Wetland Statement of FindingsPurpose of this Statement of FindingsThe purpose of this Wetland Statement of Findings is to review the East Yosemite Valley Utilities Improvement Plan in sufficient detail to:
§ Avoid, to the extent possible, the short-and long-term adverse impacts associated with the destruction or modification of wetlands and to avoid direct or indirect support of new construction in wetlands wherever there is a practicable alternative § Describe the effects on wetland values associated with the Selected Alternative § Provide a thorough description and evaluation of mitigation measures developed to achieve compliance with Executive Order 11990 (Protection of Wetlands) and National Park Service Director’s Order 77-1 and Procedural Manual 77-1: Wetland Protection § Ensure “no net loss” of wetland functions or values Affected WetlandsWetland ExtentWetlands[1] and deepwater habitats within the project area include the riverine habitat of the Merced River and numerous areas of palustrine forest, palustrine scrub shrub, and palustrine emergent within the Merced River corridor. A total of approximately twenty-six acres of riverine and palustrine wetland habitat occur within the project area. Wetland and aquatic habitats that may be affected are predominately associated with the Merced River corridor and several creeks that cross through the area. Wetland CharacteristicsSpecific wetland classes identified within the project area are limited to riverine (rivers, creeks, and streams) and palustrine (shallow ponds, marshes, swamps, and sloughs). Using the Cowardin classification, specific wetland and deepwater classes within the project area include:
§ Palustrine emergent – 18.86 acres of herbaceous (e.g., sedge, rush, grass, etc.) habitat within the Merced River corridor subject to various runoff and flooding regimes § Palustrine forest – 1.84 acres of riparian forest habitat within the Merced River corridor subject to various runoff and flooding regimes § Palustrine scrub shrub – 0.40 acres of riparian scrub (e.g., willow) habitat within the Merced River corridor subject to various runoff and flooding regimes § Riverine habitats – 4.90 acres of active channels of the Merced River, its tributaries, and other intermittent streams in the project area The size, connectivity, and integrity of wetlands in the project area, particularly palustrine forest, palustrine scrub shrub, and riverine habitat, have been directly compromised by development and visitor activities. A description of the specific wetland and deepwater classes within the project area follows.
Emergent wetlands are the most extensive Cowardin class in the project vicinity. They occupy large expanses of land comprising four different meadow communities: Carex senta wet meadow, grass/sedge meadow, mixed meadow, and Indian hemp meadow. These wetlands are characterized by a relatively dense layer of herbaceous vegetation that tends to be dominated either by obligate sedges or by a mixture of hydrophytic grasses, sedges, and forbs. The Carex senta wet meadow and grass/sedge meadow communities are the most common, occupying extensive areas on low, intermediate, and high stream terraces throughout the project vicinity. Carex senta wet meadow contains mostly pure stands of rough sedge and creeping wild-rye with woolly sedge and cow parsnip as associates. Grass/sedge meadow emergent wetlands typically have a continuous coverage of slender-beak sedge and grasses such as black bentgrass and creeping wild-rye, with blue wild-rye occurring at high points. Indian hemp communities are associated with low and intermediate terraces adjacent to intermittent streambeds. Indian hemp meadows contain almost pure stands of Indian hemp, with slender-beak sedge, black bentgrass, and grass-leaved goldenrod as associate species. The mixed meadow is the least extensive meadow community in the project vicinity, typically found on high stream terraces, between roads, and adjacent to lower lying meadow communities. Mixed meadows tend to be dominated by nonnative species such as black bentgrass and field mint with natives including cow parsnip and Carex senta occurring as associates. The emergent wetlands in the project vicinity generally appear to be primarily groundwater-driven systems; some areas, particularly those that exist within swales and topographic depressions and those adjacent to the Merced River probably also receive substantial surface water inputs.
Two forested wetland/riparian communities were found in the project area: oxbow and cutoff channel riparian forest and white alder riparian forest. Both forested wetland communities are characterized by an overstory of hydrophytic trees such as white alder and black cottonwood, and may or may not have an understory of hydrophytic grasses, forbs, sedges, and various shrubs. The oxbow and cutoff channel riparian forest community occurs in and adjacent to the oxbow channel located west of Camp 6 and east of Sentinel Drive and is the most extensive forested wetland community in the project vicinity. The oxbow and cutoff channel riparian community is dominated by white alder, a shrub understory of western azalea and Himalayan blackberry, and an herbaceous understory of rough sedge, small-fruited bulrush, creeping wild-rye, common horsetail, and field mint. The white alder riparian forest community is less extensive and occurs on low and intermediate floodplains and banks adjacent to the Merced River. The white alder riparian forest community along the Merced River is dominated by white alder with black cottonwood as an associate. Most white alder riparian forest communities in the project area contain sparse understories with shrub layers of shining willow and incense cedar saplings and herbaceous layers containing soft rush, sedges, and creeping wild-rye. All forested wetlands in the project vicinity occur in and adjacent to the oxbow located west of Camp 6 and on the banks and low floodplains of the Merced River and Yosemite Creek. Accordingly, all the forested wetlands in the project vicinity are subject to flooding and/or shallow groundwater conditions during the wet season. Because they occupy low-lying landscape positions, they probably also receive substantial surface runoff and subsurface interflow from the surrounding landscape.
The project vicinity contains only one small scrub-shrub wetland, located in a shallow topographic depression near Housekeeping Camp. The blackberry scrub-shrub wetland is dominated by Himalayan blackberry, big-leaf maple, and nimblewell, with incense cedar, black cottonwood, Douglas' wormwood, slender-beak sedge, and California laurel as associate species. The scrub-shrub wetland is bordered by mixed conifer forest and intermittent streambed habitat. Based on topography and landscape position, it is reasonable to assume that hyrologic inputs to the scrub-shrub wetland include both shallow groundwater and surface runoff.
The three classes of riverine habitat that occur in the project vicinity are Upper Perennial Unconsolidated Bottom, Upper Perennial Unconsolidated Shore, and Intermittent Streambed. All three classes are confined to the active channels of the Merced River, its tributaries, Yosemite Creek, and other intermittent streams in the project vicinity. Riverine Upper Perennial Unconsolidated Bottom habitats (unconsolidated bottom) are characterized by the high gradient and velocity of water in the channel. In addition, they must have at least 25% cover of particles smaller than stones; vegetative cover less than 30%; and a water regime that is permanently flooded, intermittently exposed, or semipermanently flooded. The Merced River and Yosemite Creek contain the only unconsolidated bottom habitat in the project area. Riverine Upper Perennial Unconsolidated Shore (unconsolidated shore) habitats are characterized by the high gradient and velocity of water in the channel. In addition, they must have unconsolidated substrates with less than 75% areal cover of stones, boulders, or bedrock; less than 30% areal cover of vegetation other than pioneering plants; and a water regime that is irregularly exposed, regularly flooded, irregularly flooded, temporarily flooded, intermittently flooded, saturated, or artificially flooded. Generally, these shores are exposed during low water periods. Unconsolidated shore habitat was mapped on the northern and southern banks of the Merced River near Housekeeping Camp. Riverine Intermittent Streambed (intermittent streambed) is characterized by the presence of flowing water for only part of the year; it may have pioneering annuals or perennials during periods of low flow. Water regimes are irregularly exposed, regularly flooded, irregularly flooded, seasonally flooded, temporarily flooded, or intermittently flooded. Intermittent streambed habitat in the project vicinity consists of a deep abandoned river channel located south of the Merced River; a few narrow, relatively incised stream channels that are partially contained within roadway culverts; and several very shallow, low gradient swales that appear to detain and transmit snowmelt short distances during spring and early summer. Wetland Functions and ValuesThe following discussion examines the wetland functions and values of each wetland type.
Palustrine Habitats
Biotic Functions. The relatively dense layer of herbaceous vegetation in the emergent wetlands and scrub-shrub wetlands provides a variety of benefits for many wildlife species. In particular, the meadow communities provide foraging habitat for raptors and perennial range habitat for deer to bed and forage. The scrub-shrub communities provide shelter for small animals and food for a wide variety of animals; for example, willow leaves and blackberries are browse for deer. The palustrine habitats also provide habitat for pollinators and invertebrates.
Hydrologic Functions. Because of their extent, palustrine habitats in the project vicinity could play an important role in flood attenuation and sediment retention. In addition, wetlands located below roads and other developed areas may serve to retain sediment and degrade nutrients before the runoff enters downstream systems.
Cultural Values. The palustrine habitats in the project vicinity area do not contain any known archeological sites. Apparent cultural values include the significant aesthetic values that meadow wetlands provide, particularly in contrast to the steep, rocky walls of the valley. Interpretive guides and the meadow clearings that allow majestic views of the park have brought appreciation and awareness of wetlands to the millions of park visitors that have visited the area for decades.
Research/Scientific Values. The palustrine habitats, particularly emergent wetlands, provide rich opportunities for scientific research. Climate change and Native American vegetation management practices have caused changes in plant communities in the meadows. Such changes may be reflected in the floodplain sediments through charcoal debris and the pollen record, which may be amenable to scientific study. The meadows may also provide opportunities for studies on the effectiveness of meadow restoration techniques.
Economic Values. For the reasons listed above, the palustrine habitats could provide significant economic value for flood protection, fisheries, and tourism.
Riverine Habitats
Biotic Functions. The Merced River provides a year-round water source for wildlife and habitat for fish and aquatic invertebrates. The intermittent channels provide a seasonal water source for wildlife and invertebrates. Because the unconsolidated shore habitats lack vegetation and usually lack water, they may not provide significant habitat or food sources for wildlife.
Hydrologic Functions. Hydrologic functions of the Merced River are flood attenuation, streamflow maintenance, water supply, erosion control, sediment retention, water purification, and detrital export (including large woody debris) to downstream systems. Additionally, because of the coarse texture of the sediments that make up the Merced River channel, riverine habitats along the Merced River could offer some degree of groundwater recharge function. The intermittent channels are periodic water sources and therefore provide less function; however, they nevertheless contribute to streamflow maintenance, water supply, erosion control, sediment retention, water purification, and detrital export to downstream systems.
Cultural Values. Because Native Americans are known to have focused some activities along streams, riverine habitats may provide archeological value. Perennial channels also provide an aesthetic value. Visitors to the park enjoy the Merced River and engage in activities such as swimming, boating, fishing, and photography. The seasonal water flow and seasonal lack of vegetation in the intermittent channels limit the aesthetic value of these habitats.
Research/Scientific Values. The riverine habitats may provide opportunities for research in groundwater-vegetation relationships and in the effectiveness of riparian habitat restoration techniques.
Economic Values. For the reasons listed above, the riverine habitats could provide significant economic value for flood protection, fisheries, and tourism. Existing Structures in WetlandsYosemite Valley utilities are currently dispersed throughout the Valley, including extensive utility infrastructure within wetland areas. Water, wastewater and electric lines and other utility infrastructure are located throughout Cook’s Meadow, Ahwahnee Meadow, Stoneman Meadow, and the former Lower and Upper River Campgrounds that are currently identified for ecological restoration. Environmental Consequences of the Selected Alternative on WetlandsAnalysisThere would be no permanent reduction in the size of wetland and aquatic habitats related to implementation of the Selected Alternative. Wetland habitats that may be temporarily affected are predominately associated with the Merced River corridor, as well as several creeks that cross through the area. Figure 4-1 illustrates the wetland and aquatic habitats found within the project vicinity. Impacts associated with Alternative 2 are summarized in table 4-1. The majority of the areas that would be affected are within existing corridors that have been previously disturbed and developed, with the exception of the Merced River Crossing Utility Corridor. Construction impacts to wetland and aquatic habitats would be related to heavy equipment and construction activities and could include soil disturbance and compaction, dust, vegetation removal, root damage, erosion, and introduction and spread of non-native species. The addition of silt, the resuspension of sediment, or the introduction of pollutants (e.g., fuels, lubricants) related to construction activities could degrade the quality of native wetland and aquatic habitats in the immediate vicinity of construction activities.
Construction of the integrated utility corridors and repairs to existing utilities are expected to have localized, short-term, minor, adverse impacts to approximately six acres of wetland and aquatic habitat. Construction activities may also have localized, long-term, minor, adverse impacts on palustrine forest wetland habitat if the removal of trees are necessary within these areas. These short-term and long-term impacts can be mitigated using mitigation measures described below (e.g., Best Management Practices). Refer to the East Yosemite Valley Utilities Improvement Plan Environmental Assessment, Chapter II, Alternatives, for mitigation measures incorporated into the Selected Alternative. The construction of and continued presence of utility infrastructure within wetland and aquatic habitats could have long-term, minor, adverse effects on the hydrologic functions of these habitats by impeding the natural subsurface water flows within wetland areas and between the river and adjacent wetlands.
Removal activities would affect approximately twenty acres of wetland and aquatic habitat. Removal activities would result in localized, short-term, minor to moderate, adverse impacts; in the long-term however, the removals would have localized, minor, beneficial effects on the hydrologic functions of these habitats associated with the removal of obstructions to normal groundwater flows. In addition, removal of the utilities in these areas will facilitate future restoration activities proposed in the Yosemite Valley Plan.
In the long term, consolidation of utilities within Yosemite Valley into integrated utility corridors would remove utility infrastructure from the riverbanks and wet meadow areas identified for ecological restoration, reducing existing environmental impacts and eliminating the potential for future impacts in these areas from ongoing repairs, maintenance, and upgrades. Special-status species potentially found in the project area include Wawona riffle beetle, Mariposa sideband snail, Sierra pygmy grasshopper, western pond turtle, 10 species of birds, 10 species of bats, and 14 species of plants. Refer to pages IV-105 through IV-109 of the East Yosemite Valley Utilities Improvement Plan Environmental Assessment for a detailed discussion of the environmental consequences of the proposed project with regard to specific special-status species. Consolidation of utility infrastructure in major developed corridors, removal of utilities from environmentally sensitive areas,
Figure 4-1a: Wetland Delineation Area Boundary [PDF] Figure 4-1b: Wetland Delineation Area Boundary [PDF] Figure 4-1c: Wetland Delineation Area Boundary [PDF] Figure 4-1d: Wetland Delineation Area Boundary [PDF] Table 4-1. Wetland & Aquatic Habitats Potentially Affected by Alternative 2
a Includes repairs to existing wastewater lines as described in Alternative 1, as well as construction of proposed consolidated utility corridors.
Note: Acreage calculations are a conservative estimate based on a 100 foot corridor within wetlands and a 150 foot corridor at river crossings. The actual construction corridor will be significantly less. This approach was taken to allow for adjustments in alignment in order to avoid wetland and aquatic habitats to the greatest extent feasible.
and ecological restoration activities planned for these areas are expected to have local, long-term, minor, beneficial effects on special-status species, as well as on other wildlife. Therefore, in the long term, the biotic function of the wetland and aquatic habitats in the project area would be enhanced. With the application of mitigation measures, minor impacts on special-status species are expected during construction activities.
Impacts to the cultural and economic values of the wetland and aquatic habitats within the project area are not anticipated as a result of Alternative 2. The removal of utility infrastructure in wetland and aquatic habitats may however provide greater opportunities for studies on the effect of removal of utilities on subsurface water flows, thereby enhancing the research/scientific values of the wetland and aquatic habitats in the project area.
Under Alternative 1, the No Action Alternative, maintenance and operation of the existing utility infrastructure in Yosemite Valley would continue, potentially minimizing the benefit of ecological restoration activities if repairs needed in the future continue to have short term, localized, adverse impacts to wetland resources. Though actions proposed in Alternative 2 (preferred) would take place in wetlands, the actions would result in long-term beneficial impacts on wetlands. Cumulative ImpactsCumulative effects to wetland and aquatic resources are based on analysis of past, present, and reasonably foreseeable future actions in Yosemite Valley in combination with potential effects of this alternative. The projects identified below include those projects that have the potential to affect local wetland patterns.
Wetland and riparian systems of the Merced River corridor have been substantially altered by development and visitor activities. These changes have negatively influenced the size, form, and function of wetlands and the plants, wildlife, and aquatic species that inhabit them. Cumulative effects would be mixed, combining both adverse and beneficial effects. Cumulative beneficial effects on wetlands include wetland restoration, rehabilitation projects, and ecosystem management. Cumulative adverse effects would be related to increased facilities, regional growth, and visitor demand.
Reasonably foreseeable future actions within Yosemite Valley are considered to have an overall beneficial effect on wetlands. For example, the Merced Wild and Scenic River Comprehensive Management Plan protects river-related natural resources through the application of management elements, including the River Protection Overlay, management zoning, protection and enhancement of Outstandingly Remarkable Values, and implementation of a Visitor Experience Resource Protection framework.
Full implementation of the Yosemite Valley Plan would result in a net gain of 118 acres of wetlands in Yosemite Valley through actions such as restoration of Upper River and a portion of Lower Pines Campgrounds to natural conditions; removal of roads through Stoneman and Ahwahnee Meadows; and removal of other bridges (e.g., Sugar Pine and possibly Stoneman) affecting the natural flow of the Merced River. Alternative 1 could minimize these benefits since utilities would remain in the restoration areas and utility repairs needed in the future could continue to have short term, localized, adverse impacts to these resources. Farther downstream, removal of the Cascades Diversion Dam would also remove an unnatural constriction to the free flow of the Merced River, thereby enhancing natural river dynamics including wetlands and aquatic systems below Yosemite Valley. Some Yosemite Valley Plan projects, such as construction of a replacement footbridge at the Happy Isles area, construction of a vehicle bridge across Yosemite Creek near Yosemite Lodge, and expansion of some campgrounds in Yosemite Valley, have the potential to adversely affect local wetlands. These projects would be designed to ensure the long-term protection of wetlands consistent with the Merced River Plan, the Clean Water Act, and Executive Order 11990: Protection of Wetlands.
Cumulative actions would have a long-term, moderate, beneficial cumulative effect on wetlands within Yosemite Valley due to wetland restoration efforts. The local, short-term, minor, adverse effects from construction activities and ongoing maintenance and repairs would be offset by the beneficial effects of the cumulative projects. ConclusionsConsolidation of utility infrastructure in major developed corridors, removal of utilities from environmentally sensitive areas, and ecological restoration activities planned for these areas are expected to have local, long-term, moderate, beneficial effects on wetland resources. Past, present, and reasonably foreseeable future projects in combination with Alternative 2 would have a net long-term, moderate, beneficial effect on wetland patterns within the Merced River corridor. Alternatives ConsideredAlternatives considered in the East Yosemite Valley Utilities Improvement Plan Environmental Assessment (Chapter II, Alternatives) include the No Action Alternative, East Yosemite Valley Utilities Improvement Plan with Merced River Crossing at Housekeeping Camp, and East Yosemite Valley Utilities Improvement Plan with Merced River Crossing near Sentinel Bridge. Alternative 1: No ActionAlternative 1, the No Action Alternative, maintains the existing utility infrastructure in the Yosemite Valley, including necessary repairs and maintenance of the utility systems. It provides a baseline from which to compare the action alternatives, to evaluate the magnitude of proposed changes, and to measure the environmental effects of those changes.
Under the No Action Alternative, no management action would be taken to implement an East Yosemite Valley Utilities Improvement Plan. The existing dispersed utility lines would remain in place, including those utility lines located within meadow areas identified for environmental restoration and other environmentally and culturally sensitive areas. Utility corridors would not be established to consolidate multiple utilities into corridors designed to follow existing utility or transportation corridors or proposed transportation corridors and to minimize potential impacts on environmentally sensitive areas. Efficient utility services would not be provided to new facilities proposed under the Yosemite Valley Plan.
The No Action Alternative would include those utility infrastructure projects currently planned for the sanitary sewer collection system and required by the California Regional Water Quality Control Board to address recent wastewater releases. These projects are required to continue the current management and operation of the existing Yosemite Valley sanitary sewer system. Alternative 2: East Yosemite Valley Utilities Improvement Plan with a Merced River crossing near Housekeeping Camp (Preferred Alternative)Alternative 2 implements an East Yosemite Valley Utilities Improvement Plan with a Merced River utility crossing at Housekeeping Camp. Under Alternative 2, the National Park Service would develop consolidated utility corridors following existing utility lines or existing or proposed transportation corridors. This alternative would also reduce utility infrastructure within the Merced River and its floodplain and from areas identified for ecological restoration in the Yosemite Valley Plan. The East Yosemite Valley Utilities Improvement Plan would also ensure efficient utility service to new facilities proposed under the Yosemite Valley Plan.
Alternative 2 also includes sewer projects currently planned and required by the California Regional Water Quality Control Board to address recent wastewater releases. Those projects currently planned that could be eliminated with implementation of the East Yosemite Valley Utilities Improvement Plan have been removed from the analysis. Alternative 3: East Yosemite Valley Utilities Improvement Plan with Merced River Crossing near Sentinel BridgeAlternative 3 implements an East Yosemite Valley Utilities Improvement Plan with a Merced River utility crossing near Sentinel Bridge. Under Alternative 3, the National Park Service would develop consolidated utility corridors following existing utility lines or existing or proposed transportation corridors. This alternative would also reduce utility infrastructure within the Merced River and its floodplain and from areas identified for ecological restoration in the Yosemite Valley Plan. The East Yosemite Valley Utilities Improvement Plan would also ensure efficient utility service to new facilities proposed under the Yosemite Valley Plan.
Alternative 3 also includes sewer projects currently planned and required by the California Regional Water Quality Control Board to address recent wastewater releases. Those projects currently planned that could be eliminated with implementation of the East Yosemite Valley Utilities Improvement Plan have been removed from the analysis. Design or Modifications to Minimize Harm to WetlandsBest Management Practices and Resource-Specific Mitigation MeasuresBest Management Practices and resource-specific mitigation measures would be implemented, as appropriate, prior to, during, and/or after removal. Best Management Practices During Construction ActivitiesThe National Park Service (and its contractors) shall implement the following Best Management Practices, as appropriate, prior to, during, and/or after construction activities. Specific tasks would include, but are not limited to, the following:
§ Inspect the project to ensure that impacts stay within the parameters of the project and do not escalate beyond the scope of the environmental assessment, as well as to ensure that the project conforms to the U.S. Army Corps of Engineers, Central Valley Regional Water Quality Control Board Waiver of Waste Discharge Requirements and Water Quality Certification, and other applicable permits or project conditions. § Implement compliance monitoring to ensure the project remains within the parameters of NEPA and National Historic Preservation Act compliance documents, U.S. Army Corps of Engineers Section 404 permits, etc. Compliance monitoring would ensure adherence to mitigation measures and would include reporting protocols. § Implement natural resource protection measures. Standard measures include construction scheduling, biological monitoring, erosion and sediment control, use of fencing or other means to protect sensitive resources adjacent to the work area, and revegetation. The measures include specific monitoring by resource specialists as well as treatment and reporting procedures. § Confine work areas within the river channel, such as workpads to support construction equipment, to the smallest area necessary. § Steam-clean heavy equipment prior to its entry into the park to prevent importation of non-native plant species, and repair all petroleum leaks prior to work near the Merced River. Tighten hydraulic hoses and ensure they are in good condition. § To minimize the possibility of hazardous materials seeping into soil or water, check equipment frequently to identify and repair any leaks, as directed in the spill prevention and countermeasure plan. Standard measures include hazardous materials storage and handling procedures; spill containment, cleanup, and reporting procedures; and limitation of refueling and other hazardous activities to upland/nonsensitive sites. Provide an adequate hydrocarbon spill containment system (e.g., floatable absorption boom, absorption materials, etc.) on site, in case of unexpected spills in the project area. Ensure equipment allowed within the river channel is equipped with a hazardous spill containment kit. Ensure that personnel trained in the use of hazardous spill containment kits are on site at all times during construction activities. § Store all construction equipment within the delineated work limits. § Ensure an emergency notification program is in place. Standard measures include notification of utilities and emergency response units prior to construction activities. Identify locations of existing utilities prior to construction activity to prevent damage to utilities. The Underground Services Alert and National Park Service maintenance staff shall be informed 72 hours prior to any ground disturbance. Construction shall not proceed until the process of locating existing utilities is completed (wastewater, electric, and telephone lines). An emergency response plan shall be required of the contractor for measures that will be taken during all high-water events during construction activities, such as evacuation of personnel, equipment, and materials from the river, etc. § Avoid damage to natural surroundings in and around the work limits. Provide temporary barriers to protect existing trees, plants, and root zones, if necessary, as determined by vegetation management staff. Trees and other vegetation shall not be removed, injured, or destroyed without prior written approval. Ropes, cables, or fencing shall not be fastened to trees. All existing resource protection fencing (post and rope) shall be left in place and protected from heavy equipment. § Remove all tools, equipment, barricades, signs, surplus materials, and rubbish from the project work limits upon project completion. Repair any asphalt surfaces that are damaged due to work on the project to original condition. Remove all debris from the project site, including all visible concrete, timber, and metal pieces. Grade disturbed areas and rake them smooth to eliminate tire tracks and tripping hazards. § Locate, contain, and stabilize excavated and stored materials within upland staging areas and prevent re-entry into wetland or aquatic habitats. § Use silt fences, sedimentation basins, etc. in work areas to reduce erosion, surface scouring, and discharge to water bodies, as defined in the erosion control plan prepared for this project. § Delineate wetlands and apply protection measures during construction. Wetlands shall be delineated by qualified National Park Service staff or certified wetland specialists and clearly marked prior to work. Perform activities in a cautious manner to prevent damage caused by equipment, erosion, siltation, etc. Resource-Specific MeasuresHydrology, Floodplains, and Water Quality§ Prepare an erosion control plan specifying measures to prevent erosion/sedimentation problems during project construction. Include a map of the project site delineating where erosion control measures will be applied. Include the following minimum criteria, as listed in the Guidelines for Protection of Water Quality During Construction and Operation of Small Hydro Projects (CVRWQCB 1983): - Construction equipment shall not be operated in flowing water, except as may be necessary to construct crossings or barriers. - Where working areas are adjacent to or encroach on live streams, barriers shall be constructed that are adequate to prevent the discharge of turbid water in excess of specified limits. - Material from construction work shall not be deposited where it could be eroded and carried to the stream by surface runoff or high stream flows. - All permanent roads shall be surfaced with materials sufficient to maintain a stable road surface. - All disturbed soil and fill slopes shall be stabilized in an appropriate manner. - Surface drainage facilities shall be designed to transport runoff in a nonerosive manner. - Riparian vegetation shall be removed only when absolutely necessary. - There shall be no discharge of petroleum products, cement washings, or other construction materials. - Erosion control measures shall be in place prior to construction activities and in good repair by October 15 of each year. - Stream diversion structures shall be designed to preclude accumulation of sediment. If this is not feasible, an operation plan shall be developed to prevent adverse downstream effects from sediment discharges. § Erosion control measures shall be inspected daily during construction activities and monthly following construction activities, and repaired as required. § Waters shall be free of changes in turbidity that cause a nuisance or adversely affect beneficial uses. Increases in turbidity attributable to controllable water quality factors shall not exceed the following limits, as described in The Water Quality Control Plan for the Central Valley Regional Water Quality Control Board (CVRWQCB 1998). In determining compliance with the limits below, appropriate averaging periods may be applied, provided that beneficial uses will be fully protected: - Where natural turbidity is between 0 and 5 Nephelometric Turbidity Units (NTUs), increases shall not exceed 1 NTU. - Where natural turbidity is between 5 and 50 NTUs, increases shall not exceed 20%. - Where natural turbidity is between 50 and 100 NTUs, increases shall not exceed 10 NTUs. - Where natural turbidity is greater than 100 NTUs, increases shall not exceed 10%. § Implement stormwater management measures to reduce nonpoint-source pollution discharge. This could include measures such as oil/sediment containment or street sweeping. § Remove hazardous waste materials generated during implementation of the project from the project site immediately. § Dispose of volatile wastes and oils in approved containers for removal from the project site to avoid contamination of soils, drainages, and watercourses. Keep absorbent pads, booms, and other materials onsite during projects that use heavy equipment to contain oil, hydraulic fluid, solvents, and hazardous materials spills. § Salvage hydric soils and use them as fill in wetland excavations to the maximum extent possible. Minimize use of fill materials with high permeability in wetland areas to prevent development of unnatural groundwater conduits. § Incorporate trench plugs into new and abandoned utility corridors through wetland areas where required to prevent formation or continuation of groundwater conduits. Vegetation§ Implement a noxious weed abatement program. Standard measures include, as appropriate, the following elements: ensure that vehicles and equipment arrive onsite free of mud or seed-bearing material, certify all seeds and straw material as weed-free, identify areas of noxious weeds before construction activities, treat noxious weeds or noxious weed topsoil prior to work (e.g., topsoil segregation and removal), and revegetate with appropriate native species. § Cover exposed soil with a combination of locally acquired native duff and forest litter from adjacent riparian sites to provide immediate groundcover and facilitate natural revegetation. § Implement the planting prescriptions prepared for this project. § Develop and implement a monitoring plan to ensure successful revegetation, maintain plantings, and replace unsuccessful plantings. § Use native or seed-free mulch to minimize surface erosion and introduction of non-native plants. § Confine all construction operations to specified project work limits. Install temporary barriers to protect natural surroundings (including trees, plants, and root zones) from damage. Avoid fastening ropes, cables, or fences to trees. § As much as possible, removed plants and materials (cuttings) shall be salvaged and stored on site for revegetation following construction activities. Refer to the East Yosemite Valley Utilities Improvement Plan Environmental Assessment (Chapter II, Alternatives) for a complete list of Best Management Practices and resource-specific mitigation measures applicable to the Selected Alternative. The Selected Alternative has been designed to mitigate harmful effects to wetlands. The East Yosemite Valley Utilities Improvement Plan does not include any elements that would require preparation of a subsequent statement of findings. Site RestorationThe last phase of the project is site restoration. Following construction activities, disturbed areas will be graded and recontoured, as necessary, to revegetate with appropriate wetland, riparian, and upland plant species. Ground surface treatment will include grading to natural contours, topsoiling, seeding, and planting. Accepted erosion protection measures, including jute mesh and hydro mulch, may be used, if necessary, to prevent soil loss. The National Park Service will prepare a prescription for revegetating any disturbed areas, including riverbanks, to be included in the construction specifications. This prescription will comply with the Yosemite Vegetation Management Plan (NPS 1997a). Revegetation of disturbed sites will be conducted by park staff immediately following construction to reduce the potential for non-native plant invasion. All plant materials will be from genetic stock indigenous to Yosemite Valley, including trees, shrubs, and forbs obtained from the construction site by salvage methods or by propagating container plants from seed or cuttings. Following restoration efforts, the reclaimed sites will be monitored to determine if reclamation efforts are successful or if additional remedial actions are necessary. Remedial actions could include the installation of erosion control structures, reseeding, and/or replanting the area, and controlling non-native plant species. Proposed CompensationNo off-site compensation is required. The proposed action is designed to remove utility infrastructure from the riverbanks and wet meadow areas identified for ecological restoration, reducing existing environmental impacts and eliminating the potential for future impacts in these areas from ongoing repairs, maintenance, and upgrades. The removal of utility infrastructure from wetland and aquatic habitats would have localized, minor, beneficial effects on the hydrologic functions of these habitats associated with the removal of obstructions to normal groundwater flows. In addition, removal of utilities from environmentally sensitive areas are expected to have local, long-term, minor, beneficial effects on special-status species, as well as on other wildlife, thereby enhancing the biotic function of the wetland and aquatic habitats in the project area. Impacts to the cultural and economic values of the wetland and aquatic habitats within the project area are not anticipated as a result of Alternative 2. However, the removal of utility infrastructure in wetland and aquatic habitats may provide greater opportunities for studies on the effect of removal of utilities on subsurface water flows, thereby enhancing the research/scientific values of the wetland and aquatic habitats in the project area.
Although the Selected Alternative will have short-term minor adverse impacts on 5.88 acres of wetland habitat (most of which is presently disturbed), the Selected Alternative will remove utilities from 20.12 acres of wetland habitat. Therefore, the ratio of wetland restoration (through utility removal) to wetland impact will be 3.4 to 1. Figure 4-1 illustrates the location of utility corridor construction and utility removals in relation to wetland and aquatic habitats. JustificationNonwetland Alternatives to the Selected AlternativeEast Yosemite Valley Utilities Improvement Plan actions would occur within the Merced River corridor, and within riverine, palustrine forest, palustrine scrub shrub, and palustrine emergent habitat. The purpose of the East Yosemite Valley Utilities Improvement Plan is to consolidate utility infrastructure into integrated utility corridors and comply with the California Regional Water Quality Control Board Cleanup and Abatement Order. There are no alternatives to the Selected Alternative that could be located outside the floodplain or wetland and aquatic habitat of the Merced River corridor.
Alternative 2 was selected because it would attain the widest range of beneficial uses of the environment by reducing utility infrastructure in environmentally sensitive areas, such as river- and creekbeds, floodplains, and wet meadows. The reduced number of river and creek crossings would reduce risks to health and safety from utility failures in these areas. The proposed new utility corridors are sited to reduce undesirable and unintended consequences, namely, continued maintenance and repairs of utility facilities in environmentally sensitive areas. Alternative 1 would result in continued degradation of the environment and risk to health and safety due to the concentration of utility infrastructure in environmentally sensitive areas. Alternative 3 is similar to Alternative 2 and would result in a slightly smaller wetland impact, but would result in a longer utility corridor route that would affect more highly valued resources than Alternative 2, particularly cultural resources. New DevelopmentThe East Yosemite Valley Utilities Improvement Plan proposes the development of integrated utility corridors primarily in developed areas. One new corridor, the Merced River Crossing Utility Corridor, is proposed to be constructed through wetland areas in the Camp 6 area. The majority of work that will occur in wetlands is the removal of utility infrastructure in areas identified for ecological restoration. This should result in a net decrease in development in wetland areas. Existing DevelopmentYosemite Valley utilities are currently located throughout the Valley including through wetland areas and in areas identified for ecological restoration. The East Yosemite Valley Utilities Improvement Plan proposes removal or abandonment of utility infrastructure within areas identified for ecological restoration and in other wet meadow areas, such as Cook’s Meadow. This is expected to result in a net decrease in development in wetland areas. RedevelopmentThe East Yosemite Valley Utilities Improvement Plan proposes the development of integrated utility corridors primarily in developed areas. This includes use of existing and proposed roadways and trails, as well as existing utility corridors. Existing utility corridors being redeveloped as integrated utility corridors are described in more detail in Chapter II, Alternatives. ConclusionThe Selected Alternative would have a beneficial impact on the extent, function, and value of wetlands by consolidation of utility infrastructure in major developed corridors and removal of utilities from environmentally sensitive areas (including wetlands). The relocation and removal actions are expected to result in a net decrease in utility infrastructure within wetland areas. In addition, removal actions would facilitate future restoration activities proposed in the Yosemite Valley Plan for these areas. The National Park Service has determined that there is no practicable alternative that could be located outside the floodplain or wetland habitat. Mitigation and compliance with regulations and policies to prevent impacts to water quality, wetland function and values, and loss of property or human life would be strictly adhered to during and after construction.
Individual permits with other federal and cooperating state and local agencies will be obtained or updated as appropriate prior to construction and removal activities. No permanent adverse impacts to wetlands would occur from implementation of the Selected Alternative. As summarized in Table 4-1, the Selected Alternative will have minor temporary adverse impacts on 5.88 acres of wetland habitat, but will improve/restore conditions on 20.12 acres of wetland habitat by removal of utilities (a 3.4 to 1 compensation ratio). Therefore, the National Park Service finds the Selected Alternative to be consistent with NPS Director’s Order 77-1, including the no net loss of wetlands policy.
[1] Consistent with NPS Procedural Manual 77-1: Wetland Protection, wetlands herein are described using the Cowardin classification system.
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