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Long Term Experimental and Management Plan

Riparian Vegetation Project Plan

FOR THE IMPLEMENTATION OF THE VEGETATION ENVIRONMENTAL 

COMMITMENTS FROM THE LTEMP ROD IN GLEN CANYON NATIONAL 

RECREATION AREA AND GRAND CANYON NATIONAL PARK BELOW 

GLEN CANYON DAM

Authored by NPS in coordination with 

the Grand Canyon Monitoring and Research Center (GCMRC). 

Project planned in partnership with the Tribes associated with the 

Glen Canyon Dam Adaptive Management Program (GCDAMP), 

and with funding from GCDAMP through the Bureau of Reclamation

August 26, 2021 
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List of Acronyms

AMWG: Glen Canyon Dam Adaptive Management Working Group

BAHG: Budget Ad-Hoc Group

CRE: Colorado River Ecosystem

CREDA: Colorado River Energy Distributors Association

CRMP: Colorado River Management Plan

CFS: Cubic Feet per Second

EA: Environmental Assessment

EIS: Environmental Impact Statement

FY: Fiscal Year/s

GCDAMP: Glen Canyon Dam Adaptive Management Program

GCNRA: Glen Canyon National Recreation Area

GLCA: Glen Canyon National Recreation Area

GCMRC: Grand Canyon Monitoring and Research Center

GPS: Global Positioning System

GRCA: Grand Canyon National Park

HFE: High-Flow Experiment 

IPM: Integrated Pest Management

LTEMP EIS: Glen Canyon Dam Long Term Experimental and Management Plan Environmental 

Impact Statement

MLFF: Modified Low Fluctuation Flow 

MRA: Minimum Requirements Analysis

MRDG: Minimum Requirements Decision Guide 

NEPA: National Environmental Policy Act 

NAU: Northern Arizona University

NPS: National Park Service

PTA: Priority Treatment Area/s 

RM: River Mile 

ROD: Record of Decision

SWFL: Southwestern willow flycatcher

TBD: To Be Determined

TWP: Triennial Work Plan

ACRE3: Acroptilon repens (Russian knapweed)

AGUTK: Agave utahensis var. kaibabensis (Kaibab agave)

ALMA12: Alhagi maurorum (camelthorn)

COJU2: Cortaderia jubata (purple pampas grass)

CUPA: Cucurbita palmata (coyote gourd)

COSE4: Cortaderia selloana (Uruguayan pampas grass)

ELAN: Elaeagnus angustifolia (Russian olive)

FAPA: Fallugia paradoxa (Apache plume) 

FOPUP: Forestiera pubescens (stretchberry) 

FRVE2: Fraxinus velutina (velvet ash)

LELA2: Lepidium latifolium (perennial pepperweed) 

PLSE: Pluchea sericea (arrowweed)

POFR2: Populus fremontii (Fremont cottonwood)
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PTTRP: Ptelea trifoliata ssp. pallida (Pallid hoptree)

SAEX: Salix exigua (coyote willow)

SAGO: Salix gooddingii (Goodding’s willow)

SARA3: Saccharum ravennae (Ravenna grass) 

SATR12: Salsola tragus (Russian thistle)

STPI: Stanleya pinnata (desert princesplume) 

TARA: Tamarix ramosissima (tamarisk)

TRTE: Tribulus terrestris (puncturevine) 

VAST3: Vanclevea stylosa (pillar false gumweed) 
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Background

The National Park Service (NPS) proposed a 20 year experimental riparian restoration project as 

part of the Glen Canyon Dam Long Term Experimental and Management Plan Environmental 

Impact Statement (LTEMP EIS – U.S. Department of Interior, 2016a). The project is designated 

in the environmental commitments in the LTEMP Record of Decision (ROD – U.S. Department 

of Interior, 2016b) as specific mitigation of the impacts of dam operation to the condition of the 

vegetation communities within the Colorado River Ecosystem. This is in keeping with the 

environmental commitments typical in a National Environmental Policy Act (NEPA) process 

and with the 1992 Grand Canyon Protection Act, which call for protecting, mitigating the 

adverse impacts to, and improving the resources downstream of the Glen Canyon Dam. The 

project was included as a specific priority of the Glen Canyon Dam Adaptive Management 

Program (GCDAMP) in the August 2019 Memorandum from the Secretary’s Office. The project 

is intended to be planned and performed in collaboration with the Tribes associated with the 

GCDAMP and with scientific guidance from the Grand Canyon Monitoring and Research Center 

(GCMRC). GCMRC can help provide monitoring and research to ensure the project is being 

implemented most efficiently to achieve the goals specified in the ROD and to answer research 

questions particularly regarding the appropriate use of native plants for restoration and the 

protection of cultural resource sites through vegetation management in strategic locations. 

The intention of this plan is to provide the rationale and detailed planning for this project. It 

should be noted that this plan will need to be updated with each triennial workplan, and that any 

details or lists of project sites may change on an annual basis. In short, this is intended to be an 

evolving document, not a static plan. 

Rationale - Resource issues to be addressed, or not addressed, by this project

This is a brief summary of the issues which the LTEMP EIS (U.S. Department of Interior, 

2016a) identified in relation to this project. This section quotes heavily from sections 3.6 and 4.6 

of the EIS but is not intended to be comprehensive. 

The Influence of Dam Operations on Vegetation

Vegetation along the river corridor is affected by the peak magnitudes, daily fluctuations, and 

seasonal pattern of river flows. Vegetation studies conducted since 1995 indicate that riparian 

vegetation composition, structure, distribution, and function are closely tied to ongoing dam 

operations. The general response of riparian vegetation to the operation of Glen Canyon Dam has 

been well studied (Kearsley and Ayers, 1999; Ralston, 2005, 2010, 2011; Ralston and others, 

2014; Sankey and others, 2015; Stevens and Ayers, 1995; Stevens and others, 1995). Most 

evidence indicates that riparian vegetation composition, structure, distribution, and function are 

closely tied to ongoing dam operations (Butterfield and others, 2018; Sankey and others, 2015; 

U.S. Department of Interior, 2016a). There are four specific vegetation issues influenced by dam 

operations that emerged in the LTEMP EIS that this project specifically seeks to address: 

 
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Encroachment of Vegetation on Sandbars

An ongoing trend with operations since the completion of the dam has been the encroachment of 

New High Water Zone vegetation onto sandy beaches (Hadley and others, 2018a; Kearsley and 

others, 1994; Webb and others, 2002). Unvegetated or sparsely vegetated sandbars form a 

fundamental element of the river landscape and are important for riparian habitat for fish and 

wildlife, cultural resources, and recreation (Bureau of Reclamation, 1995; Wright and others, 

2008). Low-elevation sandbars create zones of low velocity aquatic habitat (i.e., backwaters) that 

may be utilized by juvenile native fish. These low elevation sandbars are also a source of sand 

for wind transport that may help protect archaeological resources. In addition, beaches provide 

recreational value for visitors (e.g., camping areas for river and backcountry users). For 

recreational use (e.g., camping and boating), visitors generally prefer separation bars over 

reattachment bars because they are composed of finer grained sand, experience less frequent 

inundation by rising river levels, and have lower velocity conditions for mooring boats (Bureau 

of Reclamation, 1995). For these reasons this project was designed to mitigate the effects of dam 

operations on vegetation encroachment of sandbars. The goal is to clear sandbars periodically of 

vegetation in specific locations. One species that is a particular problem with encroachment is 

arrowweed (Pluchea sericea). Arrowweed is a native species, but it has characteristics of a 

primary colonizer and quickly occupies open sandbar areas. The LTEMP EIS concluded that 

arrowweed encroachment is influenced by dam operations, so this project includes this species 

for control and removal where this species is encroaching on campsites (U.S. Department of 

Interior, 2016a). 

Decrease in Native Plant Species

The LTEMP EIS concluded that dam operations may contribute to the loss of native species and 

this project is designed to mitigate that loss with targeted revegetation efforts in specific areas. 

Goodding’s willow (Salix gooddingii), which is important for its wildlife habitat value as shade 

for recreation along the river, appears to have been affected by the reduction in flood flows 

below Glen Canyon Dam on upper riparian terraces. Goodding’s willow has been in decline, and 

either no longer occurs at or does not reproduce at two-thirds of the sites where it previously 

existed (Grand Canyon Wildlands Council, 2011; Mortenson and others, 2008). Along with the 

coarsening of substrates, the lack of springtime recruitment floods threatens remaining stands; 

however, high flows during the mid-1980s resulted in some establishment of Goodding’s willow 

in the Grand Canyon (Mortenson and others, 2012; Ralston and others, 2014). Restoration of 

Goodding’s willow and several other native species has been a focus of NPS revegetation efforts 

(U.S. Department of Interior, 2016a). 

Increases in Invasive Nonnative Plant Species

Dam operations influence invasive nonnative plant species, and analysis in the LTEMP EIS 

showed that operations have generally led to an increase in invasive plants, so this project is 

designed to mitigate that impact. A number of nonnative plant species, many of which are 

invasive species, occur throughout the riparian zone; among the most common species are 

tamarisk (Tamarix spp.), Russian olive (Elaeagnus angustifolia), camelthorn (Alhagi 

maurorum), Russian thistle (Salsola tragus), ripgut brome (Bromus diandrus), red brome 

(Bromus rubens), cheatgrass (Bromus tectorum), yellow sweetclover (Melilotus officinalis), 

spiny sow thistle (Sonchus asper), Ravenna grass (Saccharum ravennae), perennial pepperweed

(Lepidium latifolium), and Bermuda grass (Cynodon dactylon) (Reclamation 2011d; NPS 2005a). 
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Operations since the 1996 ROD (U.S. Department of the Interior, 1996) have facilitated the 

recruitment, establishment, and expansion of both native and nonnative plant species (e.g., 

tamarisk) throughout the river corridor (Ralston and others, 2014). Furthermore, a recent analysis 

of vegetation data collected by NPS staff from 2007 to 2010 demonstrated an overall increase in 

nonnative plant cover, particularly in the New High Water Zone (U.S. Department of Interior, 

2016a; Zachmann and others, 2012). 

Erosion of Archaeological Resources

There are a number of ways in which dam operations may affect cultural resources,

including the periodicity of inundation and exposure, changing vegetation cover, streambank

erosion, slumping, and influencing the availability of sediment. Research conducted since the 

1995 Environmental Impact Statement (EIS) on the relationship between sand deposits and wind 

processes continues to provide data that suggest that windblown sand changes the surface of 

some sites of archaeological and cultural concern where sand supply and wind are active agents 

(Draut, 2012; Draut and Rubin, 2008; Sankey and Draut, 2014; U.S. Department of Interior, 

2016b). 

Narrowing and Loss of Plants in the Old High Water Zone

This is another major issue of vegetation in the canyon, but this issue is not intended to be 

addressed by this project. As discussed in the LTEMP EIS section 3.6.1, the construction of the 

Glen Canyon Dam fundamentally changed the riparian area along the Colorado River through 

Glen and Grand canyons. A zone of riparian vegetation, referred to as the Old High Water Zone, 

was well established just above the pre-dam scour zone (at and just above the approximately 

100,000-cubic feet per second (cfs) stage elevation; Carothers and Brown, 1991). Following dam 

construction, annual high flows have been limited to approximately 45,000 cfs or lower, except 

for four higher flow years (1983–1986) since 1965. The overall trend in the Old High Water 

Zone has been increased mortality of species such as mesquite (Prosopis glandulosa var. 

torreyana) and net-leaf hackberry (Celtis reticulata) (Anderson and Ruffner, 1987; Kearsley, 

2006; Webb and others, 2011). This is not a problem which this project is intended to address, as 

this project is limited to addressing the effects of dam operations, rather than dam existence and 

is limited to actions in the Colorado River Ecosystem (CRE) (U.S. Department of Interior,

2016a). 

LTEMP Analysis Conclusions and Direction for this Project

The LTEMP EIS analyzed extensive literature on the background and dynamics of dam effects 

on vegetation in Section 3.6 and then analyzed the potential effects of different alternatives using 

the best available science using a modeling approach in Section 4.6. The approach looked at four 

metrics and a combined metric. The four metrics were native cover, native diversity, native/nonnative ratio, and arrowweed. That analysis found that under all alternatives, the overall combined 

metric for vegetation condition showed that condition would be expected to degrade to some 

degree, so this experimental riparian project was conceived to mitigate those effects. The 

selected alternative was expected to perform better on most metrics than other alternatives, but 

even this alternative was found to likely result in: 1) a decrease in native vegetative cover (12% 

overall decrease in native plant community cover), 2) a 16% decrease in wetland community 

cover; and 3) a decrease in the ratio of native to nonnative community types (5% decrease in 
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ratio). All of these dynamics varied with the particular alternative, and were clearly within the 

influence of dam operations rather than problems with just dam existence. However, under all 

alternatives it was found that the Old High Water Zone would continue narrowing, regardless of 

alternative, because under normal and experimental dam operations flows would not exceed 

45,000 cfs. For this reason, the issue of Old High Water Zone narrowing is not addressed by this 

project (U.S. Department of Interior, 2016a). 

The LTEMP EIS states that activities that are included “are expected to modify the cover and 

distribution of plant communities along the Colorado River and improve the vegetation 

conditions. These vegetation treatments include removal of nonnative plants, revegetation with 

native species, clearing of undesirable plants from campsites, and management of vegetation to 

assist with cultural site protection. All vegetation treatments would occur only within the 

Colorado River Ecosystem, which could be influenced by dam operations. Native species, such 

as Goodding’s willow and cottonwood (Populus spp.), would be planted to increase and maintain 

populations of these species. Native plant materials would be developed for replanting through 

partnerships and use of regional greenhouses; this would include the collection of propagules 

(seeds, cuttings, poles, or whole plants) from riparian areas in both the river corridor and side 

canyons. Removal of nonnative plants would include mechanical means (e.g., cutting, digging, 

pulling), smothering, spot burning, or use of herbicides.” (U.S. Department of Interior, 2016a). 

LTEMP Resource Goals Relevant to this Project

The LTEMP EIS (U.S. Department of Interior, 2016a) provides these resource goals to guide this 

project: 

Riparian Vegetation. Maintain native vegetation and wildlife habitat, in various stages of 

maturity, such that they are diverse, healthy, productive, self-sustaining, and ecologically 

appropriate.

Nonnative Invasive Plant Species. Minimize or reduce the presence and expansion of aquatic 

nonnative invasive species.

Archaeological and Cultural Resources. Maintain the integrity of potentially affected National 

Register of Historic Places (NRHP)-eligible or listed historic properties in place, where possible, 

with preservation methods employed on a site-specific basis. 

Natural Processes. Restore, to the extent practicable, ecological patterns and processes within 

their range of natural variability, including the natural abundance, diversity, and genetic and 

ecological integrity of the plant and animal species native to those ecosystems.

There are also a number of NPS policies that we use to guide this project that can be found in 

Attachment A. Each park has other plans related to vegetation management, desired future 

conditions and non-native plant priorities that inform this project and are referenced below.
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Overall LTEMP Vegetation Project Design

The NPS, in partnership with Tribes and GCMRC, has proposed a phased implementation of the 

project which involves:

i) planning and developing pilot projects and experiments related to each objective 

through science-based prioritization of management locations and objectives;

ii) implementation of pilot projects and experiments;

iii) monitoring, evaluation, and dissemination of pilot project and experiment outcomes

iv) use of adaptive management principles to subsequently (iteratively) develop,

 implement, and evaluate site-specific riparian vegetation management projects 

throughout the program life.

This plan will address Glen Canyon Dam Adaptive Management Program Triennial Budget and 

Work Plan (Fiscal Year 2021 – Fiscal Year 2023) Elements C.7. - Experimental Vegetation 

Treatment, and D.1. - Geomorphic effects on dam operations and vegetation management for 

archeological sites. Specific sites and activities at those sites will be determined annually in 

coordination with Tribes and GCMRC, and with adaptation based on what was learned from the 

implementation, monitoring and research in the previous years. Details from Triennial workplans 

or annual site specifics may be appended to this plan as attachments.

Specific project objectives and priorities are detailed below and tie in with existing NPS plans 

for riparian vegetation management in the river corridor. All work under this project that is 

funded out of GCDAMP funds will be restricted to the Colorado River Ecosystem, which is a 

term defined in the 2016 LTEMP ROD. Funding from the GCDAMP will not be used for project 

areas outside of the area influenced by current dam operations.

The project locations considered for LTEMP experimental vegetation treatments are from Glen 

Canyon Dam downstream, as far downstream as the western boundary of Grand Canyon 

National Park. Coordination and/or consultation would occur between land management 

agencies, Tribes, GCMRC and Bureau of Reclamation as needed well in advance of on-site 

implementation. Sites would be selected based on ecological, recreational, and cultural resource 

conditions, with site specific feasibility selection criteria employed using the best available data. 

Originally, in 2017, the GCMRC assisted the NPS with a pilot project. Also, the Glen Canyon 

National Recreation Area (GLCA) Colorado River Riparian Revegetation Plan (GCWC, 2008)

and the Grand Canyon National Park (GRCA) Granite Camp restoration project provided a 

template for this project and helped inform suitable locations and strategies (Ralston and Sarr, 

2017). The project was implemented in phases to establish baseline conditions and standardize 

methods for implementation and monitoring. Adaptive changes will be made to treatment 

strategies as we learn more and based on results from formal and informal monitoring. Methods 

for this project are primarily manual, rather than mechanical, due to the proposed wilderness 

status and remoteness on much of the land in consideration; mechanical treatment methods (e.g., 

chainsaw tree felling) are evaluated, when necessary, through the Minimum Requirements 

Analysis (MRA) process, but can be used in most portions of the Glen Canyon Reach and along 

the Colorado River corridor through GRCA. An MRA is required by law whenever land 

managers are considering a use prohibited by Section 4(c) of the Wilderness Act of 1964. Some 
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agency policies may also require an MRA for other uses or activities in wilderness. Although 

there are other ways to complete an MRA, the Minimum Requirements Decision Guide (MRDG) 

is a process that was developed by the Arthur Carhart National Wilderness Training Center to 

help land managers make informed, defensible decisions that comply with the Wilderness Act. 

The acreage of these target sites will be somewhat limited because of the site criteria and the 

methods used. However, the experimental vegetation treatments proposed for these targeted sites 

are viewed as mitigation of impacts from dam operations under the guidance of the Grand 

Canyon Protection Act and contribute toward achieving the desired conditions in the National 

Park Service units. The five Project Objectives as described in Section 6.4 of the LTEMP ROD 

(U.S. Department of Interior, 2016b) include:

1. Control non-native plant species affected by dam operations, including tamarisk 

and other highly invasive species; 

1. Tamarisk control areas will be prioritized in areas where removal of live tamarisk 

is most effective, but may also involve clearing away dead tamarisk that remains 

after tamarisk leaf beetle (Diorhabda spp.) kill in some areas. 

2. Other highly invasive riparian species such as camelthorn, Ravenna grass, 

Russian olive, and perennial pepperweed would also be targeted. 

2. Develop native plant materials for replanting through partnerships and the use of 

regional greenhouses;

1. Prioritize native species for propagation. 

2. Determine appropriate source areas based on regional genetics research in 

cooperation with GCMRC. 

3. Develop and enhance partnerships with appropriate nurseries. 

3. Replant native plant species at priority sites along the river corridor, including 

native species of interest to Tribes, as follows:

1. In sites of extensive tamarisk mortality. 

2. At edges of campsites for shade or to direct visitor access. 

3. Areas where wildlife habitat can be improved for the benefit of native species 

including potential threatened and endangered species habitat (primarily 

southwest willow flycatcher [Empidonax traillii ssp. extimus] and western yellowbilled cuckoo [Coccyzus americanus]) in key areas. 

4. Sandbar/bank stabilization in key areas, including recreational sites.

5. Priorities for project sites will be established annually with input from Tribes and 

guidance from GCMRC. 
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4. Remove vegetation encroaching on campsites;

1. Sites that NPS determines are priorities would be considered where established 

recreational camping areas have been lost to encroachment by both native (e.g. 

arrowweed) and non-native riparian species (e.g., camelthorn, Russian thistle and 

puncturevine (Tribulus terrestris)). 

5. Manage vegetation to assist with cultural site protection.

1. Priority sites in GRCA would be chosen where GCMRC research has provided 

evidence of aeolian processes that could potentially benefit stabilization of 

cultural sites. Site selection will also include consultation with tribal colleagues to 

ensure compatibility with site management needs. 

2. In GRCA non-native vegetation may be removed in these locations to facilitate 

future river sediment deposition and wind transport of sand, which would be 

monitored within an adaptive management framework. There may also be limited 

removal of native vegetation, primarily restricted to arrowweed with very limited 

situations including other species (mesquite, seep willow [Baccharis spp.]). 

3. Native upland xeric vegetation could be planted in locations to increase aeolian 

sediment deposition, decrease erosion, and/or rehabilitate degraded cultural sites 

(i.e., Objective 3, above). 

4. Work with GCMRC to determine if similar processes may be occurring in GLCA. 

Conceptual Framework of the Project

The LTEMP EIS preferred alternative was unable to fully address the overall degradation of the 

vegetation condition below the dam (see Section 4.6.3 and specifically 4.6.3.4 of the LTEMP 

EIS), though the preferred alternative performed the best overall for vegetation condition. Since 

operational flows are limited to below 45,000 cfs, the overall size of the riparian area in GRCA 

and GLCA has been altered and the vegetation density within the riparian area is expected to 

continue to increase. The vegetation up to the New High Flow Zone of 45,000 cfs and in the 

narrow root zone buffer beyond are influenced and affected by dam operations. Non-native 

vegetation and native clonal species such as arrowweed were shown to be increasing under the 

1996 ROD Modified Low Fluctuation Flow (MLFF) dam operations and were predicted to 

increase under all operational scenarios possible resulting from the LTEMP EIS. This vegetation 

project was written into the preferred alternative and into the ROD as required mitigation to 

address the influence of dam operations and to protect and improve the vegetation at targeted 

sites along the river. 

The general response of riparian vegetation to Glen Canyon Dam operations has been well 

studied, particularly as it relates to woody vegetation expansion (Hadley and others, 2018b; 

Kasprak and others, 2018; Sankey and others, 2015; Scott and others, 2018) and tamarisk 

population dynamics (Bedford and others, 2018; Porter and Kearsley, 2001; Ralston, 2010, 

2011). The weight of evidence indicates that riparian vegetation composition, structure, 

distribution, and function are closely tied to ongoing dam operations (Butterfield and others, 

2020; Butterfield and others, 2018). For the purposes of this framework, ‘riparian vegetation’ is 
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defined to include all plants found within the fluctuating, new high water, old high water, and 

pre-dam flood terrace hydrologic zones of the mainstem Colorado River within GRCA. 

Operations under the 1996 ROD (i.e., Modified Low Fluctuating Flow) facilitated the 

recruitment, establishment, and expansion of native and non-native plant species (e.g. 

arrowweed, tamarisk spp.) throughout the river corridor (Sankey and others, 2015). Despite this 

overall expansion of riparian vegetation, Goodding’s willow and fluvial marshes are in decline 

and cottonwoods continue to be rare (Kearsley and Ayers, 1996; Mast and Waring, 1997). 

Furthermore, a recent analysis of vegetation data collected by GRCA from 2007-2010 

demonstrated an overall increase in non-native plant cover, particularly in the new high water 

zone (i.e., < ~35,000 cfs) (Zachmann and others, 2012). Although the previous Modified Low 

Fluctuating Flow operations did not exceed 25,000 cfs aside from High Flow Events (i.e., ~ 

45,000 cfs), the recruitment and growth of native and non-native plants species above the 

associated stage elevation are affected by normal operations through its influence on water table 

levels and other environmental conditions (Ralston and others, 2014). 

The project includes targeted non-native vegetation removal and other vegetation management 

actions at important sites within the CRE to mitigate and manage the predicted increases in nonnative plants at specific locations. It will also include native species replanting. Key native 

species such as Goodding’s willow have decreased due to dam operations and other factors such 

as beaver herbivory (see LTEMP EIS Sections 3.6.2 and 3.7.4; U.S. Department of Interior, 

2016a). Experimental restoration of Goodding’s willow and other species at a limited number of 

suitable locations could increase and maintain these species in Glen, Marble, and Grand 

Canyons. Dam operations have led to encroachment of vegetation into open sand beach areas 

that are desirable for camping, as well as erosion in some areas requiring shifting of camping 

areas. Targeted removal of vegetation in these areas may assist with maintaining the carrying 

capacity of the river corridor for camping. Additionally, encroaching plant cover on beaches has 

led to reduced wind transport of sediment that has and could continue to protect archeological 

resources. Targeted experimental removal of vegetation in these areas will mitigate these effects 

and have benefits for cultural resource protection.

Non-flow vegetation treatment and mitigation downstream of Glen Canyon Dam fulfill mandates 

of the Grand Canyon Protection Act which specifies protecting, mitigating and improving 

resource conditions, in this case vegetation, within Grand and Glen canyons. This type of work 

does not set a precedent for the Bureau of Reclamation or the federal government as a whole 

below other dams because the requirements of the Grand Canyon Protection Act are unique as 

they are applied to operations of Glen Canyon Dam alone.

Several Glen Canyon Dam Adaptive Management Working Group (AMWG) stakeholders 

including Tribes, environmental groups and Colorado River Energy Distributors Association 

(CREDA) originally proposed a non-flow vegetation treatment project as part of the LTEMP. 

CREDA proposed vegetation work including the campsite clearing projects, because the work 

would mitigate, to a degree, the loss of open sand areas and retain camping beaches. Discussions 

between NPS and Hualapai Tribe during the LTEMP consultation indicated great interest in a 

shared project along the river corridor to target similar areas of importance to the Hualapai. 

Discussions with Zuni leaders also indicated great interest in this project and desire to be 

consulted and potentially to have Zuni community members help on the ground with restoration 
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work. For these reasons, the ROD specifically included the statement, “NPS will work with 

Tribal partners and GCMRC to experimentally implement and evaluate a number of vegetation 

control and native replanting activities on the riparian vegetation within the Colorado River 

Ecosystem in GCNP and GCNRA.” NPS has conducted meetings each year with Tribes to 

discuss project areas, seek input on locations where conflicts or priorities might be present for 

Tribes and to have discussions with Tribes to find ways to encourage involvement from Tribal 

members and volunteers. NPS continues to consult with Tribes with specific interests in 

vegetation work for restoring native plants and for those sites where protection of archeological 

sites might be targeted.

 

This vegetation project is experimental and adaptive in nature and it is important that on-theground work with monitoring continues with GCMRC to critically assess and improve 

effectiveness and efficiency. 

GCMRC Coordination Specifics (updated for Fiscal Year 2021-Fiscal Year 

2023)

NPS will coordinate closely with GCMRC on this project. GCRMC projects C.4 and D.1 of the 

Glen Canyon Dam Adaptive Management Program Triennial Work Plan for Fiscal Years 2021 – 

2023 (FY21-23 GCDAMP TWP) provide for the GCMRC’s coordination with NPS and tribal 

partners in developing the scientific design, project site selection, implementation and 

monitoring protocols for the experimental vegetation treatments. During this triennial plan 

period, NPS and GCRMC will continue to develop and implement experiments that evaluate 

techniques for campsite clearing (GRCA), native species replanting (GLCA, GRCA), and 

invasive plant removal (GLCA, GRCA). Additionally, experiments developed in collaboration 

with GCMRC examining whether and how vegetation removal from sandbars affects cultural 

resources and sediment dynamics will continue (see GCMRC TWP D.1). The intent of these 

evaluations is to identify the most effective and environmentally-sensitive methods to achieve 

the LTEMP ROD principle elements. This will allow for an adaptive management approach to 

adopt more efficient approaches over time. 

Coordinated activities would include removal of selected plant species of concern at targeted 

sites and subreaches (e.g., live and dead tamarisk, arrowweed), replanting of native species at 

targeted sites, and ongoing monitoring of treatment areas. GCMRC project D.1 also provides a 

formal experimental design for evaluating if vegetation removal increases the probability of 

“preservation in place” of archaeological sites near high-flow experiment (HFE)-sediment 

supplied sand bars, including site selection and pre- and post- treatment data collection. This 

experiment provides the connection for how other LTEMP experiments such as spring, fall or 

extended HFEs relate to the vegetation work (as HFEs would be predicted to increase sediment 

at the strategic sandbar locations identified and then be available to be blown by wind to cover 

archeological sites). This experiment includes appropriate monitoring and controls to determine 

how much benefit to the covering of cultural sites actually accrues from such vegetation 

removals; the monitoring methods for evaluating the effectiveness of the experimental vegetation 

treatments are described in detail in GCMRC project D.1 and thus readers are referred to that 

document. 
Provisional – do not cite. 13

Additional funds are available to provide outreach and coordination with Tribes by the 

NPS/GLCA for FY2020-21. In addition, GCMRC projects C.1, C.2, C.3 and L contribute to the 

NPS vegetation work in the following ways. Project C.1 provides riparian vegetation monitoring 

data between Glen Canyon Dam and River Mile (RM) 240, which can be used to prioritize 

treatment areas and identify sources of native species for propagation. Project C.2 proposes to 

conduct manipulative experiments on hydrological tolerances of riparian species of interest, 

which can be used to inform species used for planting, locations of plantings in relation to 

surface flows, and anticipated responses of removed plants. Project C.3 proposes to develop 

predictive models of vegetation responses to flows using existing data from many sources, 

including data derived from the LTEMP non-flow vegetation experiments described here. These 

models can be utilized to develop planting and removal plans to increase treatment success. 

Project L will provide aerial image base maps for planning and navigating purposes, as well as 

spatial data sets that will contribute to project evaluation. 

The GCMRC and NPS will collaborate on quality control and data management measures to 

detect and repair data issues. For example, the NPS and GCMRC will require peer review of 

potential publications prior to release. Data integrity will be verified near the end of each fiscal 

year.

NPS Vegetation Planning and Specifics

NPS has undertaken extensive non-native plant control efforts throughout the Colorado River 

corridor, which contains over 100 non-native plant species. NPS focuses non-native plant 

management activities on those species that pose a high threat to park resources (i.e., those that 

are highly invasive and disrupt ecosystem function), and ones with a high potential for successful 

control. An Integrated Pest Management (IPM) approach is used that includes a combination of 

cultural, manual, mechanical, and chemical treatments. The program aims to control existing 

populations, prevent new introductions, promote hands-on stewardship, and educate the public. 

A comprehensive annual work plan, tied to the GRCA Exotic Plant Management Plan 

Environmental Assessment (National Park Service, 2009), guides field activities in GRCA. 

While significant resources have been focused on the control of tamarisk in side canyons, work 

along the mainstem has primarily focused on other non-native species, and has ranged from 

removal of isolated individuals (e.g., Ravenna grass, Russian olive) to systematic removal of 

target species at selected sites (e.g., camelthorn, Russian thistle) using both NPS crews and 

volunteers (e.g., ‘Adopt-A-Camp’ Program). In addition to activities covered under the GRCA 

Exotic Plant Management Plan Environmental Assessment (2009), a number of additional 

riparian rehabilitation treatments in the river corridor have been tested at Granite Camp and Soap 

Creek, under the Pilot Project to Rehabilitate Native Riparian Community at Granite Camp, 

Programmatic Categorical Exclusion for River and River Accessible Site Maintenance (2011-

2016) and Programmatic Categorical Exclusion for FY15-FY20 Vegetation Program 

Programmatic Activities. These include, but are not limited to, the selective control and removal 

of tamarisk, selective control and removal of native plant species encroaching on campsites (e.g., 

arrowweed), collection and propagation of native plant materials, installation of monitoring 

transects, and active planting and seeding of native plant species within both the new and old 

high water zones. 
Provisional – do not cite. 14

Within GLCA, an EA exists for the Lees Ferry, Lonely Dell and river corridor areas from 

approximately RM -1 to RM +2 which covers non-native plant control and restoration efforts. 

There are also an Integrated Pest Management Plan and a Colorado River Riparian Revegetation 

Plan for GLCA (GGCWC, 2008; NPS 2019). Prioritized sites are included in park documents for 

the upstream river corridor covering non-native plant control and restoration, archaeological site 

protection, wildlife habitat enhancement, infrastructure and recreation sites.

Although NPS has not actively introduced biological control agents into GRCA and GLCA as 

part of its IPM approach, the tamarisk leaf beetle and splendid tamarisk weevil (Coniatus spp.) 

have naturally dispersed throughout the river corridor from outside of both parks and are actively 

defoliating tamarisk. The extent of subsequent mortality and associated impacts on riparian 

ecosystem patterns and processes remain to be seen, but is likely to be significant given those 

that have occurred in the Upper Colorado River Basin where these agents have been active for a 

longer period of time (National Park Service, 2012 and references therein). This may include the 

degradation and loss of riparian habitat (e.g., structure and shade currently provided by tamarisk, 

fire risk posed by dead/dying tamarisk), which may necessitate replacement with native 

vegetation (e.g., Fremont cottonwood, Goodding’s willow) to maintain or enhance current levels 

of native biodiversity. 

It is anticipated that the full suite of treatments outlined above, as well as other methods, will be 

required to mitigate the direct and indirect impacts of LTEMP dam operations on the riparian 

community within the Colorado River corridor in GLCA and GRCA. Thus, work will include 

ongoing monitoring and removal of isolated non-native plants, systematic removal of nonnatives at targeted sites, and full-scale restoration at targeted sites and sub-reaches which may 

include wholesale removal of tamarisk (both live and dead) and revegetation with natives. 

Treatments will fall into two broad categories: the control of non-native and encroaching native 

plant species, and revegetation with native plant species. Table 1 provides a summary of priority 

non-native species for control. Non-flow actions may also serve to facilitate an increase in the 

abundance and/or distribution of specific native plants that are currently underrepresented in the 

corridor (e.g., Goodding’s willow), may provide replacement habitat in the wake of tamarisk 

mortality (e.g., tree species), and/or are otherwise desirable to meet management objectives like 

providing barriers to sensitive sites. Some of these species may only be appropriate to encourage 

within limited areas that are likely to support self-sustaining populations and otherwise meet 

specific management objectives. Conversely, there are some native species (e.g., arrowweed) 

that are currently interfering with meeting management objectives (e.g., open sand beaches) and 

that thus should be systematically disfavored by non-flow management actions. Specific priority 

native species to target are yet to be determined; that decision will be made on a site by site 

basis.
Provisional – do not cite. 15

Table 1: Priority non-native species for control within the Colorado River Corridor 

Scientific Name Common Name

Acroptilon repens 

Alhagi maurorum

Brassica tournefortii 

Convolvulus arvensis 

Cortaderia selloana

Echinochloa crus-galli

Eragrostis curvula

Elaeagnus angustifolia

Lepidium latifolium

Malcolmia africana

Phoenix dactylifera

Saccharum ravennae

Salsola tragus

Schedonorus phoenix

Sisymbrium altissimum

Sisymbrium irio

Sonchus asper

Sonchus oleraceus 

Tamarix aphylla

Tamarix spp.

Tribulus terrestris

Ulmus pumila

Non-native Phragmites australis

Russian knapweed 

camelthorn

Sahara mustard

field bindweed

Pampas grass

barnyardgrass

weeping lovegrass

Russian olive

perennial pepperweed

African mustard

date palm

Ravenna grass

Russian thistle

tall fescue

tumble mustard

London rocket

spiny sowthistle

common sowthistle 

athel

tamarisk/salt cedar

puncturevine 

Siberian elm

Reedgrass – a small amount of this mostly 

native species at Lees Ferry may be the invasive 

form

Potential actions are outlined below in Table 2. Details of current invasive plant treatment 

methods on a species-specific basis can be found in the GRCA Exotic Plant Management EA

(2009) and tiered annual work plans as well as Grand Canyon Wildlands Council (2008). New or 

additional management methods would be subjected to further review and will have to be 

detailed under subsequent compliance. Revegetation actions will solely be focused on 

ecologically appropriate species that will (typically) be sourced from an appropriate provenance. 

Collection provenances will be determined on a species by species basis using results from a 

population genetic study funded by GRCA and conducted by GCMRC and Northern Arizona 

University (NAU) (Palmquist et al. 2021; U.S. Department of the Interior, 2017). Regardless of 

treatment type, the scope of all non-flow actions will encompass multiple components including 

planning, implementation, maintenance, monitoring, outreach, education, and administration. 

They may also range from small-scale, ad hoc, control efforts to large-scale restoration projects 

that will necessitate significant resources. While activities falling within the scope of the former 

are covered under existing compliance documents as referenced above, activities falling within 

the scope of the latter will require additional compliance that will need to be covered under the 

LTEMP EIS or separately, as appropriate. 
Provisional – do not cite. 16

Table 2: Riparian vegetation treatments 

Treatment 

Category

Treatment 

Type

Methods 

Invasive Plant 

Management

Cultural Prevention (e.g., education/outreach), smother (e.g. plastic), mulch, spot 

burn, plant natives (e.g. to form dense cover, see below)

Invasive Plant 

Management

Mechanical/ 

Manual

Prune, cut, pull, winch, dig, hoe (e.g., using hand or power tools); dispose 

(e.g., scatter, pile, burn, dump in river) (may include removal of 

live/dying/dead tamarisk)

Invasive Plant 

Management

Chemical Herbicide applications (e.g., spot spray, basal bark application, treat cut 

stumps, hack and squirt methods)* 

Invasive Plant 

Management

Biological Biological control agents (i.e., already established for tamarisk)

Revegetation Cultural, 

Mechanical/ 

Manual

Propagule collection, storage, propagation, and transportation (incl. seeds, 

cuttings, poles, whole plants utilizing boats and/or helicopters); planting 

(e.g., broadcast seed, pole/pot plant); mulching; carbon 

augmentation/fertilizing; wildlife barriers; watering 

*In 2020, Pueblo of Zuni expressed the desire to consult further with the park units on herbicide 

applications so NPS is following up with them.

Project Treatment Areas

As stated above, specific project treatment areas would be selected on an annual basis through 

coordination with Tribes and GCMRC. See the section above for how GCMRC assists 

specifically with projects under the current triennial budget. The NPS establishes Priority 

Treatment Areas (PTAs) each year in coordination with partners (specifically Tribes and 

GCMRC, but NPS is trying to increase input from other partners such as river guides) in advance 

to delineate areas within the river corridor that would be considered for treatment first. The 

treatment areas are generally small project areas along the river chosen based on consideration of 

how many of the project goals can be fulfilled at the site, based on the likelihood of success 

given goals at the specific site. These areas are also chosen based on the logistics of the river 

missions planned for the given year and taking into account priorities and concerns from Tribes 

and input from staff and other stakeholders regarding the recreational value of given sites. The 

scale of these project areas is generally less than 10 acres rather than a larger reach-scale given 

the limitations of budget and river mission/work crew logistics. Attachment C lists the 

experimental vegetation treatments applied in GRCA and GLCA between FY2019 and FY2020, 

and Attachment D lists the experimental vegetation treatments planned for GRCA and GLCA in 

FY2021. 

 

Many of the originally identified sites were selected based on a GIS analysis in coordination with 

GCMRC using a number of spatial layers (i.e., criteria) that intersect, such that areas (i.e., sites 

or reaches) with more coincident layers are given a higher priority, noting that individual criteria 

are not weighted in this preliminary analysis (see Table 3). Prioritization criteria are detailed in 

Table 3 and the results of this preliminary spatial analysis are depicted in Figure 1. A number of

criteria (denoted with an asterisk in Table 3) depend upon GIS datasets that are currently under 

development, while many of the other criteria are highly variable over space and time (e.g., 
Provisional – do not cite. 17

tamarisk defoliation/mortality). These datasets will require updating over time, but also groundtruthing or flexibility to alter sites based on field findings prior to actual treatment. As the project 

has evolved, the extensive site knowledge of staff from NPS and GCMRC has helped refine the 

GIS data and the prioritization based on the combined quantitative and qualitive data sources in

the bulleted criteria listed below.

The general criteria used to select project sites are:

1. Does the site fulfill multiple objectives? This evaluation is done using a simple additive 

score for each objective, including recreation issues (e.g., campsite encroachment, visitor 

use), infrastructure, invasive non-native plant species present, cultural resource issues, 

wildlife species presence and available data (legacy data, primarily from bird surveys), 

and logistics.

2. Does the site fit with river logistics (is the site accessible, how large is the area from a 

work-crew perspective, in a broader vs. more narrow reach, etc.)?

3. No conflicts with cultural protection or concerns from Tribes.

Specific additional criteria are listed in Table 3, but below is a bulleted list of what is considered 

in the site selection specifically by category using a variety of quantitative and qualitative 

information: 

1. Control nonnative plant species affected by dam operations, including tamarisk and other 

highly invasive species

1. GLCA is targeting tamarisk, but not in heavily used recreation areas due to 

conflicts with visitor use, and is looking for sites of a reasonable size to fit budget 

constraints. GLCA is also targeting dead tamarisk presenting a fire risk.

2. GRCA targets invasive plant species (Russian olive, ravennagrass, 

camelthorn, 

etc., as reflected in Table 1.) that are high priorities in the GRCA Exotic Plant 

Management Plan (2009). This list is adapted further to target those species and 

areas that are being affected most by dam operations and/or for protection of 

resource values (for example habitat for southwestern willow flycatcher (SWFL), 

northern leopard frog [Lithobates pipiens], etc.) or in combination with native 

replanting sites. 

2. Replant native plant species at priority sites along the river corridor, including native 

species of interest to Tribes

1. GLCA targets areas that do not have heavy recreation use, that do have a diverse 

set of native species already present and can be used for replanting. GLCA 

incorporates plants of tribal interest as appropriate based on input from the Tribes. 

An emphasis on testing a variety of native species is being implemented, 

including Goodding’s willow, pallid hoptree (Ptelea trifoliata ssp. pallida), 

Apache plume (Fallugia paradoxa) and stretchberry (Forestiera pubescens). 

2. GRCA targets sites where they can build on past native replanting efforts, areas 

that benefit federally listed species, and areas where tamarisk is declining based 
Provisional – do not cite. 18

on beetle mortality. Accessibility is another criterion particularly important for 

replanting sites. 

3. Remove vegetation encroaching on campsites

1. GRCA maintains a list of known campsites that identifies those that have 

encroachment where treatment would result in reclaiming campable area. 

2. NPS staff and GRCMC staff have provided additional updated information. 

3. GRCA is trying to increase input from river guides on additional sites. 

4. GLCA sites typically do not have vegetation encroachment issues.

4. Manage vegetation to assist with cultural site protection

1. GCMRC recommends sites to NPS based on a review of the known 

archaeological sites combined with historical information about vegetation 

encroachment, beach building potential, site specific wind direction information 

and availability of existing monitoring data (part of the GCMRC triennial project 

D-1). 
Table 3: Criteria for Priority Treatment Areas (how these are used may vary depending on which of 

the four treatment types are being considered)

Category Variable Value Data Source Rationale

Ecological

Geomorphic 

reach

Width 

(reach by RM)

GLCA and 

GRCA Park 

Areas

Support larger and more diverse 

patches of riparian vegetation and 

wildlife habitat compared to 

narrow reaches so treatments can 

be implemented at an ecologicallysignificant scale.

Ecological Tamarisk 

defoliation

Height

(degree by RM)

GLCA, GRCA et. 

al. Tamarisk 

Beetle 

Monitoring; 

Bedford and 

others, 2018

Areas requiring proactive 

replacement of habitat where 

tamarisk beetle/weevil defoliation 

and flows will create mortality or 

fire risk. Mortality may be directly 

measured in future surveys. 

Ecological Proximity to 

non-native plant 

sources

RM -15 to +21; GCMRC River 

Miles

Includes approx. range of 

known/potential upstream/tributary 

sources (e.g. GLCA, Paria, North 

Canyon) of highly invasive plant 

species (e.g. Russian olive, 

puncturevine) where aggressive 

control can limit downstream 

spread.

Ecological Southwestern 

Willow 

Flycatcher 

habitat

Suitable/potential 

habitat (sites by 

RM)

GRCA et al. 

SWFL Surveys; 

Hidden Slough 

Restoration 

Project

Sites where SWFL have been 

historically detected or nested and 

where habitat suitability may be 

improved through proactive 

vegetation treatments. 

Ecological Vegetation 

classification*

Tamarisk spp. 

Ruderal Scrub 

Alliance 

(presence)

GRCA 

Vegetation Map; 

Durning and 

others, 2018

Pending derivation from GRCA 

vegetation map classification and 

modeled states; extent is dependent 

upon which model time-step is 

chosen (i.e. t0-tx, see text). Actual 

work will be guided by future 

vegetation survey results.

Ecological Native species 

richness*

High 

(# of spp.)

GRCA CRMP, 

GCMRC 

Vegetation 

Monitoring Data, 

GLCA data; 

Palmquist and 

others, 2018

Areas with higher native flora and 

fauna richness that are threatened 

by non-native competition. 

Ecological Sources of 

native woody 

species*

Large populations 

(# of individuals) 

GRCA CRMP, 

GCWC, 

GCMRC, GLCA, 

SEINet, Phillips 

and others, 1987; 

Palmquist and 

others, 2018

Areas (incl. mainstem /tributaries) 

with relatively large/sustainable 

populations for potential pole 

cuttings of key native woody spp. 

used for revegetation (e.g. 

Goodding’s willow, Fremont 

cottonwood, coyote willow). 

Treatment sites within reasonable 

proximity of downstream sources 

would be prioritized due to local 
Provisional – do not cite. 20

provenance and easier 

transport/feasibility.

Recreational Campsite use 

level

High or Low

(depending upon 

which type of 

treatment – based 

on frequency of 

being occupied)

GLCA data; 

GRCA CRMP 

Use levels at CRMP sites (n = 66) 

are associated with higher levels of 

non-native cover and potentially 

higher levels of disturbance and 

seed vectors. Treatments would 

also enhance visitor experience.

Recreational Vegetation 

encroachment*

High 

(% incr. from t0-x) 

GRCA CRMP, 

NAU/GCMRC; 

Hadley and 

others, 2018b; 

Palmquist and 

others, 2018

Campsites with high levels (esp. 

arrowweed) limit areas for 

camping and open sand habitat. 

Cultural Dune stability* High 

(vegetative cover 

on sandbars)

GCMRC/USGS; 

East and others, 

2016; East and 

others, 2017

Sites where vegetation 

encroachment is limiting aeolian 

transport of sediment from 

sandbars to sensitive archeological 

sites.

Cultural Social trails* High 

(#)

GRCA CRMP; 

GLCA cultural 

studies 

Campsites with social trails that 

lead from NHWZ into OHWZ 

areas with sensitive archeological 

sites could be 

revegetated/obliterated to limit 

access. Pending further 

consultation.

Cultural Tribal 

significance

High (categorical) Tribal 

representatives

It is recognized that specific sites 

and/or species have tribal 

significance that may not be 

adequately represented by other 

criteria.

Feasibility Proximity to 

boat launches

Glen Canyon (RM 

0 to -15,) Lee’s 

Ferry (RM 0-11), 

Diamond Creek 

(RM 205-231), 

Pearce Ferry (RM 

232-279)

GRCA, GCMRC Reaches where motorboat up/down 

runs are safe/feasible (pending 

river levels/rapid rating) to support 

more logistically practical and 

cost-effective projects.

Feasibility Trail 

accessibility

Campsites 

accessible by 

hiking trails 

(presence)

GRCA Trails Campsites accessible by foot 

provide additional access options 

and potential reduced costs 

compared to those only accessible 

by river.

* Denotes variables that are contingent upon future deliverables and/or warrant further analysis and are 

therefore not currently included in this preliminary prioritization.

Riparian – Subject to Glen Canyon Dam Influence

Desired Condition

The diversity, quality, abundance and distribution of riparian habitats in the Colorado River corridor is 

maintained at or above the levels found in Grand Canyon in surveys prior to the passage of the Grand 

Canyon Protection Act (U.S. Department of the Interior, 1992). Patches of vegetation dominated by 

native species occur in stands at a range of elevations below the pre-Glen Canyon Dam high water 
Provisional – do not cite. 21

mark. The high levels of native diversity and productivity of these patches is maintained by access to 

water and nutrients from the hyporheic zone. Wildlife populations, including mammal, avian, 

herpetofauna and arthropod, are supported in these riparian habitats and sustained at levels that 

contribute to a functioning community.

 

Periodic disturbance in the form of flooding and sediment deposition cause turnover of individuals and 

patches with a frequency that decreases with elevation above the level of base flow. High flows reach 

levels similar to pre-dam flows rarely. System-wide productivity and diversity are occasionally 

reduced due to longer-term disturbance from reduced annual flow volumes or extended droughts, but 

disturbance from human activities, including trampling of vegetation, broken branches, disturbance of 

soil crusts, etc., is maintained at or below levels of impairment. Tables 4 and 5 indicate the desired 

conditions per experimental vegetation treatments within GRCA and GLCA. 

Table 4: Desired Conditions per Experimental Vegetation Treatments within GRCA

Experimental 

Vegetation Treatment 

Reference

Condition

Annual Goals 20-Year Goals Desired 

Condition

Control nonnative plant 

species affected by dam 

operations, including 

tamarisk and other highly 

invasive species 

Tamarisk cover 

in GRCA 

riparian area

(Lees Ferry, 

rm. 0 to Pearce 

Ferry, rm 280)

at start of 

LTEMP ROD 

2016 = 105.79

ha and 16.36% 

of the total 

riparian 

vegetation 

(Durning et al., 

2018). 

Control nonnative 

plant species 

affected by dam 

operations at 30 to 

40 sites where

habitat degradation 

is evident since the 

implementation of 

the LTEMP ROD 

2016; which 

includes treatment 

of 5,500 to 11,000 

plants; and covers 

38,000 m^2 (9.39

acres) to 76,000

m^2 (18.78 acres).

To maintain or 

decrease the cover 

of tamarisk 

(relative to the 

reference 

condition) and 

other nonnative 

plant species at 40 

to 50 sites. 

Minimize cover 

of tamarisk 

(relative to the 

reference 

condition) and 

other nonnative 

plant species at 

40 to 50 sites, 

while also 

sustaining desired 

native-dominated 

riparian plant 

communities that 

are diverse, 

healthy, 

productive, selfsustaining, and 

ecologically 

appropriate. 

Develop native plant 

materials for replanting 

through partnerships and 

the use of regional 

greenhouses 

The restoration 

of native 

plants...will be 

accomplished 

using 

organisms 

taken from

populations as 

closely related 

genetically and 

ecologically as 

possible to park 

populations,

Develop native 

plant materials for 

replanting by 

establishing and/or 

maintaining one or 

more partnerships 

through agreements 

and/or contracts for 

production of ≥

20% of target plant 

materials. ≥

Partnerships will 

account for a 

minimum of 20% 

(≥ 5% will include

plant species of 

interest to Tribes)

of all plant 

materials

developed for 

native plant 

restoration actions. 

Establishment of 

successful 

partnerships

capable of

producing healthy 

and vigorous 

native riparian 

plant species that 

are genetically 

appropriate, 

adapted to on-the 

-ground 

ecological 
Provisional – do not cite. 22

preferably from 

similar habitats 

in adjacent or 

local areas 

(NPS 2006b).

5% of partnership 

plant production 

will include plant 

species of interest 

to Tribes.

conditions, and 

include species of 

interest to Tribes.

Replant native plant 

species at priority sites 

along the river corridor, 

including species of 

interest to Tribes 

Coyote Willow 

= 5.73 ha and 

0.89% of the 

total riparian 

vegetation 

Fremont 

Cottonwood = 

0.46ha and 

0.07% of the 

total riparian 

vegetation 

Netleaf 

Hackberry = 

2.90 ha and 

0.45% of the 

total riparian 

vegetation. 

(Durning et al., 

2018). 

Increase the cover 

of desirable native 

riparian plants 

relative to the 

reference condition 

by planning for 

and/or 

implementing 

native plant 

restoration actions 

at ≥ 1 site. Which 

include plant 

species (≥ 10% of 

out-planted 

material) of interest 

to Tribes, and 

restoration actions 

designed to benefit 

≥ one federally 

listed wildlife 

species (e.g.,

Southwestern 

willow flycatcher). 

Increase the cover 

of desirable native 

riparian plants

(e.g., willow, 

cottonwood, and 

baccharis) relative 

to the reference 

condition at 3 to 5 

sites. 

Increased cover 

of desirable 

native riparian 

plants (e.g., 

willow, 

cottonwood, and 

baccharis)

relative to the 

reference 

condition, and as 

represented by the 

Populus fremontii 

– Salix 

gooddingii 

Woodland 

Alliance

(Kearsley et al. 

2015). 

Remove vegetation 

encroaching on campsites 

At start of 

LTEMP ROD 

2016 the 37 

long-term

campsite 

monitoring 

locations 

(surveyed 

annually by 

GCMRC/NAU)

had a total 

campsite area 

of 10,000 m^2

and campsite 

area was 

estimated to be 

decreasing 

annually at a 

rate of 432 

m^2/year 

owing to 

vegetation 

encroachment 

Remove vegetation 

encroaching on 

campsites at 10 to 

20 sites where 

ongoing vegetation 

encroachment since 

the implementation 

of the LTEMP 

ROD 2016 is 

decreasing 

campable area; 

which includes 

treatment of 2,640

to 5,280 plants; and 

covers 23,856 m^2 

(5.89 acres) to 

47,712 m^2 (11.78 

acres). 

Manage vegetation 

encroaching on 

campsites to a 

desirable state at 30 

to 50 sites. 

To maintain or 

increase (relative 

to the reference 

condition) the 

total number of 

sites where 

campable area is 

increasing such 

that the long-term 

trend in such sites 

post-2016 is 

neutral or 

positive.
Provisional – do not cite. 23

(Hadley et al., 

2018). 

Manage vegetation to 

assist with cultural site 

protection 

At start of 

LTEMP ROD 

2016, 32 of the 

358 river 

corridor 

archaeological 

sites had an 

adjacent, 

upwind, 

sandbar with no 

substantial 

barriers of 

riparian 

vegetation to 

impede aeolian 

sand transport 

from the 

sandbar toward 

the 

archeological 

site, and the 

number of such 

sites was 

estimated to be 

decreasing

(e.g., by 7 sites 

during the 

preceding 

decade) owing 

to vegetation 

encroachment

(East et al., 

2016).

Manage vegetation 

to assist with 

cultural site 

protection at 5 to 

10 sites where 

ongoing vegetation 

encroachment since 

the implementation 

of the LTEMP 

ROD 2016 is 

creating vegetation 

barriers that 

impede aeolian 

sand transport; 

which includes 

treatment of 4,500 

to 9,000 plants; and 

covers 14,37500 

m^2 (3.55 acres) to 

28,750 m^2 (7.10

acres). 

Manage vegetation 

to mitigate the 

growth of 

vegetation barriers 

to aeolian transport 

at the 32 sites 

identified in the 

reference 

condition.

To maintain or 

increase (relative 

to the reference 

condition) the 

total number of 

sites with no 

substantial 

barriers of 

riparian 

vegetation that 

impedes aeolian 

sand transport 

from the sandbar 

toward the 

archaeological 

site such that the 

long-term in such 

sites post-2016 is 

neutral or 

positive.
Provisional – do not cite. 24

Table 5: Desired Conditions per Experimental Vegetation Treatments within GLCA

Experimental 

Vegetation Treatment 

Reference 

Condition

Annual Goals 20-Year Goals Desired 

Condition

Control nonnative plant 

species affected by dam 

operations, including 

tamarisk and other highly 

invasive species 

Tamarisk cover 

in GLCA 

(GCD Dam at 

RM -15.5 to 

mouth of Paria 

at RM 0). 

Several stands 

are greater than 

5 acres in size 

with sporadic 

stands along 

the entire 

reach.

Control nonnative 

plant species 

affected by dam 

operations at 2 to 5 

sites with habitat 

degradation 

evident since 

implementation of 

the LTEMP ROD 

2016; this includes 

treatment of stands 

with up to 5,000 

plants; on 1 to 5 

acre areas scattered 

along reach.

To maintain or 

decrease the cover 

of tamarisk 

(relative to the 

reference 

condition) and 

other nonnative 

plant species at 5 to 

10 of the highest 

priority sites.

Minimize cover 

of live, decadent, 

& dead tamarisk 

(relative to 

reference 

condition) and 

other priority 

nonnative plant 

species at 5 to 10 

sites, while 

replanting/ 

sustaining desired 

native-dominated 

riparian plant 

communities that 

are diverse, 

healthy, 

productive, selfsustaining, and 

ecologically 

appropriate.

Develop native plant 

materials for replanting 

through partnerships and 

the use of regional 

greenhouses 

The restoration 

of native 

plants...will be 

accomplished 

using 

organisms 

taken from 

populations as 

closely related 

genetically and 

ecologically as 

possible to 

park 

populations, 

preferably 

from similar 

habitats in 

adjacent or 

local areas 

(NPS 2006b).

Develop native 

plant materials for 

replanting by 

maintaining a 

partnership through 

agreement with the 

Page School 

District or contracts 

for production of ≥ 

50% of target plant 

materials. All plant 

production will 

focus on native 

plant species 

including 

Traditional Use and 

other plants of 

interest to Tribes.

Partnerships will 

account for a 

minimum of 50%. 

All plant 

production will 

focus on native 

plant species 

including 

Traditional Use and 

other plants of 

interest to Tribes.

Continuance of 

successful 

partnership 

capable of 

producing healthy 

and vigorous 

native riparian 

plant species that 

are genetically 

appropriate, 

adapted to on-the 

-ground 

ecological 

conditions, and 

include species of 

interest to Tribes.

Replant native plant 

species at priority sites 

along the river corridor, 

including species of 

interest to Tribes 

Coyote willow, 

Goodding’s 

willow, 

Fremont 

cottonwood, 

and netleaf 

hackberry will 

Increase the cover 

of desirable native 

riparian plants 

relative to the 

reference condition 

by planning for 

and/or 

Increase the cover 

of desirable native 

riparian plant 

species (e.g., 

willow, 

cottonwood, and 

hackberry) relative 

Increased cover 

of desirable 

native riparian 

plant species 

(e.g., willow, 

cottonwood, and 

hackberry) 
Provisional – do not cite. 25

comprise 75% 

or more of the 

total riparian 

woody 

vegetation 

planted. An 

estimated 15 to 

25 total acres 

will be restored 

during the 

LTEMP 

period.

implementing 

native plant 

restoration actions 

at 5 to 10 sites 

which includes 

native woody plant 

species of interest 

to Tribes, and 

restoration actions 

designed to 

possibly benefit ≥ 1 

federally listed 

wildlife species.

to the reference 

condition at 5 to 10 

sites.

relative to the 

reference 

condition.

Remove vegetation 

encroaching on campsites 

At the start of 

LTEMP ROD 

2016 all GLCA 

campsites have 

decadent and 

dead stands of 

large tamarisk 

in and around 

the campsites. 

This safety and 

fire issue will 

be used to 

prioritize 

restoration 

sites.

Remove 

decadent/dead 

tamarisk vegetation 

in and around 3 to 

5 campsites over 

life of LTEMP 

plan.

Manage 

decadent/dead 

tamarisk vegetation 

at 3 to 5 sites.

Remove the 

safety and fire 

issues arising 

from 

decadent/dead 

tamarisk at all 

GLCA camp 

sites.

Manage vegetation to 

assist with cultural site 

protection 

GLCA will 

watch for 

opportunities 

where native 

vegetation 

plantings may 

be used to 

stabilize small 

eroding areas 

around cultural 

sites. River and 

bank dynamics 

do not allow 

for vegetative 

stabilization to 

protect cultural 

sites.

N/A N/A Use native 

vegetation 

plantings to 

stabilize small 

eroding areas 

around cultural 

sites. Overland 

flow and small 

gullies/headcuts 

will be the focus.
 Figure 1 - Priority Treatment Areas in GRCA. 
A detailed vegetation map and an accurate estimate of riparian vegetation from the dam to Lees 

Ferry was only recently published by GCMRC (Durning and others, 2018) and has not been used 

yet to guide restoration in GLCA. However, restoration planning includes approximately 12 high 

priority sites with approximately 200 acres of riparian vegetation. 

Monitoring

Monitoring for this project has been partially formal and partially informal and is still in 

development; however, NPS and GCMRC are committed to formalizing monitoring for this 

project during the 2021-2023 triennial workplan period. This will be either an additional 

attachment to this plan or a stand-alone monitoring plan. What follows is the beginning of the 

content that will be formalized in that ‘monitoring plan’ or attachment.

The second triennial workplan (U.S. Department of the Interior, 2017) provided for the planning 

for this project and allowed for two pilot seasons of work to be completed. We have learned a 

great deal from those projects. Collaboration between GCMRC and NPS is now moving into a 

new phase where more refined science research questions can be developed for specific aspects 

of treatment and we can further define what success looks like for our specific goals. 

Riparian monitoring includes elements of the Colorado River Management Plan (CRMP) 

Monitoring Program that is currently under revision (National Park Service, 2006a) and is 

coordinated with system-wide riparian vegetation monitoring conducted by GCMRC (GCMRC 

Project C.1; Palmquist and others, 2018) and other projects such as GCMRC Project D.1. 

Treatment methods used will conform with approved plans and methods in an environmentally 

appropriate manner and with consultation from the Tribes. Currently available monitoring 

approaches from the Escalante River Watershed may be utilized as a basis for the monitoring 

plan to be developed (Escalante River Watershed Partnership, 2015).

Science Research Questions 

Generally, these research questions are as follows (to be refined in the monitoring 

plan/attachment) and designed to achieve the five Project Objectives as described in Section 6.4 

of the LTEMP ROD (U.S. Department of Interior, 2016b): 

1. Control nonnative plant species affected by dam operations

1. Can targeted invasive species be effectively reduced or maintained using 

mechanical, chemical, cultural, and/or biological methods? 

2. Will adopted invasive plant control methods result in a net increase in native plant 

cover rather than reinvasion by previously controlled invasive or secondary 

invasive plants?

2. Replant native species to priority sites along the river corridor, including native species of 

interest to Tribes

1. Which species and methods most effectively result in the establishment and 

increase of desirable native species in treatment areas? 

2. Which native plant species perform best in differing environments, i.e., wide vs. 

narrow reaches, west vs. south orientations, coarse substrates vs. sand vs. silt, 

elevations above river level, etc.? 

3. Which plant species of tribal interest can most effectively be established and 

increased in treatment areas? 
Provisional – do not cite. 28

3. Remove vegetation encroaching on campsites

1. Can areas of bare sand be effectively maintained with mechanical, chemical, 

cultural, and/or biological methods? 

4. Manage vegetation to assist with cultural site protection 

1. Does removal of riparian vegetation located between HFE-sediment supplied sand 

bars and archaeologic sites increase the probability of preservation in place? 

Current Monitoring Approach

1. Control nonnative plant species affected by dam operations

1. Evaluating treatment success will occur on an annual basis for two years posttreatment, followed up by longer intervals. Methods will include the use of 

permanent photo points, species cover estimates, success of native replanting, and 

surveys to detect the presence of new invasive species. These methods will assist 

with evaluating treatment success and track plant community changes over time 

(Hall, 2002). Photos and vegetation data will be collected pre-treatment for use as 

a baseline comparison with later photos and vegetation data. If monitoring reveals 

that treatments were not effective additional invasive plant treatments will be 

implemented.

2. Replant native species to priority sites along the river corridor, including native species of 

interest to Tribes

1. Evaluating restoration success will occur on an annual basis for five years 

following active restoration and include monitoring of planted tree survivability, 

growth, success of seed broadcasting for upland species, and repeat photography. 

At the time of planting, data collections will include: tree height, canopy cover, 

diameter at breast height, planting method, and overall tree health. Each planted 

tree will be tagged with a unique number and global positioning system (GPS) 

coordinates will be recorded. Four permanent photo points will be established per 

restoration site. Photos will be taken from points prior to active restoration for use 

as a baseline comparison with later photos. Photo point monitoring will be 

conducted on an annual basis. If restoration is not progressing towards a later 

successional stage, additional restoration treatments (i.e. seeding, planting, 

erosion control, invasive non-native plant control, etc.) may be implemented. 

3. Remove vegetation encroaching on campsites

1. Success of vegetation treatments to increase campable areas will be evaluated 

annually through pre- and post-treatment data collections. At each target 

campsite, 16 transects radiating from the geographic center of the primary 

common area of the campsite will be installed at compass bearings of 0, 23, 45, 

68, 90, 113, 135, 158, 180, 203, 225, 248, 270, 293, 315, and 338 degrees 

(Cameron, 2014). GPS coordinates will be recorded for the center point. The 

following data will be recorded along each transect line pre- and post-treatment: 

distance to the first significant occurrence of vegetation that establishes the edge 
Provisional – do not cite. 29

of the campable open space, rock obstructions limiting the campable barren core, 

or the 25K cfs flow line of the river (Cole and Hall, 1992). Subsequent visits to 

each campsite for continued monitoring will attempt to relocate the center point 

previously used for establishing transects. Treatment success will be evaluated 

annually for 2 years post-treatment and the need for additional treatments will be 

assessed. This monitoring will be coordinated with the CRMP campable area 

annual measurements and with the annual GCMRC sand bar and campsite 

monitoring approaches (GCMRC projects B.1, C.1) of the FY21-23 GCDAMP 

TWP. 

4. Manage vegetation to assist with cultural site protection 

1. GCMRC project D.1 of the FY21-23 GCDAMP TWP provides a formal 

experimental design for evaluating if vegetation removal increases the probability 

of “preservation in place” of archaeological sites near HFE-sediment supplied 

sand bars, including site selection and pre- and post- treatment data collection. 

The monitoring methods for evaluating the effectiveness of the experimental 

vegetation treatments are described in detail in GCMRC Project D.1 and thus 

readers are referred to that document. 
Provisional – do not cite. 30

Funding and Budget

This project was approved for funding through the GCDAMP in the FY2021-FY2023 Triennial 

Budget. This project fits with the purpose and need for the LTEMP project, the environmental 

commitments specified in the LTEMP ROD, the August 2019 Memorandum from the Assistant 

Secretary, and finally and most importantly, with the intent of the Grand Canyon Projection Act 

to protect, mitigate and improve the resources downstream of the Glen Canyon Dam. It is 

allowed and intended to be funded as stated in the LTEMP ROD as an activity within the CRE; 

this project is mitigation identified in LTEMP as action within the CRE area influenced and 

affected by dam operations. Phases of the project are intended to start smaller with pilot projects 

and increase in size with each phase as more experience can be applied adaptively. Funding 

would be expected to be in the range of $200,000-$265,000 annually total for work within both 

NPS park units. The degree of funding allocated may vary to a degree between years based on 

the number of priority sites identified and their locations in particular reaches. 
Provisional – do not cite. 31

Figure 2. High priority restoration sites in GLCA. The sites are: blue square Ropes Trail at 

RM –14.5R; yellow rectangle is the Duck Slough at RM –12.0L, and the red square is 

Lunch Beach at RM –7.0L. 

Suggested Citation for this Plan:

National Park Service. 2021. Long Term Experimental and Management Plan Riparian

Vegetation Project Plan: For The Implementation Of The Vegetation Environmental 

Commitments From The LTEMP ROD in Glen Canyon National Recreation Area and Grand 

Canyon National Park Below Glen Canyon Dam. 
Provisional – do not cite. 32

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Zachmann, L.J., Horncastle, V., and Dickson, B.G., 2012, Colorado River management plan--

Research, monitoring, and mitigation program data analysis: Flagstaff, Northern Arizona 

University, The Lab of Landscape Ecology and Conservation Biology, School of Earth 

Sciences and Environmental Sustainability, 68 p.
Provisional – do not cite. 39

Attachment A: NPS Policies which guide this project

Selected sections of the NPS Management Policies (NPS 2006) relevant to this project include:

4.0 The Service manages the natural resources of parks to maintain them in an unimpaired 

condition for present and future generations in accordance with NPS-specific statutes, including 

the NPS Organic Act and the National Parks Omnibus Management Act of 1998

4.1 Natural resources will be managed to preserve fundamental physical and biological 

processes, as well as individual species, features, and plant and animal communities. The Service 

will not attempt to solely preserve individual species (except threatened or endangered species) 

or individual natural processes; rather, it will try to maintain all the components and processes of 

naturally evolving park ecosystems, including the natural abundance, diversity, and genetic and 

ecological integrity of the plant and animal species native to those ecosystems. Just as all 

components of a natural system will be recognized as important, natural change will also be 

recognized as an integral part of the functioning of natural systems. By preserving these 

components and processes in their natural condition, the Service will prevent resource 

degradation and therefore avoid any subsequent need for resource restoration. In managing parks 

to preserve naturally evolving ecosystems, and in accordance with requirements of the National 

Parks Omnibus Management Act of 1998, the Service will use the findings of science and the 

analyses of scientifically trained resource specialists in decision-making.

4.1.5 The Service will reestablish natural functions and processes in parks unless otherwise 

directed by Congress. [....] The Service will use the best available technology, within available 

resources, to restore the biological and physical components of these systems, accelerating both 

their recovery and the recovery of landscape and biological community structure and

function. Efforts may include, for example: removal of invasive non-native plant species, 

restoration of native plants and animals, etc.

4.4.2.4 Landscape and vegetation conditions altered by human activity may be manipulated 

where the park management plan provides for restoring the lands to a natural condition.

Landscape revegetation efforts will use seeds, cuttings, or transplants representing species and 

gene pools native to the ecological portion of the park in which the restoration project is 

occurring. Where a natural area has become so degraded that restoration with gene pools native 

to the park has proven unsuccessful, improved varieties or closely related native species may be 

used.
Provisional – do not cite. 40

Attachment B : GCD AMP FY21-FY23 Workplan

Bureau of Reclamation 

Glen Canyon Dam Adaptive Management Program Triennial Budget and Work Plan—Fiscal 

Years 2021–2023

C.7.-C.8. GRCA and GLCA Experimental Vegetation Treatment

As described in the LTEMP Record of Decision, experimental riparian vegetation treatment is 

included as mitigation for dam operations within the Colorado River Ecosystem (CRE). This 

work is also listed as a priority in the most recent DOI policy guidance memo to the GCDAMP, 

which was issued by the Assistant Secretary for Water and Science on August 14, 2019. 

Vegetation treatment actions on NPS managed lands will be implemented by NPS consistent 

with NPS Management Policies (NPS 2006) and consistent with the goals and objectives of 

LTEMP ROD. This will occur only within the CRE in areas that are influenced by dam 

operations. The NPS will work with tribal partners and GCMRC to plan, implement and evaluate 

a number of vegetation control and native replanting activities on the riparian vegetation within 

the CRE in Grand Canyon National Park and Glen Canyon National Recreation Area.

Principal elements of this experimental riparian vegetation proposal include:

1. Control nonnative plant species affected by dam operations, including tamarisk and other 

highly invasive species through various control methods;

2. Develop native plant materials for replanting through partnerships and the use of regional 

greenhouses;

3. Replant native plant species to priority sites along the river corridor, including native 

species of interest to Tribes:

4. Remove vegetation encroaching on campsites; and

5. Manage vegetation to assist with cultural site protection.

NPS will coordinate closely with GCMRC on this project. GCRMC projects C.4 and D.1 provide 

for the GCMRC’s coordination with NPS and tribal partners in developing the scientific design, 

project site selection, implementation and monitoring protocols for the experimental vegetation 

treatments. During this triennial plan, NPS and GCRMC will develop and begin implementing 

experiments that evaluate techniques for campsite clearing (GRCA), native species replanting 

(GLCA), and invasive removal (GLCA, GRCA). Additionally, experiments developed in 

collaboration with GCMRC examining whether and how vegetation removal affects cultural 

resources and sediment dynamics will continue (see GCMRC TWP D.1). The intent of these 

evaluations is to identify the most cost-effective and environmentally-sensitive methods to 

achieve the LTEMP ROD principle elements. This will allow for an adaptive management 

approach to adopt the more efficient approaches over time.
Provisional – do not cite. 41

Coordinated activities would include removal of selected plant species of concern at targeted 

sites and subreaches (e.g., live and dead tamarisk, arrowweed), replant of native species at 

targeted sites, and ongoing monitoring of treatment areas. GCMRC project D.1 also provides a 

formal experimental design for evaluating if vegetation removal increases the probability of 

“preservation in place” of archaeological sites near HFE-sediment supplied sand bars, including 

site selection and pre- and post- treatment data collection. This experiment provides the 

connection for how other LTEMP experiments such as spring, fall or extended HFEs relate to the 

vegetation work (as HFEs would be predicted to increase sediment at the strategic locations 

identified and then be available to be blown by wind to cover archeological sites). This 

experiment includes appropriate monitoring and controls to determine how much benefit to the 

covering of cultural sites actually accrues from such removals. Additional funds are available to 

provide outreach and coordination with tribes by the NPS/GLCA for FY2020-21. In addition, 

GCMRC projects C.1, C.2, C.3 and L contribute to the NPS vegetation work in the following 

ways. Project C.1 provides riparian vegetation monitoring data between Glen Canyon Dam and 

river mile 240, which can be used to prioritize treatment areas and identify sources of native 

species for propagation. Project C.2 proposes to conduct manipulative experiments on 

hydrological tolerances of riparian species of interest, which can be used to inform species used 

for planting, locations of plantings in relation to surface flows, and anticipated responses of 

removed plants. Project C.3 proposes to develop predictive models of vegetation responses to 

flows using existing data from many sources, including data derived from the LTEMP non-flow 

vegetation experiments described here. These models can be utilized to develop planting and 

removal plans to increase treatment success. Project L will provide base maps for planning and 

navigating purposes, as well as spatial data sets that will contribute to project evaluation.

The project area is from Glen Canyon dam to Pearce Ferry. Project partners are the National 

Park Service (GLCA, GRCA), associated tribes, GCMRC, Bureau of Reclamation, youth corps 

and volunteers. Project costs include project coordination, planning and administration costs 

(including an annual coordination and planning meeting for NPS, GCMRC and tribes; GCMRC 

vegetation data processing and transfer to NPS), personnel costs (NPS seasonal and term 

biological technicians for field work, data entry and reporting; NPS term archeologist for on-site 

field work, GIS and data staff support; NPS tribal liaison to work with tribes; NPS compliance 

staff; funding tribal staff for tribal engagement as partners in planning and executing the 

experiment and for tribal on-site field work), supplies (tools and herbicides, plant propagation, 

fuel for boat travel), and contracts, agreements and river support (cooperative agreement for 

greenhouse operation costs, river support for field work, youth crew agreement to support field 

work). NPS will explore additional sources of funding external to the program to assist in 

funding tribal partners. 

Budget: 

GRCA FY21 = $170,000 GRCA FY22 = $170,000 GRCA FY23 = $170,000

GLCA FY21 = $43,000 GLCA FY22 = $84,000 GLCA FY23 = $67,000

Request Unfunded: FY23 = $25,000
Provisional – do not cite. 42

Attachment C: Planning Notes for 2021-23 TWP

Based on planning meetings with GCMRC on February 14, 2020 and with Tribes and GMCRC 

on March 5, 2020, and discussions with the Budget Ad-Hoc-Group (BAHG) between FebruaryApril 2020, the NPS has developed these planning notes:

0. GRCA - For 2021 – 2023, invasive non-native plant treatments will continue at 20 or 

more sites per year, vegetation treatments to increase campable areas will occur at 20 or 

more sites per year, cultural resource protection will occur at 6 or more sites per year, and 

native plant restoration actions at 1 to 3 sites per year. On 03/05/2020, we will be meeting 

with Tribes to discuss treatment site selection and culturally significant plant species for 

native plant restoration efforts. We will continue to engage tribal youth in project 

implementation. 

1. GCMRC and GRCA joint vegetation removal sites – We are currently partway into 

the vegetation removal experiments, but since there was no HFE in 2019 and 2020, we 

will continue the experimentation and monitoring to evaluate combined effects of 

vegetation removal and HFEs through the 2021-23 TWP.

2. GLCA continued vegetation project for 2021-2023, the 2nd site (-12L) will have 

ongoing replanting of native species and maintenance work, with initial planning and 

preparations to initiate restoration at a 3rd site at -14.5R RM (Ropes Trail), which is a 

popular camping site; this site will be cleared in 2022 with initiation of native plantings, 

which will continue through 2023; final report will be prepared for 2nd Triennial Project 

and lessons learned developed in detail. There will be an increased effort to plant species 

that provide shade and are culturally significant, especially Goodding’s willow and 

Fremont cottonwood. The Ropes Trail site will also include a joint project with BOR on 

terrace stabilization, which is a concern in the Glen Canyon reach. GLCA has seen 

greatly increased recreation impacts on the river corridor and will be initiating planning 

for additional camping sites including a potential overnight camp site at Lunch Beach. 

Currently this is a day-use only beach.

3. Expanding the greenhouse experiments to study the impacts of flow (hydrological 

conditions and burial by sediment) as well as non-flow (cutting) actions on arrowweed 

and seep willow would provide valuable information on arrowweed growth and 

performance under these conditions (as in the LTEMP treatments).
Attachment C: GRCA and GLCA Experimental Vegetation Treatment Progress Logs (FY2019 – FY2020)

River 

Mile

River 

Side

Site NonNative 

Plant 

Species 

Control 

Method

Vegetation 

Species

Management 

Method to 

Assist with 

Cultural Site 

Protection

Vegetation 

Species

Removal 

Method for 

Vegetation 

Encroaching 

on 

Campsites

Native Plant 

Species

Developed for 

Replanting

-7 L Lunch Beach TARA Chemical SAGO, VAST3, 

STPI

11.3 R Soap Creek TARA, 

PLSE

Manual

24.5 L RM 24.5L LELA2 Chemical TARA, 

PLSE

Manual TARA, 

PLSE

Manual

24.5 L RM 24.5L MENSPI Manual

38.7 L Marthas Camp LELA2 Chemical

70 R Basalt TARA, 

PLSE

Manual TARA, 

PLSE

Manual

71.6 L Cardenas TARA Chemical PLSE Manual

71.6 L Cardenas LELA2 Chemical

71.6 L Cardenas LELA2 Chemical

72.7 L Unkar Left PLSE Manual

76.1 L Nevills PLSE Manual

77.1 L Hance PLSE Manual

93.8 L Granite ALMA12 Surveyed, 

not treated

PLSE Manual

99.6 L Above Tuna 

Rapid

SARA3 Manual

108.3 L Ross Wheeler PLSE Manual

122.8 R RM 122.0R TARA, 

PLSE

Manual PLSE Manual
Provisional – do not cite. 44

172 L Mohawk ALMA12 Chemical TARA, 

PLSE

Manual TARA, 

PLSE

Manual

202.4 R RM 202.0R PLSE Manual

223.5 R RM 223.0R TARA, 

PLSE

Manual

226.4 R Truck Seat ALMA12 Chemical Various 

natives 

pruned

Manual

243 R RM 243.0R –

RM 243.2R

PLSE Manual

243.2 R RM 243.5R PLSE Manual

248.7 R Surprise Canyon SAEX Manual

274.3 L Grand Canyon 

Youth

Various 

natives 

pruned

Manual
River 

Mile

River 

Side

Site FY20 

NonNative 

Plant 

Species

Control 

Method

FY20 

Vegetation 

Species

Management 

Method to 

Assist with 

Cultural Site 

Protection

Vegetation 

Species

Removal 

Method for 

Vegetation 

Encroaching 

on 

Campsites

FY20 Native 

Plant Species

for Replanting

FY20 Replanting 

of Native Species

at Priority Sites

-12 L The 

Slough

TARA Chemical Restoration Site

-7 L Lunch 

Beach

TARA Chemical SAGO, VAST3, 

STPI

SAEX, VAST3, 

AGUTK, CUPA

2 R RM 2.0R ELAN Chemical

2.8 R Cathedral 

Wash

ELAN Chemical

5.9 R RM 6.0R ELAN Chemical

6.1 R RM 6.0R ELAN Chemical

8.1 R Badger ELAN Chemical

8.1 L Jackass 

Canyon

ELAN Chemical

8.1 L Jackass 

Canyon

ACRE3 Chemical

8.3 R RM 8.3R ELAN Chemical

8.4 L RM 8.4L ELAN Surveyed, 

no 

treatment

16.6 R Across 

from Hot 

Na

ELAN Chemical

18.4 R RM 18.4R ELAN Chemical

19.1 L RM 19.1L ELAN Chemical

19.9 R RM 19.9R ELAN Chemical

20.5 R RM 20.0R ELAN Chemical

21.4 R RM 21.4R ELAN Chemical

23.2 L RM 23.2L ELAN Chemical
Provisional – do not cite. 46

24.5 L RM 24.5L TARA Chemical TARA Chemical

24.6 R RM 24.6R ELAN Chemical

26 R Below 

Cave 

Springs 

Rapid

SARA3 Manual 

37.9 L Tatahatso SATR12 Manual

38.7 L Marthas 

Camp

LELA2 Surveyed, 

no 

treatment

45.1 L Lower End 

of Willie 

Necktie

COSE4 Surveyed, 

no 

treatment

56.2 R Kwagunt 

Marsh

SARA3 Manual

57.6 L RM 57.6L COSE4 Surveyed, 

no 

treatment

61.6 R Above 

LCR Camp

ALMA12 Chemical

61.8 L Confluence 

Island

SARA3 Manual

62.7 R Crash 

Canyon

ALMA12 Chemical

66.1 L Palisades ALMA12 Surveyed, 

no 

treatment

66.8 L Above 

Espejo

ALMA12 Surveyed, 

no 

treatment
Provisional – do not cite. 47

70 R Basalt 

(Plot A)

PLSE Chemical, 

Manual

70 R Basalt 

(Plot B) 

PLSE Manual

70 R Basalt TARA Chemical

71.6 L Cardenas LELA2 Spray SAGO Potential 

restoration site

71.6 L Cardenas TARA Spray

71.6 L Cardenas ALMA12 Chemical

71.6 L Cardenas ALMA12 Spray

72.7 L Unkar Left ALMA12 Chemical

76.1 L Nevills 

(Treatment 

Plots A & 

B) 

ALMA12 Chemical PLSE Manual

76.5 L Papago ALMA12 Chemical

77.1 L Hance PLSE Manual

81.7 L Grapevine ALMA12 Chemical

93.8 L Granite SAGO, POFR2 Potential 

restoration site

108.3 L Ross 

Wheeler

PLSE Manual

122.8 R RM 

122.0R

ALMA12 Chemical PLSE Chemical

132 R Stone 

Creek 1

ALMA12 Surveyed, 

no 

treatment

143.8 R Kanab ALMA12 Surveyed, 

no 

treatment

172 L Mohawk ALMA12 Chemical PLSE Chemical

172 L Mohawk PLSE Manual
Provisional – do not cite. 48

202.4 R RM 

202.0R

PLSE Manual

223.5 R RM 

223.0R

ALMA12 Chemical TARA Chemical

226.4 R Truck Seat ALMA12 Chemical

243 R RM 

243.0R – 

RM 

243.2R

TRTE Manual

243.2 R RM 

243.5R

ALMA12 Chemical Potential 

restoration site

243.2 R RM 

243.5R

TARA Chemical

248.7 R Surprise 

Canyon

SATR12 Manual SAGO, FRVE2 Potential 

restoration site

269.9 R Travertine 

Grotto

SAGO

274.3 L Grand 

Canyon 

Youth

TRTE Manual SAGO Potential 

restoration site

274.3 L Grand 

Canyon 

Youth

TRTE Manual

274.3 L Grand 

Canyon 

Youth

TARA Chemical

275.2 L Columbine 

Falls

SAGO
Attachment D: GRCA and GLCA Experimental Vegetation Treatments - Proposed Sites and Actions

(FY2021)

River 

Mile

River 

Side

Site FY21 NonNative 

Plant 

Species

Control 

Method

FY21 

Vegetation 

Species

Management 

Method to 

Assist with 

Cultural Site 

Protection

FY21 

Vegetation 

Species

Removal 

Method of 

Vegetation 

Encroaching 

on 

Campsites

FY20 

Develop 

Native 

Plant 

Species for 

Replanting 

FY2020 

Replant Native 

Species at 

Priority Sites

-12 L The Slough TARA Chemical Restoration Site

-7 L Lunch Beach TARA Chemical Restoration Site

0.2 R Below Lees Ferry SARA3 Manual

1.1 R Paria Beach SARA3, 

TARA

Manual, 

Chemical

SAGO, 

POFR2, 

SAEX

Restoration Site

2 R RM 2.0R ELAN Manual

2.8 R Cathedral Wash ELAN Chemical

5.9 R RM 6.0R ELAN Chemical TARA, 

PLSE

Manual, 

Chemical

6.1 R RM 6.0R SARA3 Manual

8.1 R Badger ELAN Chemical TARA, 

PLSE

Manual, 

Chemical

8.1 L Jackass Canyon ACRE3 Chemical TARA, 

PLSE

Manual, 

Chemical

8.3 R RM 8.3R ELAN Manual

8.4 L RM 8.4L ELAN Manual

10.9 L RM 10.9L SARA3 Manual

11.3 R Soap Creek TARA, 

PLSE

Chemical TARA, 

PLSE

Chemical

16.6 R Across from Hot Na ELAN Chemical

18.4 R RM 18.4R ELAN Chemical

19.1 L RM 19.1L ELAN Chemical
Provisional – do not cite. 50

19.9 R RM 19.9R ELAN Chemical

20.5 R RM 20.0R

21.4 R RM 21.4R ELAN Manual

23.2 L RM 23.2L ELAN Manual

24.5 L RM 24.5L LELA2 Chemical TARA, 

PLSE

Chemical TARA, 

PLSE

Manual, 

Chemical

26 R Below Cave Springs 

Rapid

SARA3 Manual

37.9 L Tatahatso SARA3 Manual TARA, 

PLSE

Manual, 

Chemical

45.1 L Lower End of Willie 

Necktie

COSE4 Manual

46.9 R Above Saddle SARA3 Manual

48.5 L Below Saddle SARA3 Manual

48.8 R RM 48.8R SARA3 Manual

50.3 R RM 50.3R COSE4 Manual

50.7 L RM 50.7L SARA3 Manual

51.2 R RM 51.2R SARA3 Manual

52 R Above Little 

Nankoweap

SARA3 Manual

52.1 R Little Nankoweap SARA3 Manual TARA, 

PLSE

Manual, 

Chemical

53.1 R Upper Nankoweap SARA3 Manual PLSE Chemical

53.4 R Main Nankoweap SARA3 Manual PLSE Chemical

53.5 R Lower Nankoweap SARA3 Manual PLSE Chemical

55.9 R Kwagunt Marsh SARA3 Manual

56.2 R Kwagunt (RM 56.2 -

RM 56.6)

SARA3 Manual PLSE Chemical

57.6 L RM 57.6L SARA3 Manual

61.6 R Above LCR Camp ALMA12 Chemical

61.8 L Confluence Island SARA3 Manual
Provisional – do not cite. 51

61.8 L LCR Day Use Area SARA3 Manual

62.7 R Crash Canyon ALMA12 Chemical

66.1 L Palisades SARA3 Manual PLSE Chemical

66.6 L Below Palisades SARA3 Manual

66.8 L Above Espejo ALMA12 Chemical

69 L Tanner Rapid Left

69 R Tanner Rapids Right SARA3 Manual

69.3 L Below Tanner Rapid TRTE Manual

70 R Basalt ALMA12 Chemical TARA, 

PLSE

Chemical TARA, 

PLSE

Chemical

70.8 R Above Cardenas SARA3 Manual

71.4 R No Name 71.0 

(Cardenas Marsh)

SARA3 Manual

71.6 R Across from 

Cardenas

SARA3 Manual

71.6 L Cardenas SAGO Potential 

restoration site

72.4 R Upper Unkar ALMA12 Chemical TARA, 

PLSE

Chemical

72.7 L Unkar Left ALMA12 Chemical PLSE Chemical

76.1 L Nevills ALMA12 Chemical PLSE Chemical

77.1 L Hance PLSE Chemical

81.7 L Grapevine ALMA12 Chemical

93.8 L Granite SAGO, 

POFR2

Potential 

restoration site

98.7 R Crystal ALMA12 Chemical

99.6 L Above Tuna Rapid SARA3 Manual

99.6 L Above Tuna Rapid LELA2 Chemical

99.7 R Tuna Creek SARA3 Manual

108.1 R Hotauta PLSE Chemical
Provisional – do not cite. 52

108.3 L Ross Wheeler PLSE Chemical

119.1 L Across from Big 

Dune

SARA3 Manual

122.8 R RM 122.0R ALMA12 Chemical PLSE Chemical PLSE Chemical

132 R Stone Creek 1 ALMA12 Chemical

136.9 R Deer Creek Falls SARA3 Manual

136.9 R Deer Creek Falls ALMA12 Chemical

137.8 L Backeddy LELA2 Chemical PLSE Chemical

137.9 L Backeddy SARA3 Manual

141.1 L Below Keyhole SARA3 Manual

143.8 L + R Kanab (RM 143.8 -

RM 144.8)

ALMA12 Chemical

145.9 L Above Olo SARA3 Manual

172 L Mohawk ALMA12 Chemical TARA, 

PLSE

Chemical TARA, 

PLSE

Chemical Potential 

restoration site

176.5 R Below Redslide SARA3 Manual

183 R Lower Chevron PLSE Chemical

188.8 L Below Lower 

Whitmore

SARA3 Manual

193.3 L RM 193.3L SARA3 Manual

194.6 L Hualapai Acres SARA3 Manual PLSE Chemical Potential 

restoration site

197 R Froggy Fault ALMA12 Chemical

197 R Across Froggy Fault SARA3 Manual

202.4 R RM 202.0R PLSE Chemical

206.4 L Above Indian 

Canyon

SARA3 Manual

206.5 R Above Indian 

Canyon Right

ALMA12 Chemical

206.5 R Above Indian 

Canyon Right

SARA3 Manual
Provisional – do not cite. 53

209 L Granite Park Potential 

restoration site

209.7 L Below Granite Park SARA3 Manual

223.5 R RM 223.0R ALMA12 Chemical TARA, 

PLSE

Chemical

225.2 L Above Diamond SARA3 Manual

226.4 R Truck Seat ALMA12 Chemical

226.4 R Truck Seat SARA3 Manual

239.6 L RM 239.6L SARA3 Manual

242.6 R RM 242.0R PLSE Chemical

243 R RM 243.0R – RM 

243.2R

PLSE Chemical

243.2 R RM 243.5R ALMA12 Chemical See above Potential 

restoration site

248.7 R Surprise Canyon SATR12 Manual PLSE Chemical SAGO, 

FRVE2

Potential 

restoration site

269.9 R Travertine Grotto PLSE Chemical SAGO

274.3 L Grand Canyon Youth TRTE Manual TARA, 

PLSE

Chemical SAGO Potential 

restoration site

275.2 L Columbine Falls SAGO