Expanded Non-Native Aquatic

Species Management Plan

Environmental Assessment

U.S. Department of the Interior

National Park Service

Grand Canyon National Park

Glen Canyon National Recreation Area

Intermountain Region

Expanded Non-Native 

Aquatic Species 

Management Plan below 

Glen Canyon Dam

Presentation to TWG

April 2018
Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Background

• Threats posed by aquatic non-natives were identified in: 

– Comprehensive Fisheries Management Plan (2013 CFMP)

– Long-Term Experimental and Management Plan (2016 LTEMP)

• Increases in potentially harmful non-native species (such as Green 

Sunfish and Brown Trout) have been documented since 2013.

– Rapid Response options of existing compliance

– Short term CEs

• Other species such as quagga mussels, etc. are also increasing

– Other invasive fish may appear and increase over time

– Other invasive organisms such as invertebrates and plants may also increase

• Non-native aquatic species control is needed to provide for longterm management of the native aquatic system

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Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Purpose of and Need for Action

Purpose

• Provide additional tools beyond what is available under the CFMP and the 

LTEMP

• Prevent, control, minimize, or eradicate potentially harmful non-native 

aquatic species

• Reduce the risk associated with their presence or expansion in the action 

area 

Identify adaptive approaches that will help manage these threats as they 

appear over time

Need

• Recent increases of green sunfish and brown trout

• Potential expansion or invasion of other harmful non-native aquatic 

species

• Non-native aquatic species threaten downstream native aquatic species 

and have become an increasing threat due to changing conditions since the 

completion of the 2013 CFMP and the 2016 LTEMP

• Species at risk include:

– Listed species

– Lees Ferry recreational rainbow trout fishery

Existing measures may be inadequate to address potentially harmful nonnatives

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Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Cooperating Agencies

• Arizona Game and Fish Department

• Bureau of Reclamation

• Colorado River Board of California

• Colorado River Commission of Nevada

• Pueblo of Zuni

• Southern Nevada Water Authority

• Upper Colorado River Commission

• U.S. Fish and Wildlife Service

• Utah Associated Municipal Power Systems

• Western Area Power Administration

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Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

What Are Potentially Harmful Non-Native Aquatic Species?

• Fish, amphibians, aquatic plants, or aquatic invertebrate species that are not native to the action 

area that may pose a threat to native species (including federally or state-listed species) or may 

pose a threat to the Lees Ferry recreational rainbow trout fishery 

What non-natives are not considered potentially harmful for this project?

• Common carp would not be targeted, but may be removed incidentally as part of other removal or 

monitoring efforts. We are developing a threat level rating and other species may call in this low 

level as well.

Trout-specific approaches 

• Rainbow trout management would be consistent with that described in the CFMP and LTEMP

• New actions would be designed to minimize negative effects to the recreational fishery and 

continue to be consistent with the LTEMP goal to maintain “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.”

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Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Ranking of Potentially Harmful Non-Native Aquatic Species 

DRAFT

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Species Category GLCA GRCA Level of Threat

Smallmouth Bass (Micropterus dolomieu) Fish Present Present 1- Very High

Walleye (Sander vitreous) Fish Present Present 1-Very High

Brown Trout (Salmo trutta) Fish Present Present 2-High

Northern Pike (Esox lucius) Fish Present Potential 2-High

Striped Bass (Morone saxatilis) Fish Present Present 2-High

Gizzard Shad (Dorosoma cepedianum) Fish Present Present 6-Low

American Bullfrog (Lithobates catesbeianus) Amphbians Present Potential 4-Medium

New Zealand Mudsnail (Potamopyrgus

antipodarum) Invertebrates Present Present 4-Medium

Rusty Crayfish (Orconectus rusticus) Invertebrates Potential Potential 4-Medium

Eurasian Water-milfoil (Myriophyllum spicatum) Plants Potential Potential 6-Low

Hydrilla (Hydrilla verticillata) Plants Potential Potential 6-Low

Didymo (Rocksnot) (Didymosphenia geminata) Algae Present Potential 4-Medium
Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Elements Common to All Action Alternatives

• Identify when and where different control actions could be taken

– Decision tree or matrix including condition trigger levels

– Preferred sequence of control actions using a tiered approach

– Control actions from multiple tiers could be applied at the same time

• Identify resources of concern that would be considered prior to determining action

• Monitoring and adaptive responses that would include:

– Off-ramps that would be used to determine when control actions stop because of unacceptable adverse 

effects on resources

– Mitigation actions that would be used to address adverse impacts on other resources

• All elements of the no-action alternative

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Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Adaptive Tiered Approach to Non-Native Aquatic Species 

Control

Control actions would be made in a stepwise fashion according to tiers

• Tier 1 Actions

– Applied as a first step toward control

– Have little if any impact on non-target species or resources of concern

– Focuses on non-lethal approaches

– Relatively low cost

• Tier 2 Actions

– Applied only after Tier 1 actions are determined to be ineffective on their own (triggered)

– Uses some non-lethal removal and some lethal methods in limited areas over short periods of time

– Includes some habitat alteration in limited habitats or areas

• Tier 3 Actions

– Applied only after Tier 1 and 2 actions are determined to be ineffective on their own or together (triggered)

– Uses beneficial use with lethal removal when possible, applied over broader areas and for long-term control

• Tier 4 Actions

– Applied only after Tier 1, 2 and 3 actions are determined to be ineffective on their own or together (triggered)

– Includes major modification of limited areas to remove suitable habitat

– Includes use of registered piscicides for long-term control

• Specific tiers for certain actions vary among alternatives

• Control actions and strategies would be modified as needed based on the effectiveness of actions taken

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Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Conceptual Application of Tiered Actions

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Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Refined Alternatives – Brown Trout in Glen Canyon NRA

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• 4 tier levels

• Two action alternatives with some differences

• Cornerstone is incentivized harvest for brown trout in Lees Ferry (tier 

1 action) under both alternatives 

• Triggers are DRAFT – we have started talking through with 

cooperators and GCMRC – we intend for them to be tied to risk to 

humpback chub and other downstream natives

• Triggers may be re-evaluated annually (or evey few years as needed) 

and discussed with the TWG. We will want to be able to adapt to new 

information.

• We are also identifying specific habitats where the actions apply, offramps, and mitigations, but those are not yet ready to present those
Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Controlling Brown Trout in Marble Canyon

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• The CFMP EA allows for on-going mechanical removal of brown trout source populations 

in Grand Canyon NP. This Expanded EA will not change existing compliance, so that is 

why this action does not appear in the following slides describing action alternatives.

• However, for communication purposes, the conditions under which the NPS would 

consider electrofishing in Marble Canyon under existing compliance would be:

– If large concentrations/congregations/spawning of brown trout were found in Marble 

Canyon (for instance down by 30-mile) we would consider a removal project there.

– If the population in Lees Ferry was below a trigger level (probably below the 2015 

population estimate), and large numbers were found in Marble Canyon, then we may 

only conduct the electrofishing in Marble and not in Lees Ferry.

– If the Lees Ferry brown trout population does not decline or continues to increase, 

conducting control in Marble Canyon would not be expected to be a replacement for 

removal of adults in Lees Ferry given efficacy estimates from the 2011 BOR NNF EA and 

recent work from GCMRC (Brown Trout White Paper, and Bair et al. 2018)

• However, the first tier action (Tier 1) to remove adult brown trout would be through 

incentivized harvest in Lees Ferry . Electrofishing targeting brown trout in Lees Ferry 

would not be used until triggered (Tier 3 or 4).
Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Refined Alternatives – Brown Trout in Glen Canyon NRA

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Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Refined Alternatives – Brown Trout in Glen Canyon NRA

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• Tier 1 - Bounties/tournaments/prize fish/volunteer guided fishing and other 

incentivized harvest tools

• Trigger – presence of brown trout in Lees Ferry

• TBD – who administers and how (logistics, money levels), what agencies are 

willing to contribute to funding

• Tier 1 or 2 (alt dependent) - Introduction of YY males

• Trigger: Tier 1 actions not effective alone, and brown trout population is < X 

fish (number above which cannot get enough YY males to be effective). 

• Brood stock would not be available for 5-10 years.

• Experimental – it is old technology (producing YY males has been in fish 

farming since 1920’s, but has not been used for wild population management 

until recently). Currently we are not aware of any major side effect concerns –

only that introduced YY fish could have high mortality and/or could migrate at 

a high rate downstream. But effects would disappear a few years after 

cessation.

• Discussing with tribes and cooperating agencies
Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Refined Alternatives – Brown Trout in Glen Canyon NRA

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• Tier 2 or 3 - Mechanical disruption of early life stage habitats at specific spawning 

sites, including high-pressure water flushing and mechanical gravel displacement

• Trigger: Estimates for brown trout in Glen Canyon reach now exceed [level 1 

risk - e.g. 5,000] 8+ inches long 

• Experimental 

• Analyzing efficacy and logistics – locations/depth of spawning beds

• Design with GCMRC and cooperating agencies to minimize incidental take of 

rainbow trout and disruption of recreational fishing while achieving significant 

brown trout reduction

• Tier 3 - Selective electrofishing and trapping in spawning areas only

• Trigger: Estimates for brown trout in Glen Canyon reach now exceed [level 2 

risk - e.g. 10,000 8+ inches long 

• Design with GCMRC and cooperating agencies to minimize incidental take of 

rainbow trout and disruption of recreational fishing while achieving significant 

brown trout reduction
Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Refined Alternatives – Brown Trout in Glen Canyon NRA

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• Tier 4 - Conditional species-specific electrofishing/trapping for long-term control 

• Trigger: Initiate a multi-year electrofishing project if other tiers have proven 

ineffective and there is a population of brown trout in Lees Ferry and brown 

trout have increased in the LCR and tripped the mechanical removal trigger 

there, or specifically: 

• 1) When LTEMP triggers for mechanical removal at the LCR have been exceeded, 

• 2) Brown trout are a significant proportion of the predators in the LCR area, 

• 3) estimates for brown trout in Lees Ferry Reach are documented as being over X,000 8+ 

inches fish.

• Design with GCMRC and cooperating agencies to minimize incidental take of 

rainbow trout and disruption of recreational fishing while achieving significant 

brown trout reduction
Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Refined Alternatives – Brown Trout in Glen Canyon NRA

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Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Refined Alternatives – Glen Canyon Sloughs (RM-12)

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• Reclamation helped evaluate 7 options in this area (hydrology modeling and 

engineering advice) and NPS is evaluating two of those options: 

• Tier 1 – Barriers, Periodic Dewatering of Upper Slough and Non-Lethal Removal 

to the degree possible

• In the upper slough, following periods of water overtopping when non-natives 

could be appearing, NPS would pump out the upper slough within days of the 

drop and dewater for 1-2 weeks. The expectation is that this could remove a 

small number of adult non-native fish prior to reproduction. This would avoid 

having to treat or remove thousands of fish after reproduction and so would 

result in less taking of life. 

• In lower slough if non-native species are detected then we would consider 

using non-lethal electrofishing with relocation to Lake Powell as a tier 1 action 

if possible. This may depend on the numbers of fish, whether they are NEW to 

area, and the threat level of the species as to whether this would be 

appropriate and is also subject to state permits and testing. 

• We may also consider disruption of spawning beds in lower slough using high 

pressure wash to disrupt spawning (again may depend on threat rank of fish)
Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

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Ove rtoppi lillg Fl ow-.s - circa 20-23 k cfs 

After overtop, 0111 -natives could be left ilf1I Upper Slough 

Hig Vollume Pump with Filter w ould be used t o Dew at er Upper Sloug 

0111 -native Fi sh w ould be capt ured in filter and could pot entially be 

used tor beneficial use 

o t o Sica le - diagramtic olillly 
Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Refined Alternatives – Glen Canyon Sloughs (RM-12)

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• Tier 1 or 2 (alternative dependent) – Mechanical Removal

• In the upper slough, if Tier 1 actions prove ineffective or pools remain during 

dewatering of upper slough, or if non-lethal relocation was not possible, then 

lethal mechanical removal using electrofishing would be employed using 

beneficial use if possible.

• In lower slough if NEW and higher risk non-native species are detected then 

we would consider using lethal electrofishing as a rapid response to prevent 

reproduction or dispersal (this is already permitted under the CFMP, so stated 

here only for communication purposes not for new compliance). 

• Tier 2 or 3 (alternative dependent) – Chemical Treatment

• In the upper slough, if Tier 1 and Tier 2 actions prove ineffective then we 

would consider using experimental treatment to overwhelm the ecosystem 

cycling (such as ammonia, carbon dioxide, oxygen, etc.)

• In upper or lower slough if NEW and higher risk non-native species are 

detected and Tier 1 and 2 actions were not effective, then we would consider 

using chemical treatment as a rapid response to prevent reproduction or 

dispersal. 
Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Refined Alternatives – Glen Canyon Sloughs (RM-12)

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• Tier 3 or 4 – Dredging Option

• If dewatering using pumps proved ineffective, then a dredging option would 

be consider to cut a channel between the upper and lower sloughs to better 

drain the upper slough. A headgate would be installed to control the 

dewatering and it would be deployed similarly to the pump option, 

dewatering after overtopping for a period about 2 weeks. 

• Tier 4 in alternative #2 only – Chemical Removal 

• In upper or lower slough if higher risk non-native species are detected and Tier 

1-3 actions were not effective, then we would consider using chemical 

treatment on an going basis as a last resort to prevent reproduction or 

dispersal. 
Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

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Ove rtoppi riig Flow s. - circa 20-23 ds 

A.fte If ove rtop., . orii-natives. cou Id be I eft i rii Upp e If SI oughi 

Headg.a e w ould be operii ed o dew at er he Upper Sloug 

• o t o Sica le - diagra ti c o,nily 
Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Refined Alternatives – Glen Canyon

Species other than brown trout, areas other than RM-12 sloughs

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• The approach would be similar to that used at RM-12 with a few differences...

• Similarities:

• Tier 1 – Barriers, Periodic Dewatering of backwaters and Non-Lethal Removal 

to the degree possible

• Tier 1 or 2 (depending on alternative) – Lethal Mechanical Removal with 

beneficial use or Spawning Bed Disruption

• Tier 3 or 4 (depending on alternative) – Chemical treatment using 

experimental treatment to overwhelm cycling or chemical treatment for rapid 

response of a NEW higher risk species.

• Differences (alternative #3 only):

• YY males (tier 2) – would consider for Green Sunfish or other higher risk 

species (if brood stock available) if they were found to be reproducing in areas 

other than the upper slough and tier 1 actions were ineffective

• Sonic Concussive devices (tier 4) – would consider in backwaters as tool when 

teirs x and x have proven ineffective in order to prevent reproduction and 

downstream dispersal of higher risk non-natives.

• Chemical treatment of higher species for on-going basis is other tiers failed
Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Refined Alternatives – Grand Canyon Only (main and tribs)

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• Similar approach to Glen Canyon with a few differences...

• Similarities:

• Tier 1 – Barriers, Periodic Dewatering of backwaters

• Tier 1 or 2 (depending on alternative) – Lethal Mechanical Removal with 

beneficial use or Spawning Bed Disruption

• Tier 3 or 4 (depending on alternative) – experimental treatment to overwhelm 

cycling or chemical treatment for rapid response of a NEW higher risk species.

• Differences:

• No incentivized harvest and no non-lethal electrofishing (logistics preclude)

• Tier 1 (alternative #3 only) – small scale temperature alternation on tributaries 

to disadvantage coldwater species

• Tier 1 or 2 (alt dependent)- Chemical treatment in tributaries with a natural 

barrier to removal non-natives for renovation (such as prior to translocation)

• YY males (tier 1) – would consider for small scale brown trout test

• Sonic Concussive devices (alternative #3 only tier 4) – would consider in 

backwaters as tool when tiers 1 actions have proven ineffective in order to 

prevent reproduction and downstream dispersal of higher risk non-natives.
Expanded Non-Native Aquatic Species Management Plan

Environmental Assessment

Next Steps

• After the TWG, release materials to TWG members and provide 

opportunity to comment on draft alternatives, tiers and triggers as well 

as risk rating of species – April

• Release scoping report and comments - April

• Meet with AGFD regarding incentivized harvest and other concerns

• Consultation with tribes as needed

• Refine and finalize alternatives, tiers and triggers - May

• Conduct analysis – May/June

• Work with cooperating agencies on administrative draft of EA –

May/June

• Release EA for public comment –July

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