Potential Water Year 2024 

Experiments 

AMWG February 29, 2024 

1 
Planning and Implementation 

• Planning / Implementation team coordination 

• Strives for consensus recommendation to DOI 

• Secretary of the Interior makes decision 

2 
HFE Accounting &

Implementation Windows 

3 

LTEMP Flow Experiments w/

Spring WY 2024 Potential 

Implementation GCD Experimental Flow Duration Window 

Spring HFE∆ up to 96 hours March – April 

Proactive Spring HFE∆◊ 24 hours** April – June 

Trout Management Flows 

Fall HFE up to 96 hours October - November 

* First test not to exceed 192 hours ∆ no Spring HFE in same WY as extended duration Fall HFE 

** First test 24 hours ◊ no proactive Spring HFE in same WY as sediment-driven Spring HFE

*** After first test, up to 250 hours

5 

Macroinvertebrate Flows target 2-3 replicates May – August 

up to 3 cycles/month for 4 months May – August 

Extended Duration Fall HFE 97- 192* or 97-250 hours*** October - November 
HFE Protocol – LTEMP ROD 

1. Planning and Budgeting 

 Annual resource status assessment 

 Annual Agency Reporting 

 GCDAMP Budget and Work Plan Process 

2. Modeling 

3. Decision and Implementation Component 

 Review modeling <- we are here 

 Review status of resources 

 Consultation with agencies and tribes 

 TWG / AMWG input - webinar 

 GCD Leadership Team recommendation 

 DOI Decision – Secretary’s Designee 

6 
HFE Accounting &

Implementation Windows 

7 
As of Feb. 28, 2024 

Paria River at Lees Ferry 

Colorado River above 

Little Colorado River 

near Desert View, AZ 

8 
 

 

Experimental Flow Timelines 

o PA notification 

o Monitor conditions 

o Holds on calendars, cancel if no updates in sediment conditions. 

o Discuss alternative experimental flows in Early March 

o Virtual AMWG/TWG webinar: Mid/Late March – If Needed 

o Final Technical Team call and recommendation 

o Leadership team recommendation 

o DOI decision: ~ Late March/Early April 

o Notification of decision: ~ Late March/Early April 

o Potential Implementation: ~ April 15-22, 2024 

9 
LTEMP Flow Experiments 

w/ WY 2024 Potential 

Fall HFE up to 96 hours October - November 

Extended Duration Fall HFE 97- 192* or 97-250 hours*** October - November

* First test not to exceed 192 hours ∆ no Spring HFE in same WY as extended duration Fall HFE 

** First test 24 hours ◊ no proactive Spring HFE in same WY as sediment-driven Spring HFE

*** After first test, up to 250 hours

10 

GCD Experimental Flow Duration Implementation 

Window 

March – April 

April – June  

up to 3 cycles/month for 4 months May – August 

May – August 

Spring HFE∆

Proactive Spring HFE∆◊ 24 hours**  

Trout Management Flows 

Macroinvertebrate Flows target 2-3 replicates 

up to 96 hours 
Questions? 

Jeremy Hammen 

jhammen@usbr.gov 

Brian Hines 

bhines@usbr.gov 

Bill Stewart 

wstewart@usbr.gov 


TABLE 4 (Cont.) 

Experimental Treatment 

Trigger3 and Primary 

Objective 

Aquatic Reso111·ce-Related Experiments

e 

Trout management flows Trigger: Predicted high 

trout recruitment in the 

Glen Canyon reach 

Objective: Test efficacy 

of flow regime on trout 

numbers and survival of 

humpback chub 

Tier l: Expanded Trigger: umber of adult 

translocation of humpback or subadult humpback 

chub in the Little dmb in the Little 

Colorado River 

Tier l: Implement headstart program for larval 

humpback dmb 

Colorado River reach 

below Tier 1 triggers 

Objective: Increase 

number of adult and 

subadult humpback dmb 

Trigger: umber of adult 

or subadult humpback 

dmb in the Little 

Colorado River reach 

below Tier 1 triggers 

Objective: h1crease 

number of adult and 

subadult humpback chub 

Replicates 

Implement as 

needed when 

triggered after 

consultation ,;vith 

Tribes; test may be 

conducted early in 

the 20-year period 

even if not 

triggered by high 

trout recruitment

f 

In1plement in each 

year triggered 

unless determined 

ineffective 

In1plement in each 

year triggered 

unless determined 

ineffective 

Duration 

Annual Implementation 

Considerations

b 

Implemented in as Potential shot1-tenn 

many as 4 months unacceptable impacts on 

(May-Aug.) resources listed in 

Section 1.3 

As needed 

As needed 

Potential short-tenn 

unacceptable in1pacts on 

resources listed in 

Section 1.3 

Potential shot1-tenn 

unacceptable in1pacts on 

resources listed in 

Section 1.3 

Long-Tern1 Off-Ramp 

Conditiousc Action if Successful 

TMFs have little or no 

effect on trout 

recmitment after at least 

three tests; or long-tem1 

unacceptable adverse 

in1pacts on the resources 

listed in Section 1.3 are 

observed 

Expanded translocation 

has little or no effect on 

increasing the number of 

adult or subadult 

humpback chub; or 

long-tenn unacceptable 

adverse impacts on the 

resources listed in 

Section 1.3 are observed 

Head-start program has 

little or no effect on 

increasing the number of 

adult or subadult 

humpback chub; or 

long-tenn unacceptable 

adverse impacts on the 

resources listed in 

Section 1.3 are observed 

Implement as 

adaptive treatment 

triggered by 

predicted high trout 

recruitment in Glen 

Canyon, taking into 

consideration Tribal 

concems 

Implement as 

adaptive treatment 

when triggered and 

existing resource 

conditions allow 

Implement as 

adaptive treatment 

when triggered and 

existing resource 

conditions allow 
C 

TABLE 4 (Cont.) 

Trigge1

.a and Primatyi Arurua1 Implemem.ati.on 

ExpeJ.U11ental Tre.atmem Objective 

Aquatic Resource-RR.lated E,periments (Co.11.t. .) 

Macromvertebrate Trigger: one 

prnduction. ilov;rs Objectiire: Improve food 

bare productivity and 

almndanoe or di1rersdy of 

mayllies, stoneilie , and 

caddifllies 

Riparim1 egetati'.011 E,peri'meJIH 

on-flow vegetation Trigger: one 

treatmeuts Objective: Improve 

vegetation conditions at 

key sites 

Replicates Thuation Consi.deratciollil!b 

Target twoto three Up to 4 months Potential short-term 

replicates (l'lifay-Aug.)g ll1l!acceptable impacts on 

resouroes list.ed w 

Section I J; coordinate 

p�anning i.vith other 

experiments to avoid 

confounding condif:io111 or 

results 

ot applic-.abl.e 20ye.ar if Potential short-term 

suc-eessfol pilot ll1l!acceptable impacts. on 

phase resources listed .w 

Section 1.3 

Long-Tenn Off-Ramp 

Conditioosc 

Ste.adj.• weekend flows 

have littie or no benefit 

on food base trout 

fishe,iy, or native fish; 

increase ill wamw.rater 

nonnative speci.es or 

trout at the Little 

Cofonulo River, or longtemi unacceptable 

adverne impacts 011 the 

resom1:es list.e,d .in 

Section ] .3 are observed 

Cont,l'ol. and rep!.anf:in:g 

tecbni.ques. are not 

effective or pradical; or 

fong-temi u.na�eptabl.e 

adveme impacts ou the 

resonrces listed.in 

Section ] .3 are observed 

Action .ifSu.coesfflll 

Imp.foment as 

adaptive treatment in 

target months when 

conditi.O'.llS allow 

Imp.foment as 

adaptive treat,me.nt if 

W

- VllSl. 

\f,e speciei - s c-.an 

be redured and 

native speci.es. 

increased 

a lngger.; Vi'll] be modified as needed dw:wg the 20-ye.al' LTEMP period in an adaptive mannef' through proceJ;SieS indudmg ESA c.o:nruttation and basied ou. the best available 

sci.ence utilizing the expe1'ilnental framewotk for eacb al

ternative,i

b Annual deteunii:iation by the DOI. Ally impfom-entation will consider resonroe condition assessmeuts and resolu·ce conc.ern.s lising the annual processes described in 

Sections t3 and t4. 

Sus-pension ofexpetimem .if the DOI detenni.nes effects cannot be mitigated. 

d De

tails ofimplementation of diment expet'iments ai,e p.resented in Section 2. 1..i

e De

tail ofimplem.entati.on of aqmtic rearou:ree experimeo.f:s. are preseuted in Secicion 2.2.i

f The decision to condoct TMFs in a given year w• 1 consider the resource c.ondi

ti.ons, as specified in Section 1.3 and will also in\rolive cou.si.deratioos regarding the efficacyi

ofthe t

e

st based on those resorn:ce c.onditi.O'.llS. 

g The duration and other characteristics of eKperimental macrninve.rtehrate production flow could be adjusted based on ilie results of.initial experiments. 

,