Introduction

In the 1960s, the United States came to recognize that many of the nation’s rivers were being dredged, dammed, diverted, and degraded at an alarming rate. In response, Congress established the Wild and Scenic Rivers Act in October 1968. A Wild and Scenic River is one that has been identified as having distinctively unique or “outstandingly remarkable values” that set it apart from all other rivers, making it worthy of special protection. The goal of designating a river as Wild and Scenic is to preserve its free-flowing character and unique qualities.

In 1987, the U.S. Congress designated the Merced a Wild and Scenic River to protect the river’s free-flowing condition and to protect and enhance its unique values for the benefit and enjoyment of present and future generations (16 USC 1271). This designation gives the Merced River special protection under the Wild and Scenic Rivers Act and requires the managing agencies to prepare a comprehensive management plan for the river and its immediate environment.

After reaching a Record of Decision on the Final EIS, the National Park Service released the Merced Wild and Scenic River Comprehensive Management Plan (referred to hereafter as the Merced River Plan) in February 2001, which outlines how the Merced Wild and Scenic River corridor will be managed. The Merced River Plan applies seven management elements to prescribe desired future conditions, typical visitor activities and experiences, and park facilities and management activities allowed in the river corridor. The management elements include boundaries, classifications, Outstandingly Remarkable Values, the Wild and Scenic River Act Section 7 determination process, the River Protection Overlay, management zoning, and the Visitor Experience and Resource Protection framework.

The National Park Service uses the management elements as a set of decision-making criteria with which to evaluate projects in the Merced River corridor, such as the Happy Isles Gauging Station Bridge Removal Project. This chapter evaluates the consistency of the proposed action with the management elements of the Merced River Plan.

This chapter includes the following sections:

·     Overview of the Wild and Scenic Rivers Act

·     Overview of the Merced River Plan and its management elements

·     Methods for evaluating the consistency of the proposed action with the Merced River Plan management elements

·     Analysis of the consistency of the proposed action with the Merced River Plan management elements

The Wild and Scenic River Act Section 7 Determination is included as Appendix C of this document.

Wild and Scenic Rivers Act

The Wild and Scenic Rivers Act (Public Law 90-542, as amended) states the following:

      It is hereby declared to be the policy of the United States that certain selected rivers of the Nation which, with their immediate environments, possess outstandingly remarkable scenic, recreational, geologic, fish and wildlife, historic, cultural, or other similar values, shall be preserved in free-flowing condition, and that they and their immediate environments shall be protected for the benefit and enjoyment of present and future generations. The Congress declares that the established national policy of dam and other construction at appropriate sections of the rivers of the United States needs to be complemented by a policy that would preserve other selected rivers or sections thereof in their free-flowing condition to protect the water quality of such rivers and to fulfill other vital national conservation purposes.

Outstandingly Remarkable Values are defined by the Wild and Scenic Rivers Act as those resources within a river corridor that are worthy of special protection. These are the values for which a river is added to the National Wild and Scenic Rivers System. The Wild and Scenic Rivers Act stipulates that these values are to be protected and enhanced. It also stipulates that each agency charged with administration of a segment of the Wild and Scenic Rivers System establish boundaries (an average of not more than 320 acres per mile on both sides of the river) and prepare a comprehensive management plan to provide for the protection of river values. The plan must address resource protection, development of lands and facilities, user capacities, and other management practices necessary to achieve the purposes of the act. The Merced Wild and Scenic River Comprehensive Management Plan fulfills this requirement.

Section 2 of the Wild and Scenic Rivers Act requires that the river be classified and administered as Wild, Scenic, or Recreational river segments, based on the condition of the river corridor at the time of boundary designation. The classification of a river segment indicates the level of development on the shorelines, the level of development in the watershed, and the accessibility by road or trail. Classifications are defined in the act as follows:

      Wild river areas: Those rivers or sections of rivers that are free of impoundments and generally inaccessible except by trail, with watersheds or shoreline essentially primitive and waters unpolluted.

      Scenic river areas: Those rivers or sections of rivers that are free of impoundments, with shorelines or watersheds still largely primitive and shorelines largely undeveloped, but accessible in places by roads.

      Recreational river areas: Those rivers or sections of rivers that are readily accessible by road or railroad, that may have some development along their shorelines, and that may have undergone some impoundment or diversion in the past.

1987 Designation of the Merced Wild and Scenic River

Public Law 100-149 (1987) and Public Law 102-432 (1992) placed 122 miles of the Merced River into the National Wild and Scenic Rivers System. The National Park Service administers a total of 81 miles of the Merced River, encompassing both the main stem and the South Fork in Yosemite National Park and the El Portal Administrative Site. (This portion of the Merced River is referred to hereafter as the Merced Wild and Scenic River.) The U.S. Forest Service and the Bureau of Land Management administer the remaining 41 miles of the designated river.

In February 2001, the National Park Service released the Merced Wild and Scenic River Comprehensive Management Plan. This plan lays out the policy direction by which the National Park Service will manage the 81 miles of river corridor under its jurisdiction. 

Merced Wild and Scenic River Comprehensive Management Plan

The purpose of the Merced Wild and Scenic River Comprehensive Management Plan is:

      ...to provide direction and guidance on how best to manage visitor use, development of lands and facilities, and resource protection within the river corridor. The National Park Service developed a series of planning goals to guide management decision-making in these areas. The Merced River Plan is a template against which project implementation plans will be judged to determine whether such projects will protect and enhance the values for which the Merced River was designated Wild and Scenic. As a result, the Merced River Plan provides general direction and guidance for future management decisions; it does not address the specific details of future projects.

Merced Wild and Scenic River Management Elements

As a programmatic plan, the Merced River Plan does not specify detailed actions. Instead, it applies seven management elements to prescribe desired future conditions, typical visitor activities and experiences, and park facilities and management activities allowed in the river corridor. The management elements include the following: boundaries, classifications, Outstandingly Remarkable Values, the Wild and Scenic Rivers Act Section 7 determination process, the River Protection Overlay, management zones, and the Visitor Experience and Resource Protection (VERP) framework. These management elements are described briefly below as they relate to the Happy Isles Gauging Station Bridge Removal Project. For additional information, please refer to the Merced Wild and Scenic River Comprehensive Management Plan (NPS 2001a). The Merced Wild and Scenic River Comprehensive Management Plan is available on the Internet at www.nps.gov/yose/planning.htm.

Boundaries

Boundaries define the areas to be managed under the comprehensive management plan. The act allows for river corridor boundaries that average no more than 320 acres of land per river mile, measured from the ordinary high water mark on both sides of the river. Boundaries, however, do not limit the protection of Outstandingly Remarkable Values, which must be protected regardless of whether they are inside or outside the corridor boundaries.

In the vicinity of Happy Isles Gauging Station Bridge, the river boundary is defined as one-quarter mile from ordinary high water (as defined by the U.S. Army Corps of Engineers in 33 CFR Section 328.3). Ordinary high water is the line on the shore established by the fluctuations of water and indicated by physical characteristics such as a clear, natural line impressed on the bank, shelving, changes in the character of soil, destruction of terrestrial vegetation, the presence of litter and debris, or other appropriate means that consider the characteristics of the surrounding area. The Happy Isles Gauging Station Bridge Removal Project is within the boundaries of Segment 2, Yosemite Valley.

Classifications

Classifications (Wild, Scenic, or Recreational) are applied to each segment of the river corridor and are based on the existing condition of the river at the time of river designation. The classification of a river segment indicates the level of development on the shorelines, the level of development in the watershed, and the degree of accessibility by road or trail. The east Valley river segment at Happy Isles Gauging Station Bridge, from the wilderness boundary above Nevada Fall to Sentinel Beach, is classified as Recreational due to its accessibility and the amount of development within the boundary.

Outstandingly Remarkable Values

Outstandingly Remarkable Values are the river-related values that make the river segment unique and worthy of special protection. They form the basis for the river’s designation as a Wild and Scenic River. Outstandingly Remarkable Values identified for the Valley segment of the Merced River include:

      Scientific – The entire river corridor constitutes a highly significant scientific resource because the river watershed is largely within designated Wilderness in Yosemite National Park. Scientific Outstandingly Remarkable Values relate to the Merced River’s value for research. This Outstandingly Remarkable Value applies to all the Merced River segments.

Scenic – This segment provides magnificent views from the river and its banks of waterfalls (Nevada, Vernal, Illilouette, Yosemite, Sentinel, Ribbon, Bridalveil, and Silver Strand), rock cliffs (Half Dome, North Dome/Washington Column, Glacier Point, Yosemite Point/Lost Arrow Spire, Sentinel Rock, Three Brothers, Cathedral Rock, and El Capitan), and meadows (Stoneman, Ahwahnee, Cook’s, Sentinel, Leidig, El Capitan, and Bridalveil). There is a scenic interface of river, rock, meadow, and forest throughout the segment.

      Geologic Processes/Conditions – This segment contains a classic, glaciated, U-shaped valley, providing important examples of a mature meandering river; hanging valleys such as Yosemite and Bridalveil Creeks; and evidence of glaciation (e.g., moraines below El Capitan and Bridalveil Meadows).

      Recreation – This segment offers opportunities to experience a spectrum of river-related recreational activities, from nature study and sightseeing to hiking. Yosemite Valley is one of the premier outdoor recreation areas in the world.

      Biological – Riparian areas and low-elevation meadows are the most productive communities in Yosemite Valley. The high-quality, vast riparian, wetland, and other riverine areas provide rich habitat for a diversity of river-related species, including special-status species, neotropical migrant songbirds, and numerous bat species.

      Cultural – This segment contains evidence of thousands of years of human occupation, reflected in the large number of archeological sites and continuing traditional use today. Nationally significant historic resources are found here, such as designed landscapes and developed areas, historic buildings, and circulation systems (trails, roads, and bridges) that provide visitor access to the sublime views of natural features that are culturally valuable.

      Hydrologic Processes – This segment is characterized by a meandering river, world-renowned waterfalls, an active flood regime, oxbows, unique wetlands, and fluvial processes.

Happy Isles Gauging Station Bridge is a component of the Valley segment cultural Outstandingly Remarkable Value since it is a contributing element to the Yosemite Valley Cultural Landscape, and it is part of the circulation system that provides visitor access to the sublime views of natural features that are culturally valuable.

Wild and Scenic Rivers Act Section 7 Determination

When Congress enacted the Wild and Scenic Rivers Act in 1968, it sought to end decades of damming, dredging, and diversion of some of the nation’s most spectacular waterways. However, while the Wild and Scenic Rivers Act does not prohibit development along a river corridor, it does specify guidelines for the determination of appropriate actions within the bed and banks of a Wild and Scenic River. Section 7 of the Wild and Scenic Rivers Act specifies restrictions on hydro and water resources development projects. A key management element for guiding future decisions regarding the Merced River is carried out through a Section 7 determination process. Water resources projects,[1] that is, those that are within the bed or banks
of the Merced River and that affect the river’s free-flowing condition, are subject to Section 7 of the Wild and Scenic Rivers Act (16 USC 1278). As the designated river manager for the Merced River segments addressed by this Merced River Plan, the National Park Service must carry out a Section 7 determination on all proposed water resources projects to ensure they do not directly and adversely impact the values for which the river was designated Wild and Scenic.

The Happy Isles Gauging Station Bridge Removal Project is located within the bed and banks of the Merced River, and is therefore a water resources project subject to Section 7 of the Wild and Scenic Rivers Act. The Wild and Scenic Rivers Act Section 7 determination for the proposed action is included in Appendix C.

River Protection Overlay

The areas immediately adjacent to the river channel, along with the river channel itself, are particularly important to the health and proper functioning of the river ecosystem. These areas allow for the main channel to link with backwater areas, tributaries, and groundwater systems; provide for increased channel diversity; and contribute sources of needed nutrients and woody debris to the river. In most circumstances, trees or other large woody debris falling into the river are recognized as part of the natural processes and are left in the river to aid in the recovery of aquatic and riparian habitat. Additionally, the areas immediately adjacent to the river channel can help protect surrounding development from potential flood damage and can be used to filter runoff water draining into the river.

To ensure that the river channel itself and the areas immediately adjacent to the river are protected, the Merced River Plan includes a management tool called the River Protection Overlay. It is intended as a primary mechanism to achieve the goals of the Merced River Plan. The River Protection Overlay is also intended to identify the location of highest priority for restoration of hydrologic processes and biotic habitats within the river corridor. This critical zone provides a buffer area for natural flood flows, channel formation, riparian vegetation, and wildlife habitat and would protect riverbanks from human-caused impacts and associated erosion. At Happy Isles Gauging Station Bridge, the River Protection Overlay includes the river channel itself and extends 150 feet on both sides of the river, measured from the ordinary high water mark (see Glossary). This project would occur within the River Protection Overlay.

Management Zoning

Management zoning is a technique used by the National Park Service to classify park areas and prescribe future desired resource conditions, visitor activities, and facilities. Similar to zoning found in other types of land-use planning (such as municipal zoning), management zoning prescribes future desired conditions for a particular area.

Management zoning was developed to protect and enhance the Outstandingly Remarkable Values within each segment of the river. Specifically, the Merced Wild and Scenic River Comprehensive Management Plan places an emphasis on integrating protection and enhancement of natural and cultural resource Outstandingly Remarkable Values with the protection and enhancement of the diverse recreation Outstandingly Remarkable Values within the river corridor. Management zoning prescribes certain uses and facilities that are not allowed in an area. Before such zoning existed, additional development and higher-intensity uses by park visitors could have resulted in impacts to Outstandingly Remarkable Values over the long term. Management zoning also provides opportunities for restoration of Outstandingly Remarkable Values in areas where lower use and facility levels are prescribed.

The Happy Isles Gauging Station Bridge is in management zone 2C, Day Use. The Happy Isles area, including the Nature Center at Happy Isles, is in management zone 2D, Attraction. These management zones are described briefly below.

2C. Day Use

The Day Use zone is intended to be applied to popular park destinations, where visitors can spend significant periods of time enjoying the park resources in a relatively accessible setting. The Day Use zone enhances opportunities for visitors to enjoy more intensive recreational activities near the Merced River and supports a range of active recreational opportunities such as swimming, picnicking, and rafting, which contributes to the diversity of experiences specified in the recreation Outstandingly Remarkable Value. Visitors can expect moderate to high numbers of encounters with other park users and crowding on certain peak days. Large groups can use these areas. Day Use areas may be accessible by automobile, shuttle bus, and by bicycle, with interpretive trails or other marked trails leading to waterfalls, beaches, and scenic views. In order to accommodate heavier and more concentrated activity, facilities such as parking areas, restrooms, fencing of sensitive areas, picnic tables, and recycling and trash receptacles are allowed.

Resource protection activities in this zone include restoration of natural processes affected by past or current human use, restoration of natural flood cycles and river channel dynamics to sustain native plant and wildlife species, and use of fire management practices called for in the Fire Management Plan to enhance biological and hydrologic Outstandingly Remarkable Values. This zone also encourages the protection and enhancement of cultural resource Outstandingly Remarkable Values, including archeological sites, by limiting development and access. Restoration of natural resources such as wetlands and meadows also contributes to the improvement of the cultural landscape.

However, due to the larger volume of visitors, the Day Use zone is managed with moderate tolerance for resource degradation from visitor use in specified areas. To protect and enhance cultural, biological, and hydrologic Outstandingly Remarkable Values, more extensive resource protection measures may be needed to direct visitor use away from sensitive resources.

2D. Attraction

The Attraction zone is applied to main park features that attract large numbers of visitors, such as Bridalveil Fall and the Nature Center at Happy Isles. Due to the high number of visitors, this zone is managed with moderate tolerance for resource degradation in specified areas, not to exceed established standards. The visitor experience in this zone is highly structured, with well-marked and often paved trails to guide visitors, which contributes to the diversity of experiences specified in the recreation Outstandingly Remarkable Value. Visitors can expect high numbers of encounters with other visitors in these moderately to very busy areas.

To accommodate high visitor use, substantial facilities such as restrooms, parking lots, bus access and parking, and picnic tables can be provided at the entry point of the attraction area or another appropriate site. Facilities are concentrated within the attraction area to minimize the extent of development and impacts. As a result, many areas within an Attraction zone have a well-used trail, but minimal developed uses away from the entry “hub” or access point. Trails can be paved, fenced, and well-signed to reduce potential resource impacts. Visitor use in sensitive areas is formalized and concentrated to avoid resource damage.

Visitor Experience and Resource Protection

The Visitor Experience and Resource Protection (VERP) framework is a tool developed by the National Park Service to address user capacities and was adopted by the Merced River Plan to meet the requirements of the Wild and Scenic Rivers Act. The VERP framework protects both park resources and visitor experience from impacts associated with visitor use, and helps managers address visitor use issues. The VERP framework is an ongoing, iterative process of determining desired conditions (including desired cultural resource conditions, desired natural resource conditions, and desired visitor experiences), selecting and monitoring indicators and standards that reflect these desired conditions, and taking management action when the desired conditions are not being realized.

Yosemite National Park began development of the parkwide VERP framework in 1998 and continues to develop desired conditions, indicators, standards, and monitoring protocols. The VERP framework outlined in the Merced Wild and Scenic River Comprehensive Management Plan will be implemented by 2005. In the interim, Yosemite National Park will implement existing management activities and direction contained in the Merced Wild and Scenic River Comprehensive Management Plan (e.g., Wild and Scenic Rivers Act Section 7 determination, River Protection Overlay, management zoning prescriptions) to address user capacity, protection and enhancement of Outstandingly Remarkable Values, and management of park resources, visitor use, and facilities. In addition, the National Park Service will initiate increased resource monitoring to ensure that conditions do not deteriorate. Appropriate management actions, consistent with existing management activities, will be implemented to prevent further degradation of resources.

Methodology

This assessment is based on the management elements developed in the Merced Wild and Scenic River Comprehensive Management Plan. The Merced Wild and Scenic River segment in which the Happy Isles Gauging Station Bridge Removal Project would be implemented is Segment 2, Yosemite Valley. For the purposes of this analysis of potential effects on Outstandingly Remarkable Values, the proposed action is compared to the No Action Alternative (see Chapter II, Alternatives). The focus of the analysis is on long-term effects (e.g., effects that would last ten years or more or would be permanent). Short-term effects are not addressed in this analysis unless they are of sufficient magnitude (having a substantial, highly noticeable influence) to warrant consideration.

The proposed action has been assessed with regard to (1) protection and enhancement of Outstandingly Remarkable Values; (2) compatibility with classifications; (3) consistency with the River Protection Overlay; and (4) consistency with management zoning. This Wild and Scenic Rivers Act analysis has been triggered because the proposed project is within the Wild and Scenic River boundaries. The Wild and Scenic Rivers Act Section 7 determination process for the Happy Isles Gauging Station Bridge Removal Project proposed action is included in Appendix C.

Protection and Enhancement of Outstandingly Remarkable Values

Pursuant to Section 10(a) of the Wild and Scenic Rivers Act, the Act shall be administered to protect and enhance Outstandingly Remarkable Values within the Wild and Scenic River corridor boundary. Uses that are consistent with this provision and that do not substantially interfere with public enjoyment and use of these values should not be limited (16 USC 1281[a]). Outstandingly Remarkable Values located outside the Wild and Scenic River corridor boundary must also be protected (NPS 2001a).

According to the Wild and Scenic Rivers Act, Outstandingly Remarkable Values must be protected and enhanced on a segment-wide basis. Analysis of Outstandingly Remarkable Values is thus focussed on segment-wide effects, rather than site-specific or localized effects. Exceptions to the segment-wide guideline include site-specific activities that could have substantial effects on Outstandingly Remarkable Values, such as degradation of habitat of a river-related special-status species (a biological Outstandingly Remarkable Value) that is endemic to that location. For the Happy Isles Gauging Station Bridge Removal Project, Outstandingly Remarkable Values are evaluated based on effects to such values within the Yosemite Valley segment of the Merced River.

In terms of evaluating potential effects to Outstandingly Remarkable Values, actions that could degrade Outstandingly Remarkable Values on a segment-wide basis include actions with effects that would be discernable throughout the majority of the river segment, or would be of sufficient magnitude to affect adjacent segments.

For the purposes of this analysis, the following assumptions for each Outstandingly Remarkable Value were made:

Scientific – The analysis considers whether the proposed action would effect the integrity of the Merced Wild and Scenic River as a scientific resource, or would degrade the river’s value for research.

      Scenic – The analysis considers the specific features that are listed in the scenic Outstandingly Remarkable Value for the Valley segment, and potential effects to views are analyzed from the perspective of a person situated on the riverbank or on the river.

      Geologic Processes/Conditions – The analysis gives primary consideration to designated processes, and evidence of those processes (e.g., U-shaped valley, hanging valleys, evidence of glaciation, etc.), that have been responsible for creating the river’s geologic landscape. Effects related to natural meandering of the Merced River are addressed in the hydrologic processes Outstandingly Remarkable Value.

      Recreation – The analysis considers whether opportunities to experience a spectrum of river-related recreational activities would be affected.

      Biological – The analysis focuses on effects to riparian areas, wetlands, low-elevation meadows, and other riverine areas that provide rich habitat for a diversity of river-related species.

      Cultural – The analysis considers effects to river-related cultural resources, including archeological sites, which provide evidence of thousands of years of human occupation, and continuing traditional use today. The analysis also considers effects on nationally significant historic resources, such as designed landscapes and developed areas, historic buildings, and circulation systems (trails, roads, and bridges) that provide visitor access to the sublime views of natural features that are culturally valuable.

      Hydrologic Processes – Consideration is primarily given to designated processes such as river meandering, world-renowned waterfalls, an active flood regime, oxbows, and fluvial processes. Effects to wetlands are addressed in the biological Outstandingly Remarkable Value.

It is possible for Outstandingly Remarkable Values to be in conflict with each other, or for an action to have beneficial impacts with regard to one Outstandingly Remarkable Value and adverse impacts with regard to other ORVs. The Merced Wild and Scenic River Comprehensive Management Plan recognizes this possibility, and states (page 32):

      Actions must protect all Outstandingly Remarkable Values, regardless of where they are located. When Outstandingly Remarkable Values lie within the boundary of the Wild and Scenic River, the value must be protected and enhanced. When values are in conflict with each other, the net effect to Outstandingly Remarkable Values must be beneficial.

The Wild and Scenic Rivers Act stipulates that agencies are given discretion to manage a river system with “varying degrees of intensity for its protection and development, based on the special attributes of the area.” For example, there may be conflicts between protecting cultural resources and hydrologic processes, as is the case with a historic bridge that constricts the flow of the river.

Compatibility with Classifications

The Happy Isles Gauging Station Bridge Removal Project was assessed for its compatibility with the Merced Wild and Scenic River recreational classification.

Consistency with the River Protection Overlay

The Happy Isles Gauging Station Bridge Removal Project was assessed for its consistency with the River Protection Overlay prescriptions.

Consistency with Management Zoning

The Happy Isles Gauging Station Bridge Removal Project was assessed for its consistency with the Merced River Plan management zoning and corresponding zoning prescriptions. The Happy Isles Gauging Station Bridge Removal Project is located in management zone 2C, Day Use and 2D, Attraction.

Wild and Scenic Rivers Act Section 7 Determination Process

Pursuant to the Wild and Scenic Rivers Act, the National Park Service must carry out a Section 7 determination on all proposed water resources projects. The Happy Isles Gauging Station Bridge Removal Project is located within the bed and banks of the Merced River and will affect the free-flowing condition of the river. Therefore, a water resources project subject to the Section 7 determination process has been completed. The Section 7 determination for the Happy Isles Gauging Station Bridge Removal Project appears in Appendix C. The Section 7 determination process applies only to the proposed action; as a result, the preferred alternative is the only alternative analyzed in the Section 7 determination.

Consistency with the Merced River Plan

Outstandingly Remarkable Values

The proposed action would remove Happy Isles Gauging Station Bridge using controlled demolition methods. Controlled demolition would avoid catastrophic collapse of the bridge, and the associated localized adverse effects on scientific, biological, cultural, and hydrologic processes Outstandingly Remarkable Values (see table V-1). Overall, the proposed action would have localized beneficial effects on the scenic, recreation, biological, and hydrologic processes Outstandingly Remarkable Values. Removal of the damaged Happy Isles Gauging Station Bridge would have localized adverse effects on this resource. The avoidance of damage to the historic Happy Isles Gauging Station and pool could have a beneficial effect on the scientific Outstandingly Remarkable Value on a segment-wide level. The effects of the proposed action on Outstandingly Remarkable Values are summarized below and discussed in further detail in table V-1. Generally, the effects of the proposed action largely would be localized, and limited to the immediate Happy Isles Gauging Station Bridge project area, thus having no effect on the scenic, recreation, biological, cultural, and hydrologic processes Outstandingly Remarkable Values on a segment-wide level.

The proposed action would avoid catastrophic collapse of the bridge, which could damage the historic Happy Isles Gauging Station (and pool), which is important for scientific research purposes on a segment-wide level in Yosemite Valley. The proposed action would retain the river-right abutment to protect the Happy Isles Gauging Station from damage. On a segment-wide basis, the proposed action could have a beneficial effect on the scientific Outstandingly Remarkable Value.

With respect to the scenic Outstandingly Remarkable Value, the proposed action would provide a river-viewing platform on top of the river-right abutment, which would provide opportunities from this location for views from the river and its banks of waterfalls, rock cliffs, and the scenic interface of river, rock, meadow, and forest. The proposed action would protect the scenic Outstandingly Remarkable Value on a localized level by providing a river-viewing platform. On a segment-wide level, however, the proposed action would have no effect on the scenic Outstandingly Remarkable Value.

With respect to the geologic processes/conditions, the proposed action would have no effect on this Outstandingly Remarkable Value since controlled demolition would not affect the classic U-shaped valley, hanging valleys, or evidence of glaciation.

The proposed action would provide a river-viewing platform on top of the river-right abutment, which would allow opportunities to experience a spectrum of river-related recreational activities. Provision of a river-viewing platform would negligibly enhance the recreation Outstandingly Remarkable Value on a localized level. Although the proposed action would have localized beneficial effects, on a segment-wide level the proposed action would have no effect on the recreation Outstandingly Remarkable Value.

With respect to the biological Outstandingly Remarkable Value, the proposed action would involve minor regrading and revegetation of the river banks in the immediate vicinity of the Happy Isles Gauging Station Bridge, which would have site-specific, long-term, beneficial effects on bank and vegetation integrity. Catastrophic collapse of the bridge under the No Action Alternative could result in extensive erosion, as well as an uncontrolled release of bridge debris into the Merced River that could temporarily affect downstream riparian and aquatic resources and river-related special-status species. The proposed action would avoid these impacts to biological resources. Although the proposed action would locally enhance this Outstandingly Remarkable Value, on a segment-wide level the proposed action would have no effect on the biological Outstandingly Remarkable Value.

With respect to the cultural Outstandingly Remarkable Value, although the proposed action would result in the loss of a contributing element of the Yosemite Valley Cultural Landscape and a component of the Valley segment cultural Outstandingly Remarkable Value, the effects would be localized. The Valley segment cultural Outstandingly Remarkable Value includes circulation systems (trails, roads, and bridges) in their entirety. Although the loss of an individual component of such a circulation system is locally adverse, the loss of individual elements (particularly an element that is in danger of uncontrolled collapse and whose cultural integrity has been undermined due to its inability to function in the manner for which it was designed) would not degrade the cultural Outstandingly Remarkable Value on a segment-wide basis. In addition, controlled removal of the bridge would avoid potential damages from uncontrolled collapse of the bridge to other components of the cultural Outstandingly Remarkable Value, including Happy Isles Vehicle Bridge and the Happy Isles Gauging Station. The adverse effects of the proposed action would be limited to Happy Isles Gauging Station Bridge, and would have no effect on significant historic resources throughout the remainder of Yosemite Valley. Although the proposed action would have localized adverse effects, on a segment-wide level the proposed action would have no effect on the cultural Outstandingly Remarkable Value.

Controlled removal of Happy Isles Gauging Station Bridge would help restore the active flood regime and fluvial processes in the immediate vicinity of the bridge. In addition, the proposed action would avoid localized, catastrophic adverse effects to fluvial processes in the Happy Isles area associated with collapse of the Happy Isles Gauging Station Bridge under the No Action Alternative. Although the proposed action would locally enhance this Outstandingly Remarkable Value, on a segment-wide level the proposed action would have no effect on the hydrological Outstandingly Remarkable Value.

TABLE V-1:      Effects of the Proposed Action on Outstandingly Remarkable Values in the Yosemite Valley Segment of the Merced Wild and Scenic River Corridor

Outstandingly Remarkable Value	Effects of the Proposed Action
Scientific – The entire river corridor constitutes a highly significant scientific resource because the river watershed is largely within designated Wilderness in Yosemite National Park. Scientific Outstandingly Remarkable Values relate to the Merced River’s value for research. This Outstandingly Remarkable Value applies to all the Merced River segments.	The proposed action would remove the bridge using controlled demolition methods. Controlled demolition would avoid catastrophic collapse of the bridge, which could damage the historic Happy Isles Gauging Station and alter the gauging station pool. Maintenance of the gauging station and pool is important for scientific research purposes on a segment-wide level in Yosemite Valley. The gauging station has recorded hydrologic data since 1915, and has produced the longest continuous record of streamflow data available anywhere in California and is one of the 49 benchmark gauges in the United States. The gauging station also acts as an early warning system for floods in Yosemite Valley. The proposed action would retain the river-right abutment to protect the Happy Isles Gauging Station from damage and excessive scouring in high flow conditions. Segment-wide the proposed action would contribute to the protection of the scientific Outstandingly Remarkable Value. The proposed action could have a beneficial effect on the scientific Outstandingly Remarkable Value on a segment-wide basis.
Scenic – This segment provides magnificent views from the river and its banks of waterfalls (Nevada, Vernal, Illilouette, Yosemite, Sentinel, Ribbon, Bridalveil, and Silver Strand), rock cliffs (Half Dome, North Dome/Washington Column, Glacier Point, Yosemite Point/Lost Arrow Spire, Sentinel Rock, Three Brothers, Cathedral Rock, and El Capitan), and meadows (Stoneman, Ahwahnee, Cook’s, Sentinel, Leidig, El Capitan, and Bridalveil). There is a scenic interface of river, rock, meadow, and forest throughout the segment.	The proposed action would provide a river-viewing platform on top of the river-right abutment, which would provide opportunities from this location for views from the river and its banks of waterfalls, rock cliffs, and the scenic interface of river, rock, meadow, and forest. As compared to the No Action Alternative, there are no such viewing opportunities from this location. The proposed action would protect the scenic Outstandingly Remarkable Value on a localized level by providing a river-viewing platform on the river-right abutment. On a segment-wide level, however, the proposed action would contribute only negligibly to the enhancement of the scenic Outstandingly Remarkable Value. Therefore, the proposed action would have no effect on the scenic Outstandingly Remarkable Value on a segment-wide level.
Geologic Processes/Conditions – This segment contains a classic, glaciated, U-shaped valley, providing important examples of a mature meandering river; hanging valleys such as Yosemite and Bridalveil Creeks; and evidence of glaciation (e.g., moraines below El Capitan and Bridalveil Meadows).	The proposed action would have no effect on the geologic processes/conditions Outstandingly Remarkable Value. The controlled demolition of the Happy Isles Gauging Station Bridge would not affect the classic U-shaped valley, hanging valleys, or evidence of glaciation.
Recreation – This segment offers opportunities to experience a spectrum of river-related recreational activities, from nature study and sightseeing to hiking. Yosemite Valley is one of the premier outdoor recreation areas in the world.	The proposed action would provide a river-viewing platform on top of the river-right abutment, which would allow opportunities to experience a spectrum of river-related recreational activities, including nature study, sightseeing, photography, and enjoying solitude and natural sounds along the river over the long term.
Recreation (cont.)	Provision of a river-viewing platform would negligibly enhance the recreation Outstandingly Remarkable Value on a localized level. The effects of the proposed action would be limited to the immediate vicinity of the Happy Isles Gauging Station Bridge, and would have no effect on the spectrum of river-related recreational activities throughout the remainder of Yosemite Valley. Although the proposed action would have localized beneficial effects, on a segment-wide level the proposed action would have no effect on the recreation Outstandingly Remarkable Value.
Biological – Riparian areas and low-elevation meadows are the most productive communities in Yosemite Valley. The high-quality, vast riparian, wetland, and other riverine areas provide rich habitat for a diversity of river-related species, including special-status species, neotropical migrant songbirds, and numerous bat species.	The proposed action would involve minor regrading and revegetation of the river banks in the immediate vicinity of the Happy Isles Gauging Station Bridge, which would have site-specific, long-term, beneficial effects on bank and vegetation integrity. The proposed action also would somewhat improve riparian, wetland, and other riverine areas that provide rich habitat for a diversity of river-related species, including special status species. Catastrophic collapse of the bridge under the No Action Alternative could result in extensive erosion, as well as an uncontrolled release of bridge debris into the Merced River that could temporarily affect downstream riparian and aquatic resources and river-related special-status species. The proposed action would avoid these impacts to biological resources. The effects of the proposed action would be largely limited to the Happy Isles Gauging Station Bridge area, and would have no effects on river-related biological resources throughout the remainder of Yosemite Valley. Although the proposed action would locally enhance this Outstandingly Remarkable Value, on a segment-wide level the proposed action would have no effect on the biological Outstandingly Remarkable Value.
Cultural – This segment contains evidence of thousands of years of human occupation, reflected in the large number of archeological sites and continuing traditional use today. Nationally significant historic resources are found here, such as designed landscapes and developed areas, historic buildings, and circulation systems (trails, roads, and bridges) that provide visitor access to the sublime views of natural features that are culturally valuable.	Happy Isles Gauging Station Bridge is a component of the Valley segment cultural Outstandingly Remarkable Value. As part of the National Historic Preservation Act Section 106 documentation of the Yosemite Valley Cultural Landscape, Happy Isles Gauging Station Bridge is listed as a contributing resource related to Yosemite Valley’s circulation system. Happy Isles Gauging Station Bridge has sustained extensive damage in recent years, the bridge was damaged by felled trees during the massive rockfall and related windblast in the Happy Isles area in July 1996, and was severely damaged in a major flood in January 1997. Subsequent to the flood, Happy Isles
Cultural (cont.)	Gauging Station Bridge was deemed unsafe by representatives of the Federal Highway Administration. The National Park Service closed the bridge for safety reasons in July 1997. The cultural integrity of the Happy Isles Gauging Station Bridge has been undermined due to its inability to function in the manner for which it was designed. Continued deterioration of the bridge would likely result in its uncontrolled collapse. Since the bridge is failing, controlled removal under the proposed action would be beneficial for other components of the Yosemite Valley Cultural Landscape, such as Happy Isles Vehicle Bridge and Happy Isles Gauging Station, both of which could be damaged should the Happy Isles Gauging Station Bridge catastrophically collapse. The proposed action would be undertaken by the National Park Service in accordance with stipulations in the park’s 1999 Programmatic Agreement. Although the controlled removal of the Happy Isles Gauging Station Bridge would result in the loss of a contributing element of the Yosemite Valley Cultural Landscape and a component of the Valley segment cultural Outstandingly Remarkable Value, the effects would be localized. The Valley segment cultural Outstandingly Remarkable Value includes circulation systems (trails, roads, and bridges) in their entirety. Although the loss of an individual component of such a circulation system is locally adverse, the loss of individual elements (particularly an element that is in danger of uncontrolled collapse and whose cultural integrity has been undermined due to its inability to function in the manner for which it was designed) would not degrade the cultural Outstandingly Remarkable Value on a segment-wide basis. In addition, controlled removal of the bridge would avoid potential damages to other components of the cultural Outstandingly Remarkable Value, including Happy Isles Vehicle Bridge and the Happy Isles Gauging Station. The adverse effects of the proposed action would be limited to Happy Isles Gauging Station Bridge, and would have no effect on significant historic resources throughout the remainder of Yosemite Valley. Although the proposed action would have localized adverse effects, on a segment-wide level the proposed action would have no effect on the cultural Outstandingly Remarkable Value.
Cultural (cont.)	Controlled removal of the Happy Isles Gauging Station Bridge could have an adverse impact to historic archeological resources due to ground-disturbing activities. The adverse effects of the proposed action would be limited to the immediate vicinity of the Happy Isles Gauging Station Bridge, and would have no effect on historic archeological resources throughout the remainder of Yosemite Valley. Although the proposed action would have localized adverse effects, on a segment-wide level the proposed action would have no effect on the cultural Outstandingly Remarkable Value. Ethnographic resources, including traditional use areas, would not be affected under the proposed action.
Hydrologic Processes – This segment is characterized by a meandering river, world-renowned waterfalls, an active flood regime, oxbows, unique wetlands, and fluvial processes.	Controlled removal of Happy Isles Gauging Station Bridge would help restore the active flood regime and fluvial processes in the immediate vicinity of the bridge. The removal of the Happy Isles Gauging Station Bridge would eliminate constriction of river flow and improve the local, natural hydrologic regime. The proposed action would have a localized, beneficial effect on the flood regime and fluvial processes. In addition, the proposed action would avoid localized, catastrophic adverse effects to fluvial processes in the Happy Isles area associated with collapse of the Happy Isles Gauging Station Bridge under the No Action Alternative. Controlled removal of the bridge would avoid potential bank erosion and localized flooding associated with catastrophic bridge collapse. The avoidance of these adverse effects would have a localized, beneficial effect on fluvial processes. The effects of the proposed action would be largely limited to the Happy Isles Gauging Station Bridge area, and would have no effects on fluvial processes or the flood regime throughout the remainder of Yosemite Valley. Although the proposed action would locally enhance this Outstandingly Remarkable Value, on a segment-wide level the proposed action would have no effect on the hydrological Outstandingly Remarkable Value.