Append

Mitigation Mea

Appendix E 


Mitigation Measures Applicable to 


All Action Alternatives 


The National Park Service places a strong emphasis on avoidance, minimization, and mitigation of 

impacts. To help ensure that field activities protect natural, cultural, and social resources and the 

quality of the visitor experience, mitigation measures have been developed. Project-specific 

mitigation measures and management practices were developed for the Mariposa Grove of Giant 

Sequoias during project implementation. Many of these measures and practices are based on the 

successful giant sequoia ecological restoration project in Giant Forest, Sequoia National Park (USDI 

1995). Additional mitigation measures are identified as part of the draft Statement of Findings for 

Protection of Wetlands; these measures are described in Appendix F. 

The following section discusses mitigation measures that would occur prior to, during, and after 

construction of specific management actions. 

Topic Mitigation Measure Responsibility 

Common to All Resources 

Federal and State 

Permit 

Requirements 

The NPS will apply for and comply with all federal and state 

permits required for construction-related activities, including 

Clean Water Act Section 401 and 404. 

Yosemite National 

Park, Project 

Manager 

Emergency Develop an emergency notification plan that complies with park, Yosemite National 

Notification federal, and state requirements and allows contractors to 

properly notify park, federal, and/or state personnel in the event 

of an emergency during construction activities. This plan will 

address notification requirements related to fire, personnel, 

and/or visitor injury, releases of spilled material, evacuation 

processes, etc. The emergency notification plan will be submitted 

to the park for review/approval prior to commencement of 

construction activities. 

Park, Project 

Manager 

Notify utilities prior to construction activities. Identify locations 

of existing utilities prior to removal activity to prevent damage 

to utilities. The Underground Services Alert and NPS 

maintenance staff will be informed 72 hours prior to any ground 

disturbance. Construction-related activities will not proceed until 

the process of locating existing utilities is completed (water, 

wastewater, electric, communications, and telephone lines). An 

emergency response plan will be required of the contractor. 

Yosemite National 

Park, Project 

Manager 

New Construction 

and Modification 

Design 

Guidance for the design of new construction and modifications 

will be provided by A Sense of Place: Design Guidelines for 

Yosemite National Park (NPS 2012). 

Equipment and 

Construction 

All equipment used in the Grove should have a low compaction 

factor and may include excavator, dozer, backhoe, loader, skid 

steer, and/or dump truck. 

Prior to entry into the park, steam-clean heavy equipment to Yosemite National 

prevent importation of non-native plant species, tighten Park, Project 

hydraulic fittings, ensure hydraulic hoses are in good condition Manager; Contractor 

and replace if damaged, and repair all petroleum leaks. 

E-1 
Appendix E: Mitigation Measures Applicable to All Action Alternatives 

Topic Mitigation Measure Responsibility 

Ensure that construction or restoration actions do not impact the 

surrounding area, specifically giant sequoia, wetland, or riparian 

ecosystems or any primary ecological processes, by limiting size 

and development of staging and construction areas, and 

confining them to developed or disturbed areas to the extent 

practicable. Confine work areas within creek channels to the 

smallest area necessary. Store all construction equipment within 

the delineated work limits. 

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 with all applicable permits or project 

conditions. 

Yosemite National 

Park, Project 

Manager; Contractor 

Implement compliance monitoring to ensure that the project 

remains within the parameters of National Environmental Policy 

Act (NEPA) and National Historic Preservation Act (NHPA) 

compliance documents. 

Yosemite National 

Park, Project 

Manager; Contractor 

Provide a project orientation for all construction workers to 

increase their understanding and sensitivity to the challenges of 

the special environment in which they will be working. 

Yosemite National 

Park, Project 

Manager 

If deemed necessary, demolition/construction work on weekends 

or federal government holidays may be authorized, with prior 

written approval of the Superintendent. 

Yosemite National 

Park, Project 

Manager 

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. 

Yosemite National 

Park, Project 

Manager; Contractor 

The park shall develop a Communications Strategy Plan to alert 

necessary park and Concessioner employees, residents, and 

visitors to pertinent elements of the construction work schedule. 

Yosemite National 

Park, Project 

Manager 

Verify utility locations by contacting the Underground Services 

Alert prior to the start of construction. 

Yosemite National 

Park, Project 

Manager, Contractor 

Hazardous An Oil and Hazardous Materials Spill Prevention, Control, and Contractor 

Materials Countermeasure Plan shall be prepared by the Construction 

Contractor for the project to address hazardous materials 

storage, spill prevention, and response. The Plan shall be 

submitted for park review and approval prior to construction. 

Store and use all hazardous materials in compliance with federal 

regulations. All applicable Materials Safety Data Sheets will be 

kept on site for inspection. 

Contractor 

Hazardous or flammable chemicals shall be prohibited from 

storage in the staging area, except for those substances 

identified in the Oil and Hazardous Materials Spill Prevention, 

Control, and Countermeasure Plan. Hazardous waste materials 

shall be immediately removed from project site in approved 

containers. 

Contractor 

Comply with all applicable regulations and policies during the 

removal and remediation of asbestos, lead paint, and 

polychlorinated biphenyls. 

Contractor 

E-2
 
Appendix E: Mitigation Measures Applicable to All Action Alternatives 

Topic Mitigation Measure Responsibility 

Spill Prevention/ Develop and implement a comprehensive spill prevention/ Contractor 

Response response plan that complies with federal and state regulations 

and addresses all aspects of spill prevention, notification, 

emergency spill response strategies for spills occurring on land 

and water, reporting requirements, monitoring requirements, 

personnel responsibilities, response equipment type and 

location, and drills and training requirements. The spill 

prevention/response plan will be submitted to the park for 

review/approval prior to commencement of construction 

activities. 

To minimize the possibility of hazardous materials seeping into 

Contractor soil or water, check equipment frequently to identify 

and repair any leaks. 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., 

absorption materials, etc.) on site, in case of unexpected spills in 

the project area. Ensure equipment is equipped with a 

hazardous spill containment kit at all times. Ensure that 

personnel are trained in the use of hazardous spill containment 

kits. 

Contractor 

Waste 

Management 

Require construction personnel to adhere to park regulations 

concerning food storage and refuse management. 

Yosemite National 

Park, Project 

Manager, Contractor 

Properly secure trash during the workday and remove all trash 

from site at the end of each workday. 

Yosemite National 

Park, Project 

Manager, Contractor 

Specific to Natural Resources 

Air Quality and 

Dust Abatement 

The Yosemite National Park and/or a contractor (as appropriate) 

shall implement and comply with a dust abatement program 

during construction. Measures include, but are not limited to, 

the following: 

 Water or apply soil stabilizers to disturbed areas; 

 Cover and/or seal truck beds and stockpiles to minimize 

blowing dust or loss of debris; 

 Limit truck and related construction equipment speeds in 

active construction areas to a maximum of 15 miles per hour 

and strictly adhering to park regulations and posted speed 

limits in other areas while inside park boundaries; 

 Minimize vegetation clearing; 

 Re-vegetate post construction. 

Yosemite National 

Park, Contractor 

The Yosemite National Park and/or a contractor (as appropriate) 

shall implement equipment exhaust controls during construction. 

Measures include, but are not limited to, the following: 

 Idling times shall be minimized either by shutting equipment 

off when not in use or reducing the maximum idling time to 

two minutes. Clear signage shall be provided for 

construction workers at all access points; 

 Require that all construction equipment, diesel trucks, and 

generators be equipped with Best Available Control 

Technology for emission reductions of NOx and PM; 

Yosemite National 

Park, Contractor 

E-3
 
Appendix E: Mitigation Measures Applicable to All Action Alternatives 

Topic Mitigation Measure Responsibility 

 Require all contractors use equipment that meets CARB’s 

most recent certification standard for off-road heavy duty 

diesel engines; 

 Require all equipment operations to occur during daytime 

hours to minimize effects of local inversions. 

Maintain adequate dust suppression equipment and using clean 

water to control excess airborne particulates at staging areas, 

active construction zones, and unpaved roads leading to/from 

active construction areas. 

Contractor 

Hydrology, Water 

Quality, and 

Wetlands 

An erosion control plan would be prepared specifying measures 

to prevent erosion/ sedimentation problems during project 

construction. The plan would include a map of the project site 

delineating where erosion control measures will be applied. The 

following minimum criteria, adapted from the Guidelines for 

Protection of Water Quality During Construction and Operation 

of Small Hydro Projects (CVRWQCB 1983), would be met: 

 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 disturbed soil and fill slopes shall be stabilized in an 

appropriate manner. 

 Surface drainage facilities shall be designed to transport 

runoff in a non-erosive manner. 

 Wastewater contaminated with by-products from 

construction activities shall be contained in a holding or 

settling tank to prevent contaminated material from 

entering watercourses or wetlands. 

 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: 

o Where natural turbidity is between 0 and 5 

nephelometric turbidity units (NTUs), increases shall not 

exceed 1 NTU. 

o Where natural turbidity is between 5 and 50 NTUs, 

increases shall not exceed 20% of the natural turbidity. 

o Where natural turbidity is between 50 and 100 NTUs, 

increases shall not exceed 10 NTUs. 

o 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. 

E-4
 
Appendix E: Mitigation Measures Applicable to All Action Alternatives 

Topic Mitigation Measure Responsibility 

 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. 

 Final design and installation of site drainage improvements 

will be closely coordinated with the park’s Resources 

Management and Science Division. 

 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. 

Develop and implement a comprehensive stormwater pollution 

prevention plan for construction activities that complies with 

federal and state regulations and addresses all aspects of 

stormwater pollution prevention. The plan will be submitted to 

the park for approval prior to construction activities. The plan 

will include measures such as: 

 Take measures to control erosion, sedimentation, and 

compaction, and thereby reduce water pollution and adverse 

water quality effects. Use silt fences, sedimentation basins, 

etc., in construction areas to reduce erosion, surface 

scouring, and discharge to water bodies. 

 To the extent possible, schedule the use of mechanical 

equipment during periods of low precipitation to reduce risk 

of accidental hydrocarbon leaks or spills. When mechanical 

equipment is necessary outside of low precipitation periods, 

use NPS-approved methods to protect soil and water from 

contaminants. 

 Dispose of volatile wastes and oils in approved containers for 

removal from construction sites to avoid contamination of 

soils, and drainages. Inspect equipment for hydraulic and oil 

leaks prior to use on construction sites, and implement 

inspection schedules to prevent contamination of soil and 

water. Keep absorbent pads, booms, and other materials on 

site during projects that use heavy equipment to contain oil, 

hydraulic fluid, solvents, and hazardous material spills. 

Contractor 

If special-status plant species are identified within the 

construction disturbance zone, in particular within restoration 

and revegetation areas, avoid special-status plant populations to 

the extent feasible during construction activities. 

Yosemite National 

Park, Project 

Manager; Contractor 

E-5
 
Appendix E: Mitigation Measures Applicable to All Action Alternatives 

Topic Mitigation Measure Responsibility 

If it is not feasible for construction activities to avoid special 

status plant species, species conservation measures will be 

developed in coordination with Yosemite National Park natural 

resources staff. Measures may include salvage of special-status 

plants for use in revegetating disturbed areas and transplantation of special-status plants wherever possible using 

methods and monitoring identified in the revegetation plan, 

monitoring to ensure successful revegetation, protection of 

plantings, and replacement of unsuccessful plant materials if 

practicable. 

Yosemite National 

Park, Project 

Manager; Contractor 

Provide proper and timely maintenance for vehicles and 

equipment used during construction to reduce the potential for 

mechanical breakdowns. 

Yosemite National 

Park, Project 

Manager; Contractor 

Use silt fencing at drainages to prevent construction materials 

from escaping work areas. 

Contractor 

Delineate wetlands and apply protection measures during 

construction. Wetlands shall be delineated by qualified NPS 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. 

Yosemite National 

Park, Project 

Manager; Contractor 

During heavy equipment use, spill kits are on site to prevent 

water contamination in the case of a spill. To minimize soil 

compaction when accessing riparian or riverine habitat 

unhardened by imported rock, track mats are placed on the 

ground, onto which the equipment will be driven. In areas 

impacted with imported fill and rock revetment, soils are 

decompacted as a final egress with equipment. 

Contractor 

Soils, Erosion 

Control, and Site 

Preparation 

Ensure that any soil or amendment imported from outside the 

Grove for use in the Grove is checked for pathogens (e.g., root 

rot) to limit the spread of tree diseases. 

Use approved siltation and sediment control devices in 

construction areas to reduce erosion and surface scouring. 

Contractor 

Use approved siltation and sediment control devices appropriate 

to the situation in grading areas to capture eroding soil before 

discharge to riparian channels. 

Contractor 

Where soils are heavily compacted and are covered with asphalt, 

soil conditions may be such that reestablishment of vegetation is 

unlikely without further treatment. Demetry (1997) found that 

soil impacts most frequently observed in Giant Forest were soil 

compaction, loss of organic matter, topsoil erosion, and loss or 

alteration of natural soil structure. Soil compaction was greatest 

under pavement (Demetry 1997). 

Soil conditions in restoration areas of the Mariposa Grove will be 

tested for compaction, texture, and chemical properties such as 

organic matter content and nitrogen, and amendments or 

treatment will be applied accordingly. Listed below is a range of 

soil treatments available to improve the potential for plant 

establishment, particularly giant sequoias. 

 Measure depth of compaction with a penetrometer and 

decompact to that depth (typically 6 to 10 inches) (Demetry 

1997). 

E-6
 
 

 

Appendix E: Mitigation Measures Applicable to All Action Alternatives 

Topic Mitigation Measure Responsibility 

 Decompact soils by hand or with heavy equipment (dozer or 

skid steer with rippers) under moderately moist conditions 

(may require 1 week of irrigation if work is completed in late 

summer or fall). 

 Avoid large roots during decompaction; a rototiller or hand 

decompaction may be more appropriate in these areas. 

 Add locally gathered duff to provide seeds and organic 

matter. 

 If available, add local native soil and topsoil. 

 If determined that soil conditions are not conducive to plant 

reestablishment, amendments such as peat moss, kelp, or 

other natural fertilizers may be used. 

 To provide nutrients to the soil, open cones on adult giant 

sequoias, and prepare a seedbed, woody debris may be 

scattered over the area and burned. If woody debris is not 

available for burning, fuel may be burned at a single 

location and the ashes mixed into the topsoil of the 

restoration area. 

Depending on the degree of alteration in landform, a variety of 

recontouring and topography restoration actions may be 

implemented and are listed below: 

 Regrade with existing soil: Where extensive recontouring to 

natural topography is required (e.g., road cuts), attempt to 

accomplish this through re-balancing cut and fill. 

 Fill: Where additional material is needed, soils of the same 

type from the Mariposa Grove area is preferable, but soil 

may need to be imported from South Entrance or other 

nearby locations. 

 Topsoil retention: Wherever removal or compaction of 

topsoil will occur, salvage and stockpile the top 12 inches of 

soil, and replace it on the surface. To preserve microbial 

communities and limit erosion and the establishment of 

weeds, mulch all soil piles or cover with erosion blankets. 

 Leave final grades uneven to provide microhabitat for seed 

germination and establishment. 

After decompacting soils, particularly on sloped areas, erosion 

potential can be high. Following is a list of available erosioncontrol measures: 

 Duff: Spread locally gathered litter and woody debris over 

disturbed areas for erosion control and to provide a source 

of seeds and organic matter. 

 Rice straw: If insufficient quantities of duff are available, use 

rice straw mulch (which is relatively inert and not a source of 

non-native seeds). 

 Erosion-control blankets and/or wattles: Use coconut fiber or 

rice straw erosion-control blankets and/or wattles only on 

steep slopes (3:1 or greater) and in unprotected drainages. 

 Stones, boulders, limbs, and logs: In conjunction with any 

other erosion control methods, place these materials 

(gathered from adjacent areas) on the surface to provide 

microclimate for plants and to slow water flow. 

E-7
 
Appendix E: Mitigation Measures Applicable to All Action Alternatives 

Topic Mitigation Measure Responsibility 

Soundscapes Ensure that all construction equipment has functional exhaust/ 

muffler systems. 

Contractor 

Submit a construction work plan/schedule that minimizes 

construction-related noise in noise-sensitive areas to the park for 

review/approval prior to commencement of construction 

activities. 

Contractor 

Use hydraulically or electrically powered construction 

equipment, when feasible. 

Contractor 

Locate stationary noise sources as far from sensitive receptors as 

possible. 

Contractor 

Limit the idling of motors except as necessary (e.g., concrete 

mixing trucks). 

Contractor 

To the extent possible, perform all on-site noisy work above 

76 A-weighted decibels (dBA) (such as the operation of heavy 

equipment) between the hours of 8:30 a.m and 5:00 p.m. to 

minimize disruption to nearby park users. 

Contractor 

Vegetation and 

Revegetation 

Park policy requires that all machinery brought in to the park is 

clean prior to entry and inspected by park staff to avoid 

introductions of invasive species, including seeds. Restoration 

work frequently involves ground disturbance, which has the 

potential to introduce and spread non-native plant species. For 

ground disturbing projects, park staff will survey for and treat 

invasive plants before and after restoration activities following 

the guidance of Yosemite’s 2011 Invasive Plant Management 

Plan. 

Yosemite National 

Park, Project 

Manager 

Minimize any impacts on giant sequoias including damage to 

boles, roots, root zone, and seedling habitat. 

Protect rare or sensitive plant species from direct and indirect 

impact. 

• 

Protect restoration areas from further impacts with fencing or 

appropriate deterrents. 

Establish vegetation monitoring plots (both qualitative and 

quantitative) and photo-document project implementation and 

results. 

There is a range of actions available to revegetate an area with 

native plants, and a combination of actions will provide the most 

successful restoration. For any revegetation activities within 

Mariposa Grove, only locally gathered plant material will be used 

to retain genetic integrity. 

 Natural regeneration: Rely on natural regeneration from 

adjacent seed sources and duff. 

 Seed collection, seed increase, and direct seeding: Plant the 

area with local native seed. It may not be practical to collect 

enough seed for direct seeding of the acreage involved. 

Increasing seed can provide necessary quantities. This process 

requires 3 years. 

 Seed or cutting collection and nursery propagation: Gather 

local native seeds and cuttings and plant in a nursery setting 

to provide established plants for planting in restoration 

areas. Place plants in a manner that mimics natural 

distribution – not landscaping. This requires 1 to 3 years. 

E-8
 
Appendix E: Mitigation Measures Applicable to All Action Alternatives 

Topic Mitigation Measure Responsibility 

 Plant salvage and transplanting: In cases where plants may 

be damaged or destroyed when infrastructure is removed, 

repaired, or relocated, salvage plants and replant them 

when the area is recontoured to more natural conditions, or 

in an adjacent restoration site. Store salvaged plants on site, 

and protect with shade cloth and irrigate as necessary. 

 Giant sequoias: Nearly all restoration sites lie within the 

seed-rain area of adult giant sequoias, so the need for 

propagating giant sequoias in a nursery setting and planting 

these trees is not likely to be necessary for germination and 

recruitment. Rather, prepare sites to facilitate germination, 

including burning woody debris to provide nutrients and a 

heat source to open cones on the trees. If seed dispersal does 

not occur (e.g., adequate heat is not created), hand spread 

locally collected giant sequoia seeds. 

Canopy gaps are integral to successful giant sequoia recruitment. 

The Giant Forest Restoration Project focused on creating and 

maintaining gaps as part of the restoration program because 

according to assessments of existing recruitment and gaps, 

neither was adequate. However, based on NPS assessment of the 

giant sequoia population in the Mariposa Grove, many canopy 

gaps exist in the Grove, and recruitment is relatively high when 

compared to other giant sequoia groves (Kuhn 2011). Based on 

this assessment, the park will continue to rely on fire to create 

and maintain these canopy gaps in Mariposa Grove, and to 

capitalize on the gaps created by removing existing 

infrastructure (e.g., parking areas) as areas for giant sequoia 

recruitment. 

Wildlife and 

Special Status 

Species 

Limit the effects of light and noise on adjacent habitat through 

controls on construction equipment. 

Yosemite National 

Park, Project 

Manager; Contractor 

Provide adequate education and enforcement to limit 

construction worker activities that are destructive to wildlife and 

habitats. 

Yosemite National 

Park, Project 

Manager 

Regulate speeds on the Mariposa Grove Road to reduce the 

potential for wildlife vehicle collisions.

 Alternative-specific mitigation measures: 

 Alternative 3: Grizzly Giant Hub. Close the road to the 

Grizzly Giant transit hub from dusk until dawn. 

 Alternative 4: South Entrance Hub with Modified 

Commercial Tram Service. Limit hours of commercial tram 

operation to reduce noise impacts on wildlife. 

Based on available anecdotal and scientific evidence, 

78 amphibian, reptile, mammal, and bird species occur in the 

Mariposa Grove and South Entrance project area. Of these 

78 species, 13 special status species occur or have the potential to 

occur in the project area including 6 bird species (northern 

goshawk, long-eared owl, California spotted owl, Vaux’s swift, 

olive-sided flycatcher, and yellow warbler) and 7 mammal species 

(pallid bat, Townsend’s big-eared bat, spotted bat, western red 

bat, western mastiff bat, Sierra Nevada mountain beaver, and 

Pacific fisher). 

In order to mitigate impacts to special status species during 

construction and maintenence activities, we recommend (1) 

timing construction activities to avoid the most sensitive time 

Yosemite National 

Park, Project 

Manager 

E-9
 
Appendix E: Mitigation Measures Applicable to All Action Alternatives 

Topic Mitigation Measure Responsibility 

periods for special-status animals; (2) retaining key habitat 

features for denning, roosting, nesting, and hibernating; and (3) 

adaptively managing for special-status species through 

continued targeted surveys during key time periods during the 

construction and post-construction phases. 

Mitigation to protect key habitat features for fishers, bats, and 

owls: 

 Limit the effects of light and noise on adjacent habitat 

through controls on construction equipment. 

 In construction zones, conduct visual/auditory surveys 

targeting owls and other birds, visual and acoustic surveys 

targeting bats, and remote camera surveys targeting fishers 

to inform proper mitigation actions that would reduce 

impacts on wildlife. 

 Avoid disturbing basal hollows (created by repeated fires), 

deep bark furrows, and cavities and crevices of tree crowns 

important for bats and other wildlife (Pierson et al. 2006). 

Snags are an essential habitat element for the majority of special 

status species documented using the Mariposa Grove. Removal 

of snags may indirectly result in decreased rates of reproduction 

and increased rates of mortality for fishers (USDA Forest Service 

2001), and spotted owls use cavities in snags for nesting and 

raising young. If hazard tree (snag) removal cannot be avoided: 

 Remove snags only under consultation with the park 

biologist and park forester. Tree removal should occur 

outside of sensitive time periods for special status species. 

 A wildlife biologist should examine any trees and snags for 

nesting, denning, or roosting wildlife, or the potential for 

such use, prior to removal. 

Mitigation to protect fisher dens: 

 Protect all known fisher natal (birthing) and maternal (kit 

rearing) den structures within Yosemite, and any den 

structures located in the future. This measure is particularly 

compelling because female fishers have been known to 

reuse past dens (i.e. same fisher returning to the same den 

the next season or another female using a den occupied by a 

different fisher from a previous season) (R. Sweitzer, pers. 

comm.). 

 Protect verified fisher birthing and kit rearing dens during 

fisher denning season (March 1 through June 30) with 700­

acre buffers consisting of the highest quality habitat (CWHR 

size 4 or greater and canopy closure greater than 60%) in a 

compact arrangement surrounding the den site in the 

largest, most contiguous blocks available. 

 For active dens, within this buffer, (1) enforce a night closure 

of any paved roads and (2) halt construction, restoration, fire 

management, or other disturbing activities until the 

cessation of denning season (June 30). 

Mitigation specific to the Pacific fisher: 

 Continue monitoring fishers in the park (in conjunction with 

fisher researchers working in and around Yosemite National 

Park) to establish whether fishers are actively foraging or 

denning near the project area. Establish buffers to prevent 

disturbance around any active dens. 

E-10 

 

Appendix E: Mitigation Measures Applicable to All Action Alternatives 

Topic Mitigation Measure Responsibility 

 Add wildlife crossing structures at riparian crossings near 

South Entrance and Mariposa Grove along Wawona and 

Mariposa Grove roads as construction work is being 

conducted to reduce barriers to animal movement and 

habitat fragmentation. 

 Conduct fuels reduction activities outside of fisher denning 

season. 

 Time construction and restoration activities to avoid the 

most sensitive time periods for fishers (i.e. during denning 

season [March 1 - June 30] and during juvenile dispersal 

[from early February onward]). 

 Adaptively manage for fishers through continued targeted 

surveys during key time periods during construction/ 

restoration/fire management activities. 

 Retain habitat features important to fishers including: large 

diameter black oaks, large diameter conifers, large diameter 

snags, large decayed logs, high canopy closure/multiple layer 

canopy, and coarse woody debris on the ground, in areas 

with moderate to steep slopes and drainages with running 

and/or pooled water (Zielinski et al. 2004). 

 Retain and recruit large-diameter (>11 inches diameter at 

breast height [DBH]) snags (Freel 1991; Buskirk and Powell 

1994) and large-diameter (>24 inches DBH) live conifer and 

oak trees with decadence such as broken tops or cavities 

(Freel 1991). 

 Maintain dense canopy cover (>60%) in the vicinity of large 

trees (Buskirk and Powell 1994). 

 Retain and recruit large woody debris, including largediameter (at least 15 inches DBH by 15 feet long) downed 

logs (Freel 1991, Buskirk and Powell 1994) and complex 

structure near the ground (e.g., downed logs, large downed 

branches, root masses, live branches) (Buskirk and Powell 

1994). 

 Retain a mosaic of late-successional coniferous or mixed 

forests and perform fuel treatments in patches, allowing 

adequate dispersal habitat for fishers and avoiding creation 

of large, open areas that have no overstory or shrub cover. 

 Identify additional protection measures as deemed necessary 

to avoid disturbance during construction or restorationrelated activities. 

OWLS: Conduct surveys in the spring (beginning March 15) to 

determine if spotted owls are nesting or foraging in the vicinity 

of the construction/restoration area. If owls are present, the park 

construction project manager will work with park biologists to 

determine appropriate measures to avoid disturbance, such as no 

construction activities between 30 minutes before dusk and 

30 minutes after dawn, and an approximate 1,250-foot buffer of 

no disturbance (light or noise) around nest trees from March 15 

through August 31. 

E-11 

Appendix E: Mitigation Measures Applicable to All Action Alternatives 

Topic Mitigation Measure Responsibility 

BATS: If a project targets any trees for removal during the 

winter, a biologist will survey for roosting bats the preceding fall 

(September and October). If the biologist suspects hibernation in 

a tree, do not remove that tree until mid-April to mid-May. If a 

project targets any trees for removal during the summer, a 

biologist should survey for roosting bats within one week prior 

to removal to determine if a bat maternal colony occurs in the 

tree. If bats are determined to be roosting in the tree, delay 

removal until fall (mid-August through October). 

Specific to Cultural Resources and Historic Properties 

Archeological Train all members of the restoration/construction teams in Yosemite National 

Resources proper handling of inadvertent discovery of archaeological 

resources. Training would involve information regarding the 

types of archeological materials that are likely present in the 

specific project area, how to identify archeological materials, and 

the procedures for contacting the appropriate parties in the 

event that archeological materials are encountered during 

restoration/construction activities. 

All restoration/construction personnel would be required to 

participate in the training, and written guidelines would be 

prepared and distributed to aid in identification of archeological 

materials and to inform workers of the procedures to follow in 

case of a discovery or potential discovery. If buried archeological 

resources such as flaked stone or groundstone, historic debris, 

building foundations, midden soils or human bone are 

inadvertently discovered during ground-disturbing activities, 

work shall stop in that area and within a 100-foot radius of the 

find until a qualified archeologist can assess the significance of 

the find. 

Inadvertent discoveries would be treated in accordance with 

36 CFR 800.13 (Protection of Historic Properties: Post-review 

discoveries). The archeological resource would be assessed for its 

eligibility for listing on the National Register in consultation with 

the SHPO and representatives of traditionally associated 

American Indian tribes and groups (if it is an American Indian 

archeological site), and a determination of the project effects on 

the site would be made. If the site would be adversely affected, 

a treatment plan would also be prepared as needed during the 

assessment of the site’s significance. Assessment of inadvertent 

discoveries may require archeological excavations and/or archival 

research to determine resource significance. Treatment plans 

would fully evaluate avoidance, project redesign, and data 

recovery alternatives before outlining actions proposed to 

resolve adverse effects. 

If human skeletal remains are encountered, protocols under 

federal and state law would apply. All work shall stop in the 

vicinity of the discovery, and the find would be secured and 

protected in place. The appropriate county coroner (Mariposa or 

Merced) and Park Archeologist would both be immediately 

notified. If a analyses determine that the remains are American 

Indian, and that no further coroner investigation of the cause of 

death is required, the coroner would then be required to contact 

the NAHC (pursuant to Section 7050.5[c] of the California Health 

and Safety Code) and the County Coordinator of Indian Affairs. 

The remains would also be treated in accordance with the Native 

American Graves Protection and Repatriation Regulations at 

43 CFR 10.4 (Inadvertent discoveries). 

Park, Project 

Manager 

E-12 

 

Appendix E: Mitigation Measures Applicable to All Action Alternatives 

Topic Mitigation Measure Responsibility 

Management actions involving moderate to severe ground 

disturbance (trail reroutes; formalization of social trails; 

excavations for subsurface utilities; development of 

campgrounds; removal of abandoned infrastructure and/or 

facilities, construction of buildings, structures, parking lots, and 

roads; topographic recontouring; decompaction and plant 

salvage; and actions that may focus visitor use at areas with 

sensitive surface resources) within or adjacent to the boundaries 

of known archeological sites shall be preceded by intensive 

surface survey and/or controlled subsurface testing as well as 

archeological and American Indian resource monitoring, as 

determined appropriate given past studies and findings. 

Gift shop demolition and removal should avoid ground 

disturbance. If mechanical demolition cannot avoid effects, 

alternative methods such as manual demolition and /or sling lift 

should be used to remove the piered structure. 

Within or adjacent to site boundaries, topographic recontouring 

should be achieved through fill and compaction rather than 

grading/cutting wherever possible in order to avoid ground 

disturbance. 

Initial limited testing shall be conducted in the area(s) proposed 

for ground disturbance, to first determine if the presence of site 

components can be verified. If so, the methods of achieving the 

proposed action may be modified and/or relocated, if possible. If 

effects could not be avoided, archeological treatment measures 

would be site-specific and contingent on previous studies’ results 

and the level of work proposed. 

Yosemite National 

Park, Project 

Manager 

Management actions involving minor ground disturbance within 

or adjacent to the boundaries of known archeological sites shall 

be conducted with an archeological monitor present to ensure 

that activities (restoration, revegetation of denuded areas, 

removal of hazard fuels or unwanted vegetation, etc.) do not 

adversely affect the integrity of site stratigraphy or horizontal 

artifact context. Monitoring may also be included as part of a 

treatment plan for individual resources following initial testing 

as per AR-MM-2. 

The archeological monitor shall record and be authorized to 

collect soil samples and artifactual/ecofactual material as 

warranted for analysis. If the monitor determines that any 

portion of the proposed action could have an adverse effect on 

the site, alternative methods of accomplishing the action shall be 

discussed with the restoration personnel. 

Yosemite National 

Park, Project 

Manager 

E-13 

Appendix E: Mitigation Measures Applicable to All Action Alternatives 

Topic Mitigation Measure Responsibility 

Historic Properties Avoidance, mimimization, and mitigation of actions affecting 

historic properties will be addressed through a project specific 

memorandum of agreement (MOA) between NPS and the 

California State Historic Preservation Officer consistent with 

guidance in 36CFR 800.6(b). These efforts could include screening 

and/or sensitive design that would be compatible with cultural 

landscape resources. Should avoidance of adverse impacts not be 

possible, documentation and treatment would be identified to 

reduce the intensity of the impact. A draft MOA is included in 

Appendix G. 

As per Section 106 of the NHPA, prior to construction or 

demolition activities, the park shall conduct a review of impacts 

to historic buildings, structures, and districts within the project 

area of potential effect (APE). This will include a review of 

existing known historic resources for their continued integrity 

and eligibility for listing in the National Register, identification 

of currently unknown historic properties within the APE, and 

determination of potential adverse effects in compliance with 

36 CFR Part 800 – Protection of Historic Properties. 

Yosemite National 

Park, Project 

Manager 

Actions will be consistent with the Secretary of Interior’s 

Standards for the Treatment of Historic Properties. The park 

would seek to first avoid, then minimize, and lastly mitigate any 

actions adversely affecting historic properties. 

To minimize the effect of new culvert construction on historic 

road character, new headwalls would be considered where the 

culverts are visible from the roads. The new walls should be 

stone (not veneer), constructed using compatible stone in a form 

and masonry pattern that is compatible with the nearby historic 

period masonry. 

Yosemite National 

Park, Project 

Manager 

Prior to any ground disturbing activities associated with 

revetment, further analysis and possible documentation at each 

site would be required in order to assess potential adverse 

effects to historic resources. 

Yosemite National 

Park, Project 

Manager 

American Indian 

Traditional 

Cultural Resources 

Memorandum of Agreement is under development and may 

stipulate additional mitigation measures (see Appendix G). 

NPS American Indian Liaison should be contacted immediately 

upon discovery of human remains. 

Specific to Sociocultural Resources 

Park Operations Install appropriate traffic signs. Yosemite National 

Park, Project 

Manager 

Conduct a Minimum Requirement Analysis for all actions that 

would take place in Wilderness (e.g., repairs to the water line in 

Biledo Meadow). 

E-14 

Appendix E: Mitigation Measures Applicable to All Action Alternatives 

Topic Mitigation Measure Responsibility 

Ongoing monitoring undertaken by Yosemite’s interdisciplinary 

Visitor Use and Impacts Monitoring Program regularly assesses 

conditions in meadows and along riverbanks, providing 

important information on the success of restoration efforts. In 

addition, the park performs regular monitoring for invasive 

plants, stock use impacts, wildlife abundance and diversity, and 

visitor experience. To evaluate the success of particular 

restoration actions, monitoring plans will be implemented 

specific to each restoration project. Geophysical and biological 

parameters will be monitored over time to determine restoration 

success and recovery rates. Pre- and post-restoration vegetation 

and soil sampling and photo points are examples of monitoring 

to measure project success. 

Yosemite National 

Park, Project 

Manager 

Visitor Experience 

and Recreation 

Fence construction staging areas and construction activity areas 

to visually screen construction activity and materials. 

Contractor 

Consolidate construction equipment and materials to the staging 

areas at the end of each work day to limit the visual intrusion of 

construction equipment during nonwork hours. 

Contractor 

Provide protective fencing enclosures around construction areas, 

including utility trenches to protect public health and safety. 

Contractor 

Limit construction activities to the off-season to allow for 

continued visitor access to the ski area during the winter. 

Yosemite National 

Park, Project 

Manager, Contractor 

All new sources of lighting, or substantial modifications to 

structures with existing sources of exterior lighting, shall 

conform to the standards set forth in the Yosemite Lighting 

Guidelines. 

Contractor 

Restoration work provides many opportunities to teach other 

park employees and visitors about natural processes in Yosemite. 

Each restoration project incorporates an element of outreach or 

interpretation such as informative signs or self-guided nature 

trails. Biologists work closely with interpretive staff to 

disseminate messages to visitors regarding trails and areas that 

are currently closed due to ongoing restoration efforts. 

Yosemite National 

Park, Project 

Manager 

E-15