeit with higher than normal fuel loads) because of the lack of change in infrastructure, transportation routes, and trail systems.

Natural Structure, Diversity, and Productivity

A forest community’s diversity and productivity are directly related to the integrity of its structure (overstory, understory, and ground layers). The natural structure of the developed and disturbed upland communities in the Valley has been severely degraded due to lack of fire, resulting in an increasingly dense overgrown understory and a shift in species composition over time to more shade-tolerant coniferous species such as white fir, Douglas-fir, and incense-cedar. Therefore, under Alternative 1, the understory integrity, diversity, and overall productivity would continue to be impacted by a lack of native understory and lack of regeneration due to trampling in developed zones. Two examples where no action is considered a continued adverse impact are:

• Yellow Pine Campground and Sentinel Beach, formerly known for outstandingly large individual ponderosa pines, would continue to sustain a mixture of coniferous species in dense stands that would not facilitate re-establishment of the natural large individuals found there historically. This would be a direct result of the lack of prescribed fire and lack of ability to manage for more naturally open characteristics.

• Small portions of canyon live oak communities in the east Valley at the Upper Tecoya housing area would continue to lack a natural understory structure because of the continued existence of housing, with its associated trampling, landscaping, and non-native plant encroachment.

Continued degradation of this upland vegetation type would occur under the No Action Alternative and impacts would continue to be long-term and adverse, as there would be no measurable change from the existing condition.

California Black Oak Communities

Approximately 20 acres of the California black oak vegetation type have been heavily disturbed by past actions. Under the No Action Alternative, degradation would continue within those developed/disturbed areas of California black oak. The following describes the current condition of California black oak communities in the Valley.

Size and Continuity

• Existing stands would continue to be fragmented throughout the east Valley by development, roads, and encroaching conifers.

• Stands in the west Valley would continue to decline in size because of conifer encroachment and changes in hydrology resulting from the presence of roads. For example, Northside Drive impedes natural cross-slope drainage from Ribbon Fall to the Merced River, impounding water on the north side of the road. This unnaturally moist area encourages armillaria root rot in the remaining large trees at this site, causing tree failure either through collapse or increased susceptibility to other diseases. As a result, continuity of the California black oak canopy does not exist, and regeneration is not occurring at this site.

• Stands would continue to be impacted by summer irrigation in housing and landscaped areas (including the National Park Service historic housing district and landscaped areas surrounding The Ahwahnee), leading to further permanent loss of California California black oaks from mortality caused by armillaria root rot and lack of regeneration from armillaria and trampling.

• The continued inability to manage California black oak stands through prescribed fire (due to the presence of infrastructure) would continue to support mistletoe infestations and large infestations of oak galls. Lack of fire results in reduced nutrient cycling, which leads to tree stress and mortality of mature trees.

• The ability of the National Park Service to enhance California black oak woodlands would continue to be hampered by development and infrastructure through all developed California black oak areas of the Valley. Efforts to re-establish oak woodlands would continue to be done on a site-by-site basis rather than a holistic Valley wide basis.

Natural Structure, Diversity, and Productivity

• In developed areas, California black oak woodlands would continue to have little to no regeneration due to trampling, landscaping with irrigation, and other stresses, which increase the susceptibility of both young and old trees to armillaria root rot.

• Throughout the Valley, understory integrity would continue to be impacted by non-natives and/or lack of native vegetation as a result of paving, structures, and trampling.

• Continued loss of overstory trees to disease and the inability to manage the area through prescribed fire would continue to lead to an overall decline of California black oak in the Valley, with a loss of productivity and integrity for wildlife habitat.

• Due to the decline in California black oaks from lack of fire and alteration in drainages, other components of California black oak communities, such as deer grass (an important ethnographic resource), would continue to decline.

• Woodlands west of Curry Village would continue to be relatively unimpacted by human activities. However, the lack of fire would allow continued encroachment by conifers, leading to a gradual shift from a California black oak-dominated community to a mixed conifer California black oak community that is more common (thus less highly valued) in the Valley.

• The California black oak stand at the base of Bridalveil Fall would continue to be actively restored, as would stands at the Yosemite Valley elementary school, near The Ahwahnee, and along the Merced River in river restoration sites.

Continued degradation of California black oak communities would occur under the No Action Alternative, and impacts would continue to be long-term and adverse, as there would be no measurable improvement from the existing condition.

Meadow Communities

Approximately 8% of Valley vegetation falls in the meadow vegetation type (NPS 1994e). Many historic meadows have been converted to upland vegetation types or no longer exhibit meadow characteristics due to development. The following describes the current condition of meadow communities within the Valley.

Size and Continuity

• Meadow size would continue to gradually decrease in all meadows because of conifer encroachment, loss of natural drainage patterns because roads, bike paths with inadequate culverts, and river diversions (e.g., channelization of the confluence of Yosemite Creek with the Merced River).

• Continuity would continue to be disrupted because of fingers of conifers following raised portions of land along roadways and the bike path from Yosemite Lodge to Swinging Bridge.

• Areas of former meadow at the Upper and Lower River Campgrounds area; Northside Drive where it goes through Ahwahnee Meadow; portions of Lower Pines Campground; and roads through Sentinel Meadow and Cook’s Meadow would continue to either be altered or non-existent. These conditions are the result of raised road alignments, buried meadow soils where fill was added to raise land to increase suitability for development, and dominance by non-native herbaceous species due to altered soil and hydrologic conditions.

• Connectedness of meadows to riparian and wetland areas would continue to be cut off by roads and bike paths. Connectedness of meadow systems through the Valley would continue to be minimal at best due to unnaturally large areas of conifers between meadows and loss of oxbow and cutoff channels (see Glossary) which would have provided links from meadow to meadow.

Natural Structure, Diversity, and Productivity

• Meadows in the Valley would continue to have decreased integrity due to the presence of non-native plants and the introduction of stormwater runoff contaminants from adjacent roads, parking, and lodging.