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The purpose of the proposed action is to provide a comprehensive framework for adaptively
managing Glen Canyon Dam over the next 20 years consistent with the GCPA and other
provisions of applicable Federal law. The proposed action will help determine specific dam
operations and actions that could be implemented to improve conditions and continue to meet the
GCPA's requirements and to minimize, consistent with law-adverse impacts on the
downstream natural, recreational, and cultural resources in the two park units, including
resources of importance to American Indian Tribes.
The need for the proposed action stems from the need to use scientific information developed
since the 1996 ROD to better inform DOI decisions on dam operations and other management
and experimental actions so that the Secretary of the Interior may continue to meet statutory
responsibilities for protecting downstream resources for future generations, conserving species
listed under the Endangered Species Act (ESA), avoiding or mitigating impacts on National
Register of Historic Places (NRHP)-eligible properties, and protecting the interests of American
Indian Tribes, while meeting obligations for water delivery and the generation of hydroelectric
power.
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Reclamation and NPS developed resource goals considering public input and Desired Future Conditions (DFCs) previously adopted by the Adaptive Management Work Group (AMWG). The following resource goals were identified:
- Archaeological and Cultural Resources. Maintain the integrity of potentially affected 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.
- Humpback Chub. Meet humpback chub recovery goals, including maintaining a self-sustaining population, spawning habitat, and aggregations in the Colorado River and its tributaries below the Glen Canyon Dam.
- Hydropower and Energy. Maintain or increase Glen Canyon Dam electric energy generation, load following capability, and ramp rate capability, and minimize emissions and costs to the greatest extent practicable, consistent with improvement and long-term sustainability of downstream resources.
- Other Native Fish Species. Maintain self-sustaining native fish species populations and their habitats in their natural ranges on the Colorado River and its tributaries.
- Recreational Experience. Maintain and improve the quality of recreational experiences for the users of the Colorado River Ecosystem. Recreation includes, but is not limited to, flatwater and whitewater boating, river corridor camping, and angling in Glen Canyon.
- Sediment. Increase and retain fine sediment volume, area, and distribution in the Glen, Marble, and Grand Canyon reaches above the elevation of the average base flow for ecological, cultural, and recreational purposes.
- Tribal Resources. Maintain the diverse values and resources of traditionally associated Tribes along the Colorado River corridor through Glen, Marble, and Grand Canyons.
- Rainbow Trout Fishery. Achieve a healthy high-quality recreational rainbow trout fishery in GCNRA and reduce or eliminate downstream trout migration consistent with NPS fish management and ESA compliance.
- Nonnative Invasive Species. Minimize or reduce the presence and expansion of aquatic nonnative invasive species.
- 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.
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Tier 1 Trigger – Early Intervention Through Conservation Actions:
- 1a. If the combined point estimate for adult HBC (adults defined ≥200 mm) in the Colorado River mainstem LCR aggregation; RM 57-65.9) and Little Colorado River (LCR) falls below 9,000 as estimated by the currently accepted HBC population model (e.g., ASMR, multi-state).
-OR-
- 1b. If recruitment of sub-adult HBC (150-199mm) does not equal or exceed estimated adult mortality such that:
- Sub-adult abundance falls below a three-year running average of 1,250 fish in the spring LCR population estimates, or
- Sub-adult abundance falls below a three-year running average of 810 fish in the mainstem Juvenile Chub Monitoring reach (JCM annual fall population estimate; RM 63.45-65.2).
Tier 1 Trigger Response:
- Tier 1 conservation actions listed below will be immediately implemented either in the LCR or in the adjacent mainstem. Conservation actions will focus on increasing growth, survival and distribution of HBC in the LCR & LCR mainstem aggregation area.
Tier 2 Trigger - Reduce threat using mechanical removal if conservation actions in Tier 1 are insufficient to arrest a population decline:
Mechanical removal of nonnative aquatic predator will ensue:
- If the point abundance estimate of adult HBC decline to <7,000, as estimated by the currently accepted HBC population model.
Mechanical removal will terminate if:
- Predator index (described below) is depleted to less than 60 RBT/km for at least two years in the JCM reach and immigration rate is low (the long term feasibility of using immigration rates as a metric still needs to be assessed),
-OR-
- Adult HBC population estimates exceed 7,500 and recruitment of sub-adult chub exceed adult mortality for at least two years.
If immigration rate of predators into JCM reach is high, mechanical removal may need to continue. These triggers are intended to be adaptive based on ongoing and future research (e.g., Lees Ferry recruitment and emigration dynamics, effects of trout suppression flows, effects of Paria River turbidity inputs on predator survival and immigration rates, interactions between humpback chub and rainbow trout, other predation studies).
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Ongoing actions:
Reclamation would continue to support the NPS, FWS, GCMRC, and GCDAMP in
funding and implementing translocations of humpback chub into tributaries of the
Colorado River in Marble and Grand Canyons, and in monitoring the results of these
translocations, consistent with agencies’ plans and guidance (e.g., NPS Comprehensive
Fisheries Management Plan [CFMP], FWS Humpback Chub Genetics Management Plan
and Translocation Framework, and GCMRC Triennial Work Plan). Translocations allow
for opportunities to expand the area occupied by humpback chub and improve the overall
status of the species. Specifically, the following would occur:
- Humpback chub would be translocated from the lower reaches of the Little Colorado River to areas above Chute Falls in an effort to increase growth rates and survivorship.
- Monitoring would be conducted annually, or as needed, depending on the data required, to determine survivability, population status, or genetic integrity of the Havasu Creek humpback chub population. Intermittent translocations of additional humpback chub in Havasu Creek would be conducted if the FWS and NPS determine it is necessary to maintain genetic integrity of the population.
Reclamation would continue to fund a spring and fall population estimate annually, or at
a different frequency as deemed appropriate in consultation with FWS, using a mark
recapture based model for the Little Colorado River or the most appropriate model
developed for the current collecting techniques and data. Monitoring the chub population
allows us to determine its status (whether it is stable, increasing, or decreasing).
Reclamation would continue to fund control or removal of nonnative fish in tributaries
prior to chub translocations depending on the existing fish community in each tributary.
Reclamation, NPS, and FWS would lead any investigation into the possibility of using a
chemical piscicide, or other tools, as appropriate. Tributaries and the appropriate control
methods would be identified by the FWS, NPS, Reclamation, and GCMRC, in
consultation with the Arizona Game and Fish Department (AGFD). Depending on the
removal methods identified, additional planning and compliance may be necessary.
Removal of nonnative fishes improves the status of chub and other native fishes by
reducing competition and predation. The regulation and control of nonnative fish is a
management action identified in the Humpback Chub Recovery Goals (USFWS 2002a)
and Razorback Sucker Recovery Goals (USFWS 2002b).
Reclamation would continue to fund the FWS in maintenance of a humpback chub refuge
population at a federal hatchery (Reclamation has assisted the FWS in creating a
humpback chub refuge at the Southwestern Native Aquatic Resources and Recovery
Center [SNARRC]) or other appropriate facility by providing funding to assist in annual
maintenance (including the collection of additional humpback chub from the Little
Colorado River for this purpose). In the unlikely event of a catastrophic loss of the
Grand Canyon population of humpback chub, the refuge would provide a permanent
source of sufficient numbers of genetically representative stock for repatriating the
species.
Reclamation would continue to assist the FWS, NPS and the GCDAMP to ensure that a
stable or upward trend of humpback chub mainstem aggregations can be achieved by:
- Continuing to conduct annual monitoring of the Little Colorado River humpback chub aggregation (e.g., juvenile chub monitoring parameters). Periodically, an open or multistate model should be run to estimate abundance of the entire Little Colorado River aggregation inclusive of mainstem fish.
- Supporting annual monitoring in the mainstem Colorado River to determine status and trends of humpback chub and continuing to investigate sampling and analytical methods to estimate abundance of chub in the mainstem.
- Conducting periodic surveys to identify additional aggregations and individual humpback chub.
- Evaluating existing aggregations and determining drivers of these aggregations, for example, recruitment, natal origins, spawning locations, and spawning habitat (e.g., consider new and innovative methods such as telemetry or the Judas-fish approach) (Kegerries et al. 2015).
- Exploring means of expanding humpback chub populations outside of the Little Colorado River Inflow aggregation. Evaluate the feasibility of mainstem augmentation of humpback chub that would include larval collection, rearing, and release into the mainstem at suitable areas outside of or within existing aggregations.
Reclamation would, through the GCDAMP, conduct disease and parasite monitoring in
humpback chub and other fishes in the mainstem Colorado. The GCMRC is currently
conducting parasite monitoring in the Little Colorado River. However, in order to better
understand how/if disease and parasites (primarily Asian tapeworm) are affecting chub
and how temperature differences may affect parasite occurrence, this work would be
expanded to include investigations of parasites in humpback chub (and surrogate fish if
necessary) in the mainstem. Ensuring adequate protection from diseases and parasites is
an identified management action needed in the Humpback Chub Recovery Goals
(USFWS 2002a) and Razorback Sucker Recovery Goals (USFWS 2002b).
New actions:
Reclamation would collaborate with the FWS, GCMRC, NPS, and the Havasupai Tribe
to conduct preliminary surveys and a feasibility study for translocation of humpback chub into Upper Havasu Creek (above Beaver Falls). The implementation of surveys and
translocations, following the feasibility study, would be dependent on interagency
discussions, planning and compliance, and resulting outcomes of tribal consultation. As
stated above, translocations of chub into currently unoccupied habitat aid in expanding
the area occupied by the species. In addition, using a tributary to the Colorado River,
such as Upper Havasu Creek, protects translocated fish from the effects of dam
operations in the mainstem, but still allow for chub in Havasu Creek to contribute to the
mainstem population.
Reclamation would, in cooperation with the FWS, NPS, GCMRC, and AGFD, explore
and evaluate other tributaries for potential translocations.
Razorback Sucker
Ongoing actions:
Reclamation would continue to assist the NPS, FWS, and the GCDAMP in funding larval and small-bodied fish monitoring in order to:
- Determine the extent of hybridization in flannelmouth and razorback sucker collected in the western Grand Canyon.
- Determine habitat use and distribution of different life stages of razorback sucker to assist in future management of flows that may help conserve the species. Sensitive habitats to flow fluctuations could be identified and prioritized for monitoring.
- Assess the effects of TMFs and other dam operations on razorback sucker.
Actions to benefit all native aquatic species
Ongoing actions:
Reclamation, in collaboration with the NPS and FWS, and in consultation with the
AZGFD, would investigate the possibility of renovating Bright Angel and Shinumo Creeks with a chemical piscicide, or other tools, as appropriate. Additional planning and
compliance, and tribal consultation under Section 106 of the NHPA, would be required.
This feasibility study is outlined in the NPS CFMP (2013; see “Feasibility Study for Use
of Chemical Fish Control Methods”). The action benefits humpback chub and other
native fish by removing nonnative fish that can predate upon and compete with
humpback chub. The regulation and control of nonnative fish is a management action
identified in the Humpback Chub Recovery Goals (USFWS 2002a) and Razorback
Sucker Recovery Goals (USFWS 2002b).
Reclamation would continue to fund efforts of the GCMRC and NPS to remove brown trout (and other nonnative species) from Bright Angel Creek and the Bright Angel Creek
Inflow reach of the Colorado River, and from other areas where new or expanded
spawning populations develop, consistent with the NPS CFMP. After 5 years of removal
efforts are completed (in 2017), an analysis of success would be conducted. Piscicides
may be considered for removal of nonnative species if determined to be appropriate and
following completion of the necessary planning and compliance actions. The regulation
and control of nonnative fish is a management action identified in the Humpback Chub
Recovery Goals (USFWS 2002a) and Razorback Sucker Recovery Goals (USFWS
2002b).
New actions:
Reclamation would explore the efficacy of a temperature control device at the dam to
respond to potential extremes in hydrological conditions due to climate conditions that
could result in nonnative fish establishment. Evaluations would be ongoing for all
current and evolving technological advances that could provide for warming and cooling
the river in both high- and low-flow discharge scenarios, and high and low reservoir
levels. These studies should include evaluating and pursuing new technologies, an
analysis of the feasibility, and a risk assessment and cost analysis for any potential
solutions. The regulation and control of nonnative fish is a management action identified
in the Humpback Chub Recovery Goals (USFWS 2002a) and Razorback Sucker
Recovery Goals (USFWS 2002b).
Reclamation would pursue means of preventing the passage of deleterious invasive nonnative fish through Glen Canyon Dam. Because Glen Canyon Dam release
temperatures are expected to be warmer under low reservoir elevations that may occur
through the LTEMP period, options to hinder expansion of warmwater nonnative fishes
into Glen and Grand Canyons would be evaluated. Potential options to minimize or
eliminate passage through the turbine or bypass intakes, or minimize survival of
nonnative fish that pass through the dam would be assessed (flows, provide cold water,
other). While feasible options may not currently exist, technology may be developed
during the LTEMP period that could help achieve this goal. The regulation and control
of nonnative fish is a management action identified in the Humpback Chub Recovery
Goals (USFWS 2002a) and Razorback Sucker Recovery Goals (USFWS 2002b).
Reclamation would, in consultation with the FWS and AGFD, fund the NPS and
GCMRC on the completion of planning and compliance to alter the backwater slough at River Mile (RM) 12 (commonly referred to as “Upper Slough”), making it unsuitable or
inaccessible to warmwater nonnative species that can compete with and predate upon
native fish, including humpback chub. Depending on the outcome of NPS planning and
compliance, Reclamation would implement the plan in coordination with the FWS,
AGFD, NPS and GCMRC. Additional coordination would be conducted to determine
and access any habitats that may support warmwater nonnatives. The regulation and
control of nonnative fish is a management action identified in the Humpback Chub
Recovery Goals (USFWS 2002a) and Razorback Sucker Recovery Goals (USFWS
2002b).
Reclamation would support the GCMRC and NPS in consultation with the FWS and
AGFD on the completion of planning and compliance of a plan for implementing rapid response control efforts for newly establishing or existing deleterious invasive nonnative species within and contiguous to the action area. Control efforts may include chemical,
mechanical, or physical methods. While feasible options may not currently exist, new
technology or innovative methods may be developed in the LTEMP period that could
help achieve this goal. Rapid response to new warmwater fish invasions may become a
more frequent need in the future with lower reservoir elevations and warmer dam
releases. The regulation and control of nonnative fish is a management action identified
in the Humpback Chub Recovery Goals (USFWS 2002a) and Razorback Sucker
Recovery Goals (USFWS 2002b).
Reclamation, will consider, in consultation with the GCDAMP, the experimental use of TMFs to inhibit brown trout spawning and recruitment in Glen Canyon, or other
mainstem locations. Inhibiting brown trout spawning and recruitment will benefit chub
by reducing the potential for brown trout to predate upon humpback chub. The
regulation and control of nonnative fish is a management action identified in the
Humpback Chub Recovery Goals (USFWS 2002a) and Razorback Sucker Recovery
Goals (USFWS 2002b).
Southwestern willow flycatcher and Yuma Ridgway’s rail
Reclamation would partially assist in funding NPS to conduct Yuma Ridgway’s rail surveys once every three years for the life of the LTEMP.
Reclamation would partially assist in funding NPS to conduct southwestern willow flycatcher surveys once every two years for the life of the LTEMP.
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LTEMP Experimental Actions
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Experimental treatments are grouped under three categories: (1) Sediment-Related Experimental
Treatments; (2) Aquatic Resource-Related Experimental Treatments; and, (3) Native and Nonnative
Plant Management and Experimental Actions. The specific types of experimental
treatments included under each category are described below.
Spring and fall HFEs would be implemented when triggered, based on the estimated sand mass balance
resulting from Paria River sediment inputs during the spring and fall accounting periods,
to rebuild sandbars. These HFEs include sediment-triggered HFEs in spring or fall,
proactive spring HFEs as triggered by high annual release volume (> 10 maf), and
extended duration (>96 hr) fall HFEs.
Nonnative fish control actions would be implemented if the Little Colorado River humpback chub
population declined and proactive conservation actions failed to reverse declining
populations.
Mechanical removal of nonnative species is a controversial issue in the Colorado
River through Glen and Grand Canyons. A spring 2015 meeting of Grand
Canyon biologists (NPS, FWS, AGFD, GCMRC) to assess current trout removal
triggers resulted in a concept of early conservation measure intervention to
maximize conservation benefit to humpback chub and minimize the likelihood of
mechanical predator removal. Under the preferred alternative, mechanical
removal of nonnative rainbow and brown trout (and other nonnative predators)
would be implemented through a triggered, tiered approach (see Appendix D in
BA) near the confluence of the Little Colorado River and the Colorado River if
conservation actions designed to reverse declines in the Little Colorado River
humpback chub aggregation were ineffective. Two different tiers of population
metrics would be used to trigger responses such as actions to increase growth and
survival of humpback chub (Conservation Actions, Tier 1), or mechanical
nonnative fish control (Tier 2), which would only be implemented when Tier 1
conservation actions (actions would focus on increasing growth, survival and
distribution of chub in the Little Colorado River and LCR mainstem aggregation
area) fail to slow or reverse the decline in the humpback chub population (see
Appendix D in BA, Young et al. 2015). In addition, if humpback chub decline
and the identified actions are not working, the FWS, in coordination with action
agencies and traditionally associated Tribes, will identify future appropriate
actions (among other caveats specified in Young et al. 2015).
Experimental Trout Management Flows (TMFs) could be used to control annual
rainbow trout production in the Glen Canyon reach for the purposes of managing
the rainbow trout fishery and for limiting emigration to Marble Canyon and the
Little Colorado River reach. TMFs would be tested early in the experimental
period, preferably in the first 5 years.
Low summer flows may be tested in the second 10 years of the LTEMP period,
for the purpose of achieving warmer river temperatures (> 14°C) to benefit
humpback chub and other native species. Under low summer flows, daily
fluctuations would be less than under base operations (e.g., approximately 2,000
cfs). Investigating the anticipated effects of and options for providing warmer
water temperatures in the mainstem Colorado River through Grand Canyon is an
identified management action in the Humpback Chub Recovery Goals (USFWS
2002a).
Low steady weekend flows (“bug flows”) would be conducted to test whether the
flows would increase insect abundance. On an experimental basis, for example,
flows would be held low and steady for two days per week (weekends) from May
through August to attempt to improve the productivity of the aquatic food base,
and increase the diversity and abundance of mayflies (Ephemeroptera), stoneflies
(Plecoptera), and caddisflies (Trichoptera), which are collectively referred to as
EPT.
Experimental riparian vegetation treatment activities would be implemented by NPS
under the proposed action and would modify the cover and distribution of riparian plant
communities along the Colorado River. All activities would be consistent with NPS
Management Policies (NPS 2006) and would occur only within the Colorado River
Ecosystem in areas that are influenced by dam operations. NPS would 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. These activities would include ongoing
monitoring and removal of selected nonnative plant species, systematic removal of
nonnative vegetation at targeted sites, and native replanting at targeted sites, which may
include complete removal of tamarisk (both live and dead) and re-vegetation with native
plants. Treatments would include the control of nonnative plant species and revegetation
with native plant species.
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Documents and Links
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2016 LTEMP EIS
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Papers and Presentations
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2024
2023
2022
2021
2020
2019
2018
2017
2016
2015
2014
2013
2012
2011
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The Planning and Implementation (P&I) Process
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1.4 COMMUNICATION AND CONSULTATION PROCESS FOR ALTERNATIVE D
To determine whether conditions are suitable for implementing or discontinuing experimental treatments or management actions, the DOI will schedule implementation/planning meetings or calls with the DOI bureaus (USGS, NPS, FWS, BIA, and Reclamation), WAPA, AZGFD, and one liaison from each Basin State and from the UCRC, as needed or requested by the participants. The implementation/planning group will strive to develop a consensus recommendation to bring forth to the DOI regarding resource issues as detailed at the beginning of this section, as well as including WAPA’s assessment of the status of the Basin Fund. The Secretary of the Interior will consider the consensus recommendations of the implementation/planning group, but retains sole discretion to decide how best to accomplish operations and experiments in any given year pursuant to the ROD and other binding obligations. (B-17 in the LTEMP ROD)
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